Version abc71001

28 files changed, 15791 insertions, 0 deletions

diff --git a/src/aig/ivy/attr.h b/src/aig/ivy/attr.h
new file mode 100644
index 00000000..16cf0b84
--- /dev/null
+++ b/src/aig/ivy/attr.h
@@ -0,0 +1,414 @@
+/**CFile****************************************************************
+
+  FileName    [attr.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network attributes.]
+
+  Synopsis    [External declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: attr.h,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#ifndef __ATTR_H__
+#define __ATTR_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+#include "extra.h"
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Attr_ManStruct_t_     Attr_Man_t;
+struct Attr_ManStruct_t_
+{
+    // attribute info
+    int                        nAttrSize;     // the size of each attribute in bytes
+    Extra_MmFixed_t *          pManMem;       // memory manager for attributes
+    int                        nAttrs;        // the number of attributes allocated
+    void **                    pAttrs;        // the array of attributes
+    int                        fUseInt;       // uses integer attributes
+    // attribute specific info
+    void *                     pManAttr;      // the manager for this attribute
+    void (*pFuncFreeMan) (void *);            // the procedure to call to free attribute-specific manager
+    void (*pFuncFreeObj) (void *, void *);    // the procedure to call to free attribute-specific data
+};
+
+// at any time, an attribute of the given ID can be
+// - not available (p->nAttrs < Id)
+// - available but not allocated (p->nAttrs >= Id && p->pAttrs[Id] == NULL)
+// - available and allocated (p->nAttrs >= Id && p->pAttrs[Id] != NULL)
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFINITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Allocates the attribute manager.]
+
+  Description [The manager is simple if it does not need memory manager.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Attr_Man_t * Attr_ManAlloc( int nAttrSize, int fManMem )
+{
+    Attr_Man_t * p;
+    p = ALLOC( Attr_Man_t, 1 );
+    memset( p, 0, sizeof(Attr_Man_t) );
+    p->nAttrSize = nAttrSize;
+    if ( fManMem )
+        p->pManMem = Extra_MmFixedStart( nAttrSize );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Start the attribute manager for integers.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Attr_Man_t * Attr_ManStartInt( int nAttrs )
+{
+    Attr_Man_t * p;
+    p = Attr_ManAlloc( sizeof(int), 0 );
+    p->nAttrs  = nAttrs;
+    p->pAttrs  = (void **)ALLOC( int, nAttrs );
+    memset( (int *)p->pAttrs, 0, sizeof(int) * nAttrs );
+    p->fUseInt = 1;
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Start the attribute manager for pointers.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Attr_Man_t * Attr_ManStartPtr( int nAttrs )
+{
+    Attr_Man_t * p;
+    p = Attr_ManAlloc( sizeof(void *), 0 );
+    p->nAttrs  = nAttrs;
+    p->pAttrs  = ALLOC( void *, nAttrs );
+    memset( p->pAttrs, 0, sizeof(void *) * nAttrs );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Start the attribute manager for the fixed entry size.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Attr_Man_t * Attr_ManStartPtrMem( int nAttrs, int nAttrSize )
+{
+    Attr_Man_t * p;
+    int i;
+    p = Attr_ManAlloc( nAttrSize, 1 );
+    p->nAttrs  = nAttrs;
+    p->pAttrs  = ALLOC( void *, nAttrs );
+    for ( i = 0; i < p->nAttrs; i++ )
+    {
+        p->pAttrs[i] = Extra_MmFixedEntryFetch( p->pManMem );
+        memset( p->pAttrs[i], 0, nAttrSize );
+    }
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stop the attribute manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Attr_ManStop( Attr_Man_t * p )
+{
+    // free the attributes of objects
+    if ( p->pFuncFreeObj )
+    {
+        int i;
+        if ( p->fUseInt )
+        {
+            for ( i = 0; i < p->nAttrs; i++ )
+                if ( ((int *)p->pAttrs)[i] )
+                    p->pFuncFreeObj( p->pManAttr, (void *)((int *)p->pAttrs)[i] );
+        }
+        else
+        {
+            for ( i = 0; i < p->nAttrs; i++ )
+                if ( p->pAttrs[i] )
+                    p->pFuncFreeObj( p->pManAttr, p->pAttrs[i] );
+        }
+    }
+    // free the attribute manager
+    if ( p->pManAttr && p->pFuncFreeMan )
+        p->pFuncFreeMan( p->pManAttr );
+    // free the memory manager
+    if ( p->pManMem )  
+        Extra_MmFixedStop( p->pManMem);
+    // free the attribute manager
+    FREE( p->pAttrs );
+    free( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Reads the attribute of the given object.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Attr_ManReadAttrInt( Attr_Man_t * p, int Id )
+{
+    assert( p->fUseInt );
+    if ( Id >= p->nAttrs )
+        return 0;
+    return ((int *)p->pAttrs)[Id]; 
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Reads the attribute of the given object.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void * Attr_ManReadAttrPtr( Attr_Man_t * p, int Id )
+{
+    assert( !p->fUseInt );
+    if ( Id >= p->nAttrs )
+        return NULL;
+    return p->pAttrs[Id]; 
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Writes the attribute of the given object.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Attr_ManWriteAttrInt( Attr_Man_t * p, int Id, int Attr )
+{
+    assert( p->fUseInt );
+    ((int *)p->pAttrs)[Id] = Attr; 
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Writes the attribute of the given object.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Attr_ManWriteAttrPtr( Attr_Man_t * p, int Id, void * pAttr )
+{
+    assert( !p->fUseInt );
+    assert( p->pManMem == NULL );
+    p->pAttrs[Id] = pAttr; 
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns or creates the pointer to the attribute of the given object.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int * Attr_ManFetchSpotInt( Attr_Man_t * p, int Id )
+{
+    assert( p->fUseInt );
+    if ( Id >= p->nAttrs )
+    {
+        // save the old size
+        int i, nAttrsOld = p->nAttrs;
+        // get the new size
+        p->nAttrs = p->nAttrs? 2*p->nAttrs : 1024;
+        p->pAttrs = realloc( p->pAttrs, sizeof(int) * p->nAttrs ); 
+        // fill in the empty spots
+        for ( i = nAttrsOld; i < p->nAttrs; i++ )
+            ((int *)p->pAttrs)[Id] = 0;
+    }
+    return ((int *)p->pAttrs) + Id;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns or creates the pointer to the attribute of the given object.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void ** Attr_ManFetchSpotPtr( Attr_Man_t * p, int Id )
+{
+    assert( !p->fUseInt );
+    if ( Id >= p->nAttrs )
+    {
+        // save the old size
+        int i, nAttrsOld = p->nAttrs;
+        // get the new size
+        p->nAttrs = p->nAttrs? 2*p->nAttrs : 1024;
+        p->pAttrs = realloc( p->pAttrs, sizeof(void *) * p->nAttrs ); 
+        // fill in the empty spots
+        for ( i = nAttrsOld; i < p->nAttrs; i++ )
+            p->pAttrs[Id] = NULL;
+    }
+    // if memory manager is available but entry is not created, create it
+    if ( p->pManMem && p->pAttrs[Id] != NULL ) 
+    {
+        p->pAttrs[Id] = Extra_MmFixedEntryFetch( p->pManMem );
+        memset( p->pAttrs[Id], 0, p->nAttrSize );
+    }
+    return p->pAttrs + Id;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns or creates the attribute of the given object.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Attr_ManFetchAttrInt( Attr_Man_t * p, int Id )
+{
+    return *Attr_ManFetchSpotInt( p, Id );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns or creates the attribute of the given object.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void * Attr_ManFetchAttrPtr( Attr_Man_t * p, int Id )
+{
+    return *Attr_ManFetchSpotPtr( p, Id );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the attribute of the given object.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Attr_ManSetAttrInt( Attr_Man_t * p, int Id, int Attr )
+{
+    *Attr_ManFetchSpotInt( p, Id ) = Attr;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the attribute of the given object.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Attr_ManSetAttrPtr( Attr_Man_t * p, int Id, void * pAttr )
+{
+    assert( p->pManMem == NULL );
+    *Attr_ManFetchSpotPtr( p, Id ) = pAttr;
+}
+
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/aig/ivy/ivy.h b/src/aig/ivy/ivy.h
new file mode 100644
index 00000000..c7435a63
--- /dev/null
+++ b/src/aig/ivy/ivy.h
@@ -0,0 +1,557 @@
+/**CFile****************************************************************
+
+  FileName    [ivy.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [External declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivy.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#ifndef __IVY_H__
+#define __IVY_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif 
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+#include <stdio.h>
+#include "extra.h"
+#include "vec.h"
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Ivy_Man_t_            Ivy_Man_t;
+typedef struct Ivy_Obj_t_            Ivy_Obj_t;
+typedef int                          Ivy_Edge_t;
+typedef struct Ivy_FraigParams_t_    Ivy_FraigParams_t;
+
+// object types
+typedef enum { 
+    IVY_NONE,                        // 0: non-existent object
+    IVY_PI,                          // 1: primary input (and constant 1 node)
+    IVY_PO,                          // 2: primary output
+    IVY_ASSERT,                      // 3: assertion
+    IVY_LATCH,                       // 4: sequential element
+    IVY_AND,                         // 5: AND node
+    IVY_EXOR,                        // 6: EXOR node
+    IVY_BUF,                         // 7: buffer (temporary)
+    IVY_VOID                         // 8: unused object
+} Ivy_Type_t;
+
+// latch initial values
+typedef enum { 
+    IVY_INIT_NONE,                   // 0: not a latch
+    IVY_INIT_0,                      // 1: zero
+    IVY_INIT_1,                      // 2: one
+    IVY_INIT_DC                      // 3: don't-care
+} Ivy_Init_t;
+
+// the AIG node
+struct Ivy_Obj_t_  // 24 bytes (32-bit) or 32 bytes (64-bit)   // 10 words - 16 words
+{
+    int              Id;             // integer ID
+    int              TravId;         // traversal ID
+    unsigned         Type     :  4;  // object type
+    unsigned         fMarkA   :  1;  // multipurpose mask
+    unsigned         fMarkB   :  1;  // multipurpose mask
+    unsigned         fExFan   :  1;  // set to 1 if last fanout added is EXOR
+    unsigned         fPhase   :  1;  // value under 000...0 pattern
+    unsigned         fFailTfo :  1;  // the TFO of the failed node
+    unsigned         Init     :  2;  // latch initial value
+    unsigned         Level    : 21;  // logic level
+    int              nRefs;          // reference counter
+    Ivy_Obj_t *      pFanin0;        // fanin
+    Ivy_Obj_t *      pFanin1;        // fanin
+    Ivy_Obj_t *      pFanout;        // fanout
+    Ivy_Obj_t *      pNextFan0;      // next fanout of the first fanin
+    Ivy_Obj_t *      pNextFan1;      // next fanout of the second fanin
+    Ivy_Obj_t *      pPrevFan0;      // prev fanout of the first fanin
+    Ivy_Obj_t *      pPrevFan1;      // prev fanout of the second fanin
+    Ivy_Obj_t *      pEquiv;         // equivalent node
+};
+
+// the AIG manager
+struct Ivy_Man_t_
+{
+    // AIG nodes
+    Vec_Ptr_t *      vPis;           // the array of PIs
+    Vec_Ptr_t *      vPos;           // the array of POs
+    Vec_Ptr_t *      vBufs;          // the array of buffers
+    Vec_Ptr_t *      vObjs;          // the array of objects
+    Ivy_Obj_t *      pConst1;        // the constant 1 node
+    Ivy_Obj_t        Ghost;          // the ghost node
+    // AIG node counters
+    int              nObjs[IVY_VOID];// the number of objects by type
+    int              nCreated;       // the number of created objects
+    int              nDeleted;       // the number of deleted objects
+    // stuctural hash table
+    int *            pTable;         // structural hash table
+    int              nTableSize;     // structural hash table size
+    // various data members
+    int              fCatchExor;     // set to 1 to detect EXORs
+    int              nTravIds;       // the traversal ID
+    int              nLevelMax;      // the maximum level
+    Vec_Int_t *      vRequired;      // required times
+    int              fFanout;        // fanout is allocated
+    void *           pData;          // the temporary data
+    void *           pCopy;          // the temporary data
+    Ivy_Man_t *      pHaig;          // history AIG if present
+    int              nClassesSkip;   // the number of skipped classes
+    // memory management
+    Vec_Ptr_t *      vChunks;        // allocated memory pieces
+    Vec_Ptr_t *      vPages;         // memory pages used by nodes
+    Ivy_Obj_t *      pListFree;      // the list of free nodes 
+    // timing statistics
+    int              time1;
+    int              time2;
+};
+
+struct Ivy_FraigParams_t_
+{
+    int              nSimWords;         // the number of words in the simulation info
+    double           dSimSatur;         // the ratio of refined classes when saturation is reached
+    int              fPatScores;        // enables simulation pattern scoring
+    int              MaxScore;          // max score after which resimulation is used
+    double           dActConeRatio;     // the ratio of cone to be bumped
+    double           dActConeBumpMax;   // the largest bump in activity
+    int              fProve;            // prove the miter outputs
+    int              fVerbose;          // verbose output
+    int              fDoSparse;         // skip sparse functions
+    int              nBTLimitNode;      // conflict limit at a node
+    int              nBTLimitMiter;     // conflict limit at an output
+//    int              nBTLimitGlobal;    // conflict limit global
+//    int              nInsLimitNode;     // inspection limit at a node
+//    int              nInsLimitMiter;    // inspection limit at an output
+//    int              nInsLimitGlobal;   // inspection limit global
+};
+
+
+#define IVY_CUT_LIMIT     256
+#define IVY_CUT_INPUT       6
+
+typedef struct Ivy_Cut_t_ Ivy_Cut_t;
+struct Ivy_Cut_t_
+{
+    int         nLatches;
+    short       nSize;
+    short       nSizeMax;
+    int         pArray[IVY_CUT_INPUT];
+    unsigned    uHash;
+};
+
+typedef struct Ivy_Store_t_ Ivy_Store_t;
+struct Ivy_Store_t_
+{
+    int         nCuts;
+    int         nCutsM;
+    int         nCutsMax;
+    int         fSatur;
+    Ivy_Cut_t   pCuts[IVY_CUT_LIMIT]; // storage for cuts
+};
+
+#define IVY_LEAF_MASK     255
+#define IVY_LEAF_BITS       8
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFINITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+#define IVY_MIN(a,b)       (((a) < (b))? (a) : (b))
+#define IVY_MAX(a,b)       (((a) > (b))? (a) : (b))
+
+static inline int          Ivy_BitWordNum( int nBits )            { return (nBits>>5) + ((nBits&31) > 0);           }
+static inline int          Ivy_TruthWordNum( int nVars )          { return nVars <= 5 ? 1 : (1 << (nVars - 5));     }
+static inline int          Ivy_InfoHasBit( unsigned * p, int i )  { return (p[(i)>>5] & (1<<((i) & 31))) > 0;       }
+static inline void         Ivy_InfoSetBit( unsigned * p, int i )  { p[(i)>>5] |= (1<<((i) & 31));                   }
+static inline void         Ivy_InfoXorBit( unsigned * p, int i )  { p[(i)>>5] ^= (1<<((i) & 31));                   }
+
+static inline Ivy_Obj_t *  Ivy_Regular( Ivy_Obj_t * p )           { return (Ivy_Obj_t *)((unsigned long)(p) & ~01); }
+static inline Ivy_Obj_t *  Ivy_Not( Ivy_Obj_t * p )               { return (Ivy_Obj_t *)((unsigned long)(p) ^  01); }
+static inline Ivy_Obj_t *  Ivy_NotCond( Ivy_Obj_t * p, int c )    { return (Ivy_Obj_t *)((unsigned long)(p) ^ (c)); }
+static inline int          Ivy_IsComplement( Ivy_Obj_t * p )      { return (int)((unsigned long)(p) & 01);          }
+
+static inline Ivy_Obj_t *  Ivy_ManConst0( Ivy_Man_t * p )         { return Ivy_Not(p->pConst1);                     }
+static inline Ivy_Obj_t *  Ivy_ManConst1( Ivy_Man_t * p )         { return p->pConst1;                              }
+static inline Ivy_Obj_t *  Ivy_ManGhost( Ivy_Man_t * p )          { return &p->Ghost;                               }
+static inline Ivy_Obj_t *  Ivy_ManPi( Ivy_Man_t * p, int i )      { return (Ivy_Obj_t *)Vec_PtrEntry(p->vPis, i);   }
+static inline Ivy_Obj_t *  Ivy_ManPo( Ivy_Man_t * p, int i )      { return (Ivy_Obj_t *)Vec_PtrEntry(p->vPos, i);   }
+static inline Ivy_Obj_t *  Ivy_ManObj( Ivy_Man_t * p, int i )     { return (Ivy_Obj_t *)Vec_PtrEntry(p->vObjs, i);  }
+
+static inline Ivy_Edge_t   Ivy_EdgeCreate( int Id, int fCompl )            { return (Id << 1) | fCompl;             }
+static inline int          Ivy_EdgeId( Ivy_Edge_t Edge )                   { return Edge >> 1;                      }
+static inline int          Ivy_EdgeIsComplement( Ivy_Edge_t Edge )         { return Edge & 1;                       }
+static inline Ivy_Edge_t   Ivy_EdgeRegular( Ivy_Edge_t Edge )              { return (Edge >> 1) << 1;               }
+static inline Ivy_Edge_t   Ivy_EdgeNot( Ivy_Edge_t Edge )                  { return Edge ^ 1;                       }
+static inline Ivy_Edge_t   Ivy_EdgeNotCond( Ivy_Edge_t Edge, int fCond )   { return Edge ^ fCond;                   }
+static inline Ivy_Edge_t   Ivy_EdgeFromNode( Ivy_Obj_t * pNode )           { return Ivy_EdgeCreate( Ivy_Regular(pNode)->Id, Ivy_IsComplement(pNode) );          }
+static inline Ivy_Obj_t *  Ivy_EdgeToNode( Ivy_Man_t * p, Ivy_Edge_t Edge ){ return Ivy_NotCond( Ivy_ManObj(p, Ivy_EdgeId(Edge)), Ivy_EdgeIsComplement(Edge) ); }
+
+static inline int          Ivy_LeafCreate( int Id, int Lat )      { return (Id << IVY_LEAF_BITS) | Lat;         }
+static inline int          Ivy_LeafId( int Leaf )                 { return Leaf >> IVY_LEAF_BITS;               }
+static inline int          Ivy_LeafLat( int Leaf )                { return Leaf & IVY_LEAF_MASK;                }
+
+static inline int          Ivy_ManPiNum( Ivy_Man_t * p )          { return p->nObjs[IVY_PI];                    }
+static inline int          Ivy_ManPoNum( Ivy_Man_t * p )          { return p->nObjs[IVY_PO];                    }
+static inline int          Ivy_ManAssertNum( Ivy_Man_t * p )      { return p->nObjs[IVY_ASSERT];                }
+static inline int          Ivy_ManLatchNum( Ivy_Man_t * p )       { return p->nObjs[IVY_LATCH];                 }
+static inline int          Ivy_ManAndNum( Ivy_Man_t * p )         { return p->nObjs[IVY_AND];                   }
+static inline int          Ivy_ManExorNum( Ivy_Man_t * p )        { return p->nObjs[IVY_EXOR];                  }
+static inline int          Ivy_ManBufNum( Ivy_Man_t * p )         { return p->nObjs[IVY_BUF];                   }
+static inline int          Ivy_ManObjNum( Ivy_Man_t * p )         { return p->nCreated - p->nDeleted;           }
+static inline int          Ivy_ManObjIdMax( Ivy_Man_t * p )       { return Vec_PtrSize(p->vObjs)-1;             }
+static inline int          Ivy_ManNodeNum( Ivy_Man_t * p )        { return p->nObjs[IVY_AND]+p->nObjs[IVY_EXOR];}
+static inline int          Ivy_ManHashObjNum( Ivy_Man_t * p )     { return p->nObjs[IVY_AND]+p->nObjs[IVY_EXOR]+p->nObjs[IVY_LATCH];     }
+static inline int          Ivy_ManGetCost( Ivy_Man_t * p )        { return p->nObjs[IVY_AND]+3*p->nObjs[IVY_EXOR]+8*p->nObjs[IVY_LATCH]; }
+
+static inline Ivy_Type_t   Ivy_ObjType( Ivy_Obj_t * pObj )        { return pObj->Type;               }
+static inline Ivy_Init_t   Ivy_ObjInit( Ivy_Obj_t * pObj )        { return pObj->Init;               }
+static inline int          Ivy_ObjIsConst1( Ivy_Obj_t * pObj )    { return pObj->Id == 0;            }
+static inline int          Ivy_ObjIsGhost( Ivy_Obj_t * pObj )     { return pObj->Id < 0;             }
+static inline int          Ivy_ObjIsNone( Ivy_Obj_t * pObj )      { return pObj->Type == IVY_NONE;   }
+static inline int          Ivy_ObjIsPi( Ivy_Obj_t * pObj )        { return pObj->Type == IVY_PI;     }
+static inline int          Ivy_ObjIsPo( Ivy_Obj_t * pObj )        { return pObj->Type == IVY_PO;     }
+static inline int          Ivy_ObjIsCi( Ivy_Obj_t * pObj )        { return pObj->Type == IVY_PI || pObj->Type == IVY_LATCH; }
+static inline int          Ivy_ObjIsCo( Ivy_Obj_t * pObj )        { return pObj->Type == IVY_PO || pObj->Type == IVY_LATCH; }
+static inline int          Ivy_ObjIsAssert( Ivy_Obj_t * pObj )    { return pObj->Type == IVY_ASSERT; }
+static inline int          Ivy_ObjIsLatch( Ivy_Obj_t * pObj )     { return pObj->Type == IVY_LATCH;  }
+static inline int          Ivy_ObjIsAnd( Ivy_Obj_t * pObj )       { return pObj->Type == IVY_AND;    }
+static inline int          Ivy_ObjIsExor( Ivy_Obj_t * pObj )      { return pObj->Type == IVY_EXOR;   }
+static inline int          Ivy_ObjIsBuf( Ivy_Obj_t * pObj )       { return pObj->Type == IVY_BUF;    }
+static inline int          Ivy_ObjIsNode( Ivy_Obj_t * pObj )      { return pObj->Type == IVY_AND || pObj->Type == IVY_EXOR; }
+static inline int          Ivy_ObjIsTerm( Ivy_Obj_t * pObj )      { return pObj->Type == IVY_PI  || pObj->Type == IVY_PO || pObj->Type == IVY_ASSERT; }
+static inline int          Ivy_ObjIsHash( Ivy_Obj_t * pObj )      { return pObj->Type == IVY_AND || pObj->Type == IVY_EXOR || pObj->Type == IVY_LATCH; }
+static inline int          Ivy_ObjIsOneFanin( Ivy_Obj_t * pObj )  { return pObj->Type == IVY_PO  || pObj->Type == IVY_ASSERT || pObj->Type == IVY_BUF || pObj->Type == IVY_LATCH; }
+
+static inline int          Ivy_ObjIsMarkA( Ivy_Obj_t * pObj )     { return pObj->fMarkA;  }
+static inline void         Ivy_ObjSetMarkA( Ivy_Obj_t * pObj )    { pObj->fMarkA = 1;     }
+static inline void         Ivy_ObjClearMarkA( Ivy_Obj_t * pObj )  { pObj->fMarkA = 0;     }
+ 
+static inline void         Ivy_ObjSetTravId( Ivy_Obj_t * pObj, int TravId )                { pObj->TravId = TravId;                               }
+static inline void         Ivy_ObjSetTravIdCurrent( Ivy_Man_t * p, Ivy_Obj_t * pObj )      { pObj->TravId = p->nTravIds;                          }
+static inline void         Ivy_ObjSetTravIdPrevious( Ivy_Man_t * p, Ivy_Obj_t * pObj )     { pObj->TravId = p->nTravIds - 1;                      }
+static inline int          Ivy_ObjIsTravIdCurrent( Ivy_Man_t * p, Ivy_Obj_t * pObj )       { return (int )((int)pObj->TravId == p->nTravIds);     }
+static inline int          Ivy_ObjIsTravIdPrevious( Ivy_Man_t * p, Ivy_Obj_t * pObj )      { return (int )((int)pObj->TravId == p->nTravIds - 1); }
+
+static inline int          Ivy_ObjId( Ivy_Obj_t * pObj )          { return pObj->Id;                               }
+static inline int          Ivy_ObjTravId( Ivy_Obj_t * pObj )      { return pObj->TravId;                           }
+static inline int          Ivy_ObjPhase( Ivy_Obj_t * pObj )       { return pObj->fPhase;                           }
+static inline int          Ivy_ObjExorFanout( Ivy_Obj_t * pObj )  { return pObj->fExFan;                           }
+static inline int          Ivy_ObjRefs( Ivy_Obj_t * pObj )        { return pObj->nRefs;                            }
+static inline void         Ivy_ObjRefsInc( Ivy_Obj_t * pObj )     { pObj->nRefs++;                                 }
+static inline void         Ivy_ObjRefsDec( Ivy_Obj_t * pObj )     { assert( pObj->nRefs > 0 ); pObj->nRefs--;      }
+static inline int          Ivy_ObjFaninId0( Ivy_Obj_t * pObj )    { return pObj->pFanin0? Ivy_ObjId(Ivy_Regular(pObj->pFanin0)) : 0; }
+static inline int          Ivy_ObjFaninId1( Ivy_Obj_t * pObj )    { return pObj->pFanin1? Ivy_ObjId(Ivy_Regular(pObj->pFanin1)) : 0; }
+static inline int          Ivy_ObjFaninC0( Ivy_Obj_t * pObj )     { return Ivy_IsComplement(pObj->pFanin0);        }
+static inline int          Ivy_ObjFaninC1( Ivy_Obj_t * pObj )     { return Ivy_IsComplement(pObj->pFanin1);        }
+static inline Ivy_Obj_t *  Ivy_ObjFanin0( Ivy_Obj_t * pObj )      { return Ivy_Regular(pObj->pFanin0);             }
+static inline Ivy_Obj_t *  Ivy_ObjFanin1( Ivy_Obj_t * pObj )      { return Ivy_Regular(pObj->pFanin1);             }
+static inline Ivy_Obj_t *  Ivy_ObjChild0( Ivy_Obj_t * pObj )      { return pObj->pFanin0;                          }
+static inline Ivy_Obj_t *  Ivy_ObjChild1( Ivy_Obj_t * pObj )      { return pObj->pFanin1;                          }
+static inline Ivy_Obj_t *  Ivy_ObjChild0Equiv( Ivy_Obj_t * pObj ) { assert( !Ivy_IsComplement(pObj) ); return Ivy_ObjFanin0(pObj)? Ivy_NotCond(Ivy_ObjFanin0(pObj)->pEquiv, Ivy_ObjFaninC0(pObj)) : NULL;  }
+static inline Ivy_Obj_t *  Ivy_ObjChild1Equiv( Ivy_Obj_t * pObj ) { assert( !Ivy_IsComplement(pObj) ); return Ivy_ObjFanin1(pObj)? Ivy_NotCond(Ivy_ObjFanin1(pObj)->pEquiv, Ivy_ObjFaninC1(pObj)) : NULL;  }
+static inline Ivy_Obj_t *  Ivy_ObjEquiv( Ivy_Obj_t * pObj )       { return Ivy_Regular(pObj)->pEquiv? Ivy_NotCond(Ivy_Regular(pObj)->pEquiv, Ivy_IsComplement(pObj)) : NULL; }
+static inline int          Ivy_ObjLevel( Ivy_Obj_t * pObj )       { return pObj->Level;                            }
+static inline int          Ivy_ObjLevelNew( Ivy_Obj_t * pObj )    { return 1 + Ivy_ObjIsExor(pObj) + IVY_MAX(Ivy_ObjFanin0(pObj)->Level, Ivy_ObjFanin1(pObj)->Level);       }
+static inline int          Ivy_ObjFaninPhase( Ivy_Obj_t * pObj )  { return Ivy_IsComplement(pObj)? !Ivy_Regular(pObj)->fPhase : pObj->fPhase; }
+
+static inline void         Ivy_ObjClean( Ivy_Obj_t * pObj )       
+{ 
+    int IdSaved = pObj->Id; 
+    memset( pObj, 0, sizeof(Ivy_Obj_t) ); 
+    pObj->Id = IdSaved; 
+}
+static inline void         Ivy_ObjOverwrite( Ivy_Obj_t * pBase, Ivy_Obj_t * pData )   
+{ 
+    int IdSaved = pBase->Id; 
+    memcpy( pBase, pData, sizeof(Ivy_Obj_t) ); 
+    pBase->Id = IdSaved;         
+}
+static inline int          Ivy_ObjWhatFanin( Ivy_Obj_t * pObj, Ivy_Obj_t * pFanin )    
+{ 
+    if ( Ivy_ObjFanin0(pObj) == pFanin ) return 0; 
+    if ( Ivy_ObjFanin1(pObj) == pFanin ) return 1; 
+    assert(0); return -1; 
+}
+static inline int          Ivy_ObjFanoutC( Ivy_Obj_t * pObj, Ivy_Obj_t * pFanout )    
+{ 
+    if ( Ivy_ObjFanin0(pFanout) == pObj ) return Ivy_ObjFaninC0(pObj); 
+    if ( Ivy_ObjFanin1(pFanout) == pObj ) return Ivy_ObjFaninC1(pObj); 
+    assert(0); return -1; 
+}
+
+// create the ghost of the new node
+static inline Ivy_Obj_t *  Ivy_ObjCreateGhost( Ivy_Man_t * p, Ivy_Obj_t * p0, Ivy_Obj_t * p1, Ivy_Type_t Type, Ivy_Init_t Init )    
+{
+    Ivy_Obj_t * pGhost, * pTemp;
+    assert( Type != IVY_AND || !Ivy_ObjIsConst1(Ivy_Regular(p0)) );
+    assert( p1 == NULL || !Ivy_ObjIsConst1(Ivy_Regular(p1)) );
+    assert( Type == IVY_PI || Ivy_Regular(p0) != Ivy_Regular(p1) );
+    assert( Type != IVY_LATCH || !Ivy_IsComplement(p0) );
+//    assert( p1 == NULL || (!Ivy_ObjIsLatch(Ivy_Regular(p0)) || !Ivy_ObjIsLatch(Ivy_Regular(p1))) );
+    pGhost = Ivy_ManGhost(p);
+    pGhost->Type = Type;
+    pGhost->Init = Init;
+    pGhost->pFanin0 = p0;
+    pGhost->pFanin1 = p1;
+    if ( p1 && Ivy_ObjFaninId0(pGhost) > Ivy_ObjFaninId1(pGhost) )
+        pTemp = pGhost->pFanin0, pGhost->pFanin0 = pGhost->pFanin1, pGhost->pFanin1 = pTemp;
+    return pGhost;
+}
+
+// get the complemented initial state
+static Ivy_Init_t Ivy_InitNotCond( Ivy_Init_t Init, int fCompl )
+{
+    assert( Init != IVY_INIT_NONE );
+    if ( fCompl == 0 )
+        return Init;
+    if ( Init == IVY_INIT_0 )
+        return IVY_INIT_1;
+    if ( Init == IVY_INIT_1 )
+        return IVY_INIT_0;
+    return IVY_INIT_DC;
+}
+
+// get the initial state after forward retiming over AND gate
+static Ivy_Init_t Ivy_InitAnd( Ivy_Init_t InitA, Ivy_Init_t InitB )
+{
+    assert( InitA != IVY_INIT_NONE && InitB != IVY_INIT_NONE );
+    if ( InitA == IVY_INIT_0 || InitB == IVY_INIT_0 )
+        return IVY_INIT_0;
+    if ( InitA == IVY_INIT_DC || InitB == IVY_INIT_DC )
+        return IVY_INIT_DC;
+    return IVY_INIT_1;
+}
+
+// get the initial state after forward retiming over EXOR gate
+static Ivy_Init_t Ivy_InitExor( Ivy_Init_t InitA, Ivy_Init_t InitB )
+{
+    assert( InitA != IVY_INIT_NONE && InitB != IVY_INIT_NONE );
+    if ( InitA == IVY_INIT_DC || InitB == IVY_INIT_DC )
+        return IVY_INIT_DC;
+    if ( InitA == IVY_INIT_0 && InitB == IVY_INIT_1 )
+        return IVY_INIT_1;
+    if ( InitA == IVY_INIT_1 && InitB == IVY_INIT_0 )
+        return IVY_INIT_1;
+    return IVY_INIT_0;
+}
+
+// internal memory manager
+static inline Ivy_Obj_t * Ivy_ManFetchMemory( Ivy_Man_t * p )  
+{ 
+    extern void Ivy_ManAddMemory( Ivy_Man_t * p );
+    Ivy_Obj_t * pTemp;
+    if ( p->pListFree == NULL )
+        Ivy_ManAddMemory( p );
+    pTemp = p->pListFree;
+    p->pListFree = *((Ivy_Obj_t **)pTemp);
+    memset( pTemp, 0, sizeof(Ivy_Obj_t) ); 
+    return pTemp;
+}
+static inline void Ivy_ManRecycleMemory( Ivy_Man_t * p, Ivy_Obj_t * pEntry )
+{
+    pEntry->Type = IVY_NONE; // distinquishes dead node from live node
+    *((Ivy_Obj_t **)pEntry) = p->pListFree;
+    p->pListFree = pEntry;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                             ITERATORS                            ///
+////////////////////////////////////////////////////////////////////////
+
+// iterator over the primary inputs
+#define Ivy_ManForEachPi( p, pObj, i )                                          \
+    Vec_PtrForEachEntry( p->vPis, pObj, i )
+// iterator over the primary outputs
+#define Ivy_ManForEachPo( p, pObj, i )                                          \
+    Vec_PtrForEachEntry( p->vPos, pObj, i )
+// iterator over all objects, including those currently not used
+#define Ivy_ManForEachObj( p, pObj, i )                                         \
+    Vec_PtrForEachEntry( p->vObjs, pObj, i ) if ( (pObj) == NULL ) {} else
+// iterator over the combinational inputs
+#define Ivy_ManForEachCi( p, pObj, i )                                          \
+    Ivy_ManForEachObj( p, pObj, i ) if ( !Ivy_ObjIsCi(pObj) ) {} else
+// iterator over the combinational outputs
+#define Ivy_ManForEachCo( p, pObj, i )                                          \
+    Ivy_ManForEachObj( p, pObj, i ) if ( !Ivy_ObjIsCo(pObj) ) {} else
+// iterator over logic nodes (AND and EXOR gates)
+#define Ivy_ManForEachNode( p, pObj, i )                                        \
+    Ivy_ManForEachObj( p, pObj, i ) if ( !Ivy_ObjIsNode(pObj) ) {} else
+// iterator over logic latches
+#define Ivy_ManForEachLatch( p, pObj, i )                                       \
+    Ivy_ManForEachObj( p, pObj, i ) if ( !Ivy_ObjIsLatch(pObj) ) {} else
+// iterator over the nodes whose IDs are stored in the array
+#define Ivy_ManForEachNodeVec( p, vIds, pObj, i )                               \
+    for ( i = 0; i < Vec_IntSize(vIds) && ((pObj) = Ivy_ManObj(p, Vec_IntEntry(vIds,i))); i++ )
+// iterator over the fanouts of an object
+#define Ivy_ObjForEachFanout( p, pObj, vArray, pFanout, i )                     \
+    for ( i = 0, Ivy_ObjCollectFanouts(p, pObj, vArray);                        \
+          i < Vec_PtrSize(vArray) && ((pFanout) = Vec_PtrEntry(vArray,i)); i++ )
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== ivyBalance.c ========================================================*/
+extern Ivy_Man_t *     Ivy_ManBalance( Ivy_Man_t * p, int fUpdateLevel );
+extern Ivy_Obj_t *     Ivy_NodeBalanceBuildSuper( Ivy_Man_t * p, Vec_Ptr_t * vSuper, Ivy_Type_t Type, int fUpdateLevel );
+/*=== ivyCanon.c ========================================================*/
+extern Ivy_Obj_t *     Ivy_CanonAnd( Ivy_Man_t * p, Ivy_Obj_t * p0, Ivy_Obj_t * p1 );
+extern Ivy_Obj_t *     Ivy_CanonExor( Ivy_Man_t * p, Ivy_Obj_t * p0, Ivy_Obj_t * p1 );
+extern Ivy_Obj_t *     Ivy_CanonLatch( Ivy_Man_t * p, Ivy_Obj_t * pObj, Ivy_Init_t Init );
+/*=== ivyCheck.c ========================================================*/
+extern int             Ivy_ManCheck( Ivy_Man_t * p );
+extern int             Ivy_ManCheckFanoutNums( Ivy_Man_t * p );
+extern int             Ivy_ManCheckFanouts( Ivy_Man_t * p );
+extern int             Ivy_ManCheckChoices( Ivy_Man_t * p );
+/*=== ivyCut.c ==========================================================*/
+extern void            Ivy_ManSeqFindCut( Ivy_Man_t * p, Ivy_Obj_t * pNode, Vec_Int_t * vFront, Vec_Int_t * vInside, int nSize );
+extern Ivy_Store_t *   Ivy_NodeFindCutsAll( Ivy_Man_t * p, Ivy_Obj_t * pObj, int nLeaves );
+/*=== ivyDfs.c ==========================================================*/
+extern Vec_Int_t *     Ivy_ManDfs( Ivy_Man_t * p );
+extern Vec_Int_t *     Ivy_ManDfsSeq( Ivy_Man_t * p, Vec_Int_t ** pvLatches );
+extern void            Ivy_ManCollectCone( Ivy_Obj_t * pObj, Vec_Ptr_t * vFront, Vec_Ptr_t * vCone );
+extern Vec_Vec_t *     Ivy_ManLevelize( Ivy_Man_t * p );
+extern Vec_Int_t *     Ivy_ManRequiredLevels( Ivy_Man_t * p );
+extern int             Ivy_ManIsAcyclic( Ivy_Man_t * p );
+extern int             Ivy_ManSetLevels( Ivy_Man_t * p, int fHaig );
+/*=== ivyDsd.c ==========================================================*/
+extern int             Ivy_TruthDsd( unsigned uTruth, Vec_Int_t * vTree );
+extern void            Ivy_TruthDsdPrint( FILE * pFile, Vec_Int_t * vTree );
+extern unsigned        Ivy_TruthDsdCompute( Vec_Int_t * vTree );
+extern void            Ivy_TruthDsdComputePrint( unsigned uTruth );
+extern Ivy_Obj_t *     Ivy_ManDsdConstruct( Ivy_Man_t * p, Vec_Int_t * vFront, Vec_Int_t * vTree );
+/*=== ivyFanout.c ==========================================================*/
+extern void            Ivy_ManStartFanout( Ivy_Man_t * p );
+extern void            Ivy_ManStopFanout( Ivy_Man_t * p );
+extern void            Ivy_ObjAddFanout( Ivy_Man_t * p, Ivy_Obj_t * pObj, Ivy_Obj_t * pFanout );
+extern void            Ivy_ObjDeleteFanout( Ivy_Man_t * p, Ivy_Obj_t * pObj, Ivy_Obj_t * pFanout );
+extern void            Ivy_ObjPatchFanout( Ivy_Man_t * p, Ivy_Obj_t * pObj, Ivy_Obj_t * pFanoutOld, Ivy_Obj_t * pFanoutNew );
+extern void            Ivy_ObjCollectFanouts( Ivy_Man_t * p, Ivy_Obj_t * pObj, Vec_Ptr_t * vArray );
+extern Ivy_Obj_t *     Ivy_ObjReadFirstFanout( Ivy_Man_t * p, Ivy_Obj_t * pObj );
+extern int             Ivy_ObjFanoutNum( Ivy_Man_t * p, Ivy_Obj_t * pObj );
+/*=== ivyFastMap.c =============================================================*/
+extern void            Ivy_FastMapPerform( Ivy_Man_t * pAig, int nLimit, int fRecovery, int fVerbose );
+extern void            Ivy_FastMapStop( Ivy_Man_t * pAig );
+extern void            Ivy_FastMapReadSupp( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, Vec_Int_t * vLeaves );
+extern void            Ivy_FastMapReverseLevel( Ivy_Man_t * pAig );
+/*=== ivyFraig.c ==========================================================*/
+extern int             Ivy_FraigProve( Ivy_Man_t ** ppManAig, void * pPars );
+extern Ivy_Man_t *     Ivy_FraigPerform( Ivy_Man_t * pManAig, Ivy_FraigParams_t * pParams );
+extern Ivy_Man_t *     Ivy_FraigMiter( Ivy_Man_t * pManAig, Ivy_FraigParams_t * pParams );
+extern void            Ivy_FraigParamsDefault( Ivy_FraigParams_t * pParams );
+/*=== ivyHaig.c ==========================================================*/
+extern void            Ivy_ManHaigStart( Ivy_Man_t * p, int fVerbose );
+extern void            Ivy_ManHaigTrasfer( Ivy_Man_t * p, Ivy_Man_t * pNew );
+extern void            Ivy_ManHaigStop( Ivy_Man_t * p );
+extern void            Ivy_ManHaigPostprocess( Ivy_Man_t * p, int fVerbose );
+extern void            Ivy_ManHaigCreateObj( Ivy_Man_t * p, Ivy_Obj_t * pObj );
+extern void            Ivy_ManHaigCreateChoice( Ivy_Man_t * p, Ivy_Obj_t * pObjOld, Ivy_Obj_t * pObjNew );
+extern void            Ivy_ManHaigSimulate( Ivy_Man_t * p );
+/*=== ivyMan.c ==========================================================*/
+extern Ivy_Man_t *     Ivy_ManStart();
+extern Ivy_Man_t *     Ivy_ManStartFrom( Ivy_Man_t * p );
+extern Ivy_Man_t *     Ivy_ManDup( Ivy_Man_t * p );
+extern Ivy_Man_t *     Ivy_ManFrames( Ivy_Man_t * pMan, int nLatches, int nFrames, int fInit, Vec_Ptr_t ** pvMapping );
+extern void            Ivy_ManStop( Ivy_Man_t * p );
+extern int             Ivy_ManCleanup( Ivy_Man_t * p );
+extern int             Ivy_ManPropagateBuffers( Ivy_Man_t * p, int fUpdateLevel );
+extern void            Ivy_ManPrintStats( Ivy_Man_t * p );
+extern void            Ivy_ManMakeSeq( Ivy_Man_t * p, int nLatches, int * pInits );
+/*=== ivyMem.c ==========================================================*/
+extern void            Ivy_ManStartMemory( Ivy_Man_t * p );
+extern void            Ivy_ManStopMemory( Ivy_Man_t * p );
+/*=== ivyMulti.c ==========================================================*/
+extern Ivy_Obj_t *     Ivy_Multi( Ivy_Man_t * p, Ivy_Obj_t ** pArgs, int nArgs, Ivy_Type_t Type );
+extern Ivy_Obj_t *     Ivy_Multi1( Ivy_Man_t * p, Ivy_Obj_t ** pArgs, int nArgs, Ivy_Type_t Type );
+extern Ivy_Obj_t *     Ivy_Multi_rec( Ivy_Man_t * p, Ivy_Obj_t ** ppObjs, int nObjs, Ivy_Type_t Type );
+extern Ivy_Obj_t *     Ivy_MultiBalance_rec( Ivy_Man_t * p, Ivy_Obj_t ** pArgs, int nArgs, Ivy_Type_t Type );
+extern int             Ivy_MultiPlus( Ivy_Man_t * p, Vec_Ptr_t * vLeaves, Vec_Ptr_t * vCone, Ivy_Type_t Type, int nLimit, Vec_Ptr_t * vSol );
+/*=== ivyObj.c ==========================================================*/
+extern Ivy_Obj_t *     Ivy_ObjCreatePi( Ivy_Man_t * p );
+extern Ivy_Obj_t *     Ivy_ObjCreatePo( Ivy_Man_t * p, Ivy_Obj_t * pDriver );
+extern Ivy_Obj_t *     Ivy_ObjCreate( Ivy_Man_t * p, Ivy_Obj_t * pGhost );
+extern void            Ivy_ObjConnect( Ivy_Man_t * p, Ivy_Obj_t * pObj, Ivy_Obj_t * pFan0, Ivy_Obj_t * pFan1 );
+extern void            Ivy_ObjDisconnect( Ivy_Man_t * p, Ivy_Obj_t * pObj );
+extern void            Ivy_ObjPatchFanin0( Ivy_Man_t * p, Ivy_Obj_t * pObj, Ivy_Obj_t * pFaninNew );
+extern void            Ivy_ObjDelete( Ivy_Man_t * p, Ivy_Obj_t * pObj, int fFreeTop );
+extern void            Ivy_ObjDelete_rec( Ivy_Man_t * p, Ivy_Obj_t * pObj, int fFreeTop );
+extern void            Ivy_ObjReplace( Ivy_Man_t * p, Ivy_Obj_t * pObjOld, Ivy_Obj_t * pObjNew, int fDeleteOld, int fFreeTop, int fUpdateLevel );
+extern void            Ivy_NodeFixBufferFanins( Ivy_Man_t * p, Ivy_Obj_t * pNode, int fUpdateLevel );
+/*=== ivyOper.c =========================================================*/
+extern Ivy_Obj_t *     Ivy_Oper( Ivy_Man_t * p, Ivy_Obj_t * p0, Ivy_Obj_t * p1, Ivy_Type_t Type );
+extern Ivy_Obj_t *     Ivy_And( Ivy_Man_t * p, Ivy_Obj_t * p0, Ivy_Obj_t * p1 );
+extern Ivy_Obj_t *     Ivy_Or( Ivy_Man_t * p, Ivy_Obj_t * p0, Ivy_Obj_t * p1 );
+extern Ivy_Obj_t *     Ivy_Exor( Ivy_Man_t * p, Ivy_Obj_t * p0, Ivy_Obj_t * p1 );
+extern Ivy_Obj_t *     Ivy_Mux( Ivy_Man_t * p, Ivy_Obj_t * pC, Ivy_Obj_t * p1, Ivy_Obj_t * p0 );
+extern Ivy_Obj_t *     Ivy_Maj( Ivy_Man_t * p, Ivy_Obj_t * pA, Ivy_Obj_t * pB, Ivy_Obj_t * pC );
+extern Ivy_Obj_t *     Ivy_Miter( Ivy_Man_t * p, Vec_Ptr_t * vPairs );
+extern Ivy_Obj_t *     Ivy_Latch( Ivy_Man_t * p, Ivy_Obj_t * pObj, Ivy_Init_t Init );
+/*=== ivyResyn.c =========================================================*/
+extern Ivy_Man_t *     Ivy_ManResyn0( Ivy_Man_t * p, int fUpdateLevel, int fVerbose );
+extern Ivy_Man_t *     Ivy_ManResyn( Ivy_Man_t * p, int fUpdateLevel, int fVerbose );
+extern Ivy_Man_t *     Ivy_ManRwsat( Ivy_Man_t * pMan, int fVerbose );
+/*=== ivyRewrite.c =========================================================*/
+extern int             Ivy_ManSeqRewrite( Ivy_Man_t * p, int fUpdateLevel, int fUseZeroCost );
+extern int             Ivy_ManRewriteAlg( Ivy_Man_t * p, int fUpdateLevel, int fUseZeroCost );
+extern int             Ivy_ManRewritePre( Ivy_Man_t * p, int fUpdateLevel, int fUseZeroCost, int fVerbose );
+/*=== ivySeq.c =========================================================*/
+extern int             Ivy_ManRewriteSeq( Ivy_Man_t * p, int fUseZeroCost, int fVerbose );
+/*=== ivyShow.c =========================================================*/
+extern void            Ivy_ManShow( Ivy_Man_t * pMan, int fHaig, Vec_Ptr_t * vBold );
+/*=== ivyTable.c ========================================================*/
+extern Ivy_Obj_t *     Ivy_TableLookup( Ivy_Man_t * p, Ivy_Obj_t * pObj );
+extern void            Ivy_TableInsert( Ivy_Man_t * p, Ivy_Obj_t * pObj );
+extern void            Ivy_TableDelete( Ivy_Man_t * p, Ivy_Obj_t * pObj );
+extern void            Ivy_TableUpdate( Ivy_Man_t * p, Ivy_Obj_t * pObj, int ObjIdNew );
+extern int             Ivy_TableCountEntries( Ivy_Man_t * p );
+extern void            Ivy_TableProfile( Ivy_Man_t * p );
+/*=== ivyUtil.c =========================================================*/
+extern void            Ivy_ManIncrementTravId( Ivy_Man_t * p );
+extern void            Ivy_ManCleanTravId( Ivy_Man_t * p );
+extern unsigned *      Ivy_ManCutTruth( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Vec_Int_t * vLeaves, Vec_Int_t * vNodes, Vec_Int_t * vTruth );
+extern void            Ivy_ManCollectCut( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Vec_Int_t * vLeaves, Vec_Int_t * vNodes );
+extern Vec_Int_t *     Ivy_ManLatches( Ivy_Man_t * p );
+extern int             Ivy_ManLevels( Ivy_Man_t * p );
+extern void            Ivy_ManResetLevels( Ivy_Man_t * p );
+extern int             Ivy_ObjMffcLabel( Ivy_Man_t * p, Ivy_Obj_t * pObj );
+extern void            Ivy_ObjUpdateLevel_rec( Ivy_Man_t * p, Ivy_Obj_t * pObj );
+extern void            Ivy_ObjUpdateLevelR_rec( Ivy_Man_t * p, Ivy_Obj_t * pObj, int ReqNew );
+extern int             Ivy_ObjIsMuxType( Ivy_Obj_t * pObj );
+extern Ivy_Obj_t *     Ivy_ObjRecognizeMux( Ivy_Obj_t * pObj, Ivy_Obj_t ** ppObjT, Ivy_Obj_t ** ppObjE );
+extern Ivy_Obj_t *     Ivy_ObjReal( Ivy_Obj_t * pObj );
+extern void            Ivy_ObjPrintVerbose( Ivy_Man_t * p, Ivy_Obj_t * pObj, int fHaig );
+extern void            Ivy_ManPrintVerbose( Ivy_Man_t * p, int fHaig );
+extern int             Ivy_CutTruthPrint( Ivy_Man_t * p, Ivy_Cut_t * pCut, unsigned uTruth );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/aig/ivy/ivyBalance.c b/src/aig/ivy/ivyBalance.c
new file mode 100644
index 00000000..5627039a
--- /dev/null
+++ b/src/aig/ivy/ivyBalance.c
@@ -0,0 +1,404 @@
+/**CFile****************************************************************
+
+  FileName    [ivyBalance.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Algebraic AIG balancing.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyBalance.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static int         Ivy_NodeBalance_rec( Ivy_Man_t * pNew, Ivy_Obj_t * pObj, Vec_Vec_t * vStore, int Level, int fUpdateLevel );
+static Vec_Ptr_t * Ivy_NodeBalanceCone( Ivy_Obj_t * pObj, Vec_Vec_t * vStore, int Level );
+static int         Ivy_NodeBalanceFindLeft( Vec_Ptr_t * vSuper );
+static void        Ivy_NodeBalancePermute( Ivy_Man_t * p, Vec_Ptr_t * vSuper, int LeftBound, int fExor );
+static void        Ivy_NodeBalancePushUniqueOrderByLevel( Vec_Ptr_t * vStore, Ivy_Obj_t * pObj );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Performs algebraic balancing of the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Man_t * Ivy_ManBalance( Ivy_Man_t * p, int fUpdateLevel )
+{
+    Ivy_Man_t * pNew;
+    Ivy_Obj_t * pObj, * pDriver;
+    Vec_Vec_t * vStore;
+    int i, NewNodeId;
+    // clean the old manager
+    Ivy_ManCleanTravId( p );
+    // create the new manager 
+    pNew = Ivy_ManStart();
+    // map the nodes
+    Ivy_ManConst1(p)->TravId = Ivy_EdgeFromNode( Ivy_ManConst1(pNew) );
+    Ivy_ManForEachPi( p, pObj, i )
+        pObj->TravId = Ivy_EdgeFromNode( Ivy_ObjCreatePi(pNew) );
+    // if HAIG is defined, trasfer the pointers to the PIs/latches
+//    if ( p->pHaig )
+//        Ivy_ManHaigTrasfer( p, pNew );
+    // balance the AIG
+    vStore = Vec_VecAlloc( 50 );
+    Ivy_ManForEachPo( p, pObj, i )
+    {
+        pDriver   = Ivy_ObjReal( Ivy_ObjChild0(pObj) );
+        NewNodeId = Ivy_NodeBalance_rec( pNew, Ivy_Regular(pDriver), vStore, 0, fUpdateLevel );
+        NewNodeId = Ivy_EdgeNotCond( NewNodeId, Ivy_IsComplement(pDriver) );
+        Ivy_ObjCreatePo( pNew, Ivy_EdgeToNode(pNew, NewNodeId) );
+    }
+    Vec_VecFree( vStore );
+    if ( i = Ivy_ManCleanup( pNew ) )
+    {
+//        printf( "Cleanup after balancing removed %d dangling nodes.\n", i );
+    }
+    // check the resulting AIG
+    if ( !Ivy_ManCheck(pNew) )
+        printf( "Ivy_ManBalance(): The check has failed.\n" );
+    return pNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Procedure used for sorting the nodes in decreasing order of levels.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeCompareLevelsDecrease( Ivy_Obj_t ** pp1, Ivy_Obj_t ** pp2 )
+{
+    int Diff = Ivy_Regular(*pp1)->Level - Ivy_Regular(*pp2)->Level;
+    if ( Diff > 0 )
+        return -1;
+    if ( Diff < 0 ) 
+        return 1;
+    return 0; 
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the ID of new node constructed.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeBalance_rec( Ivy_Man_t * pNew, Ivy_Obj_t * pObjOld, Vec_Vec_t * vStore, int Level, int fUpdateLevel )
+{
+    Ivy_Obj_t * pObjNew;
+    Vec_Ptr_t * vSuper;
+    int i, NewNodeId;
+    assert( !Ivy_IsComplement(pObjOld) );
+    assert( !Ivy_ObjIsBuf(pObjOld) );
+    // return if the result is known
+    if ( Ivy_ObjIsConst1(pObjOld) )
+        return pObjOld->TravId;
+    if ( pObjOld->TravId )
+        return pObjOld->TravId;
+    assert( Ivy_ObjIsNode(pObjOld) );
+    // get the implication supergate
+    vSuper = Ivy_NodeBalanceCone( pObjOld, vStore, Level );
+    if ( vSuper->nSize == 0 )
+    { // it means that the supergate contains two nodes in the opposite polarity
+        pObjOld->TravId = Ivy_EdgeFromNode( Ivy_ManConst0(pNew) );
+        return pObjOld->TravId;
+    }
+    if ( vSuper->nSize < 2 )
+        printf( "BUG!\n" );
+    // for each old node, derive the new well-balanced node
+    for ( i = 0; i < vSuper->nSize; i++ )
+    {
+        NewNodeId = Ivy_NodeBalance_rec( pNew, Ivy_Regular(vSuper->pArray[i]), vStore, Level + 1, fUpdateLevel );
+        NewNodeId = Ivy_EdgeNotCond( NewNodeId, Ivy_IsComplement(vSuper->pArray[i]) );
+        vSuper->pArray[i] = Ivy_EdgeToNode( pNew, NewNodeId );
+    }
+    // build the supergate
+    pObjNew = Ivy_NodeBalanceBuildSuper( pNew, vSuper, Ivy_ObjType(pObjOld), fUpdateLevel );
+    vSuper->nSize = 0;
+    // make sure the balanced node is not assigned
+    assert( pObjOld->TravId == 0 );
+    pObjOld->TravId = Ivy_EdgeFromNode( pObjNew );
+//    assert( pObjOld->Level >= Ivy_Regular(pObjNew)->Level );
+    return pObjOld->TravId;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Builds implication supergate.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_NodeBalanceBuildSuper( Ivy_Man_t * p, Vec_Ptr_t * vSuper, Ivy_Type_t Type, int fUpdateLevel )
+{
+    Ivy_Obj_t * pObj1, * pObj2;
+    int LeftBound;
+    assert( vSuper->nSize > 1 );
+    // sort the new nodes by level in the decreasing order
+    Vec_PtrSort( vSuper, Ivy_NodeCompareLevelsDecrease );
+    // balance the nodes
+    while ( vSuper->nSize > 1 )
+    {
+        // find the left bound on the node to be paired
+        LeftBound = (!fUpdateLevel)? 0 : Ivy_NodeBalanceFindLeft( vSuper );
+        // find the node that can be shared (if no such node, randomize choice)
+        Ivy_NodeBalancePermute( p, vSuper, LeftBound, Type == IVY_EXOR );
+        // pull out the last two nodes
+        pObj1 = Vec_PtrPop(vSuper);
+        pObj2 = Vec_PtrPop(vSuper);
+        Ivy_NodeBalancePushUniqueOrderByLevel( vSuper, Ivy_Oper(p, pObj1, pObj2, Type) );
+    }
+    return Vec_PtrEntry(vSuper, 0);
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects the nodes of the supergate.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeBalanceCone_rec( Ivy_Obj_t * pRoot, Ivy_Obj_t * pObj, Vec_Ptr_t * vSuper )
+{
+    int RetValue1, RetValue2, i;
+    // check if the node is visited
+    if ( Ivy_Regular(pObj)->fMarkB )
+    {
+        // check if the node occurs in the same polarity
+        for ( i = 0; i < vSuper->nSize; i++ )
+            if ( vSuper->pArray[i] == pObj )
+                return 1;
+        // check if the node is present in the opposite polarity
+        for ( i = 0; i < vSuper->nSize; i++ )
+            if ( vSuper->pArray[i] == Ivy_Not(pObj) )
+                return -1;
+        assert( 0 );
+        return 0;
+    }
+    // if the new node is complemented or a PI, another gate begins
+    if ( pObj != pRoot && (Ivy_IsComplement(pObj) || Ivy_ObjType(pObj) != Ivy_ObjType(pRoot) || Ivy_ObjRefs(pObj) > 1) )
+    {
+        Vec_PtrPush( vSuper, pObj );
+        Ivy_Regular(pObj)->fMarkB = 1;
+        return 0;
+    }
+    assert( !Ivy_IsComplement(pObj) );
+    assert( Ivy_ObjIsNode(pObj) );
+    // go through the branches
+    RetValue1 = Ivy_NodeBalanceCone_rec( pRoot, Ivy_ObjReal( Ivy_ObjChild0(pObj) ), vSuper );
+    RetValue2 = Ivy_NodeBalanceCone_rec( pRoot, Ivy_ObjReal( Ivy_ObjChild1(pObj) ), vSuper );
+    if ( RetValue1 == -1 || RetValue2 == -1 )
+        return -1;
+    // return 1 if at least one branch has a duplicate
+    return RetValue1 || RetValue2;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects the nodes of the supergate.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Ivy_NodeBalanceCone( Ivy_Obj_t * pObj, Vec_Vec_t * vStore, int Level )
+{
+    Vec_Ptr_t * vNodes;
+    int RetValue, i;
+    assert( !Ivy_IsComplement(pObj) );
+    // extend the storage
+    if ( Vec_VecSize( vStore ) <= Level )
+        Vec_VecPush( vStore, Level, 0 );
+    // get the temporary array of nodes
+    vNodes = Vec_VecEntry( vStore, Level );
+    Vec_PtrClear( vNodes );
+    // collect the nodes in the implication supergate
+    RetValue = Ivy_NodeBalanceCone_rec( pObj, pObj, vNodes );
+    assert( vNodes->nSize > 1 );
+    // unmark the visited nodes
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+        Ivy_Regular(pObj)->fMarkB = 0;
+    // if we found the node and its complement in the same implication supergate, 
+    // return empty set of nodes (meaning that we should use constant-0 node)
+    if ( RetValue == -1 )
+        vNodes->nSize = 0;
+    return vNodes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Finds the left bound on the next candidate to be paired.]
+
+  Description [The nodes in the array are in the decreasing order of levels. 
+  The last node in the array has the smallest level. By default it would be paired 
+  with the next node on the left. However, it may be possible to pair it with some
+  other node on the left, in such a way that the new node is shared. This procedure
+  finds the index of the left-most node, which can be paired with the last node.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeBalanceFindLeft( Vec_Ptr_t * vSuper )
+{
+    Ivy_Obj_t * pObjRight, * pObjLeft;
+    int Current;
+    // if two or less nodes, pair with the first
+    if ( Vec_PtrSize(vSuper) < 3 )
+        return 0;
+    // set the pointer to the one before the last
+    Current = Vec_PtrSize(vSuper) - 2;
+    pObjRight = Vec_PtrEntry( vSuper, Current );
+    // go through the nodes to the left of this one
+    for ( Current--; Current >= 0; Current-- )
+    {
+        // get the next node on the left
+        pObjLeft = Vec_PtrEntry( vSuper, Current );
+        // if the level of this node is different, quit the loop
+        if ( Ivy_Regular(pObjLeft)->Level != Ivy_Regular(pObjRight)->Level )
+            break;
+    }
+    Current++;    
+    // get the node, for which the equality holds
+    pObjLeft = Vec_PtrEntry( vSuper, Current );
+    assert( Ivy_Regular(pObjLeft)->Level == Ivy_Regular(pObjRight)->Level );
+    return Current;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Moves closer to the end the node that is best for sharing.]
+
+  Description [If there is no node with sharing, randomly chooses one of 
+  the legal nodes.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeBalancePermute( Ivy_Man_t * p, Vec_Ptr_t * vSuper, int LeftBound, int fExor )
+{
+    Ivy_Obj_t * pObj1, * pObj2, * pObj3, * pGhost;
+    int RightBound, i;
+    // get the right bound
+    RightBound = Vec_PtrSize(vSuper) - 2;
+    assert( LeftBound <= RightBound );
+    if ( LeftBound == RightBound )
+        return;
+    // get the two last nodes
+    pObj1 = Vec_PtrEntry( vSuper, RightBound + 1 );
+    pObj2 = Vec_PtrEntry( vSuper, RightBound     );
+    if ( Ivy_Regular(pObj1) == p->pConst1 || Ivy_Regular(pObj2) == p->pConst1 )
+        return;
+    // find the first node that can be shared
+    for ( i = RightBound; i >= LeftBound; i-- )
+    {
+        pObj3 = Vec_PtrEntry( vSuper, i );
+        if ( Ivy_Regular(pObj3) == p->pConst1 )
+        {
+            Vec_PtrWriteEntry( vSuper, i,          pObj2 );
+            Vec_PtrWriteEntry( vSuper, RightBound, pObj3 );
+            return;
+        }
+        pGhost = Ivy_ObjCreateGhost( p, pObj1, pObj3, fExor? IVY_EXOR : IVY_AND, IVY_INIT_NONE );
+        if ( Ivy_TableLookup( p, pGhost ) )
+        {
+            if ( pObj3 == pObj2 )
+                return;
+            Vec_PtrWriteEntry( vSuper, i,          pObj2 );
+            Vec_PtrWriteEntry( vSuper, RightBound, pObj3 );
+            return;
+        }
+    }
+/*
+    // we did not find the node to share, randomize choice
+    {
+        int Choice = rand() % (RightBound - LeftBound + 1);
+        pObj3 = Vec_PtrEntry( vSuper, LeftBound + Choice );
+        if ( pObj3 == pObj2 )
+            return;
+        Vec_PtrWriteEntry( vSuper, LeftBound + Choice, pObj2 );
+        Vec_PtrWriteEntry( vSuper, RightBound,         pObj3 );
+    }
+*/
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Inserts a new node in the order by levels.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeBalancePushUniqueOrderByLevel( Vec_Ptr_t * vStore, Ivy_Obj_t * pObj )
+{
+    Ivy_Obj_t * pObj1, * pObj2;
+    int i;
+    if ( Vec_PtrPushUnique(vStore, pObj) )
+        return;
+    // find the p of the node
+    for ( i = vStore->nSize-1; i > 0; i-- )
+    {
+        pObj1 = vStore->pArray[i  ];
+        pObj2 = vStore->pArray[i-1];
+        if ( Ivy_Regular(pObj1)->Level <= Ivy_Regular(pObj2)->Level )
+            break;
+        vStore->pArray[i  ] = pObj2;
+        vStore->pArray[i-1] = pObj1;
+    }
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyCanon.c b/src/aig/ivy/ivyCanon.c
new file mode 100644
index 00000000..5768b87e
--- /dev/null
+++ b/src/aig/ivy/ivyCanon.c
@@ -0,0 +1,144 @@
+/**CFile****************************************************************
+
+  FileName    [ivyCanon.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Finding canonical form of objects.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyCanon.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static Ivy_Obj_t * Ivy_TableLookupPair_rec( Ivy_Man_t * p, Ivy_Obj_t * pObj0, Ivy_Obj_t * pObj1, int fCompl0, int fCompl1, Ivy_Type_t Type );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the canonical form of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_CanonPair_rec( Ivy_Man_t * p, Ivy_Obj_t * pGhost )
+{
+    Ivy_Obj_t * pResult, * pLat0, * pLat1;
+    Ivy_Init_t Init, Init0, Init1;
+    int fCompl0, fCompl1;
+    Ivy_Type_t Type;
+    assert( Ivy_ObjIsNode(pGhost) );
+    assert( Ivy_ObjIsAnd(pGhost) || (!Ivy_ObjFaninC0(pGhost) && !Ivy_ObjFaninC1(pGhost)) );
+    assert( Ivy_ObjFaninId0(pGhost) != 0 && Ivy_ObjFaninId1(pGhost) != 0 );
+    // consider the case when the pair is canonical
+    if ( !Ivy_ObjIsLatch(Ivy_ObjFanin0(pGhost)) || !Ivy_ObjIsLatch(Ivy_ObjFanin1(pGhost)) )
+    {
+        if ( pResult = Ivy_TableLookup( p, pGhost ) )
+            return pResult;
+        return Ivy_ObjCreate( p, pGhost );
+    }
+    /// remember the latches
+    pLat0 = Ivy_ObjFanin0(pGhost);
+    pLat1 = Ivy_ObjFanin1(pGhost);
+    // remember type and compls
+    Type = Ivy_ObjType(pGhost);
+    fCompl0 = Ivy_ObjFaninC0(pGhost);
+    fCompl1 = Ivy_ObjFaninC1(pGhost);
+    // call recursively
+    pResult = Ivy_Oper( p, Ivy_NotCond(Ivy_ObjFanin0(pLat0), fCompl0), Ivy_NotCond(Ivy_ObjFanin0(pLat1), fCompl1), Type );
+    // build latch on top of this
+    Init0 = Ivy_InitNotCond( Ivy_ObjInit(pLat0), fCompl0 );
+    Init1 = Ivy_InitNotCond( Ivy_ObjInit(pLat1), fCompl1 );
+    Init  = (Type == IVY_AND)? Ivy_InitAnd(Init0, Init1) : Ivy_InitExor(Init0, Init1);
+    return Ivy_Latch( p, pResult, Init );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the canonical form of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_CanonAnd( Ivy_Man_t * p, Ivy_Obj_t * pObj0, Ivy_Obj_t * pObj1 )
+{
+    Ivy_Obj_t * pGhost, * pResult;
+    pGhost = Ivy_ObjCreateGhost( p, pObj0, pObj1, IVY_AND, IVY_INIT_NONE );
+    pResult = Ivy_CanonPair_rec( p, pGhost );
+    return pResult;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the canonical form of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_CanonExor( Ivy_Man_t * p, Ivy_Obj_t * pObj0, Ivy_Obj_t * pObj1 )
+{
+    Ivy_Obj_t * pGhost, * pResult;
+    int fCompl = Ivy_IsComplement(pObj0) ^ Ivy_IsComplement(pObj1);
+    pObj0 = Ivy_Regular(pObj0);
+    pObj1 = Ivy_Regular(pObj1);
+    pGhost = Ivy_ObjCreateGhost( p, pObj0, pObj1, IVY_EXOR, IVY_INIT_NONE );
+    pResult = Ivy_CanonPair_rec( p, pGhost );
+    return Ivy_NotCond( pResult, fCompl );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the canonical form of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_CanonLatch( Ivy_Man_t * p, Ivy_Obj_t * pObj, Ivy_Init_t Init )
+{
+    Ivy_Obj_t * pGhost, * pResult;
+    int fCompl = Ivy_IsComplement(pObj);
+    pObj = Ivy_Regular(pObj);
+    pGhost = Ivy_ObjCreateGhost( p, pObj, NULL, IVY_LATCH, Ivy_InitNotCond(Init, fCompl) );
+    pResult = Ivy_TableLookup( p, pGhost );
+    if ( pResult == NULL )
+        pResult = Ivy_ObjCreate( p, pGhost );
+    return Ivy_NotCond( pResult, fCompl );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyCheck.c b/src/aig/ivy/ivyCheck.c
new file mode 100644
index 00000000..55448f19
--- /dev/null
+++ b/src/aig/ivy/ivyCheck.c
@@ -0,0 +1,273 @@
+/**CFile****************************************************************
+
+  FileName    [ivyCheck.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [AIG checking procedures.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyCheck.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Checks the consistency of the AIG manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManCheck( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj, * pObj2;
+    int i;
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        // skip deleted nodes
+        if ( Ivy_ObjId(pObj) != i )
+        {
+            printf( "Ivy_ManCheck: Node with ID %d is listed as number %d in the array of objects.\n", pObj->Id, i );
+            return 0;
+        }
+        // consider the constant node and PIs
+        if ( i == 0 || Ivy_ObjIsPi(pObj) )
+        {
+            if ( Ivy_ObjFaninId0(pObj) || Ivy_ObjFaninId1(pObj) || Ivy_ObjLevel(pObj) )
+            {
+                printf( "Ivy_ManCheck: The AIG has non-standard constant or PI node with ID \"%d\".\n", pObj->Id );
+                return 0;
+            }
+            continue;
+        }
+        if ( Ivy_ObjIsPo(pObj) )
+        {
+            if ( Ivy_ObjFaninId1(pObj) )
+            {
+                printf( "Ivy_ManCheck: The AIG has non-standard PO node with ID \"%d\".\n", pObj->Id );
+                return 0;
+            }
+            continue;
+        }
+        if ( Ivy_ObjIsBuf(pObj) )
+        {
+            if ( Ivy_ObjFanin1(pObj) )
+            {
+                printf( "Ivy_ManCheck: The buffer with ID \"%d\" contains second fanin.\n", pObj->Id );
+                return 0;
+            }
+            continue;
+        }
+        if ( Ivy_ObjIsLatch(pObj) )
+        {
+            if ( Ivy_ObjFanin1(pObj) )
+            {
+                printf( "Ivy_ManCheck: The latch with ID \"%d\" contains second fanin.\n", pObj->Id );
+                return 0;
+            }
+            if ( Ivy_ObjInit(pObj) == IVY_INIT_NONE )
+            {
+                printf( "Ivy_ManCheck: The latch with ID \"%d\" does not have initial state.\n", pObj->Id );
+                return 0;
+            }
+            pObj2 = Ivy_TableLookup( p, pObj );
+            if ( pObj2 != pObj )
+                printf( "Ivy_ManCheck: Latch with ID \"%d\" is not in the structural hashing table.\n", pObj->Id );
+                continue;
+        }
+        // consider the AND node
+        if ( !Ivy_ObjFanin0(pObj) || !Ivy_ObjFanin1(pObj) )
+        {
+            printf( "Ivy_ManCheck: The AIG has internal node \"%d\" with a NULL fanin.\n", pObj->Id );
+            return 0;
+        }
+        if ( Ivy_ObjFaninId0(pObj) >= Ivy_ObjFaninId1(pObj) )
+        {
+            printf( "Ivy_ManCheck: The AIG has node \"%d\" with a wrong ordering of fanins.\n", pObj->Id );
+            return 0;
+        }
+        if ( Ivy_ObjLevel(pObj) != Ivy_ObjLevelNew(pObj) )
+            printf( "Ivy_ManCheck: Node with ID \"%d\" has level %d but should have level %d.\n", pObj->Id, Ivy_ObjLevel(pObj), Ivy_ObjLevelNew(pObj) );
+        pObj2 = Ivy_TableLookup( p, pObj );
+        if ( pObj2 != pObj )
+            printf( "Ivy_ManCheck: Node with ID \"%d\" is not in the structural hashing table.\n", pObj->Id );
+        if ( Ivy_ObjRefs(pObj) == 0 )
+            printf( "Ivy_ManCheck: Node with ID \"%d\" has no fanouts.\n", pObj->Id );
+        // check fanouts
+        if ( p->fFanout && Ivy_ObjRefs(pObj) != Ivy_ObjFanoutNum(p, pObj) )
+            printf( "Ivy_ManCheck: Node with ID \"%d\" has mismatch between the number of fanouts and refs.\n", pObj->Id );
+    }
+    // count the number of nodes in the table
+    if ( Ivy_TableCountEntries(p) != Ivy_ManAndNum(p) + Ivy_ManExorNum(p) + Ivy_ManLatchNum(p) )
+    {
+        printf( "Ivy_ManCheck: The number of nodes in the structural hashing table is wrong.\n" );
+        return 0;
+    }
+//    if ( !Ivy_ManCheckFanouts(p) )
+//        return 0;
+    if ( !Ivy_ManIsAcyclic(p) )
+        return 0;
+    return 1; 
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Verifies the fanouts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManCheckFanoutNums( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i, Counter = 0;
+    Ivy_ManForEachObj( p, pObj, i )
+        if ( Ivy_ObjIsNode(pObj) )
+            Counter += (Ivy_ObjRefs(pObj) == 0);
+    if ( Counter )
+        printf( "Sequential AIG has %d dangling nodes.\n", Counter );
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Verifies the fanouts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManCheckFanouts( Ivy_Man_t * p )
+{
+    Vec_Ptr_t * vFanouts;
+    Ivy_Obj_t * pObj, * pFanout, * pFanin;
+    int i, k, RetValue = 1;
+    if ( !p->fFanout )
+        return 1;
+    vFanouts = Vec_PtrAlloc( 100 );
+    // make sure every fanin is a fanout
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        pFanin = Ivy_ObjFanin0(pObj);
+        if ( pFanin == NULL )
+            continue;
+        Ivy_ObjForEachFanout( p, pFanin, vFanouts, pFanout, k )
+            if ( pFanout == pObj )
+                break;
+        if ( k == Vec_PtrSize(vFanouts) )
+        {
+            printf( "Node %d is a fanin of node %d but the fanout is not there.\n", pFanin->Id, pObj->Id );
+            RetValue = 0;
+        }
+
+        pFanin = Ivy_ObjFanin1(pObj);
+        if ( pFanin == NULL )
+            continue;
+        Ivy_ObjForEachFanout( p, pFanin, vFanouts, pFanout, k )
+            if ( pFanout == pObj )
+                break;
+        if ( k == Vec_PtrSize(vFanouts) )
+        {
+            printf( "Node %d is a fanin of node %d but the fanout is not there.\n", pFanin->Id, pObj->Id );
+            RetValue = 0;
+        }
+        // check that the previous fanout has the same fanin
+        if ( pObj->pPrevFan0 )
+        {
+            if ( Ivy_ObjFanin0(pObj->pPrevFan0) != Ivy_ObjFanin0(pObj) && 
+                 Ivy_ObjFanin0(pObj->pPrevFan0) != Ivy_ObjFanin1(pObj) && 
+                 Ivy_ObjFanin1(pObj->pPrevFan0) != Ivy_ObjFanin0(pObj) && 
+                 Ivy_ObjFanin1(pObj->pPrevFan0) != Ivy_ObjFanin1(pObj) )
+            {
+                printf( "Node %d has prev %d without common fanin.\n", pObj->Id, pObj->pPrevFan0->Id );
+                RetValue = 0;
+            }
+        }
+        // check that the previous fanout has the same fanin
+        if ( pObj->pPrevFan1 )
+        {
+            if ( Ivy_ObjFanin0(pObj->pPrevFan1) != Ivy_ObjFanin0(pObj) && 
+                 Ivy_ObjFanin0(pObj->pPrevFan1) != Ivy_ObjFanin1(pObj) && 
+                 Ivy_ObjFanin1(pObj->pPrevFan1) != Ivy_ObjFanin0(pObj) && 
+                 Ivy_ObjFanin1(pObj->pPrevFan1) != Ivy_ObjFanin1(pObj) )
+            {
+                printf( "Node %d has prev %d without common fanin.\n", pObj->Id, pObj->pPrevFan1->Id );
+                RetValue = 0;
+            }
+        }
+    }
+    // make sure every fanout is a fanin
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        Ivy_ObjForEachFanout( p, pObj, vFanouts, pFanout, k )
+            if ( Ivy_ObjFanin0(pFanout) != pObj && Ivy_ObjFanin1(pFanout) != pObj )
+            {
+                printf( "Node %d is a fanout of node %d but the fanin is not there.\n", pFanout->Id, pObj->Id );
+                RetValue = 0;
+            }
+    }
+    Vec_PtrFree( vFanouts );
+    return RetValue;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Checks that each choice node has exactly one node with fanouts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManCheckChoices( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj, * pTemp;
+    int i;
+    Ivy_ManForEachObj( p->pHaig, pObj, i )
+    {
+        if ( Ivy_ObjRefs(pObj) == 0 )
+            continue;
+        // count the number of nodes in the loop
+        assert( !Ivy_IsComplement(pObj->pEquiv) );
+        for ( pTemp = pObj->pEquiv; pTemp && pTemp != pObj; pTemp = Ivy_Regular(pTemp->pEquiv) )
+            if ( Ivy_ObjRefs(pTemp) > 1 )
+                printf( "Node %d has member %d in its equiv class with %d fanouts.\n", pObj->Id, pTemp->Id, Ivy_ObjRefs(pTemp) );
+    }
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyCut.c b/src/aig/ivy/ivyCut.c
new file mode 100644
index 00000000..e257d8a6
--- /dev/null
+++ b/src/aig/ivy/ivyCut.c
@@ -0,0 +1,989 @@
+/**CFile****************************************************************
+
+  FileName    [ivyCut.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Computes reconvergence driven sequential cut.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyCut.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static inline int Ivy_NodeCutHashValue( int NodeId )  { return 1 << (NodeId % 31); }
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Evaluate the cost of removing the node from the set of leaves.]
+
+  Description [Returns the number of new leaves that will be brought in.
+  Returns large number if the node cannot be removed from the set of leaves.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Ivy_NodeGetLeafCostOne( Ivy_Man_t * p, int Leaf, Vec_Int_t * vInside )
+{
+    Ivy_Obj_t * pNode;
+    int nLatches, FaninLeaf, Cost;
+    // make sure leaf is not a contant node
+    assert( Leaf > 0 ); 
+    // get the node
+    pNode = Ivy_ManObj( p, Ivy_LeafId(Leaf) );
+    // cannot expand over the PI node
+    if ( Ivy_ObjIsPi(pNode) || Ivy_ObjIsConst1(pNode) )
+        return 999;
+    // get the number of latches
+    nLatches = Ivy_LeafLat(Leaf) + Ivy_ObjIsLatch(pNode);
+    if ( nLatches > 15 )
+        return 999;
+    // get the first fanin
+    FaninLeaf = Ivy_LeafCreate( Ivy_ObjFaninId0(pNode), nLatches );
+    Cost = FaninLeaf && (Vec_IntFind(vInside, FaninLeaf) == -1);
+    // quit if this is the one fanin node
+    if ( Ivy_ObjIsLatch(pNode) || Ivy_ObjIsBuf(pNode) )
+        return Cost;
+    assert( Ivy_ObjIsNode(pNode) );
+    // get the second fanin
+    FaninLeaf = Ivy_LeafCreate( Ivy_ObjFaninId1(pNode), nLatches );
+    Cost += FaninLeaf && (Vec_IntFind(vInside, FaninLeaf) == -1);
+    return Cost;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Builds reconvergence-driven cut by changing one leaf at a time.]
+
+  Description [This procedure looks at the current leaves and tries to change 
+  one leaf at a time in such a way that the cut grows as little as possible.
+  In evaluating the fanins, this procedure looks only at their immediate 
+  predecessors (this is why it is called a one-level construction procedure).]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManSeqFindCut_int( Ivy_Man_t * p, Vec_Int_t * vFront, Vec_Int_t * vInside, int nSizeLimit )
+{
+    Ivy_Obj_t * pNode;
+    int CostBest, CostCur, Leaf, LeafBest, Next, nLatches, i;
+    int LeavesBest[10];
+    int Counter;
+
+    // add random selection of the best fanin!!!
+
+    // find the best fanin
+    CostBest = 99;
+    LeafBest = -1;
+    Counter = -1;
+//printf( "Evaluating fanins of the cut:\n" );
+    Vec_IntForEachEntry( vFront, Leaf, i )
+    {
+        CostCur = Ivy_NodeGetLeafCostOne( p, Leaf, vInside );
+//printf( "    Fanin %s has cost %d.\n", Ivy_ObjName(pNode), CostCur );
+        if ( CostBest > CostCur )
+        {
+            CostBest = CostCur;
+            LeafBest = Leaf;
+            LeavesBest[0] = Leaf;
+            Counter = 1;
+        }
+        else if ( CostBest == CostCur )
+            LeavesBest[Counter++] = Leaf;
+
+        if ( CostBest <= 1 ) // can be if ( CostBest <= 1 )
+            break;
+    }
+    if ( CostBest == 99 )
+        return 0;
+//        return Ivy_NodeBuildCutLevelTwo_int( vInside, vFront, nFaninLimit );
+
+    assert( CostBest < 3 );
+    if ( Vec_IntSize(vFront) - 1 + CostBest > nSizeLimit )
+        return 0;
+//        return Ivy_NodeBuildCutLevelTwo_int( vInside, vFront, nFaninLimit );
+
+    assert( Counter > 0 );
+printf( "%d", Counter );
+
+    LeafBest = LeavesBest[rand() % Counter];
+
+    // remove the node from the array
+    assert( LeafBest >= 0 );
+    Vec_IntRemove( vFront, LeafBest );
+//printf( "Removing fanin %s.\n", Ivy_ObjName(pNode) );
+
+    // get the node and its latches
+    pNode = Ivy_ManObj( p, Ivy_LeafId(LeafBest) );
+    nLatches = Ivy_LeafLat(LeafBest) + Ivy_ObjIsLatch(pNode);
+    assert( Ivy_ObjIsNode(pNode) || Ivy_ObjIsLatch(pNode) || Ivy_ObjIsBuf(pNode) );
+
+    // add the left child to the fanins
+    Next = Ivy_LeafCreate( Ivy_ObjFaninId0(pNode), nLatches );
+    if ( Next && Vec_IntFind(vInside, Next) == -1 )
+    {
+//printf( "Adding fanin %s.\n", Ivy_ObjName(pNext) );
+        Vec_IntPush( vFront, Next );
+        Vec_IntPush( vInside, Next );
+    }
+
+    // quit if this is the one fanin node
+    if ( Ivy_ObjIsLatch(pNode) || Ivy_ObjIsBuf(pNode) )
+        return 1;
+    assert( Ivy_ObjIsNode(pNode) );
+
+    // add the right child to the fanins
+    Next = Ivy_LeafCreate( Ivy_ObjFaninId1(pNode), nLatches );
+    if ( Next && Vec_IntFind(vInside, Next) == -1 )
+    {
+//printf( "Adding fanin %s.\n", Ivy_ObjName(pNext) );
+        Vec_IntPush( vFront, Next );
+        Vec_IntPush( vInside, Next );
+    }
+    assert( Vec_IntSize(vFront) <= nSizeLimit );
+    // keep doing this
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes one sequential cut of the given size.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManSeqFindCut( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Vec_Int_t * vFront, Vec_Int_t * vInside, int nSize )
+{
+    assert( !Ivy_IsComplement(pRoot) );
+    assert( Ivy_ObjIsNode(pRoot) );
+    assert( Ivy_ObjFaninId0(pRoot) );
+    assert( Ivy_ObjFaninId1(pRoot) );
+
+    // start the cut 
+    Vec_IntClear( vFront );
+    Vec_IntPush( vFront, Ivy_LeafCreate(Ivy_ObjFaninId0(pRoot), 0) );
+    Vec_IntPush( vFront, Ivy_LeafCreate(Ivy_ObjFaninId1(pRoot), 0) );
+
+    // start the visited nodes
+    Vec_IntClear( vInside );
+    Vec_IntPush( vInside, Ivy_LeafCreate(pRoot->Id, 0) );
+    Vec_IntPush( vInside, Ivy_LeafCreate(Ivy_ObjFaninId0(pRoot), 0) );
+    Vec_IntPush( vInside, Ivy_LeafCreate(Ivy_ObjFaninId1(pRoot), 0) );
+
+    // compute the cut
+    while ( Ivy_ManSeqFindCut_int( p, vFront, vInside, nSize ) );
+    assert( Vec_IntSize(vFront) <= nSize );
+}
+
+
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computing Boolean cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManFindBoolCut_rec( Ivy_Man_t * p, Ivy_Obj_t * pObj, Vec_Ptr_t * vLeaves, Vec_Ptr_t * vVolume, Ivy_Obj_t * pPivot )
+{
+    int RetValue0, RetValue1;
+    if ( pObj == pPivot )
+    {
+        Vec_PtrPushUnique( vLeaves, pObj );
+        Vec_PtrPushUnique( vVolume, pObj );
+        return 1;        
+    }
+    if ( pObj->fMarkA )
+        return 0;
+
+//    assert( !Ivy_ObjIsCi(pObj) );
+    if ( Ivy_ObjIsCi(pObj) )
+        return 0;
+
+    if ( Ivy_ObjIsBuf(pObj) )
+    {
+        RetValue0 = Ivy_ManFindBoolCut_rec( p, Ivy_ObjFanin0(pObj), vLeaves, vVolume, pPivot );
+        if ( !RetValue0 )
+            return 0;
+        Vec_PtrPushUnique( vVolume, pObj );
+        return 1;
+    }
+    assert( Ivy_ObjIsNode(pObj) );
+    RetValue0 = Ivy_ManFindBoolCut_rec( p, Ivy_ObjFanin0(pObj), vLeaves, vVolume, pPivot );
+    RetValue1 = Ivy_ManFindBoolCut_rec( p, Ivy_ObjFanin1(pObj), vLeaves, vVolume, pPivot );
+    if ( !RetValue0 && !RetValue1 )
+        return 0;
+    // add new leaves
+    if ( !RetValue0 )
+    {
+        Vec_PtrPushUnique( vLeaves, Ivy_ObjFanin0(pObj) );
+        Vec_PtrPushUnique( vVolume, Ivy_ObjFanin0(pObj) );
+    }
+    if ( !RetValue1 )
+    {
+        Vec_PtrPushUnique( vLeaves, Ivy_ObjFanin1(pObj) );
+        Vec_PtrPushUnique( vVolume, Ivy_ObjFanin1(pObj) );
+    }
+    Vec_PtrPushUnique( vVolume, pObj );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the cost of one node (how many new nodes are added.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManFindBoolCutCost( Ivy_Obj_t * pObj )
+{
+    int Cost;
+    // make sure the node is in the construction zone
+    assert( pObj->fMarkA == 1 );  
+    // cannot expand over the PI node
+    if ( Ivy_ObjIsCi(pObj) )
+        return 999;
+    // always expand over the buffer
+    if ( Ivy_ObjIsBuf(pObj) )
+        return !Ivy_ObjFanin0(pObj)->fMarkA;
+    // get the cost of the cone
+    Cost = (!Ivy_ObjFanin0(pObj)->fMarkA) + (!Ivy_ObjFanin1(pObj)->fMarkA);
+    // return the number of nodes to be added to the leaves if this node is removed
+    return Cost;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computing Boolean cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManFindBoolCut( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Vec_Ptr_t * vFront, Vec_Ptr_t * vVolume, Vec_Ptr_t * vLeaves )
+{
+    Ivy_Obj_t * pObj, * pFaninC, * pFanin0, * pFanin1, * pPivot;
+    int RetValue, LevelLimit, Lev, k;
+    assert( !Ivy_IsComplement(pRoot) );
+    // clear the frontier and collect the nodes
+    Vec_PtrClear( vFront );
+    Vec_PtrClear( vVolume );
+    if ( Ivy_ObjIsMuxType(pRoot) )
+        pFaninC = Ivy_ObjRecognizeMux( pRoot, &pFanin0, &pFanin1 );
+    else
+    {
+        pFaninC = NULL;
+        pFanin0 = Ivy_ObjFanin0(pRoot);
+        pFanin1 = Ivy_ObjFanin1(pRoot); 
+    }
+    // start cone A
+    pFanin0->fMarkA = 1;
+    Vec_PtrPush( vFront, pFanin0 );
+    Vec_PtrPush( vVolume, pFanin0 );
+    // start cone B
+    pFanin1->fMarkB = 1;
+    Vec_PtrPush( vFront, pFanin1 );
+    Vec_PtrPush( vVolume, pFanin1 );
+    // iteratively expand until the common node (pPivot) is found or limit is reached
+    assert( Ivy_ObjLevel(pRoot) == Ivy_ObjLevelNew(pRoot) );
+    pPivot = NULL;
+    LevelLimit = IVY_MAX( Ivy_ObjLevel(pRoot) - 10, 1 );
+    for ( Lev = Ivy_ObjLevel(pRoot) - 1; Lev >= LevelLimit; Lev-- )
+    {
+        while ( 1 )
+        {
+            // find the next node to expand on this level
+            Vec_PtrForEachEntry( vFront, pObj, k )
+                if ( (int)pObj->Level == Lev )
+                    break;
+            if ( k == Vec_PtrSize(vFront) )
+                break;
+            assert( (int)pObj->Level <= Lev );
+            assert( pObj->fMarkA ^ pObj->fMarkB );
+            // remove the old node
+            Vec_PtrRemove( vFront, pObj );
+
+            // expand this node
+            pFanin0 = Ivy_ObjFanin0(pObj);
+            if ( !pFanin0->fMarkA && !pFanin0->fMarkB )
+            {
+                Vec_PtrPush( vFront, pFanin0 );
+                Vec_PtrPush( vVolume, pFanin0 );
+            }
+            // mark the new nodes
+            if ( pObj->fMarkA )
+                pFanin0->fMarkA = 1; 
+            if ( pObj->fMarkB )
+                pFanin0->fMarkB = 1; 
+
+            if ( Ivy_ObjIsBuf(pObj) )
+            {
+                if ( pFanin0->fMarkA && pFanin0->fMarkB )
+                {
+                    pPivot = pFanin0;
+                    break;
+                }
+                continue;
+            }
+
+            // expand this node
+            pFanin1 = Ivy_ObjFanin1(pObj); 
+            if ( !pFanin1->fMarkA && !pFanin1->fMarkB )
+            {
+                Vec_PtrPush( vFront, pFanin1 );
+                Vec_PtrPush( vVolume, pFanin1 );
+            }
+            // mark the new nodes
+            if ( pObj->fMarkA )
+                pFanin1->fMarkA = 1; 
+            if ( pObj->fMarkB )
+                pFanin1->fMarkB = 1; 
+
+            // consider if it is time to quit
+            if ( pFanin0->fMarkA && pFanin0->fMarkB )
+            {
+                pPivot = pFanin0;
+                break;
+            }
+            if ( pFanin1->fMarkA && pFanin1->fMarkB )
+            {
+                pPivot = pFanin1;
+                break;
+            }
+        }
+        if ( pPivot != NULL )
+            break;
+    }
+    if ( pPivot == NULL )
+        return 0;
+    // if the MUX control is defined, it should not be
+    if ( pFaninC && !pFaninC->fMarkA && !pFaninC->fMarkB )
+        Vec_PtrPush( vFront, pFaninC );
+    // clean the markings
+    Vec_PtrForEachEntry( vVolume, pObj, k )
+        pObj->fMarkA = pObj->fMarkB = 0;
+
+    // mark the nodes on the frontier (including the pivot)
+    Vec_PtrForEachEntry( vFront, pObj, k )
+        pObj->fMarkA = 1;
+    // cut exists, collect all the nodes on the shortest path to the pivot
+    Vec_PtrClear( vLeaves );
+    Vec_PtrClear( vVolume );
+    RetValue = Ivy_ManFindBoolCut_rec( p, pRoot, vLeaves, vVolume, pPivot );
+    assert( RetValue == 1 );
+    // unmark the nodes on the frontier (including the pivot)
+    Vec_PtrForEachEntry( vFront, pObj, k )
+        pObj->fMarkA = 0;
+
+    // mark the nodes in the volume
+    Vec_PtrForEachEntry( vVolume, pObj, k )
+        pObj->fMarkA = 1;
+    // expand the cut without increasing its size
+    while ( 1 )
+    {
+        Vec_PtrForEachEntry( vLeaves, pObj, k )
+            if ( Ivy_ManFindBoolCutCost(pObj) < 2 )
+                break;
+        if ( k == Vec_PtrSize(vLeaves) )
+            break;
+        // the node can be expanded
+        // remove the old node
+        Vec_PtrRemove( vLeaves, pObj );
+        // expand this node
+        pFanin0 = Ivy_ObjFanin0(pObj);
+        if ( !pFanin0->fMarkA )
+        {
+            pFanin0->fMarkA = 1;
+            Vec_PtrPush( vVolume, pFanin0 );
+            Vec_PtrPush( vLeaves, pFanin0 );
+        }
+        if ( Ivy_ObjIsBuf(pObj) )
+            continue;
+        // expand this node
+        pFanin1 = Ivy_ObjFanin1(pObj);
+        if ( !pFanin1->fMarkA )
+        {
+            pFanin1->fMarkA = 1;
+            Vec_PtrPush( vVolume, pFanin1 );
+            Vec_PtrPush( vLeaves, pFanin1 );
+        }        
+    }
+    // unmark the nodes in the volume
+    Vec_PtrForEachEntry( vVolume, pObj, k )
+        pObj->fMarkA = 0;
+    return 1;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManTestCutsBool( Ivy_Man_t * p )
+{
+    Vec_Ptr_t * vFront, * vVolume, * vLeaves;
+    Ivy_Obj_t * pObj;//, * pTemp;
+    int i, RetValue;//, k;
+    vFront = Vec_PtrAlloc( 100 );
+    vVolume = Vec_PtrAlloc( 100 );
+    vLeaves = Vec_PtrAlloc( 100 );
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        if ( !Ivy_ObjIsNode(pObj) )
+            continue;
+        if ( Ivy_ObjIsMuxType(pObj) )
+        {
+            printf( "m" );
+            continue;
+        }
+        if ( Ivy_ObjIsExor(pObj) )
+            printf( "x" );
+        RetValue = Ivy_ManFindBoolCut( p, pObj, vFront, vVolume, vLeaves );
+        if ( RetValue == 0 )
+            printf( "- " );
+        else
+            printf( "%d ", Vec_PtrSize(vLeaves) );
+/*        
+        printf( "( " );
+        Vec_PtrForEachEntry( vFront, pTemp, k )
+            printf( "%d ", Ivy_ObjRefs(Ivy_Regular(pTemp)) );
+        printf( ")\n" );
+*/
+    }
+    printf( "\n" );
+    Vec_PtrFree( vFront );
+    Vec_PtrFree( vVolume );
+    Vec_PtrFree( vLeaves );
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Find the hash value of the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline unsigned Ivy_NodeCutHash( Ivy_Cut_t * pCut )
+{
+    int i;
+//    for ( i = 1; i < pCut->nSize; i++ )
+//        assert( pCut->pArray[i-1] < pCut->pArray[i] );
+    pCut->uHash = 0;
+    for ( i = 0; i < pCut->nSize; i++ )
+        pCut->uHash |= (1 << (pCut->pArray[i] % 31));
+    return pCut->uHash;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Removes one node to the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Ivy_NodeCutShrink( Ivy_Cut_t * pCut, int iOld )
+{
+    int i, k;
+    for ( i = k = 0; i < pCut->nSize; i++ )
+        if ( pCut->pArray[i] != iOld )
+            pCut->pArray[k++] = pCut->pArray[i];
+    assert( k == pCut->nSize - 1 );
+    pCut->nSize--;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node to the cut.]
+
+  Description [Returns 1 if the cuts is still okay.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Ivy_NodeCutExtend( Ivy_Cut_t * pCut, int iNew )
+{
+    int i;
+    for ( i = 0; i < pCut->nSize; i++ )
+        if ( pCut->pArray[i] == iNew )
+            return 1;
+    // check if there is room
+    if ( pCut->nSize == pCut->nSizeMax )
+        return 0;
+    // add the new one
+    for ( i = pCut->nSize - 1; i >= 0; i-- )
+        if ( pCut->pArray[i] > iNew )
+            pCut->pArray[i+1] = pCut->pArray[i];
+        else
+        {
+            assert( pCut->pArray[i] < iNew );
+            break;
+        }
+    pCut->pArray[i+1] = iNew;
+    pCut->nSize++;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the cut can be constructed; 0 otherwise.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Ivy_NodeCutPrescreen( Ivy_Cut_t * pCut, int Id0, int Id1 )
+{
+    int i;
+    if ( pCut->nSize < pCut->nSizeMax )
+        return 1;
+    for ( i = 0; i < pCut->nSize; i++ )
+        if ( pCut->pArray[i] == Id0 || pCut->pArray[i] == Id1 )
+            return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Derives new cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Ivy_NodeCutDeriveNew( Ivy_Cut_t * pCut, Ivy_Cut_t * pCutNew, int IdOld, int IdNew0, int IdNew1 )
+{
+    unsigned uHash = 0;
+    int i, k; 
+    assert( pCut->nSize > 0 );
+    assert( IdNew0 < IdNew1 );
+    for ( i = k = 0; i < pCut->nSize; i++ )
+    {
+        if ( pCut->pArray[i] == IdOld )
+            continue;
+        if ( IdNew0 <= pCut->pArray[i] )
+        {
+            if ( IdNew0 < pCut->pArray[i] )
+            {
+                pCutNew->pArray[ k++ ] = IdNew0;
+                uHash |= Ivy_NodeCutHashValue( IdNew0 );
+            }
+            IdNew0 = 0x7FFFFFFF;
+        }
+        if ( IdNew1 <= pCut->pArray[i] )
+        {
+            if ( IdNew1 < pCut->pArray[i] )
+            {
+                pCutNew->pArray[ k++ ] = IdNew1;
+                uHash |= Ivy_NodeCutHashValue( IdNew1 );
+            }
+            IdNew1 = 0x7FFFFFFF;
+        }
+        pCutNew->pArray[ k++ ] = pCut->pArray[i];
+        uHash |= Ivy_NodeCutHashValue( pCut->pArray[i] );
+    }
+    if ( IdNew0 < 0x7FFFFFFF )
+    {
+        pCutNew->pArray[ k++ ] = IdNew0;
+        uHash |= Ivy_NodeCutHashValue( IdNew0 );
+    }
+    if ( IdNew1 < 0x7FFFFFFF )
+    {
+        pCutNew->pArray[ k++ ] = IdNew1;
+        uHash |= Ivy_NodeCutHashValue( IdNew1 );
+    }
+    pCutNew->nSize = k;
+    pCutNew->uHash = uHash;
+    assert( pCutNew->nSize <= pCut->nSizeMax );
+//    for ( i = 1; i < pCutNew->nSize; i++ )
+//        assert( pCutNew->pArray[i-1] < pCutNew->pArray[i] );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Check if the cut exists.]
+
+  Description [Returns 1 if the cut exists.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeCutFindOrAdd( Ivy_Store_t * pCutStore, Ivy_Cut_t * pCutNew )
+{
+    Ivy_Cut_t * pCut;
+    int i, k;
+    assert( pCutNew->uHash );
+    // try to find the cut
+    for ( i = 0; i < pCutStore->nCuts; i++ )
+    {
+        pCut = pCutStore->pCuts + i;
+        if ( pCut->uHash == pCutNew->uHash && pCut->nSize == pCutNew->nSize )
+        {
+            for ( k = 0; k < pCutNew->nSize; k++ )
+                if ( pCut->pArray[k] != pCutNew->pArray[k] )
+                    break;
+            if ( k == pCutNew->nSize )
+                return 1;
+        }
+    }
+    assert( pCutStore->nCuts < pCutStore->nCutsMax );
+    // add the cut
+    pCut = pCutStore->pCuts + pCutStore->nCuts++;
+    *pCut = *pCutNew;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if pDom is contained in pCut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Ivy_CutCheckDominance( Ivy_Cut_t * pDom, Ivy_Cut_t * pCut )
+{
+    int i, k;
+    for ( i = 0; i < pDom->nSize; i++ )
+    {
+        for ( k = 0; k < pCut->nSize; k++ )
+            if ( pDom->pArray[i] == pCut->pArray[k] )
+                break;
+        if ( k == pCut->nSize ) // node i in pDom is not contained in pCut
+            return 0;
+    }
+    // every node in pDom is contained in pCut
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Check if the cut exists.]
+
+  Description [Returns 1 if the cut exists.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeCutFindOrAddFilter( Ivy_Store_t * pCutStore, Ivy_Cut_t * pCutNew )
+{
+    Ivy_Cut_t * pCut;
+    int i, k;
+    assert( pCutNew->uHash );
+    // try to find the cut
+    for ( i = 0; i < pCutStore->nCuts; i++ )
+    {
+        pCut = pCutStore->pCuts + i;
+        if ( pCut->nSize == 0 )
+            continue;
+        if ( pCut->nSize == pCutNew->nSize )
+        {
+            if ( pCut->uHash == pCutNew->uHash )
+            {
+                for ( k = 0; k < pCutNew->nSize; k++ )
+                    if ( pCut->pArray[k] != pCutNew->pArray[k] )
+                        break;
+                if ( k == pCutNew->nSize )
+                    return 1;
+            }
+            continue;
+        }
+        if ( pCut->nSize < pCutNew->nSize )
+        {
+            // skip the non-contained cuts
+            if ( (pCut->uHash & pCutNew->uHash) != pCut->uHash )
+                continue;
+            // check containment seriously
+            if ( Ivy_CutCheckDominance( pCut, pCutNew ) )
+                return 1;
+            continue;
+        }
+        // check potential containment of other cut
+
+        // skip the non-contained cuts
+        if ( (pCut->uHash & pCutNew->uHash) != pCutNew->uHash )
+            continue;
+        // check containment seriously
+        if ( Ivy_CutCheckDominance( pCutNew, pCut ) )
+        {
+            // remove the current cut
+//            --pCutStore->nCuts;
+//            for ( k = i; k < pCutStore->nCuts; k++ )
+//                pCutStore->pCuts[k] = pCutStore->pCuts[k+1];
+//            i--;
+            pCut->nSize = 0;
+        }
+    }
+    assert( pCutStore->nCuts < pCutStore->nCutsMax );
+    // add the cut
+    pCut = pCutStore->pCuts + pCutStore->nCuts++;
+    *pCut = *pCutNew;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Print the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeCompactCuts( Ivy_Store_t * pCutStore )
+{
+    Ivy_Cut_t * pCut;
+    int i, k;
+    for ( i = k = 0; i < pCutStore->nCuts; i++ )
+    {
+        pCut = pCutStore->pCuts + i;
+        if ( pCut->nSize == 0 )
+            continue;
+        pCutStore->pCuts[k++] = *pCut;
+    }
+    pCutStore->nCuts = k;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Print the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodePrintCut( Ivy_Cut_t * pCut )
+{
+    int i;
+    assert( pCut->nSize > 0 );
+    printf( "%d : {", pCut->nSize );
+    for ( i = 0; i < pCut->nSize; i++ )
+        printf( " %d", pCut->pArray[i] );
+    printf( " }\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodePrintCuts( Ivy_Store_t * pCutStore )
+{
+    int i;
+    printf( "Node %d\n", pCutStore->pCuts[0].pArray[0] );
+    for ( i = 0; i < pCutStore->nCuts; i++ )
+        Ivy_NodePrintCut( pCutStore->pCuts + i );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Ivy_Obj_t * Ivy_ObjRealFanin( Ivy_Obj_t * pObj )
+{
+    if ( !Ivy_ObjIsBuf(pObj) )
+        return pObj;
+    return Ivy_ObjRealFanin( Ivy_ObjFanin0(pObj) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Store_t * Ivy_NodeFindCutsAll( Ivy_Man_t * p, Ivy_Obj_t * pObj, int nLeaves )
+{
+    static Ivy_Store_t CutStore, * pCutStore = &CutStore;
+    Ivy_Cut_t CutNew, * pCutNew = &CutNew, * pCut;
+    Ivy_Obj_t * pLeaf;
+    int i, k, iLeaf0, iLeaf1;
+
+    assert( nLeaves <= IVY_CUT_INPUT );
+
+    // start the structure
+    pCutStore->nCuts = 0;
+    pCutStore->nCutsMax = IVY_CUT_LIMIT;
+    // start the trivial cut
+    pCutNew->uHash = 0;
+    pCutNew->nSize = 1;
+    pCutNew->nSizeMax = nLeaves;
+    pCutNew->pArray[0] = pObj->Id;
+    Ivy_NodeCutHash( pCutNew );
+    // add the trivial cut
+    Ivy_NodeCutFindOrAdd( pCutStore, pCutNew );
+    assert( pCutStore->nCuts == 1 );
+
+    // explore the cuts
+    for ( i = 0; i < pCutStore->nCuts; i++ )
+    {
+        // expand this cut
+        pCut = pCutStore->pCuts + i;
+        if ( pCut->nSize == 0 )
+            continue;
+        for ( k = 0; k < pCut->nSize; k++ )
+        {
+            pLeaf = Ivy_ManObj( p, pCut->pArray[k] );
+            if ( Ivy_ObjIsCi(pLeaf) )
+                continue;
+/*
+            *pCutNew = *pCut;
+            Ivy_NodeCutShrink( pCutNew, pLeaf->Id );
+            if ( !Ivy_NodeCutExtend( pCutNew, Ivy_ObjFaninId0(pLeaf) ) )
+                continue;
+            if ( Ivy_ObjIsNode(pLeaf) && !Ivy_NodeCutExtend( pCutNew, Ivy_ObjFaninId1(pLeaf) ) )
+                continue;
+            Ivy_NodeCutHash( pCutNew );
+*/
+            iLeaf0 = Ivy_ObjId( Ivy_ObjRealFanin(Ivy_ObjFanin0(pLeaf)) );
+            iLeaf1 = Ivy_ObjId( Ivy_ObjRealFanin(Ivy_ObjFanin1(pLeaf)) );
+//            if ( iLeaf0 == iLeaf1 ) // strange situation observed on Jan 18, 2007
+//                continue;
+            if ( !Ivy_NodeCutPrescreen( pCut, iLeaf0, iLeaf1 ) )
+                continue;
+            if ( iLeaf0 > iLeaf1 )
+                Ivy_NodeCutDeriveNew( pCut, pCutNew, pCut->pArray[k], iLeaf1, iLeaf0 );
+            else
+                Ivy_NodeCutDeriveNew( pCut, pCutNew, pCut->pArray[k], iLeaf0, iLeaf1 );
+            Ivy_NodeCutFindOrAddFilter( pCutStore, pCutNew );
+            if ( pCutStore->nCuts == IVY_CUT_LIMIT )
+                break;
+        }
+        if ( pCutStore->nCuts == IVY_CUT_LIMIT )
+            break;
+    }
+    Ivy_NodeCompactCuts( pCutStore );
+//    Ivy_NodePrintCuts( pCutStore );
+    return pCutStore;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManTestCutsAll( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i, nCutsCut, nCutsTotal, nNodeTotal, nNodeOver;
+    int clk = clock();
+    nNodeTotal = nNodeOver = 0;
+    nCutsTotal = -Ivy_ManNodeNum(p);
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        if ( !Ivy_ObjIsNode(pObj) )
+            continue;
+        nCutsCut    = Ivy_NodeFindCutsAll( p, pObj, 5 )->nCuts;
+        nCutsTotal += nCutsCut;
+        nNodeOver  += (nCutsCut == IVY_CUT_LIMIT);
+        nNodeTotal++;
+    }
+    printf( "Total cuts = %6d. Trivial = %6d.   Nodes = %6d. Satur = %6d.  ", 
+        nCutsTotal, Ivy_ManPiNum(p) + Ivy_ManNodeNum(p), nNodeTotal, nNodeOver );
+    PRT( "Time", clock() - clk );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyCutTrav.c b/src/aig/ivy/ivyCutTrav.c
new file mode 100644
index 00000000..ea57c9f5
--- /dev/null
+++ b/src/aig/ivy/ivyCutTrav.c
@@ -0,0 +1,473 @@
+/**CFile****************************************************************
+
+  FileName    [ivyCutTrav.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyCutTrav.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static unsigned * Ivy_NodeCutElementary( Vec_Int_t * vStore, int nWords, int NodeId );
+static void Ivy_NodeComputeVolume( Ivy_Obj_t * pObj, int nNodeLimit, Vec_Ptr_t * vNodes, Vec_Ptr_t * vFront );
+static void Ivy_NodeFindCutsMerge( Vec_Ptr_t * vCuts0, Vec_Ptr_t * vCuts1, Vec_Ptr_t * vCuts, int nLeaves, int nWords, Vec_Int_t * vStore );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes cuts for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Store_t * Ivy_NodeFindCutsTravAll( Ivy_Man_t * p, Ivy_Obj_t * pObj, int nLeaves, int nNodeLimit, 
+                                      Vec_Ptr_t * vNodes, Vec_Ptr_t * vFront, Vec_Int_t * vStore, Vec_Vec_t * vBitCuts )
+{
+    static Ivy_Store_t CutStore, * pCutStore = &CutStore;
+    Vec_Ptr_t * vCuts, * vCuts0, * vCuts1;
+    unsigned * pBitCut;
+    Ivy_Obj_t * pLeaf;
+    Ivy_Cut_t * pCut;
+    int i, k, nWords, nNodes;
+
+    assert( nLeaves <= IVY_CUT_INPUT );
+
+    // find the given number of nodes in the TFI
+    Ivy_NodeComputeVolume( pObj, nNodeLimit - 1, vNodes, vFront );
+    nNodes = Vec_PtrSize(vNodes);
+//    assert( nNodes <= nNodeLimit );
+
+    // make sure vBitCuts has enough room
+    Vec_VecExpand( vBitCuts, nNodes-1 );
+    Vec_VecClear( vBitCuts );
+
+    // prepare the memory manager
+    Vec_IntClear( vStore );
+    Vec_IntGrow( vStore, 64000 );
+
+    // set elementary cuts for the leaves
+    nWords = Extra_BitWordNum( nNodes );
+    Vec_PtrForEachEntry( vFront, pLeaf, i )
+    {
+        assert( Ivy_ObjTravId(pLeaf) < nNodes );
+        // get the new bitcut
+        pBitCut = Ivy_NodeCutElementary( vStore, nWords, Ivy_ObjTravId(pLeaf) );
+        // set it as the cut of this leaf
+        Vec_VecPush( vBitCuts, Ivy_ObjTravId(pLeaf), pBitCut );
+    }
+
+    // compute the cuts for each node
+    Vec_PtrForEachEntry( vNodes, pLeaf, i )
+    {
+        // skip the leaves
+        vCuts = Vec_VecEntry( vBitCuts, Ivy_ObjTravId(pLeaf) );
+        if ( Vec_PtrSize(vCuts) > 0 )
+            continue;
+        // add elementary cut
+        pBitCut = Ivy_NodeCutElementary( vStore, nWords, Ivy_ObjTravId(pLeaf) );
+        // set it as the cut of this leaf
+        Vec_VecPush( vBitCuts, Ivy_ObjTravId(pLeaf), pBitCut );
+        // get the fanin cuts
+        vCuts0 = Vec_VecEntry( vBitCuts, Ivy_ObjTravId( Ivy_ObjFanin0(pLeaf) ) );
+        vCuts1 = Vec_VecEntry( vBitCuts, Ivy_ObjTravId( Ivy_ObjFanin1(pLeaf) ) );
+        assert( Vec_PtrSize(vCuts0) > 0 );
+        assert( Vec_PtrSize(vCuts1) > 0 );
+        // merge the cuts
+        Ivy_NodeFindCutsMerge( vCuts0, vCuts1, vCuts, nLeaves, nWords, vStore );
+    }
+
+    // start the structure
+    pCutStore->nCuts = 0;
+    pCutStore->nCutsMax = IVY_CUT_LIMIT;
+    // collect the cuts of the root node
+    vCuts = Vec_VecEntry( vBitCuts, Ivy_ObjTravId(pObj) );
+    Vec_PtrForEachEntry( vCuts, pBitCut, i )
+    {
+        pCut = pCutStore->pCuts + pCutStore->nCuts++;
+        pCut->nSize = 0;
+        pCut->nSizeMax = nLeaves;
+        pCut->uHash = 0;
+        for ( k = 0; k < nNodes; k++ )
+            if ( Extra_TruthHasBit(pBitCut, k) )
+                pCut->pArray[ pCut->nSize++ ] = Ivy_ObjId( Vec_PtrEntry(vNodes, k) );
+        assert( pCut->nSize <= nLeaves );
+        if ( pCutStore->nCuts == pCutStore->nCutsMax )
+            break;
+    }
+
+    // clean the travIds
+    Vec_PtrForEachEntry( vNodes, pLeaf, i )
+        pLeaf->TravId = 0;
+    return pCutStore;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates elementary bit-cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned * Ivy_NodeCutElementary( Vec_Int_t * vStore, int nWords, int NodeId )
+{
+    unsigned * pBitCut;
+    pBitCut = Vec_IntFetch( vStore, nWords );
+    memset( pBitCut, 0, 4 * nWords );
+    Extra_TruthSetBit( pBitCut, NodeId );
+    return pBitCut;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compares the node by level.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_CompareNodesByLevel( Ivy_Obj_t ** ppObj1, Ivy_Obj_t ** ppObj2 )
+{
+    Ivy_Obj_t * pObj1 = *ppObj1;
+    Ivy_Obj_t * pObj2 = *ppObj2;
+    if ( pObj1->Level < pObj2->Level )
+        return -1;
+    if ( pObj1->Level > pObj2->Level )
+        return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Mark all nodes up to the given depth.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeComputeVolumeTrav1_rec( Ivy_Obj_t * pObj, int Depth )
+{
+    if ( Ivy_ObjIsCi(pObj) || Depth == 0 )
+        return;
+    Ivy_NodeComputeVolumeTrav1_rec( Ivy_ObjFanin0(pObj), Depth - 1 );
+    Ivy_NodeComputeVolumeTrav1_rec( Ivy_ObjFanin1(pObj), Depth - 1 );
+    pObj->fMarkA = 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collect the marked nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeComputeVolumeTrav2_rec( Ivy_Obj_t * pObj, Vec_Ptr_t * vNodes )
+{
+    if ( !pObj->fMarkA )
+        return;
+    Ivy_NodeComputeVolumeTrav2_rec( Ivy_ObjFanin0(pObj), vNodes );
+    Ivy_NodeComputeVolumeTrav2_rec( Ivy_ObjFanin1(pObj), vNodes );
+    Vec_PtrPush( vNodes, pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeComputeVolume( Ivy_Obj_t * pObj, int nNodeLimit, Vec_Ptr_t * vNodes, Vec_Ptr_t * vFront )
+{
+    Ivy_Obj_t * pTemp, * pFanin;
+    int i, nNodes;
+    // mark nodes up to the given depth
+    Ivy_NodeComputeVolumeTrav1_rec( pObj, 6 );
+    // collect the marked nodes
+    Vec_PtrClear( vFront );
+    Ivy_NodeComputeVolumeTrav2_rec( pObj, vFront );
+    // find the fanins that are not marked
+    Vec_PtrClear( vNodes );
+    Vec_PtrForEachEntry( vFront, pTemp, i )
+    {
+        pFanin = Ivy_ObjFanin0(pTemp);
+        if ( !pFanin->fMarkA )
+        {
+            pFanin->fMarkA = 1;
+            Vec_PtrPush( vNodes, pFanin );
+        }
+        pFanin = Ivy_ObjFanin1(pTemp);
+        if ( !pFanin->fMarkA )
+        {
+            pFanin->fMarkA = 1;
+            Vec_PtrPush( vNodes, pFanin );
+        }
+    }
+    // remember the number of nodes in the frontier
+    nNodes = Vec_PtrSize( vNodes );
+    // add the remaining nodes
+    Vec_PtrForEachEntry( vFront, pTemp, i )
+        Vec_PtrPush( vNodes, pTemp );
+    // unmark the nodes
+    Vec_PtrForEachEntry( vNodes, pTemp, i )
+    {
+        pTemp->fMarkA = 0;
+        pTemp->TravId = i;
+    }
+    // collect the frontier nodes
+    Vec_PtrClear( vFront );
+    Vec_PtrForEachEntryStop( vNodes, pTemp, i, nNodes )
+        Vec_PtrPush( vFront, pTemp );
+//    printf( "%d ", Vec_PtrSize(vNodes) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeComputeVolume2( Ivy_Obj_t * pObj, int nNodeLimit, Vec_Ptr_t * vNodes, Vec_Ptr_t * vFront )
+{
+    Ivy_Obj_t * pLeaf, * pPivot, * pFanin;
+    int LevelMax, i;
+    assert( Ivy_ObjIsNode(pObj) );
+    // clear arrays
+    Vec_PtrClear( vNodes );
+    Vec_PtrClear( vFront );
+    // add the root
+    pObj->fMarkA = 1;
+    Vec_PtrPush( vNodes, pObj );
+    Vec_PtrPush( vFront, pObj );
+    // expand node with maximum level
+    LevelMax = pObj->Level;
+    do {
+        // get the node to expand
+        pPivot = NULL;
+        Vec_PtrForEachEntryReverse( vFront, pLeaf, i )
+        {
+            if ( (int)pLeaf->Level == LevelMax )
+            {
+                pPivot = pLeaf;
+                break;
+            }
+        }
+        // decrease level if we did not find the node
+        if ( pPivot == NULL )
+        {
+            if ( --LevelMax == 0 )
+                break;
+            continue;
+        }
+        // the node to expand is found
+        // remove it from frontier
+        Vec_PtrRemove( vFront, pPivot );
+        // add fanins
+        pFanin = Ivy_ObjFanin0(pPivot); 
+        if ( !pFanin->fMarkA )
+        {
+            pFanin->fMarkA = 1;
+            Vec_PtrPush( vNodes, pFanin );
+            Vec_PtrPush( vFront, pFanin );
+        }
+        pFanin = Ivy_ObjFanin1(pPivot); 
+        if ( pFanin && !pFanin->fMarkA )
+        {
+            pFanin->fMarkA = 1;
+            Vec_PtrPush( vNodes, pFanin );
+            Vec_PtrPush( vFront, pFanin );
+        }
+        // quit if we collected enough nodes
+    } while ( Vec_PtrSize(vNodes) < nNodeLimit );
+
+    // sort nodes by level
+    Vec_PtrSort( vNodes, Ivy_CompareNodesByLevel );
+    // make sure the nodes are ordered in the increasing number of levels
+    pFanin = Vec_PtrEntry( vNodes, 0 );
+    pPivot = Vec_PtrEntryLast( vNodes );
+    assert( pFanin->Level <= pPivot->Level );
+
+    // clean the marks and remember node numbers in the TravId
+    Vec_PtrForEachEntry( vNodes, pFanin, i )
+    {
+        pFanin->fMarkA = 0;
+        pFanin->TravId = i;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Extra_TruthOrWords( unsigned * pOut, unsigned * pIn0, unsigned * pIn1, int nWords )
+{
+    int w;
+    for ( w = nWords-1; w >= 0; w-- )
+        pOut[w] = pIn0[w] | pIn1[w];
+}
+static inline int Extra_TruthIsImplyWords( unsigned * pIn1, unsigned * pIn2, int nWords )
+{
+    int w;
+    for ( w = nWords-1; w >= 0; w-- )
+        if ( pIn1[w] & ~pIn2[w] )
+            return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Merges two sets of bit-cuts at a node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeFindCutsMerge( Vec_Ptr_t * vCuts0, Vec_Ptr_t * vCuts1, Vec_Ptr_t * vCuts, 
+                           int nLeaves, int nWords, Vec_Int_t * vStore )
+{
+    unsigned * pBitCut, * pBitCut0, * pBitCut1, * pBitCutTest;
+    int i, k, c, w, Counter;
+    // iterate through the cut pairs
+    Vec_PtrForEachEntry( vCuts0, pBitCut0, i )
+    Vec_PtrForEachEntry( vCuts1, pBitCut1, k )
+    {
+        // skip infeasible cuts
+        Counter = 0;
+        for ( w = 0; w < nWords; w++ )
+        {
+            Counter += Extra_WordCountOnes( pBitCut0[w] | pBitCut1[w] );
+            if ( Counter > nLeaves )
+                break;
+        }
+        if ( Counter > nLeaves )
+            continue;
+        // the new cut is feasible - create it
+        pBitCutTest = Vec_IntFetch( vStore, nWords );
+        Extra_TruthOrWords( pBitCutTest, pBitCut0, pBitCut1, nWords );
+        // filter contained cuts; try to find containing cut
+        w = 0;
+        Vec_PtrForEachEntry( vCuts, pBitCut, c )
+        {
+            if ( Extra_TruthIsImplyWords( pBitCut, pBitCutTest, nWords ) )
+                break;
+            if ( Extra_TruthIsImplyWords( pBitCutTest, pBitCut, nWords ) )
+                continue;
+            Vec_PtrWriteEntry( vCuts, w++, pBitCut );
+        }
+        if ( c != Vec_PtrSize(vCuts) )
+            continue;
+        Vec_PtrShrink( vCuts, w );
+        // add the cut
+        Vec_PtrPush( vCuts, pBitCutTest );
+    }
+}
+ 
+/**Function*************************************************************
+
+  Synopsis    [Compute the set of all cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManTestCutsTravAll( Ivy_Man_t * p )
+{
+    Ivy_Store_t * pStore;
+    Ivy_Obj_t * pObj;
+    Vec_Ptr_t * vNodes, * vFront;
+    Vec_Int_t * vStore;
+    Vec_Vec_t * vBitCuts;
+    int i, nCutsCut, nCutsTotal, nNodeTotal, nNodeOver;
+    int clk = clock();
+
+    vNodes = Vec_PtrAlloc( 100 );
+    vFront = Vec_PtrAlloc( 100 );
+    vStore = Vec_IntAlloc( 100 );
+    vBitCuts = Vec_VecAlloc( 100 );
+
+    nNodeTotal = nNodeOver = 0;
+    nCutsTotal = -Ivy_ManNodeNum(p);
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        if ( !Ivy_ObjIsNode(pObj) )
+            continue;
+        pStore = Ivy_NodeFindCutsTravAll( p, pObj, 4, 60, vNodes, vFront, vStore, vBitCuts );
+        nCutsCut    = pStore->nCuts;
+        nCutsTotal += nCutsCut;
+        nNodeOver  += (nCutsCut == IVY_CUT_LIMIT);
+        nNodeTotal++;
+    }
+    printf( "Total cuts = %6d. Trivial = %6d.   Nodes = %6d. Satur = %6d.  ", 
+        nCutsTotal, Ivy_ManPiNum(p) + Ivy_ManNodeNum(p), nNodeTotal, nNodeOver );
+    PRT( "Time", clock() - clk );
+
+    Vec_PtrFree( vNodes );
+    Vec_PtrFree( vFront );
+    Vec_IntFree( vStore );
+    Vec_VecFree( vBitCuts );
+
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyDfs.c b/src/aig/ivy/ivyDfs.c
new file mode 100644
index 00000000..c27cba31
--- /dev/null
+++ b/src/aig/ivy/ivyDfs.c
@@ -0,0 +1,493 @@
+/**CFile****************************************************************
+
+  FileName    [ivyDfs.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [DFS collection procedures.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyDfs.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Collects nodes in the DFS order.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManDfs_rec( Ivy_Man_t * p, Ivy_Obj_t * pObj, Vec_Int_t * vNodes )
+{
+    if ( Ivy_ObjIsMarkA(pObj) )
+        return;
+    Ivy_ObjSetMarkA(pObj);
+    if ( Ivy_ObjIsConst1(pObj) || Ivy_ObjIsCi(pObj) )
+    {
+        if ( p->pHaig == NULL && pObj->pEquiv )
+            Ivy_ManDfs_rec( p, Ivy_Regular(pObj->pEquiv), vNodes );
+        return;
+    }
+//printf( "visiting node %d\n", pObj->Id );
+/*
+    if ( pObj->Id == 87 || pObj->Id == 90 )
+    {
+        int y = 0;
+    }
+*/
+    assert( Ivy_ObjIsBuf(pObj) || Ivy_ObjIsAnd(pObj) || Ivy_ObjIsExor(pObj) );
+    Ivy_ManDfs_rec( p, Ivy_ObjFanin0(pObj), vNodes );
+    if ( !Ivy_ObjIsBuf(pObj) )
+        Ivy_ManDfs_rec( p, Ivy_ObjFanin1(pObj), vNodes );
+    if ( p->pHaig == NULL && pObj->pEquiv )
+        Ivy_ManDfs_rec( p, Ivy_Regular(pObj->pEquiv), vNodes );
+    Vec_IntPush( vNodes, pObj->Id );
+
+//printf( "adding node %d with fanins %d and %d and equiv %d (refs = %d)\n", 
+//       pObj->Id, Ivy_ObjFanin0(pObj)->Id, Ivy_ObjFanin1(pObj)->Id, 
+//       pObj->pEquiv? Ivy_Regular(pObj->pEquiv)->Id: -1, Ivy_ObjRefs(pObj) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects AND/EXOR nodes in the DFS order from CIs to COs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Ivy_ManDfs( Ivy_Man_t * p )
+{
+    Vec_Int_t * vNodes;
+    Ivy_Obj_t * pObj;
+    int i;
+    assert( Ivy_ManLatchNum(p) == 0 );
+    // make sure the nodes are not marked
+    Ivy_ManForEachObj( p, pObj, i )
+        assert( !pObj->fMarkA && !pObj->fMarkB );
+    // collect the nodes
+    vNodes = Vec_IntAlloc( Ivy_ManNodeNum(p) );
+    Ivy_ManForEachPo( p, pObj, i )
+        Ivy_ManDfs_rec( p, Ivy_ObjFanin0(pObj), vNodes );
+    // unmark the collected nodes
+//    Ivy_ManForEachNodeVec( p, vNodes, pObj, i )
+//        Ivy_ObjClearMarkA(pObj);
+    Ivy_ManForEachObj( p, pObj, i )
+        Ivy_ObjClearMarkA(pObj);
+    // make sure network does not have dangling nodes
+    assert( Vec_IntSize(vNodes) == Ivy_ManNodeNum(p) + Ivy_ManBufNum(p) );
+    return vNodes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects AND/EXOR nodes in the DFS order from CIs to COs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Ivy_ManDfsSeq( Ivy_Man_t * p, Vec_Int_t ** pvLatches )
+{
+    Vec_Int_t * vNodes, * vLatches;
+    Ivy_Obj_t * pObj;
+    int i;
+//    assert( Ivy_ManLatchNum(p) > 0 );
+    // make sure the nodes are not marked
+    Ivy_ManForEachObj( p, pObj, i )
+        assert( !pObj->fMarkA && !pObj->fMarkB );
+    // collect the latches
+    vLatches = Vec_IntAlloc( Ivy_ManLatchNum(p) );
+    Ivy_ManForEachLatch( p, pObj, i )
+        Vec_IntPush( vLatches, pObj->Id );
+    // collect the nodes
+    vNodes = Vec_IntAlloc( Ivy_ManNodeNum(p) );
+    Ivy_ManForEachPo( p, pObj, i )
+        Ivy_ManDfs_rec( p, Ivy_ObjFanin0(pObj), vNodes );
+    Ivy_ManForEachNodeVec( p, vLatches, pObj, i )
+        Ivy_ManDfs_rec( p, Ivy_ObjFanin0(pObj), vNodes );
+    // unmark the collected nodes
+//    Ivy_ManForEachNodeVec( p, vNodes, pObj, i )
+//        Ivy_ObjClearMarkA(pObj);
+    Ivy_ManForEachObj( p, pObj, i )
+        Ivy_ObjClearMarkA(pObj);
+    // make sure network does not have dangling nodes
+//    assert( Vec_IntSize(vNodes) == Ivy_ManNodeNum(p) + Ivy_ManBufNum(p) );
+
+// temporary!!!
+
+    if ( pvLatches == NULL )
+        Vec_IntFree( vLatches );
+    else
+        *pvLatches = vLatches;
+    return vNodes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects nodes in the cone.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManCollectCone_rec( Ivy_Obj_t * pObj, Vec_Ptr_t * vCone )
+{
+    if ( pObj->fMarkA )
+        return;
+    if ( Ivy_ObjIsBuf(pObj) )
+    {
+        Ivy_ManCollectCone_rec( Ivy_ObjFanin0(pObj), vCone );
+        Vec_PtrPush( vCone, pObj );
+        return;
+    }
+    assert( Ivy_ObjIsNode(pObj) );
+    Ivy_ManCollectCone_rec( Ivy_ObjFanin0(pObj), vCone );
+    Ivy_ManCollectCone_rec( Ivy_ObjFanin1(pObj), vCone );
+    Vec_PtrPushUnique( vCone, pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects nodes in the cone.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManCollectCone( Ivy_Obj_t * pObj, Vec_Ptr_t * vFront, Vec_Ptr_t * vCone )
+{
+    Ivy_Obj_t * pTemp;
+    int i;
+    assert( !Ivy_IsComplement(pObj) );
+    assert( Ivy_ObjIsNode(pObj) );
+    // mark the nodes
+    Vec_PtrForEachEntry( vFront, pTemp, i )
+        Ivy_Regular(pTemp)->fMarkA = 1;
+    assert( pObj->fMarkA == 0 );
+    // collect the cone
+    Vec_PtrClear( vCone );
+    Ivy_ManCollectCone_rec( pObj, vCone );
+    // unmark the nodes
+    Vec_PtrForEachEntry( vFront, pTemp, i )
+        Ivy_Regular(pTemp)->fMarkA = 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the nodes by level.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Vec_t * Ivy_ManLevelize( Ivy_Man_t * p )
+{
+    Vec_Vec_t * vNodes;
+    Ivy_Obj_t * pObj;
+    int i;
+    vNodes = Vec_VecAlloc( 100 );
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        assert( !Ivy_ObjIsBuf(pObj) );
+        if ( Ivy_ObjIsNode(pObj) )
+            Vec_VecPush( vNodes, pObj->Level, pObj );
+    }
+    return vNodes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes required levels for each node.]
+
+  Description [Assumes topological ordering of the nodes.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Ivy_ManRequiredLevels( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj;
+    Vec_Int_t * vLevelsR;
+    Vec_Vec_t * vNodes;
+    int i, k, Level, LevelMax;
+    assert( p->vRequired == NULL );
+    // start the required times
+    vLevelsR = Vec_IntStart( Ivy_ManObjIdMax(p) + 1 );
+    // iterate through the nodes in the reverse order
+    vNodes = Ivy_ManLevelize( p );
+    Vec_VecForEachEntryReverseReverse( vNodes, pObj, i, k )
+    {
+        Level = Vec_IntEntry( vLevelsR, pObj->Id ) + 1 + Ivy_ObjIsExor(pObj);
+        if ( Vec_IntEntry( vLevelsR, Ivy_ObjFaninId0(pObj) ) < Level )
+            Vec_IntWriteEntry( vLevelsR, Ivy_ObjFaninId0(pObj), Level );
+        if ( Vec_IntEntry( vLevelsR, Ivy_ObjFaninId1(pObj) ) < Level )
+            Vec_IntWriteEntry( vLevelsR, Ivy_ObjFaninId1(pObj), Level );
+    }
+    Vec_VecFree( vNodes );
+    // convert it into the required times
+    LevelMax = Ivy_ManLevels( p );
+//printf( "max %5d\n",LevelMax );
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        Level = Vec_IntEntry( vLevelsR, pObj->Id );
+        Vec_IntWriteEntry( vLevelsR, pObj->Id, LevelMax - Level );
+//printf( "%5d : %5d %5d\n", pObj->Id, Level, LevelMax - Level );
+    }
+    p->vRequired = vLevelsR;
+    return vLevelsR;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively detects combinational loops.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManIsAcyclic_rec( Ivy_Man_t * p, Ivy_Obj_t * pObj )
+{
+    // skip the node if it is already visited
+    if ( Ivy_ObjIsTravIdPrevious(p, pObj) )
+        return 1;
+    // check if the node is part of the combinational loop
+    if ( Ivy_ObjIsTravIdCurrent(p, pObj) )
+    {
+        fprintf( stdout, "Manager contains combinational loop!\n" );
+        fprintf( stdout, "Node \"%d\" is encountered twice on the following path:\n",  Ivy_ObjId(pObj) );
+        fprintf( stdout, " %d",  Ivy_ObjId(pObj) );
+        return 0;
+    }
+    // mark this node as a node on the current path
+    Ivy_ObjSetTravIdCurrent( p, pObj );
+    // explore equivalent nodes if pObj is the main node
+    if ( p->pHaig == NULL && pObj->pEquiv && Ivy_ObjRefs(pObj) > 0 )
+    {
+        Ivy_Obj_t * pTemp;
+        assert( !Ivy_IsComplement(pObj->pEquiv) );
+        for ( pTemp = pObj->pEquiv; pTemp != pObj; pTemp = Ivy_Regular(pTemp->pEquiv) )
+        {
+            // traverse the fanin's cone searching for the loop
+            if ( !Ivy_ManIsAcyclic_rec(p, pTemp) )
+            {
+                // return as soon as the loop is detected
+                fprintf( stdout, " -> (%d", Ivy_ObjId(pObj) );
+                for ( pTemp = pObj->pEquiv; pTemp != pObj; pTemp = Ivy_Regular(pTemp->pEquiv) )
+                    fprintf( stdout, " %d", Ivy_ObjId(pTemp) );
+                fprintf( stdout, ")" );
+                return 0; 
+            }
+        }
+    }
+    // quite if it is a CI node
+    if ( Ivy_ObjIsCi(pObj) || Ivy_ObjIsConst1(pObj) )
+    {
+        // mark this node as a visited node
+        Ivy_ObjSetTravIdPrevious( p, pObj );
+        return 1;
+    }
+    assert( Ivy_ObjIsNode(pObj) || Ivy_ObjIsBuf(pObj) );
+    // traverse the fanin's cone searching for the loop
+    if ( !Ivy_ManIsAcyclic_rec(p, Ivy_ObjFanin0(pObj)) )
+    {
+        // return as soon as the loop is detected
+        fprintf( stdout, " -> %d", Ivy_ObjId(pObj) );
+        return 0;
+    }
+    // traverse the fanin's cone searching for the loop
+    if ( Ivy_ObjIsNode(pObj) && !Ivy_ManIsAcyclic_rec(p, Ivy_ObjFanin1(pObj)) )
+    {
+        // return as soon as the loop is detected
+        fprintf( stdout, " -> %d", Ivy_ObjId(pObj) );
+        return 0;
+    }
+    // mark this node as a visited node
+    Ivy_ObjSetTravIdPrevious( p, pObj );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Detects combinational loops.]
+
+  Description [This procedure is based on the idea suggested by Donald Chai. 
+  As we traverse the network and visit the nodes, we need to distinquish 
+  three types of nodes: (1) those that are visited for the first time, 
+  (2) those that have been visited in this traversal but are currently not 
+  on the traversal path, (3) those that have been visited and are currently 
+  on the travesal path. When the node of type (3) is encountered, it means 
+  that there is a combinational loop. To mark the three types of nodes, 
+  two new values of the traversal IDs are used.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManIsAcyclic( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int fAcyclic, i;
+    // set the traversal ID for this DFS ordering
+    Ivy_ManIncrementTravId( p );   
+    Ivy_ManIncrementTravId( p );   
+    // pObj->TravId == pNet->nTravIds      means "pObj is on the path"
+    // pObj->TravId == pNet->nTravIds - 1  means "pObj is visited but is not on the path"
+    // pObj->TravId <  pNet->nTravIds - 1  means "pObj is not visited"
+    // traverse the network to detect cycles
+    fAcyclic = 1;
+    Ivy_ManForEachCo( p, pObj, i )
+    {
+        // traverse the output logic cone
+        if ( fAcyclic = Ivy_ManIsAcyclic_rec(p, Ivy_ObjFanin0(pObj)) )
+            continue;
+        // stop as soon as the first loop is detected
+        fprintf( stdout, " (cone of %s \"%d\")\n", Ivy_ObjIsLatch(pObj)? "latch" : "PO", Ivy_ObjId(pObj) );
+        break;
+    }
+    return fAcyclic;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the levels of the nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManSetLevels_rec( Ivy_Obj_t * pObj, int fHaig )
+{
+    // quit if the node is visited
+    if ( Ivy_ObjIsMarkA(pObj) )
+        return pObj->Level;
+    Ivy_ObjSetMarkA(pObj);
+    // quit if this is a CI
+    if ( Ivy_ObjIsConst1(pObj) || Ivy_ObjIsCi(pObj) )
+        return 0;
+    assert( Ivy_ObjIsBuf(pObj) || Ivy_ObjIsAnd(pObj) || Ivy_ObjIsExor(pObj) );
+    // get levels of the fanins
+    Ivy_ManSetLevels_rec( Ivy_ObjFanin0(pObj), fHaig );
+    if ( !Ivy_ObjIsBuf(pObj) )
+        Ivy_ManSetLevels_rec( Ivy_ObjFanin1(pObj), fHaig );
+    // get level of the node
+    if ( Ivy_ObjIsBuf(pObj) )
+        pObj->Level = 1 + Ivy_ObjFanin0(pObj)->Level;
+    else if ( Ivy_ObjIsNode(pObj) )
+        pObj->Level = Ivy_ObjLevelNew( pObj );
+    else assert( 0 );
+    // get level of other choices
+    if ( fHaig && pObj->pEquiv && Ivy_ObjRefs(pObj) > 0 )
+    {
+        Ivy_Obj_t * pTemp;
+        unsigned LevelMax = pObj->Level;
+        for ( pTemp = pObj->pEquiv; pTemp != pObj; pTemp = Ivy_Regular(pTemp->pEquiv) )
+        {
+            Ivy_ManSetLevels_rec( pTemp, fHaig );
+            LevelMax = IVY_MAX( LevelMax, pTemp->Level );
+        }
+        // get this level
+        pObj->Level = LevelMax;
+        for ( pTemp = pObj->pEquiv; pTemp != pObj; pTemp = Ivy_Regular(pTemp->pEquiv) )
+            pTemp->Level = LevelMax;
+    }
+    return pObj->Level;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the levels of the nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManSetLevels( Ivy_Man_t * p, int fHaig )
+{
+    Ivy_Obj_t * pObj;
+    int i, LevelMax;
+    // check if CIs have choices
+    if ( fHaig )
+    {
+        Ivy_ManForEachCi( p, pObj, i )
+            if ( pObj->pEquiv )
+                printf( "CI %d has a choice, which will not be visualized.\n", pObj->Id );
+    }
+    // clean the levels
+    Ivy_ManForEachObj( p, pObj, i )
+        pObj->Level = 0;
+    // compute the levels
+    LevelMax = 0;
+    Ivy_ManForEachCo( p, pObj, i )
+    {
+        Ivy_ManSetLevels_rec( Ivy_ObjFanin0(pObj), fHaig );
+        LevelMax = IVY_MAX( LevelMax, (int)Ivy_ObjFanin0(pObj)->Level );
+    }
+    // compute levels of nodes without fanout
+    Ivy_ManForEachObj( p, pObj, i )
+        if ( (Ivy_ObjIsNode(pObj) || Ivy_ObjIsBuf(pObj)) && Ivy_ObjRefs(pObj) == 0 )
+        {
+            Ivy_ManSetLevels_rec( pObj, fHaig );
+            LevelMax = IVY_MAX( LevelMax, (int)pObj->Level );
+        }
+    // clean the marks
+    Ivy_ManForEachObj( p, pObj, i )
+        Ivy_ObjClearMarkA(pObj);
+    return LevelMax;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyDsd.c b/src/aig/ivy/ivyDsd.c
new file mode 100644
index 00000000..3b8a2e68
--- /dev/null
+++ b/src/aig/ivy/ivyDsd.c
@@ -0,0 +1,819 @@
+/**CFile****************************************************************
+
+  FileName    [ivyDsd.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Disjoint-support decomposition.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyDsd.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+// decomposition types
+typedef enum { 
+    IVY_DEC_PI,             // 0: var
+    IVY_DEC_CONST1,         // 1: CONST1
+    IVY_DEC_BUF,            // 2: BUF
+    IVY_DEC_AND,            // 3: AND
+    IVY_DEC_EXOR,           // 4: EXOR
+    IVY_DEC_MUX,            // 5: MUX
+    IVY_DEC_MAJ,            // 6: MAJ
+    IVY_DEC_PRIME           // 7: undecomposable
+} Ivy_DecType_t;
+
+typedef struct Ivy_Dec_t_ Ivy_Dec_t;
+struct Ivy_Dec_t_
+{
+    unsigned  Type   : 4;   // the node type (PI, CONST1, AND, EXOR, MUX, PRIME)
+    unsigned  fCompl : 1;   // shows if node is complemented (root node only)
+    unsigned  nFans  : 3;   // the number of fanins
+    unsigned  Fan0   : 4;   // fanin 0
+    unsigned  Fan1   : 4;   // fanin 1 
+    unsigned  Fan2   : 4;   // fanin 2
+    unsigned  Fan3   : 4;   // fanin 3 
+    unsigned  Fan4   : 4;   // fanin 4 
+    unsigned  Fan5   : 4;   // fanin 5
+};
+
+static inline int        Ivy_DecToInt( Ivy_Dec_t Node )     { return *((int *)&Node);       }
+static inline Ivy_Dec_t  Ivy_IntToDec( int Node )           { return *((Ivy_Dec_t *)&Node); }
+static inline void       Ivy_DecClear( Ivy_Dec_t * pNode )  { *((int *)pNode) = 0;          }
+
+
+static unsigned s_Masks[6][2] = {
+    { 0x55555555, 0xAAAAAAAA },
+    { 0x33333333, 0xCCCCCCCC },
+    { 0x0F0F0F0F, 0xF0F0F0F0 },
+    { 0x00FF00FF, 0xFF00FF00 },
+    { 0x0000FFFF, 0xFFFF0000 },
+    { 0x00000000, 0xFFFFFFFF }
+};
+
+static inline int        Ivy_TruthWordCountOnes( unsigned uWord )
+{
+    uWord = (uWord & 0x55555555) + ((uWord>>1) & 0x55555555);
+    uWord = (uWord & 0x33333333) + ((uWord>>2) & 0x33333333);
+    uWord = (uWord & 0x0F0F0F0F) + ((uWord>>4) & 0x0F0F0F0F);
+    uWord = (uWord & 0x00FF00FF) + ((uWord>>8) & 0x00FF00FF);
+    return  (uWord & 0x0000FFFF) + (uWord>>16);
+}
+
+static inline int        Ivy_TruthCofactorIsConst( unsigned uTruth, int Var, int Cof, int Const )
+{
+    if ( Const == 0 )
+        return (uTruth & s_Masks[Var][Cof]) == 0;
+    else
+        return (uTruth & s_Masks[Var][Cof]) == s_Masks[Var][Cof];
+}
+
+static inline int        Ivy_TruthCofactorIsOne( unsigned uTruth, int Var )
+{
+    return (uTruth & s_Masks[Var][0]) == 0;
+}
+
+static inline unsigned   Ivy_TruthCofactor( unsigned uTruth, int Var )
+{
+    unsigned uCofactor = uTruth & s_Masks[Var >> 1][(Var & 1) == 0];
+    int Shift = (1 << (Var >> 1));
+    if ( Var & 1 )
+        return uCofactor | (uCofactor << Shift);
+    return uCofactor | (uCofactor >> Shift);
+}
+
+static inline unsigned   Ivy_TruthCofactor2( unsigned uTruth, int Var0, int Var1 )
+{
+    return Ivy_TruthCofactor( Ivy_TruthCofactor(uTruth, Var0), Var1 );
+}
+
+// returns 1 if the truth table depends on this var (var is regular interger var)
+static inline int        Ivy_TruthDepends( unsigned uTruth, int Var )
+{
+    return Ivy_TruthCofactor(uTruth, Var << 1) != Ivy_TruthCofactor(uTruth, (Var << 1) | 1);
+}
+
+static inline void       Ivy_DecSetVar( Ivy_Dec_t * pNode, int iNum, unsigned Var )
+{
+    assert( iNum >= 0 && iNum <= 5 );
+    switch( iNum )
+    {
+        case 0: pNode->Fan0 = Var; break;
+        case 1: pNode->Fan1 = Var; break;
+        case 2: pNode->Fan2 = Var; break;
+        case 3: pNode->Fan3 = Var; break;
+        case 4: pNode->Fan4 = Var; break;
+        case 5: pNode->Fan5 = Var; break;
+    }
+}
+
+static inline unsigned   Ivy_DecGetVar( Ivy_Dec_t * pNode, int iNum )
+{
+    assert( iNum >= 0 && iNum <= 5 );
+    switch( iNum )
+    {
+        case 0: return pNode->Fan0;
+        case 1: return pNode->Fan1;
+        case 2: return pNode->Fan2;
+        case 3: return pNode->Fan3;
+        case 4: return pNode->Fan4;
+        case 5: return pNode->Fan5;
+    }
+    return ~0;
+}
+
+static int   Ivy_TruthDecompose_rec( unsigned uTruth, Vec_Int_t * vTree );
+static int   Ivy_TruthRecognizeMuxMaj( unsigned uTruth, int * pSupp, int nSupp, Vec_Int_t * vTree );
+
+//int nTruthDsd;
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes DSD of truth table of 5 variables or less.]
+
+  Description [Returns 1 if the function is a constant or is fully 
+  DSD decomposable using AND/EXOR/MUX gates.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_TruthDsd( unsigned uTruth, Vec_Int_t * vTree )
+{
+    Ivy_Dec_t Node;
+    int i, RetValue;
+    // set the PI variables
+    Vec_IntClear( vTree );
+    for ( i = 0; i < 5; i++ )
+        Vec_IntPush( vTree, 0 );
+    // check if it is a constant
+    if ( uTruth == 0 || ~uTruth == 0 )
+    {
+        Ivy_DecClear( &Node );
+        Node.Type = IVY_DEC_CONST1;
+        Node.fCompl = (uTruth == 0);
+        Vec_IntPush( vTree, Ivy_DecToInt(Node) );
+        return 1;
+    }
+    // perform the decomposition
+    RetValue = Ivy_TruthDecompose_rec( uTruth, vTree );
+    if ( RetValue == -1 )
+        return 0;
+    // get the topmost node
+    if ( (RetValue >> 1) < 5 )
+    { // add buffer
+        Ivy_DecClear( &Node );
+        Node.Type = IVY_DEC_BUF;
+        Node.fCompl = (RetValue & 1);
+        Node.Fan0 = ((RetValue >> 1) << 1);
+        Vec_IntPush( vTree, Ivy_DecToInt(Node) );
+    }
+    else if ( RetValue & 1 )
+    { // check if the topmost node has to be complemented
+        Node = Ivy_IntToDec( Vec_IntPop(vTree) );
+        assert( Node.fCompl == 0 );
+        Node.fCompl = (RetValue & 1);
+        Vec_IntPush( vTree, Ivy_DecToInt(Node) );
+    }
+    if ( uTruth != Ivy_TruthDsdCompute(vTree) )
+        printf( "Verification failed.\n" );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes DSD of truth table.]
+
+  Description [Returns the number of topmost decomposition node.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_TruthDecompose_rec( unsigned uTruth, Vec_Int_t * vTree )
+{
+    Ivy_Dec_t Node;
+    int Supp[5], Vars0[5], Vars1[5], Vars2[5], * pVars;
+    int nSupp, Count0, Count1, Count2, nVars, RetValue, fCompl, i;
+    unsigned uTruthCof, uCof0, uCof1;
+
+    // get constant confactors
+    Count0 = Count1 = Count2 = nSupp = 0;
+    for ( i = 0; i < 5; i++ )
+    {
+        if ( Ivy_TruthCofactorIsConst(uTruth, i, 0, 0) )
+            Vars0[Count0++] = (i << 1) | 0;
+        else if ( Ivy_TruthCofactorIsConst(uTruth, i, 1, 0) )
+            Vars0[Count0++] = (i << 1) | 1;
+        else if ( Ivy_TruthCofactorIsConst(uTruth, i, 0, 1) )
+            Vars1[Count1++] = (i << 1) | 0;
+        else if ( Ivy_TruthCofactorIsConst(uTruth, i, 1, 1) )
+            Vars1[Count1++] = (i << 1) | 1;
+        else
+        {
+            uCof0 = Ivy_TruthCofactor( uTruth, (i << 1) | 1 );
+            uCof1 = Ivy_TruthCofactor( uTruth, (i << 1) | 0 );
+            if ( uCof0 == ~uCof1 )
+                Vars2[Count2++] = (i << 1) | 0;
+            else if ( uCof0 != uCof1 )
+                Supp[nSupp++] = i;
+        }
+    }
+    assert( Count0 == 0 || Count1 == 0 );
+    assert( Count0 == 0 || Count2 == 0 );
+    assert( Count1 == 0 || Count2 == 0 );
+
+    // consider the case of a single variable
+    if ( Count0 == 1 && nSupp == 0 )
+        return Vars0[0];
+
+    // consider more complex decompositions
+    if ( Count0 == 0 && Count1 == 0 && Count2 == 0 )
+        return Ivy_TruthRecognizeMuxMaj( uTruth, Supp, nSupp, vTree );
+
+    // extract the nodes
+    Ivy_DecClear( &Node );
+    if ( Count0 > 0 )
+        nVars = Count0, pVars = Vars0, Node.Type = IVY_DEC_AND,  fCompl = 0;
+    else if ( Count1 > 0 )
+        nVars = Count1, pVars = Vars1, Node.Type = IVY_DEC_AND,  fCompl = 1, uTruth = ~uTruth;
+    else if ( Count2 > 0 )
+        nVars = Count2, pVars = Vars2, Node.Type = IVY_DEC_EXOR, fCompl = 0;
+    else 
+        assert( 0 );
+    Node.nFans = nVars+(nSupp>0);
+
+    // compute cofactor
+    uTruthCof = uTruth;
+    for ( i = 0; i < nVars; i++ )
+    {
+        uTruthCof = Ivy_TruthCofactor( uTruthCof, pVars[i] );
+        Ivy_DecSetVar( &Node, i, pVars[i] );
+    }
+
+    if ( Node.Type == IVY_DEC_EXOR )
+        fCompl ^= ((Node.nFans & 1) == 0);
+
+    if ( nSupp > 0 )
+    {
+        assert( uTruthCof != 0 && ~uTruthCof != 0 );
+        // call recursively
+        RetValue = Ivy_TruthDecompose_rec( uTruthCof, vTree );
+        // quit if non-decomposable
+        if ( RetValue == -1 )
+            return -1;
+        // remove the complement from the child if the node is EXOR
+        if ( Node.Type == IVY_DEC_EXOR && (RetValue & 1) )
+        {
+            fCompl ^= 1;
+            RetValue ^= 1;
+        }
+        // set the new decomposition
+        Ivy_DecSetVar( &Node, nVars, RetValue );
+    }
+    else if ( Node.Type == IVY_DEC_EXOR )
+        fCompl ^= (uTruthCof == 0);
+
+    Vec_IntPush( vTree, Ivy_DecToInt(Node) );
+    return ((Vec_IntSize(vTree)-1) << 1) | fCompl;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns a non-negative number if the truth table is a MUX.]
+
+  Description [If the truth table is a MUX, returns the variable as follows:
+  first, control variable; second, positive cofactor; third, negative cofactor.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_TruthRecognizeMuxMaj( unsigned uTruth, int * pSupp, int nSupp, Vec_Int_t * vTree )
+{
+    Ivy_Dec_t Node;
+    int i, k, RetValue0, RetValue1;
+    unsigned uCof0, uCof1, Num;
+    char Count[3];
+    assert( nSupp >= 3 );
+    // start the node
+    Ivy_DecClear( &Node );
+    Node.Type = IVY_DEC_MUX;
+    Node.nFans = 3;
+    // try each of the variables
+    for ( i = 0; i < nSupp; i++ )
+    {
+        // get the cofactors with respect to these variables
+        uCof0 = Ivy_TruthCofactor( uTruth, (pSupp[i] << 1) | 1 );
+        uCof1 = Ivy_TruthCofactor( uTruth,  pSupp[i] << 1 );
+        // go through all other variables and make sure 
+        // each of them belongs to the support of one cofactor
+        for ( k = 0; k < nSupp; k++ )
+        {
+            if ( k == i )
+                continue;
+            if ( Ivy_TruthDepends(uCof0, pSupp[k]) && Ivy_TruthDepends(uCof1, pSupp[k]) )
+                break;
+        }
+        if ( k < nSupp )
+            continue;
+        // MUX decomposition exists
+        RetValue0 = Ivy_TruthDecompose_rec( uCof0, vTree );
+        if ( RetValue0 == -1 )
+            break;
+        RetValue1 = Ivy_TruthDecompose_rec( uCof1, vTree );
+        if ( RetValue1 == -1 )
+            break;
+        // both of them exist; create the node
+        Ivy_DecSetVar( &Node, 0, pSupp[i] << 1 );
+        Ivy_DecSetVar( &Node, 1, RetValue1 );
+        Ivy_DecSetVar( &Node, 2, RetValue0 );
+        Vec_IntPush( vTree, Ivy_DecToInt(Node) );
+        return ((Vec_IntSize(vTree)-1) << 1) | 0;
+    }
+    // check majority gate
+    if ( nSupp > 3 )
+        return -1;
+    if ( Ivy_TruthWordCountOnes(uTruth) != 16 )
+        return -1;
+    // this is a majority gate; determine polarity
+    Node.Type = IVY_DEC_MAJ;
+    Count[0] = Count[1] = Count[2] = 0;
+    for ( i = 0; i < 8; i++ )
+    {
+        Num = 0;
+        for ( k = 0; k < 3; k++ )
+            if ( i & (1 << k) )
+                Num |= (1 << pSupp[k]);
+        assert( Num < 32 );
+        if ( (uTruth & (1 << Num)) == 0 )
+            continue;
+        for ( k = 0; k < 3; k++ )
+            if ( i & (1 << k) )
+                Count[k]++;
+    }
+    assert( Count[0] == 1 || Count[0] == 3 );
+    assert( Count[1] == 1 || Count[1] == 3 );
+    assert( Count[2] == 1 || Count[2] == 3 );
+    Ivy_DecSetVar( &Node, 0, (pSupp[0] << 1)|(Count[0] == 1) );
+    Ivy_DecSetVar( &Node, 1, (pSupp[1] << 1)|(Count[1] == 1) );
+    Ivy_DecSetVar( &Node, 2, (pSupp[2] << 1)|(Count[2] == 1) );
+    Vec_IntPush( vTree, Ivy_DecToInt(Node) );
+    return ((Vec_IntSize(vTree)-1) << 1) | 0;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computes truth table of decomposition tree for verification.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Ivy_TruthDsdCompute_rec( int iNode, Vec_Int_t * vTree )
+{
+    unsigned uTruthChild, uTruthTotal;
+    int Var, i;
+    // get the node
+    Ivy_Dec_t Node = Ivy_IntToDec( Vec_IntEntry(vTree, iNode) );
+    // compute the node function
+    if ( Node.Type == IVY_DEC_CONST1 )
+        return s_Masks[5][ !Node.fCompl ];
+    if ( Node.Type == IVY_DEC_PI )
+        return s_Masks[iNode][ !Node.fCompl ];
+    if ( Node.Type == IVY_DEC_BUF )
+    {
+        uTruthTotal = Ivy_TruthDsdCompute_rec( Node.Fan0 >> 1, vTree );
+        return Node.fCompl? ~uTruthTotal : uTruthTotal;
+    }
+    if ( Node.Type == IVY_DEC_AND )
+    {
+        uTruthTotal = s_Masks[5][1];
+        for ( i = 0; i < (int)Node.nFans; i++ )
+        {
+            Var = Ivy_DecGetVar( &Node, i );
+            uTruthChild = Ivy_TruthDsdCompute_rec( Var >> 1, vTree );
+            uTruthTotal = (Var & 1)? uTruthTotal & ~uTruthChild : uTruthTotal & uTruthChild;
+        }
+        return Node.fCompl? ~uTruthTotal : uTruthTotal;
+    }
+    if ( Node.Type == IVY_DEC_EXOR )
+    {
+        uTruthTotal = 0;
+        for ( i = 0; i < (int)Node.nFans; i++ )
+        {
+            Var = Ivy_DecGetVar( &Node, i );
+            uTruthTotal ^= Ivy_TruthDsdCompute_rec( Var >> 1, vTree );
+            assert( (Var & 1) == 0 );
+        }
+        return Node.fCompl? ~uTruthTotal : uTruthTotal;
+    }
+    assert( Node.fCompl == 0 );
+    if ( Node.Type == IVY_DEC_MUX || Node.Type == IVY_DEC_MAJ )
+    {
+        unsigned uTruthChildC, uTruthChild1, uTruthChild0;
+        int VarC, Var1, Var0;
+        VarC = Ivy_DecGetVar( &Node, 0 );
+        Var1 = Ivy_DecGetVar( &Node, 1 );
+        Var0 = Ivy_DecGetVar( &Node, 2 );
+        uTruthChildC = Ivy_TruthDsdCompute_rec( VarC >> 1, vTree );
+        uTruthChild1 = Ivy_TruthDsdCompute_rec( Var1 >> 1, vTree );
+        uTruthChild0 = Ivy_TruthDsdCompute_rec( Var0 >> 1, vTree );
+        assert( Node.Type == IVY_DEC_MAJ || (VarC & 1) == 0 );
+        uTruthChildC = (VarC & 1)? ~uTruthChildC : uTruthChildC;
+        uTruthChild1 = (Var1 & 1)? ~uTruthChild1 : uTruthChild1;
+        uTruthChild0 = (Var0 & 1)? ~uTruthChild0 : uTruthChild0;
+        if ( Node.Type == IVY_DEC_MUX )
+            return (uTruthChildC & uTruthChild1) | (~uTruthChildC & uTruthChild0);
+        else
+            return (uTruthChildC & uTruthChild1) | (uTruthChildC & uTruthChild0) | (uTruthChild1 & uTruthChild0);
+    }
+    assert( 0 );
+    return 0;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computes truth table of decomposition tree for verification.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Ivy_TruthDsdCompute( Vec_Int_t * vTree )
+{
+    return Ivy_TruthDsdCompute_rec( Vec_IntSize(vTree)-1, vTree );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the decomposition tree.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_TruthDsdPrint_rec( FILE * pFile, int iNode, Vec_Int_t * vTree )
+{
+    int Var, i;
+    // get the node
+    Ivy_Dec_t Node = Ivy_IntToDec( Vec_IntEntry(vTree, iNode) );
+    // compute the node function
+    if ( Node.Type == IVY_DEC_CONST1 )
+        fprintf( pFile, "Const1%s", (Node.fCompl? "\'" : "") );
+    else if ( Node.Type == IVY_DEC_PI )
+        fprintf( pFile, "%c%s", 'a' + iNode, (Node.fCompl? "\'" : "") );
+    else if ( Node.Type == IVY_DEC_BUF )
+    {
+        Ivy_TruthDsdPrint_rec( pFile, Node.Fan0 >> 1, vTree );
+        fprintf( pFile, "%s", (Node.fCompl? "\'" : "") );
+    }
+    else if ( Node.Type == IVY_DEC_AND )
+    {
+        fprintf( pFile, "AND(" );
+        for ( i = 0; i < (int)Node.nFans; i++ )
+        {
+            Var = Ivy_DecGetVar( &Node, i );
+            Ivy_TruthDsdPrint_rec( pFile, Var >> 1, vTree );
+            fprintf( pFile, "%s", (Var & 1)? "\'" : "" );
+            if ( i != (int)Node.nFans-1 )
+                fprintf( pFile, "," );
+        }
+        fprintf( pFile, ")%s", (Node.fCompl? "\'" : "") );
+    }
+    else if ( Node.Type == IVY_DEC_EXOR )
+    {
+        fprintf( pFile, "EXOR(" );
+        for ( i = 0; i < (int)Node.nFans; i++ )
+        {
+            Var = Ivy_DecGetVar( &Node, i );
+            Ivy_TruthDsdPrint_rec( pFile, Var >> 1, vTree );
+            if ( i != (int)Node.nFans-1 )
+                fprintf( pFile, "," );
+            assert( (Var & 1) == 0 );
+        }
+        fprintf( pFile, ")%s", (Node.fCompl? "\'" : "") );
+    }
+    else if ( Node.Type == IVY_DEC_MUX || Node.Type == IVY_DEC_MAJ )
+    {
+        int VarC, Var1, Var0;
+        assert( Node.fCompl == 0 );
+        VarC = Ivy_DecGetVar( &Node, 0 );
+        Var1 = Ivy_DecGetVar( &Node, 1 );
+        Var0 = Ivy_DecGetVar( &Node, 2 );
+        fprintf( pFile, "%s", (Node.Type == IVY_DEC_MUX)? "MUX(" : "MAJ(" );
+        Ivy_TruthDsdPrint_rec( pFile, VarC >> 1, vTree );
+        fprintf( pFile, "%s", (VarC & 1)? "\'" : "" );
+        fprintf( pFile, "," );
+        Ivy_TruthDsdPrint_rec( pFile, Var1 >> 1, vTree );
+        fprintf( pFile, "%s", (Var1 & 1)? "\'" : "" );
+        fprintf( pFile, "," );
+        Ivy_TruthDsdPrint_rec( pFile, Var0 >> 1, vTree );
+        fprintf( pFile, "%s", (Var0 & 1)? "\'" : "" );
+        fprintf( pFile, ")" );
+    }
+    else assert( 0 );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the decomposition tree.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_TruthDsdPrint( FILE * pFile, Vec_Int_t * vTree )
+{
+    fprintf( pFile, "F = " );
+    Ivy_TruthDsdPrint_rec( pFile, Vec_IntSize(vTree)-1, vTree );
+    fprintf( pFile, "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implement DSD in the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_ManDsdConstruct_rec( Ivy_Man_t * p, Vec_Int_t * vFront, int iNode, Vec_Int_t * vTree )
+{
+    Ivy_Obj_t * pResult, * pChild, * pNodes[16];
+    int Var, i;
+    // get the node
+    Ivy_Dec_t Node = Ivy_IntToDec( Vec_IntEntry(vTree, iNode) );
+    // compute the node function
+    if ( Node.Type == IVY_DEC_CONST1 )
+        return Ivy_NotCond( Ivy_ManConst1(p), Node.fCompl );
+    if ( Node.Type == IVY_DEC_PI )
+    {
+        pResult = Ivy_ManObj( p, Vec_IntEntry(vFront, iNode) );
+        return Ivy_NotCond( pResult, Node.fCompl );
+    }
+    if ( Node.Type == IVY_DEC_BUF )
+    {
+        pResult = Ivy_ManDsdConstruct_rec( p, vFront, Node.Fan0 >> 1, vTree );
+        return Ivy_NotCond( pResult, Node.fCompl );
+    }
+    if ( Node.Type == IVY_DEC_AND || Node.Type == IVY_DEC_EXOR )
+    {
+        for ( i = 0; i < (int)Node.nFans; i++ )
+        {
+            Var = Ivy_DecGetVar( &Node, i );
+            assert( Node.Type == IVY_DEC_AND || (Var & 1) == 0 );
+            pChild = Ivy_ManDsdConstruct_rec( p, vFront, Var >> 1, vTree );
+            pChild = Ivy_NotCond( pChild, (Var & 1) );
+            pNodes[i] = pChild;
+        }
+
+//        Ivy_MultiEval( pNodes, Node.nFans, Node.Type == IVY_DEC_AND ? IVY_AND : IVY_EXOR );
+
+        pResult = Ivy_Multi( p, pNodes, Node.nFans, Node.Type == IVY_DEC_AND ? IVY_AND : IVY_EXOR );
+        return Ivy_NotCond( pResult, Node.fCompl );
+    }
+    assert( Node.fCompl == 0 );
+    if ( Node.Type == IVY_DEC_MUX || Node.Type == IVY_DEC_MAJ )
+    {
+        int VarC, Var1, Var0;
+        VarC = Ivy_DecGetVar( &Node, 0 );
+        Var1 = Ivy_DecGetVar( &Node, 1 );
+        Var0 = Ivy_DecGetVar( &Node, 2 );
+        pNodes[0] = Ivy_ManDsdConstruct_rec( p, vFront, VarC >> 1, vTree );
+        pNodes[1] = Ivy_ManDsdConstruct_rec( p, vFront, Var1 >> 1, vTree );
+        pNodes[2] = Ivy_ManDsdConstruct_rec( p, vFront, Var0 >> 1, vTree );
+        assert( Node.Type == IVY_DEC_MAJ || (VarC & 1) == 0 );
+        pNodes[0] = Ivy_NotCond( pNodes[0], (VarC & 1) );
+        pNodes[1] = Ivy_NotCond( pNodes[1], (Var1 & 1) );
+        pNodes[2] = Ivy_NotCond( pNodes[2], (Var0 & 1) );
+        if ( Node.Type == IVY_DEC_MUX )
+            return Ivy_Mux( p, pNodes[0], pNodes[1], pNodes[2] );
+        else
+            return Ivy_Maj( p, pNodes[0], pNodes[1], pNodes[2] );
+    }
+    assert( 0 );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implement DSD in the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_ManDsdConstruct( Ivy_Man_t * p, Vec_Int_t * vFront, Vec_Int_t * vTree )
+{
+    int Entry, i;
+    // implement latches on the frontier (TEMPORARY!!!)
+    Vec_IntForEachEntry( vFront, Entry, i )
+        Vec_IntWriteEntry( vFront, i, Ivy_LeafId(Entry) );
+    // recursively construct the tree
+    return Ivy_ManDsdConstruct_rec( p, vFront, Vec_IntSize(vTree)-1, vTree );
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_TruthDsdComputePrint( unsigned uTruth )
+{
+    static Vec_Int_t * vTree = NULL;
+    if ( vTree == NULL )
+        vTree = Vec_IntAlloc( 12 );
+    if ( Ivy_TruthDsd( uTruth, vTree ) )
+        Ivy_TruthDsdPrint( stdout, vTree );
+    else
+        printf( "Undecomposable\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_TruthTestOne( unsigned uTruth )
+{
+    static int Counter = 0;
+    static Vec_Int_t * vTree = NULL;
+    // decompose
+    if ( vTree == NULL )
+        vTree = Vec_IntAlloc( 12 );
+
+    if ( !Ivy_TruthDsd( uTruth, vTree ) )
+    {
+//        printf( "Undecomposable\n" );
+    }
+    else
+    {
+//        nTruthDsd++;
+        printf( "%5d : ", Counter++ );
+        Extra_PrintBinary( stdout, &uTruth, 32 );
+        printf( "  " );
+        Ivy_TruthDsdPrint( stdout, vTree );
+        if ( uTruth != Ivy_TruthDsdCompute(vTree) )
+            printf( "Verification failed.\n" );
+    }
+//    Vec_IntFree( vTree );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_TruthTest()
+{
+    FILE * pFile;
+    char Buffer[100];
+    unsigned uTruth;
+    int i;
+
+    pFile = fopen( "npn4.txt", "r" );
+    for ( i = 0; i < 222; i++ )
+//    pFile = fopen( "npn5.txt", "r" );
+//    for ( i = 0; i < 616126; i++ )
+    {
+        fscanf( pFile, "%s", Buffer );
+        Extra_ReadHexadecimal( &uTruth, Buffer+2, 4 );
+//        Extra_ReadHexadecimal( &uTruth, Buffer+2, 5 );
+        uTruth |= (uTruth << 16);
+//        uTruth = ~uTruth;
+        Ivy_TruthTestOne( uTruth );
+    }
+    fclose( pFile );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_TruthTest3()
+{
+    FILE * pFile;
+    char Buffer[100];
+    unsigned uTruth;
+    int i;
+
+    pFile = fopen( "npn3.txt", "r" );
+    for ( i = 0; i < 14; i++ )
+    {
+        fscanf( pFile, "%s", Buffer );
+        Extra_ReadHexadecimal( &uTruth, Buffer+2, 3 );
+        uTruth = uTruth | (uTruth << 8) | (uTruth << 16) | (uTruth << 24);
+        Ivy_TruthTestOne( uTruth );
+    }
+    fclose( pFile );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_TruthTest5()
+{
+    FILE * pFile;
+    char Buffer[100];
+    unsigned uTruth;
+    int i;
+
+//    pFile = fopen( "npn4.txt", "r" );
+//    for ( i = 0; i < 222; i++ )
+    pFile = fopen( "npn5.txt", "r" );
+    for ( i = 0; i < 616126; i++ )
+    {
+        fscanf( pFile, "%s", Buffer );
+//        Extra_ReadHexadecimal( &uTruth, Buffer+2, 4 );
+        Extra_ReadHexadecimal( &uTruth, Buffer+2, 5 );
+//        uTruth |= (uTruth << 16);
+//        uTruth = ~uTruth;
+        Ivy_TruthTestOne( uTruth );
+    }
+    fclose( pFile );
+}
+
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyFanout.c b/src/aig/ivy/ivyFanout.c
new file mode 100644
index 00000000..3930186a
--- /dev/null
+++ b/src/aig/ivy/ivyFanout.c
@@ -0,0 +1,309 @@
+/**CFile****************************************************************
+
+  FileName    [ivyFanout.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Representation of the fanouts.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyFanout.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+// getting hold of the next fanout of the node
+static inline Ivy_Obj_t * Ivy_ObjNextFanout( Ivy_Obj_t * pObj, Ivy_Obj_t * pFanout )
+{
+    assert( !Ivy_IsComplement(pObj) );
+    assert( !Ivy_IsComplement(pFanout) );
+    if ( pFanout == NULL )
+        return NULL;
+    if ( Ivy_ObjFanin0(pFanout) == pObj )
+        return pFanout->pNextFan0;
+    assert( Ivy_ObjFanin1(pFanout) == pObj );
+    return pFanout->pNextFan1;
+}
+
+// getting hold of the previous fanout of the node
+static inline Ivy_Obj_t * Ivy_ObjPrevFanout( Ivy_Obj_t * pObj, Ivy_Obj_t * pFanout )
+{
+    assert( !Ivy_IsComplement(pObj) );
+    assert( !Ivy_IsComplement(pFanout) );
+    if ( pFanout == NULL )
+        return NULL;
+    if ( Ivy_ObjFanin0(pFanout) == pObj )
+        return pFanout->pPrevFan0;
+    assert( Ivy_ObjFanin1(pFanout) == pObj );
+    return pFanout->pPrevFan1;
+}
+
+// getting hold of the place where the next fanout will be attached
+static inline Ivy_Obj_t ** Ivy_ObjNextFanoutPlace( Ivy_Obj_t * pObj, Ivy_Obj_t * pFanout )
+{
+    assert( !Ivy_IsComplement(pObj) );
+    assert( !Ivy_IsComplement(pFanout) );
+    if ( Ivy_ObjFanin0(pFanout) == pObj )
+        return &pFanout->pNextFan0;
+    assert( Ivy_ObjFanin1(pFanout) == pObj );
+    return &pFanout->pNextFan1;
+}
+
+// getting hold of the place where the next fanout will be attached
+static inline Ivy_Obj_t ** Ivy_ObjPrevFanoutPlace( Ivy_Obj_t * pObj, Ivy_Obj_t * pFanout )
+{
+    assert( !Ivy_IsComplement(pObj) );
+    assert( !Ivy_IsComplement(pFanout) );
+    if ( Ivy_ObjFanin0(pFanout) == pObj )
+        return &pFanout->pPrevFan0;
+    assert( Ivy_ObjFanin1(pFanout) == pObj );
+    return &pFanout->pPrevFan1;
+}
+
+// getting hold of the place where the next fanout will be attached
+static inline Ivy_Obj_t ** Ivy_ObjPrevNextFanoutPlace( Ivy_Obj_t * pObj, Ivy_Obj_t * pFanout )
+{
+    Ivy_Obj_t * pTemp;
+    assert( !Ivy_IsComplement(pObj) );
+    assert( !Ivy_IsComplement(pFanout) );
+    pTemp = Ivy_ObjPrevFanout(pObj, pFanout);
+    if ( pTemp == NULL )
+        return &pObj->pFanout;
+    if ( Ivy_ObjFanin0(pTemp) == pObj )
+        return &pTemp->pNextFan0;
+    assert( Ivy_ObjFanin1(pTemp) == pObj );
+    return &pTemp->pNextFan1;
+}
+
+// getting hold of the place where the next fanout will be attached
+static inline Ivy_Obj_t ** Ivy_ObjNextPrevFanoutPlace( Ivy_Obj_t * pObj, Ivy_Obj_t * pFanout )
+{
+    Ivy_Obj_t * pTemp;
+    assert( !Ivy_IsComplement(pObj) );
+    assert( !Ivy_IsComplement(pFanout) );
+    pTemp = Ivy_ObjNextFanout(pObj, pFanout);
+    if ( pTemp == NULL )
+        return NULL;
+    if ( Ivy_ObjFanin0(pTemp) == pObj )
+        return &pTemp->pPrevFan0;
+    assert( Ivy_ObjFanin1(pTemp) == pObj );
+    return &pTemp->pPrevFan1;
+}
+
+// iterator through the fanouts of the node
+#define Ivy_ObjForEachFanoutInt( pObj, pFanout )                 \
+    for ( pFanout = (pObj)->pFanout; pFanout;                    \
+          pFanout = Ivy_ObjNextFanout(pObj, pFanout) )
+
+// safe iterator through the fanouts of the node
+#define Ivy_ObjForEachFanoutIntSafe( pObj, pFanout, pFanout2 )   \
+    for ( pFanout  = (pObj)->pFanout,                            \
+          pFanout2 = Ivy_ObjNextFanout(pObj, pFanout);           \
+          pFanout;                                               \
+          pFanout  = pFanout2,                                   \
+          pFanout2 = Ivy_ObjNextFanout(pObj, pFanout) )
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the fanout representation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManStartFanout( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i;
+    assert( !p->fFanout );
+    p->fFanout = 1;
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        if ( Ivy_ObjFanin0(pObj) )
+            Ivy_ObjAddFanout( p, Ivy_ObjFanin0(pObj), pObj );
+        if ( Ivy_ObjFanin1(pObj) )
+            Ivy_ObjAddFanout( p, Ivy_ObjFanin1(pObj), pObj );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the fanout representation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManStopFanout( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i;
+    assert( p->fFanout );
+    p->fFanout = 0;
+    Ivy_ManForEachObj( p, pObj, i )
+        pObj->pFanout = pObj->pNextFan0 = pObj->pNextFan1 = pObj->pPrevFan0 = pObj->pPrevFan1 = NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Add the fanout.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjAddFanout( Ivy_Man_t * p, Ivy_Obj_t * pFanin, Ivy_Obj_t * pFanout )
+{
+    assert( p->fFanout );
+    if ( pFanin->pFanout )
+    {
+        *Ivy_ObjNextFanoutPlace(pFanin, pFanout) = pFanin->pFanout;
+        *Ivy_ObjPrevFanoutPlace(pFanin, pFanin->pFanout) = pFanout;
+    }
+    pFanin->pFanout = pFanout;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Removes the fanout.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjDeleteFanout( Ivy_Man_t * p, Ivy_Obj_t * pFanin, Ivy_Obj_t * pFanout )
+{
+    Ivy_Obj_t ** ppPlace1, ** ppPlace2, ** ppPlaceN;
+    assert( pFanin->pFanout != NULL );
+
+    ppPlace1 = Ivy_ObjNextFanoutPlace(pFanin, pFanout);
+    ppPlaceN = Ivy_ObjPrevNextFanoutPlace(pFanin, pFanout);
+    assert( *ppPlaceN == pFanout );
+    if ( ppPlaceN )
+        *ppPlaceN = *ppPlace1;
+
+    ppPlace2 = Ivy_ObjPrevFanoutPlace(pFanin, pFanout);
+    ppPlaceN = Ivy_ObjNextPrevFanoutPlace(pFanin, pFanout);
+    assert( ppPlaceN == NULL || *ppPlaceN == pFanout );
+    if ( ppPlaceN )
+        *ppPlaceN = *ppPlace2;
+
+    *ppPlace1 = NULL;
+    *ppPlace2 = NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Replaces the fanout of pOld to be pFanoutNew.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjPatchFanout( Ivy_Man_t * p, Ivy_Obj_t * pFanin, Ivy_Obj_t * pFanoutOld, Ivy_Obj_t * pFanoutNew )
+{
+    Ivy_Obj_t ** ppPlace;
+    ppPlace = Ivy_ObjPrevNextFanoutPlace(pFanin, pFanoutOld);
+    assert( *ppPlace == pFanoutOld );
+    if ( ppPlace )
+        *ppPlace = pFanoutNew;
+    ppPlace = Ivy_ObjNextPrevFanoutPlace(pFanin, pFanoutOld);
+    assert( ppPlace == NULL || *ppPlace == pFanoutOld );
+    if ( ppPlace )
+        *ppPlace = pFanoutNew;
+    // assuming that pFanoutNew already points to the next fanout
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Starts iteration through the fanouts.]
+
+  Description [Copies the currently available fanouts into the array.]
+               
+  SideEffects [Can be used while the fanouts are being removed.]
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjCollectFanouts( Ivy_Man_t * p, Ivy_Obj_t * pObj, Vec_Ptr_t * vArray )
+{
+    Ivy_Obj_t * pFanout;
+    assert( p->fFanout );
+    assert( !Ivy_IsComplement(pObj) );
+    Vec_PtrClear( vArray );
+    Ivy_ObjForEachFanoutInt( pObj, pFanout )
+        Vec_PtrPush( vArray, pFanout );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Reads one fanout.]
+
+  Description [Returns fanout if there is only one fanout.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_ObjReadFirstFanout( Ivy_Man_t * p, Ivy_Obj_t * pObj )
+{
+    return pObj->pFanout;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Reads one fanout.]
+
+  Description [Returns fanout if there is only one fanout.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ObjFanoutNum( Ivy_Man_t * p, Ivy_Obj_t * pObj )
+{
+    Ivy_Obj_t * pFanout;
+    int Counter = 0;
+    Ivy_ObjForEachFanoutInt( pObj, pFanout )
+        Counter++;
+    return Counter;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyFastMap.c b/src/aig/ivy/ivyFastMap.c
new file mode 100644
index 00000000..c4a043f2
--- /dev/null
+++ b/src/aig/ivy/ivyFastMap.c
@@ -0,0 +1,1593 @@
+/**CFile****************************************************************
+
+  FileName    [ivyFastMap.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Fast FPGA mapping.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyFastMap.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define IVY_INFINITY   10000
+
+typedef struct Ivy_SuppMan_t_ Ivy_SuppMan_t;
+struct Ivy_SuppMan_t_ 
+{
+    int         nLimit;    // the limit on the number of inputs
+    int         nObjs;     // the number of entries
+    int         nSize;     // size of each entry in bytes
+    char *      pMem;      // memory allocated
+    Vec_Vec_t * vLuts;     // the array of nodes used in the mapping
+};
+
+typedef struct Ivy_Supp_t_ Ivy_Supp_t;
+struct Ivy_Supp_t_ 
+{
+    char        nSize;     // the number of support nodes
+    char        fMark;     // multipurpose mask
+    char        fMark2;    // multipurpose mask 
+    char        fMark3;    // multipurpose mask 
+    int         nRefs;     // the number of references
+    short       Delay;     // the delay of the node
+    short       DelayR;    // the reverse delay of the node
+    int         pArray[0]; // the support nodes
+};
+
+static inline Ivy_Supp_t * Ivy_ObjSupp( Ivy_Man_t * pAig, Ivy_Obj_t * pObj )      
+{ 
+    return (Ivy_Supp_t *)(((Ivy_SuppMan_t*)pAig->pData)->pMem + pObj->Id * ((Ivy_SuppMan_t*)pAig->pData)->nSize); 
+}
+static inline Ivy_Supp_t * Ivy_ObjSuppStart( Ivy_Man_t * pAig, Ivy_Obj_t * pObj ) 
+{ 
+    Ivy_Supp_t * pSupp;
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    pSupp->fMark = 0;
+    pSupp->Delay = 0;
+    pSupp->nSize = 1;
+    pSupp->pArray[0] = pObj->Id;
+    return pSupp;
+}
+
+static void Ivy_FastMapPrint( Ivy_Man_t * pAig, int Delay, int Area, int Time, char * pStr );
+static int  Ivy_FastMapDelay( Ivy_Man_t * pAig );
+static int  Ivy_FastMapArea( Ivy_Man_t * pAig );
+static void Ivy_FastMapNode( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit );
+static void Ivy_FastMapNodeArea( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit );
+static int  Ivy_FastMapMerge( Ivy_Supp_t * pSupp0, Ivy_Supp_t * pSupp1, Ivy_Supp_t * pSupp, int nLimit );
+static void Ivy_FastMapRequired( Ivy_Man_t * pAig, int Delay, int fSetInter );
+static void Ivy_FastMapRecover( Ivy_Man_t * pAig, int nLimit );
+static int  Ivy_FastMapNodeDelay( Ivy_Man_t * pAig, Ivy_Obj_t * pObj );
+static int  Ivy_FastMapNodeAreaRefed( Ivy_Man_t * pAig, Ivy_Obj_t * pObj );
+static int  Ivy_FastMapNodeAreaDerefed( Ivy_Man_t * pAig, Ivy_Obj_t * pObj );
+static void Ivy_FastMapNodeRecover( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit, Vec_Ptr_t * vFront, Vec_Ptr_t * vFrontOld );
+static int  Ivy_FastMapNodeRef( Ivy_Man_t * pAig, Ivy_Obj_t * pObj );
+static int  Ivy_FastMapNodeDeref( Ivy_Man_t * pAig, Ivy_Obj_t * pObj );
+
+
+extern int s_MappingTime;
+extern int s_MappingMem;
+
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fast K-LUT mapping of the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapPerform( Ivy_Man_t * pAig, int nLimit, int fRecovery, int fVerbose )
+{
+    Ivy_SuppMan_t * pMan;
+    Ivy_Obj_t * pObj;
+    int i, Delay, Area, clk, clkTotal = clock();
+    // start the memory for supports
+    pMan = ALLOC( Ivy_SuppMan_t, 1 );
+    memset( pMan, 0, sizeof(Ivy_SuppMan_t) );
+    pMan->nLimit = nLimit;
+    pMan->nObjs  = Ivy_ManObjIdMax(pAig) + 1;
+    pMan->nSize  = sizeof(Ivy_Supp_t) + nLimit * sizeof(int);
+    pMan->pMem   = (char *)malloc( pMan->nObjs * pMan->nSize );
+    memset( pMan->pMem, 0, pMan->nObjs * pMan->nSize );
+    pMan->vLuts  = Vec_VecAlloc( 100 );
+    pAig->pData  = pMan;
+clk = clock();
+    // set the PI mapping
+    Ivy_ObjSuppStart( pAig, Ivy_ManConst1(pAig) );
+    Ivy_ManForEachPi( pAig, pObj, i )
+        Ivy_ObjSuppStart( pAig, pObj );
+    // iterate through all nodes in the topological order
+    Ivy_ManForEachNode( pAig, pObj, i )
+        Ivy_FastMapNode( pAig, pObj, nLimit );
+    // find the best arrival time and area
+    Delay = Ivy_FastMapDelay( pAig );
+    Area = Ivy_FastMapArea(pAig);
+    if ( fVerbose )
+        Ivy_FastMapPrint( pAig, Delay, Area, clock() - clk, "Delay oriented mapping: " );
+
+// 2-1-2 (doing 2-1-2-1-2 improves 0.5%)
+
+    if ( fRecovery )
+    {
+clk = clock();
+    Ivy_FastMapRequired( pAig, Delay, 0 );
+    // remap the nodes
+    Ivy_FastMapRecover( pAig, nLimit );
+    Delay = Ivy_FastMapDelay( pAig );
+    Area = Ivy_FastMapArea(pAig);
+    if ( fVerbose )
+        Ivy_FastMapPrint( pAig, Delay, Area, clock() - clk, "Area recovery 2       : " );
+
+clk = clock();
+    Ivy_FastMapRequired( pAig, Delay, 0 );
+    // iterate through all nodes in the topological order
+    Ivy_ManForEachNode( pAig, pObj, i )
+        Ivy_FastMapNodeArea( pAig, pObj, nLimit );
+    Delay = Ivy_FastMapDelay( pAig );
+    Area = Ivy_FastMapArea(pAig);
+    if ( fVerbose )
+        Ivy_FastMapPrint( pAig, Delay, Area, clock() - clk, "Area recovery 1       : " );
+
+clk = clock();
+    Ivy_FastMapRequired( pAig, Delay, 0 );
+    // remap the nodes
+    Ivy_FastMapRecover( pAig, nLimit );
+    Delay = Ivy_FastMapDelay( pAig );
+    Area = Ivy_FastMapArea(pAig);
+    if ( fVerbose )
+        Ivy_FastMapPrint( pAig, Delay, Area, clock() - clk, "Area recovery 2       : " );
+    }
+
+
+    s_MappingTime = clock() - clkTotal;
+    s_MappingMem = pMan->nObjs * pMan->nSize;
+/*
+    {
+        Vec_Ptr_t * vNodes;
+        vNodes = Vec_PtrAlloc( 100 );
+        Vec_VecForEachEntry( pMan->vLuts, pObj, i, k )
+            Vec_PtrPush( vNodes, pObj );
+        Ivy_ManShow( pAig, 0, vNodes );
+        Vec_PtrFree( vNodes );
+    }
+*/
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Cleans memory used for decomposition.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapStop( Ivy_Man_t * pAig )
+{
+    Ivy_SuppMan_t * p = pAig->pData;
+    Vec_VecFree( p->vLuts );
+    free( p->pMem );
+    free( p );
+    pAig->pData = NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints statistics.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapPrint( Ivy_Man_t * pAig, int Delay, int Area, int Time, char * pStr )
+{
+    printf( "%s : Delay = %3d. Area = %6d. ", pStr, Delay, Area );
+    PRT( "Time", Time );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes delay after LUT mapping.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapDelay( Ivy_Man_t * pAig )
+{
+    Ivy_Supp_t * pSupp;
+    Ivy_Obj_t * pObj;
+    int i, DelayMax = 0;
+    Ivy_ManForEachPo( pAig, pObj, i )
+    {
+        pObj = Ivy_ObjFanin0(pObj);
+        if ( !Ivy_ObjIsNode(pObj) )
+            continue;
+        pSupp = Ivy_ObjSupp( pAig, pObj );
+        if ( DelayMax < pSupp->Delay )
+            DelayMax = pSupp->Delay;
+    }
+    return DelayMax;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes area after mapping.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapArea_rec( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, Vec_Vec_t * vLuts )
+{
+    Ivy_Supp_t * pSupp;
+    int i, Counter;
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    // skip visited nodes and PIs
+    if ( pSupp->fMark || pSupp->nSize == 1 )
+        return 0;
+    pSupp->fMark = 1;
+    // compute the area of this node
+    Counter = 0;
+    for ( i = 0; i < pSupp->nSize; i++ )
+        Counter += Ivy_FastMapArea_rec( pAig, Ivy_ManObj(pAig, pSupp->pArray[i]), vLuts );
+    // add the node to the array of LUTs
+    Vec_VecPush( vLuts, pSupp->Delay, pObj );
+    return 1 + Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes area after mapping.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapArea( Ivy_Man_t * pAig )
+{
+    Vec_Vec_t * vLuts;
+    Ivy_Obj_t * pObj;
+    int i, Counter = 0;
+    // get the array to store the nodes
+    vLuts = ((Ivy_SuppMan_t *)pAig->pData)->vLuts;
+    Vec_VecClear( vLuts );
+    // explore starting from each node
+    Ivy_ManForEachPo( pAig, pObj, i )
+        Counter += Ivy_FastMapArea_rec( pAig, Ivy_ObjFanin0(pObj), vLuts );
+    // clean the marks
+    Ivy_ManForEachNode( pAig, pObj, i )
+        Ivy_ObjSupp( pAig, pObj )->fMark = 0;
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fast mapping for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Ivy_ObjIsNodeInt1( Ivy_Obj_t * pObj )
+{
+    return Ivy_ObjIsNode(pObj) && Ivy_ObjRefs(pObj) == 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fast mapping for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Ivy_ObjIsNodeInt2( Ivy_Obj_t * pObj )
+{
+    return Ivy_ObjIsNode(pObj) && Ivy_ObjRefs(pObj) <= 2;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fast mapping for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Vec_IntSelectSort( int * pArray, int nSize )
+{
+    int temp, i, j, best_i;
+    for ( i = 0; i < nSize-1; i++ )
+    {
+        best_i = i;
+        for ( j = i+1; j < nSize; j++ )
+            if ( pArray[j] < pArray[best_i] )
+                best_i = j;
+        temp = pArray[i]; 
+        pArray[i] = pArray[best_i]; 
+        pArray[best_i] = temp;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fast mapping for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Vec_IntRemoveDup( int * pArray, int nSize )
+{
+    int i, k;
+    if ( nSize < 2 )
+        return nSize;
+    for ( i = k = 1; i < nSize; i++ )
+        if ( pArray[i] != pArray[i-1] )
+            pArray[k++] = pArray[i];
+    return k;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fast mapping for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapNodeArea2( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit )
+{
+    static int Store[32], StoreSize;
+    static char Supp0[16], Supp1[16];
+    static Ivy_Supp_t * pTemp0 = (Ivy_Supp_t *)Supp0;
+    static Ivy_Supp_t * pTemp1 = (Ivy_Supp_t *)Supp1;
+    Ivy_Obj_t * pFanin0, * pFanin1;
+    Ivy_Supp_t * pSupp0, * pSupp1, * pSupp;
+    int RetValue, DelayOld;
+    assert( nLimit <= 32 );
+    assert( Ivy_ObjIsNode(pObj) );
+    // get the fanins
+    pFanin0 = Ivy_ObjFanin0(pObj);
+    pFanin1 = Ivy_ObjFanin1(pObj);
+    // get the supports
+    pSupp0 = Ivy_ObjSupp( pAig, pFanin0 );
+    pSupp1 = Ivy_ObjSupp( pAig, pFanin1 );
+    pSupp  = Ivy_ObjSupp( pAig, pObj );
+    assert( pSupp->fMark == 0 );
+    // get the old delay of the node
+    DelayOld = Ivy_FastMapNodeDelay(pAig, pObj);
+    assert( DelayOld <= pSupp->DelayR );
+    // copy the current cut
+    memcpy( Store, pSupp->pArray, sizeof(int) * pSupp->nSize );
+    StoreSize = pSupp->nSize;
+    // get the fanin support
+    if ( Ivy_ObjRefs(pFanin0) > 1 && pSupp0->Delay < pSupp->DelayR )
+    {
+        pSupp0 = pTemp0;
+        pSupp0->nSize = 1;
+        pSupp0->pArray[0] = Ivy_ObjFaninId0(pObj);
+    }
+    // get the fanin support
+    if ( Ivy_ObjRefs(pFanin1) > 1 && pSupp1->Delay < pSupp->DelayR )
+    {
+        pSupp1 = pTemp1;
+        pSupp1->nSize = 1;
+        pSupp1->pArray[0] = Ivy_ObjFaninId1(pObj);
+    }
+    // merge the cuts
+    if ( pSupp0->nSize < pSupp1->nSize )
+        RetValue = Ivy_FastMapMerge( pSupp1, pSupp0, pSupp, nLimit );
+    else
+        RetValue = Ivy_FastMapMerge( pSupp0, pSupp1, pSupp, nLimit );
+    if ( !RetValue )
+    {
+        pSupp->nSize = 2;
+        pSupp->pArray[0] = Ivy_ObjFaninId0(pObj);
+        pSupp->pArray[1] = Ivy_ObjFaninId1(pObj);
+    }
+    // check the resulting delay
+    pSupp->Delay = Ivy_FastMapNodeDelay(pAig, pObj);
+    if ( pSupp->Delay > pSupp->DelayR )
+    {
+        pSupp->nSize = StoreSize;
+        memcpy( pSupp->pArray, Store, sizeof(int) * pSupp->nSize );
+        pSupp->Delay = DelayOld;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fast mapping for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapNodeArea( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit )
+{
+    static int Store[32], StoreSize;
+    static char Supp0[16], Supp1[16];
+    static Ivy_Supp_t * pTemp0 = (Ivy_Supp_t *)Supp0;
+    static Ivy_Supp_t * pTemp1 = (Ivy_Supp_t *)Supp1;
+    Ivy_Obj_t * pFanin0, * pFanin1;
+    Ivy_Supp_t * pSupp0, * pSupp1, * pSupp;
+    int RetValue, DelayOld, RefsOld;
+    int AreaBef, AreaAft;
+    assert( nLimit <= 32 );
+    assert( Ivy_ObjIsNode(pObj) );
+    // get the fanins
+    pFanin0 = Ivy_ObjFanin0(pObj);
+    pFanin1 = Ivy_ObjFanin1(pObj);
+    // get the supports
+    pSupp0 = Ivy_ObjSupp( pAig, pFanin0 );
+    pSupp1 = Ivy_ObjSupp( pAig, pFanin1 );
+    pSupp  = Ivy_ObjSupp( pAig, pObj );
+    assert( pSupp->fMark == 0 );
+
+    // get the area
+    if ( pSupp->nRefs == 0 )
+        AreaBef = Ivy_FastMapNodeAreaDerefed( pAig, pObj );
+    else
+        AreaBef = Ivy_FastMapNodeAreaRefed( pAig, pObj );
+//    if ( AreaBef == 1 )
+//        return;
+
+    // deref the cut if the node is refed
+    if ( pSupp->nRefs != 0 )
+        Ivy_FastMapNodeDeref( pAig, pObj );
+
+    // get the old delay of the node
+    DelayOld = Ivy_FastMapNodeDelay(pAig, pObj);
+    assert( DelayOld <= pSupp->DelayR );
+    // copy the current cut
+    memcpy( Store, pSupp->pArray, sizeof(int) * pSupp->nSize );
+    StoreSize = pSupp->nSize;
+    // get the fanin support
+    if ( Ivy_ObjRefs(pFanin0) > 2 && pSupp0->Delay < pSupp->DelayR )
+//    if ( pSupp0->nRefs > 0 && pSupp0->Delay < pSupp->DelayR ) // this leads to 2% worse results
+    {
+        pSupp0 = pTemp0;
+        pSupp0->nSize = 1;
+        pSupp0->pArray[0] = Ivy_ObjFaninId0(pObj);
+    }
+    // get the fanin support
+    if ( Ivy_ObjRefs(pFanin1) > 2 && pSupp1->Delay < pSupp->DelayR )
+//    if ( pSupp1->nRefs > 0 && pSupp1->Delay < pSupp->DelayR )
+    {
+        pSupp1 = pTemp1;
+        pSupp1->nSize = 1;
+        pSupp1->pArray[0] = Ivy_ObjFaninId1(pObj);
+    }
+    // merge the cuts
+    if ( pSupp0->nSize < pSupp1->nSize )
+        RetValue = Ivy_FastMapMerge( pSupp1, pSupp0, pSupp, nLimit );
+    else
+        RetValue = Ivy_FastMapMerge( pSupp0, pSupp1, pSupp, nLimit );
+    if ( !RetValue )
+    {
+        pSupp->nSize = 2;
+        pSupp->pArray[0] = Ivy_ObjFaninId0(pObj);
+        pSupp->pArray[1] = Ivy_ObjFaninId1(pObj);
+    }
+
+    // check the resulting delay
+    pSupp->Delay = Ivy_FastMapNodeDelay(pAig, pObj);
+
+    RefsOld = pSupp->nRefs; pSupp->nRefs = 0;
+    AreaAft = Ivy_FastMapNodeAreaDerefed( pAig, pObj );
+    pSupp->nRefs = RefsOld;
+
+    if ( AreaAft > AreaBef || pSupp->Delay > pSupp->DelayR )
+//    if ( pSupp->Delay > pSupp->DelayR )
+    {
+        pSupp->nSize = StoreSize;
+        memcpy( pSupp->pArray, Store, sizeof(int) * pSupp->nSize );
+        pSupp->Delay = DelayOld;
+//        printf( "-" );
+    }
+//    else
+//        printf( "+" );
+
+    if ( pSupp->nRefs != 0 )
+        Ivy_FastMapNodeRef( pAig, pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fast mapping for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapNode( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit )
+{
+    Ivy_Supp_t * pSupp0, * pSupp1, * pSupp;
+    int fFaninParam = 2;
+    int RetValue;
+    assert( Ivy_ObjIsNode(pObj) );
+    // get the supports
+    pSupp0 = Ivy_ObjSupp( pAig, Ivy_ObjFanin0(pObj) );
+    pSupp1 = Ivy_ObjSupp( pAig, Ivy_ObjFanin1(pObj) );
+    pSupp  = Ivy_ObjSupp( pAig, pObj );
+    pSupp->fMark = 0;
+    // get the delays
+    if ( pSupp0->Delay == pSupp1->Delay )
+        pSupp->Delay = (pSupp0->Delay == 0) ? pSupp0->Delay + 1: pSupp0->Delay;
+    else if ( pSupp0->Delay > pSupp1->Delay )
+    {
+        pSupp->Delay = pSupp0->Delay;
+        pSupp1 = Ivy_ObjSupp( pAig, Ivy_ManConst1(pAig) );
+        pSupp1->pArray[0] = Ivy_ObjFaninId1(pObj);
+    }
+    else // if ( pSupp0->Delay < pSupp1->Delay )
+    {
+        pSupp->Delay = pSupp1->Delay;
+        pSupp0 = Ivy_ObjSupp( pAig, Ivy_ManConst1(pAig) );
+        pSupp0->pArray[0] = Ivy_ObjFaninId0(pObj);
+    }
+    // merge the cuts
+    if ( pSupp0->nSize < pSupp1->nSize )
+        RetValue = Ivy_FastMapMerge( pSupp1, pSupp0, pSupp, nLimit );
+    else
+        RetValue = Ivy_FastMapMerge( pSupp0, pSupp1, pSupp, nLimit );
+    if ( !RetValue )
+    {
+        pSupp->Delay++;
+        if ( fFaninParam == 2 )
+        {
+            pSupp->nSize = 2;
+            pSupp->pArray[0] = Ivy_ObjFaninId0(pObj);
+            pSupp->pArray[1] = Ivy_ObjFaninId1(pObj);
+        }
+        else if ( fFaninParam == 3 )
+        {
+            Ivy_Obj_t * pFanin0, * pFanin1, * pFaninA, * pFaninB;
+            pFanin0 = Ivy_ObjFanin0(pObj);
+            pFanin1 = Ivy_ObjFanin1(pObj);
+            pSupp->nSize = 0;
+            // process the first fanin
+            if ( Ivy_ObjIsNodeInt1(pFanin0) )
+            {
+                pFaninA = Ivy_ObjFanin0(pFanin0);
+                pFaninB = Ivy_ObjFanin1(pFanin0);
+                if ( Ivy_ObjIsNodeInt1(pFaninA) && Ivy_ObjIsNodeInt1(pFaninB) )
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFanin0);
+                else
+                {
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFaninA);
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFaninB);
+                }
+            }
+            else
+                pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFanin0);
+            // process the second fanin
+            if ( Ivy_ObjIsNodeInt1(pFanin1) )
+            {
+                pFaninA = Ivy_ObjFanin0(pFanin1);
+                pFaninB = Ivy_ObjFanin1(pFanin1);
+                if ( Ivy_ObjIsNodeInt1(pFaninA) && Ivy_ObjIsNodeInt1(pFaninB) )
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFanin1);
+                else
+                {
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFaninA);
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFaninB);
+                }
+            }
+            else
+                pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFanin1);
+            // sort the fanins
+            Vec_IntSelectSort( pSupp->pArray, pSupp->nSize );
+            pSupp->nSize = Vec_IntRemoveDup( pSupp->pArray, pSupp->nSize );
+            assert( pSupp->pArray[0] < pSupp->pArray[1] );
+        }
+        else if ( fFaninParam == 4 )
+        {
+            Ivy_Obj_t * pFanin0, * pFanin1, * pFaninA, * pFaninB;
+            pFanin0 = Ivy_ObjFanin0(pObj);
+            pFanin1 = Ivy_ObjFanin1(pObj);
+            pSupp->nSize = 0;
+            // consider the case when exactly one of them is internal
+            if ( Ivy_ObjIsNodeInt1(pFanin0) ^ Ivy_ObjIsNodeInt1(pFanin1) )
+            {
+                pSupp0 = Ivy_ObjSupp( pAig, Ivy_ObjFanin0(pObj) );
+                pSupp1 = Ivy_ObjSupp( pAig, Ivy_ObjFanin1(pObj) );
+                if ( Ivy_ObjIsNodeInt1(pFanin0) && pSupp0->nSize < nLimit )
+                {
+                    pSupp->Delay = IVY_MAX( pSupp0->Delay, pSupp1->Delay + 1 );
+                    pSupp1 = Ivy_ObjSupp( pAig, Ivy_ManConst1(pAig) );
+                    pSupp1->pArray[0] = Ivy_ObjId(pFanin1);
+                    // merge the cuts
+                    RetValue = Ivy_FastMapMerge( pSupp0, pSupp1, pSupp, nLimit );
+                    assert( RetValue );
+                    assert( pSupp->nSize > 1 );
+                    return;
+                }
+                if ( Ivy_ObjIsNodeInt1(pFanin1) && pSupp1->nSize < nLimit )
+                {
+                    pSupp->Delay = IVY_MAX( pSupp1->Delay, pSupp0->Delay + 1 );
+                    pSupp0 = Ivy_ObjSupp( pAig, Ivy_ManConst1(pAig) );
+                    pSupp0->pArray[0] = Ivy_ObjId(pFanin0);
+                    // merge the cuts
+                    RetValue = Ivy_FastMapMerge( pSupp1, pSupp0, pSupp, nLimit );
+                    assert( RetValue );
+                    assert( pSupp->nSize > 1 );
+                    return;
+                }
+            }
+            // process the first fanin
+            if ( Ivy_ObjIsNodeInt1(pFanin0) )
+            {
+                pFaninA = Ivy_ObjFanin0(pFanin0);
+                pFaninB = Ivy_ObjFanin1(pFanin0);
+                if ( Ivy_ObjIsNodeInt1(pFaninA) && Ivy_ObjIsNodeInt1(pFaninB) )
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFanin0);
+                else
+                {
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFaninA);
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFaninB);
+                }
+            }
+            else
+                pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFanin0);
+            // process the second fanin
+            if ( Ivy_ObjIsNodeInt1(pFanin1) )
+            {
+                pFaninA = Ivy_ObjFanin0(pFanin1);
+                pFaninB = Ivy_ObjFanin1(pFanin1);
+                if ( Ivy_ObjIsNodeInt1(pFaninA) && Ivy_ObjIsNodeInt1(pFaninB) )
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFanin1);
+                else
+                {
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFaninA);
+                    pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFaninB);
+                }
+            }
+            else
+                pSupp->pArray[pSupp->nSize++] = Ivy_ObjId(pFanin1);
+            // sort the fanins
+            Vec_IntSelectSort( pSupp->pArray, pSupp->nSize );
+            pSupp->nSize = Vec_IntRemoveDup( pSupp->pArray, pSupp->nSize );
+            assert( pSupp->pArray[0] < pSupp->pArray[1] );
+            assert( pSupp->nSize > 1 );
+        }
+    }
+    assert( pSupp->Delay > 0 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Merges two supports]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapMerge( Ivy_Supp_t * pSupp0, Ivy_Supp_t * pSupp1, Ivy_Supp_t * pSupp, int nLimit )
+{ 
+    int i, k, c;
+    assert( pSupp0->nSize >= pSupp1->nSize );
+    // the case of the largest cut sizes
+    if ( pSupp0->nSize == nLimit && pSupp1->nSize == nLimit )
+    {
+        for ( i = 0; i < pSupp0->nSize; i++ )
+            if ( pSupp0->pArray[i] != pSupp1->pArray[i] )
+                return 0;
+        for ( i = 0; i < pSupp0->nSize; i++ )
+            pSupp->pArray[i] = pSupp0->pArray[i];
+        pSupp->nSize = pSupp0->nSize;
+        return 1;
+    }
+    // the case when one of the cuts is the largest
+    if ( pSupp0->nSize == nLimit )
+    {
+        for ( i = 0; i < pSupp1->nSize; i++ )
+        {
+            for ( k = pSupp0->nSize - 1; k >= 0; k-- )
+                if ( pSupp0->pArray[k] == pSupp1->pArray[i] )
+                    break;
+            if ( k == -1 ) // did not find
+                return 0;
+        }
+        for ( i = 0; i < pSupp0->nSize; i++ )
+            pSupp->pArray[i] = pSupp0->pArray[i];
+        pSupp->nSize = pSupp0->nSize;
+        return 1;
+    }
+
+    // compare two cuts with different numbers
+    i = k = 0;
+    for ( c = 0; c < nLimit; c++ )
+    {
+        if ( k == pSupp1->nSize )
+        {
+            if ( i == pSupp0->nSize )
+            {
+                pSupp->nSize = c;
+                return 1;
+            }
+            pSupp->pArray[c] = pSupp0->pArray[i++];
+            continue;
+        }
+        if ( i == pSupp0->nSize )
+        {
+            if ( k == pSupp1->nSize )
+            {
+                pSupp->nSize = c;
+                return 1;
+            }
+            pSupp->pArray[c] = pSupp1->pArray[k++];
+            continue;
+        }
+        if ( pSupp0->pArray[i] < pSupp1->pArray[k] )
+        {
+            pSupp->pArray[c] = pSupp0->pArray[i++];
+            continue;
+        }
+        if ( pSupp0->pArray[i] > pSupp1->pArray[k] )
+        {
+            pSupp->pArray[c] = pSupp1->pArray[k++];
+            continue;
+        }
+        pSupp->pArray[c] = pSupp0->pArray[i++]; 
+        k++;
+    }
+    if ( i < pSupp0->nSize || k < pSupp1->nSize )
+        return 0;
+    pSupp->nSize = c;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates integer vector with the support of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapReadSupp( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, Vec_Int_t * vLeaves )
+{
+    Ivy_Supp_t * pSupp;
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    vLeaves->nCap   = 8;
+    vLeaves->nSize  = pSupp->nSize;
+    vLeaves->pArray = pSupp->pArray;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the required times of the intermediate nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapRequired_rec( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, Ivy_Obj_t * pRoot, int DelayR )
+{
+    Ivy_Supp_t * pSupp;
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    if ( pObj != pRoot && (pSupp->nRefs > 0 || Ivy_ObjIsCi(pObj)) )
+        return;
+    Ivy_FastMapRequired_rec( pAig, Ivy_ObjFanin0(pObj), pRoot, DelayR );
+    Ivy_FastMapRequired_rec( pAig, Ivy_ObjFanin1(pObj), pRoot, DelayR );
+//    assert( pObj == pRoot || pSupp->DelayR == IVY_INFINITY );
+    pSupp->DelayR = DelayR;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the required times for each node.]
+
+  Description [Sets reference counters for each node.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapRequired( Ivy_Man_t * pAig, int Delay, int fSetInter )
+{
+    Vec_Vec_t * vLuts;
+    Vec_Ptr_t * vNodes;
+    Ivy_Obj_t * pObj;
+    Ivy_Supp_t * pSupp, * pSuppF;
+    int i, k, c;
+    // clean the required times
+    Ivy_ManForEachPi( pAig, pObj, i )
+    {
+        pSupp = Ivy_ObjSupp( pAig, pObj );
+        pSupp->DelayR = IVY_INFINITY;
+        pSupp->nRefs = 0;
+    }
+    Ivy_ManForEachNode( pAig, pObj, i )
+    {
+        pSupp = Ivy_ObjSupp( pAig, pObj );
+        pSupp->DelayR = IVY_INFINITY;
+        pSupp->nRefs = 0;
+    }
+    // set the required times of the POs
+    Ivy_ManForEachPo( pAig, pObj, i )
+    {
+        pSupp = Ivy_ObjSupp( pAig, Ivy_ObjFanin0(pObj) );
+        pSupp->DelayR = Delay;
+        pSupp->nRefs++;
+    }
+    // get the levelized nodes used in the mapping
+    vLuts = ((Ivy_SuppMan_t *)pAig->pData)->vLuts;
+    // propagate the required times
+    Vec_VecForEachLevelReverse( vLuts, vNodes, i )
+    Vec_PtrForEachEntry( vNodes, pObj, k )
+    {
+        pSupp = Ivy_ObjSupp( pAig, pObj );
+        assert( pSupp->nRefs > 0 );
+        for ( c = 0; c < pSupp->nSize; c++ )
+        {
+            pSuppF = Ivy_ObjSupp( pAig, Ivy_ManObj(pAig, pSupp->pArray[c]) );
+            pSuppF->DelayR = IVY_MIN( pSuppF->DelayR, pSupp->DelayR - 1 );
+            pSuppF->nRefs++;
+        }
+    }
+/*
+    // print out some of the required times
+    Ivy_ManForEachPi( pAig, pObj, i )
+    {
+        pSupp = Ivy_ObjSupp( pAig, pObj );
+        printf( "%d ", pSupp->DelayR );
+    }
+    printf( "\n" );    
+*/
+
+    if ( fSetInter )
+    {
+        // set the required times of the intermediate nodes
+        Vec_VecForEachLevelReverse( vLuts, vNodes, i )
+        Vec_PtrForEachEntry( vNodes, pObj, k )
+        {
+            pSupp = Ivy_ObjSupp( pAig, pObj );
+            Ivy_FastMapRequired_rec( pAig, pObj, pObj, pSupp->DelayR ); 
+        }
+        // make sure that all required times are assigned
+        Ivy_ManForEachNode( pAig, pObj, i )
+        {
+            pSupp = Ivy_ObjSupp( pAig, pObj );
+            assert( pSupp->DelayR < IVY_INFINITY );
+        }
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs area recovery for each node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapRecover( Ivy_Man_t * pAig, int nLimit )
+{
+    Vec_Ptr_t * vFront, * vFrontOld;
+    Ivy_Obj_t * pObj;
+    int i;
+    vFront = Vec_PtrAlloc( nLimit );
+    vFrontOld = Vec_PtrAlloc( nLimit );
+    Ivy_ManCleanTravId( pAig );
+    // iterate through all nodes in the topological order
+    Ivy_ManForEachNode( pAig, pObj, i )
+        Ivy_FastMapNodeRecover( pAig, pObj, nLimit, vFront, vFrontOld );
+    Vec_PtrFree( vFrontOld );
+    Vec_PtrFree( vFront );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the delay of the cut rooted at this node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapNodeDelay( Ivy_Man_t * pAig, Ivy_Obj_t * pObj )
+{
+    Ivy_Supp_t * pSupp, * pSuppF;
+    int c, Delay = 0;
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    for ( c = 0; c < pSupp->nSize; c++ )
+    {
+        pSuppF = Ivy_ObjSupp( pAig, Ivy_ManObj(pAig, pSupp->pArray[c]) );
+        Delay = IVY_MAX( Delay, pSuppF->Delay );
+    }
+    return 1 + Delay;
+}
+
+
+/**function*************************************************************
+
+  synopsis    [References the cut.]
+
+  description [This procedure is similar to the procedure NodeReclaim.]
+               
+  sideeffects []
+
+  seealso     []
+
+***********************************************************************/
+int Ivy_FastMapNodeRef( Ivy_Man_t * pAig, Ivy_Obj_t * pObj )
+{
+    Ivy_Supp_t * pSupp, * pSuppF;
+    Ivy_Obj_t * pNodeChild;
+    int aArea, i;
+    // start the area of this cut
+    aArea = 1;
+    // go through the children
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    assert( pSupp->nSize > 1 );
+    for ( i = 0; i < pSupp->nSize; i++ )
+    {
+        pNodeChild = Ivy_ManObj(pAig, pSupp->pArray[i]);
+        pSuppF = Ivy_ObjSupp( pAig, pNodeChild );
+        assert( pSuppF->nRefs >= 0 );
+        if ( pSuppF->nRefs++ > 0 )  
+            continue;
+        if ( pSuppF->nSize == 1 ) 
+            continue;
+        aArea += Ivy_FastMapNodeRef( pAig, pNodeChild );
+    }
+    return aArea;
+}
+
+/**function*************************************************************
+
+  synopsis    [Dereferences the cut.]
+
+  description [This procedure is similar to the procedure NodeRecusiveDeref.]
+               
+  sideeffects []
+
+  seealso     []
+
+***********************************************************************/
+int Ivy_FastMapNodeDeref( Ivy_Man_t * pAig, Ivy_Obj_t * pObj )
+{
+    Ivy_Supp_t * pSupp, * pSuppF;
+    Ivy_Obj_t * pNodeChild;
+    int aArea, i;
+    // start the area of this cut
+    aArea = 1;
+    // go through the children
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    assert( pSupp->nSize > 1 );
+    for ( i = 0; i < pSupp->nSize; i++ )
+    {
+        pNodeChild = Ivy_ManObj(pAig, pSupp->pArray[i]);
+        pSuppF = Ivy_ObjSupp( pAig, pNodeChild );
+        assert( pSuppF->nRefs > 0 );
+        if ( --pSuppF->nRefs > 0 )  
+            continue;
+        if ( pSuppF->nSize == 1 ) 
+            continue;
+        aArea += Ivy_FastMapNodeDeref( pAig, pNodeChild );
+    }
+    return aArea;
+}
+
+/**function*************************************************************
+
+  synopsis    [Computes the exact area associated with the cut.]
+
+  description []
+               
+  sideeffects []
+
+  seealso     []
+
+***********************************************************************/
+int Ivy_FastMapNodeAreaRefed( Ivy_Man_t * pAig, Ivy_Obj_t * pObj )
+{
+    Ivy_Supp_t * pSupp;
+    int aResult, aResult2;
+    if ( Ivy_ObjIsCi(pObj) )
+        return 0;
+    assert( Ivy_ObjIsNode(pObj) );
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    assert( pSupp->nRefs > 0 );
+    aResult  = Ivy_FastMapNodeDeref( pAig, pObj );
+    aResult2 = Ivy_FastMapNodeRef( pAig, pObj );
+    assert( aResult == aResult2 );
+    return aResult;
+}
+
+/**function*************************************************************
+
+  synopsis    [Computes the exact area associated with the cut.]
+
+  description []
+               
+  sideeffects []
+
+  seealso     []
+
+***********************************************************************/
+int Ivy_FastMapNodeAreaDerefed( Ivy_Man_t * pAig, Ivy_Obj_t * pObj )
+{
+    Ivy_Supp_t * pSupp;
+    int aResult, aResult2;
+    if ( Ivy_ObjIsCi(pObj) )
+        return 0;
+    assert( Ivy_ObjIsNode(pObj) );
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    assert( pSupp->nRefs == 0 );
+    aResult2 = Ivy_FastMapNodeRef( pAig, pObj );
+    aResult  = Ivy_FastMapNodeDeref( pAig, pObj );
+    assert( aResult == aResult2 );
+    return aResult;
+}
+
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of nodes with no external fanout.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapCutCost( Ivy_Man_t * pAig, Vec_Ptr_t * vFront )
+{
+    Ivy_Supp_t * pSuppF;
+    Ivy_Obj_t * pFanin;
+    int i, Counter = 0;
+    Vec_PtrForEachEntry( vFront, pFanin, i )
+    {
+        pSuppF = Ivy_ObjSupp( pAig, pFanin );
+        if ( pSuppF->nRefs == 0 )
+            Counter++;
+    }
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs area recovery for each node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapMark_rec( Ivy_Man_t * pAig, Ivy_Obj_t * pObj )
+{
+    if ( Ivy_ObjIsTravIdCurrent(pAig, pObj) )
+        return;
+    assert( Ivy_ObjIsNode(pObj) );
+    Ivy_FastMapMark_rec( pAig, Ivy_ObjFanin0(pObj) );
+    Ivy_FastMapMark_rec( pAig, Ivy_ObjFanin1(pObj) );
+    Ivy_ObjSetTravIdCurrent(pAig, pObj);
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the number of fanins will grow.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapNodeWillGrow( Ivy_Man_t * pAig, Ivy_Obj_t * pObj )
+{
+    Ivy_Obj_t * pFanin0, * pFanin1;
+    assert( Ivy_ObjIsNode(pObj) );
+    pFanin0 = Ivy_ObjFanin0(pObj);
+    pFanin1 = Ivy_ObjFanin1(pObj);
+    return !Ivy_ObjIsTravIdCurrent(pAig, pFanin0) && !Ivy_ObjIsTravIdCurrent(pAig, pFanin1);
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the increase in the number of fanins with no external refs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapNodeFaninCost( Ivy_Man_t * pAig, Ivy_Obj_t * pObj )
+{
+    Ivy_Supp_t * pSuppF;
+    Ivy_Obj_t * pFanin;
+    int Counter = 0;
+    assert( Ivy_ObjIsNode(pObj) );
+    // check if the node has external refs
+    pSuppF = Ivy_ObjSupp( pAig, pObj );
+    if ( pSuppF->nRefs == 0 )
+        Counter--;
+    // increment the number of fanins without external refs
+    pFanin = Ivy_ObjFanin0(pObj);
+    pSuppF = Ivy_ObjSupp( pAig, pFanin );
+    if ( !Ivy_ObjIsTravIdCurrent(pAig, pFanin) && pSuppF->nRefs == 0 )
+        Counter++;
+    // increment the number of fanins without external refs
+    pFanin = Ivy_ObjFanin1(pObj);
+    pSuppF = Ivy_ObjSupp( pAig, pFanin );
+    if ( !Ivy_ObjIsTravIdCurrent(pAig, pFanin) && pSuppF->nRefs == 0 )
+        Counter++;
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Updates the frontier.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapNodeFaninUpdate( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, Vec_Ptr_t * vFront )
+{
+    Ivy_Obj_t * pFanin;
+    assert( Ivy_ObjIsNode(pObj) );
+    Vec_PtrRemove( vFront, pObj );
+    pFanin = Ivy_ObjFanin0(pObj);
+    if ( !Ivy_ObjIsTravIdCurrent(pAig, pFanin) )
+    {
+        Ivy_ObjSetTravIdCurrent(pAig, pFanin);
+        Vec_PtrPush( vFront, pFanin );
+    }
+    pFanin = Ivy_ObjFanin1(pObj);
+    if ( !Ivy_ObjIsTravIdCurrent(pAig, pFanin) )
+    {
+        Ivy_ObjSetTravIdCurrent(pAig, pFanin);
+        Vec_PtrPush( vFront, pFanin );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compacts the number of external refs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapNodeFaninCompact0( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit, Vec_Ptr_t * vFront )
+{
+    Ivy_Obj_t * pFanin;
+    int i;
+    Vec_PtrForEachEntry( vFront, pFanin, i )
+    {
+        if ( Ivy_ObjIsCi(pFanin) )
+            continue;
+        if ( Ivy_FastMapNodeWillGrow(pAig, pFanin) )
+            continue;
+        if ( Ivy_FastMapNodeFaninCost(pAig, pFanin) <= 0 )
+        {
+            Ivy_FastMapNodeFaninUpdate( pAig, pFanin, vFront );
+            return 1;
+        }
+    }
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compacts the number of external refs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapNodeFaninCompact1( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit, Vec_Ptr_t * vFront )
+{
+    Ivy_Obj_t * pFanin;
+    int i;
+    Vec_PtrForEachEntry( vFront, pFanin, i )
+    {
+        if ( Ivy_ObjIsCi(pFanin) )
+            continue;
+        if ( Ivy_FastMapNodeFaninCost(pAig, pFanin) < 0 )
+        {
+            Ivy_FastMapNodeFaninUpdate( pAig, pFanin, vFront );
+            return 1;
+        }
+    }
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compacts the number of external refs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapNodeFaninCompact2( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit, Vec_Ptr_t * vFront )
+{
+    Ivy_Obj_t * pFanin;
+    int i;
+    Vec_PtrForEachEntry( vFront, pFanin, i )
+    {
+        if ( Ivy_ObjIsCi(pFanin) )
+            continue;
+        if ( Ivy_FastMapNodeFaninCost(pAig, pFanin) <= 0 )
+        {
+            Ivy_FastMapNodeFaninUpdate( pAig, pFanin, vFront );
+            return 1;
+        }
+    }
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compacts the number of external refs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FastMapNodeFaninCompact_int( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit, Vec_Ptr_t * vFront )
+{
+    if ( Ivy_FastMapNodeFaninCompact0(pAig, pObj, nLimit, vFront) )
+        return 1;
+    if (  Vec_PtrSize(vFront) < nLimit && Ivy_FastMapNodeFaninCompact1(pAig, pObj, nLimit, vFront) )
+        return 1;
+    if ( Vec_PtrSize(vFront) < nLimit && Ivy_FastMapNodeFaninCompact2(pAig, pObj, nLimit, vFront) )
+        return 1;
+    assert( Vec_PtrSize(vFront) <= nLimit );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compacts the number of external refs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapNodeFaninCompact( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit, Vec_Ptr_t * vFront )
+{
+    while ( Ivy_FastMapNodeFaninCompact_int( pAig, pObj, nLimit, vFront ) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prepares node mapping.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapNodePrepare( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit, Vec_Ptr_t * vFront, Vec_Ptr_t * vFrontOld )
+{
+    Ivy_Supp_t * pSupp;
+    Ivy_Obj_t * pFanin;
+    int i;
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    // expand the cut downwards from the given place
+    Vec_PtrClear( vFront );
+    Vec_PtrClear( vFrontOld );
+    Ivy_ManIncrementTravId( pAig );
+    for ( i = 0; i < pSupp->nSize; i++ )
+    {
+        pFanin = Ivy_ManObj(pAig, pSupp->pArray[i]);
+        Vec_PtrPush( vFront, pFanin );
+        Vec_PtrPush( vFrontOld, pFanin );
+        Ivy_ObjSetTravIdCurrent( pAig, pFanin );
+    }
+    // mark the nodes in the cone
+    Ivy_FastMapMark_rec( pAig, pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Updates the frontier.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapNodeUpdate( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, Vec_Ptr_t * vFront )
+{
+    Ivy_Supp_t * pSupp;
+    Ivy_Obj_t * pFanin;
+    int i;
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    // deref node's cut
+    Ivy_FastMapNodeDeref( pAig, pObj );
+    // update the node's cut
+    pSupp->nSize = Vec_PtrSize(vFront);
+    Vec_PtrForEachEntry( vFront, pFanin, i )
+        pSupp->pArray[i] = pFanin->Id;
+    // ref the new cut
+    Ivy_FastMapNodeRef( pAig, pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs area recovery for each node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapNodeRecover2( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit, Vec_Ptr_t * vFront, Vec_Ptr_t * vFrontOld )
+{
+    Ivy_Supp_t * pSupp;
+    int CostBef, CostAft;
+    int AreaBef, AreaAft;
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+//    if ( pSupp->nRefs == 0 )
+//        return;
+    if ( pSupp->nRefs == 0 )
+        AreaBef = Ivy_FastMapNodeAreaDerefed( pAig, pObj );
+    else
+        AreaBef = Ivy_FastMapNodeAreaRefed( pAig, pObj );
+    // get the area
+    if ( AreaBef == 1 )
+        return;
+
+    if ( pSupp->nRefs == 0 )
+    {
+        pSupp->nRefs = 1000000;
+        Ivy_FastMapNodeRef( pAig, pObj );
+    }
+    // the cut is non-trivial
+    Ivy_FastMapNodePrepare( pAig, pObj, nLimit, vFront, vFrontOld );
+    // iteratively modify the cut
+    CostBef = Ivy_FastMapCutCost( pAig, vFront );
+    Ivy_FastMapNodeFaninCompact( pAig, pObj, nLimit, vFront );
+    CostAft = Ivy_FastMapCutCost( pAig, vFront );
+    assert( CostBef >= CostAft );
+    // update the node
+    Ivy_FastMapNodeUpdate( pAig, pObj, vFront );
+    // get the new area
+    AreaAft = Ivy_FastMapNodeAreaRefed( pAig, pObj );
+    if ( AreaAft > AreaBef )
+    {
+        Ivy_FastMapNodeUpdate( pAig, pObj, vFrontOld );
+        AreaAft = Ivy_FastMapNodeAreaRefed( pAig, pObj );
+        assert( AreaAft == AreaBef );
+    }
+    if ( pSupp->nRefs == 1000000 )
+    {
+        pSupp->nRefs = 0;
+        Ivy_FastMapNodeDeref( pAig, pObj );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs area recovery for each node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapNodeRecover( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit, Vec_Ptr_t * vFront, Vec_Ptr_t * vFrontOld )
+{
+    Ivy_Supp_t * pSupp;
+    int CostBef, CostAft;
+    int AreaBef, AreaAft;
+    int DelayOld;
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    DelayOld = pSupp->Delay = Ivy_FastMapNodeDelay( pAig, pObj );
+    assert( pSupp->Delay <= pSupp->DelayR );
+    if ( pSupp->nRefs == 0 )
+        return;
+    // get the area
+    AreaBef = Ivy_FastMapNodeAreaRefed( pAig, pObj );
+//    if ( AreaBef == 1 )
+//        return;
+    if ( pObj->Id == 102 )
+    {
+        int x = 0;
+    }
+    // the cut is non-trivial
+    Ivy_FastMapNodePrepare( pAig, pObj, nLimit, vFront, vFrontOld );
+    // iteratively modify the cut
+    Ivy_FastMapNodeDeref( pAig, pObj );
+    CostBef = Ivy_FastMapCutCost( pAig, vFront );
+    Ivy_FastMapNodeFaninCompact( pAig, pObj, nLimit, vFront );
+    CostAft = Ivy_FastMapCutCost( pAig, vFront );
+    Ivy_FastMapNodeRef( pAig, pObj );
+    assert( CostBef >= CostAft );
+    // update the node
+    Ivy_FastMapNodeUpdate( pAig, pObj, vFront );
+    pSupp->Delay = Ivy_FastMapNodeDelay( pAig, pObj );
+    // get the new area
+    AreaAft = Ivy_FastMapNodeAreaRefed( pAig, pObj );
+    if ( AreaAft > AreaBef || pSupp->Delay > pSupp->DelayR )
+    {
+        Ivy_FastMapNodeUpdate( pAig, pObj, vFrontOld );
+        AreaAft = Ivy_FastMapNodeAreaRefed( pAig, pObj );
+        assert( AreaAft == AreaBef );
+        pSupp->Delay = DelayOld;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs area recovery for each node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FastMapNodeRecover4( Ivy_Man_t * pAig, Ivy_Obj_t * pObj, int nLimit, Vec_Ptr_t * vFront, Vec_Ptr_t * vFrontOld )
+{
+    Ivy_Supp_t * pSupp;
+    int CostBef, CostAft;
+    int AreaBef, AreaAft;
+    int DelayOld;
+    pSupp = Ivy_ObjSupp( pAig, pObj );
+    DelayOld = pSupp->Delay = Ivy_FastMapNodeDelay( pAig, pObj );
+    assert( pSupp->Delay <= pSupp->DelayR );
+//    if ( pSupp->nRefs == 0 )
+//        return;
+//    AreaBef = Ivy_FastMapNodeAreaRefed( pAig, pObj );
+    // get the area
+    if ( pSupp->nRefs == 0 )
+        AreaBef = Ivy_FastMapNodeAreaDerefed( pAig, pObj );
+    else
+        AreaBef = Ivy_FastMapNodeAreaRefed( pAig, pObj );
+    if ( AreaBef == 1 )
+        return;
+
+    if ( pSupp->nRefs == 0 )
+    {
+        pSupp->nRefs = 1000000;
+        Ivy_FastMapNodeRef( pAig, pObj );
+    }
+    // the cut is non-trivial
+    Ivy_FastMapNodePrepare( pAig, pObj, nLimit, vFront, vFrontOld );
+    // iteratively modify the cut
+    CostBef = Ivy_FastMapCutCost( pAig, vFront );
+    Ivy_FastMapNodeFaninCompact( pAig, pObj, nLimit, vFront );
+    CostAft = Ivy_FastMapCutCost( pAig, vFront );
+    assert( CostBef >= CostAft );
+    // update the node
+    Ivy_FastMapNodeUpdate( pAig, pObj, vFront );
+    pSupp->Delay = Ivy_FastMapNodeDelay( pAig, pObj );
+    // get the new area
+    AreaAft = Ivy_FastMapNodeAreaRefed( pAig, pObj );
+    if ( AreaAft > AreaBef || pSupp->Delay > pSupp->DelayR )
+    {
+        Ivy_FastMapNodeUpdate( pAig, pObj, vFrontOld );
+        AreaAft = Ivy_FastMapNodeAreaRefed( pAig, pObj );
+        assert( AreaAft == AreaBef );
+        pSupp->Delay = DelayOld;
+    }
+    if ( pSupp->nRefs == 1000000 )
+    {
+        pSupp->nRefs = 0;
+        Ivy_FastMapNodeDeref( pAig, pObj );
+    }
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyFraig.c b/src/aig/ivy/ivyFraig.c
new file mode 100644
index 00000000..4079b6ed
--- /dev/null
+++ b/src/aig/ivy/ivyFraig.c
@@ -0,0 +1,2760 @@
+/**CFile****************************************************************
+
+  FileName    [ivyFraig.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Functional reduction of AIGs]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyFraig.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "satSolver.h"
+#include "extra.h"
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Ivy_FraigMan_t_        Ivy_FraigMan_t;
+typedef struct Ivy_FraigSim_t_        Ivy_FraigSim_t;
+typedef struct Ivy_FraigList_t_       Ivy_FraigList_t;
+
+struct Ivy_FraigList_t_
+{
+    Ivy_Obj_t *         pHead;
+    Ivy_Obj_t *         pTail;
+    int                 nItems;
+};
+
+struct Ivy_FraigSim_t_
+{
+    int                 Type;
+    Ivy_FraigSim_t *    pNext;
+    Ivy_FraigSim_t *    pFanin0;
+    Ivy_FraigSim_t *    pFanin1;
+    unsigned            pData[0];
+};
+
+struct Ivy_FraigMan_t_
+{
+    // general info 
+    Ivy_FraigParams_t * pParams;        // various parameters
+    // temporary backtrack limits because "sint64" cannot be defined in Ivy_FraigParams_t ...
+    sint64              nBTLimitGlobal; // global limit on the number of backtracks
+    sint64              nInsLimitGlobal;// global limit on the number of clause inspects
+    // AIG manager
+    Ivy_Man_t *         pManAig;        // the starting AIG manager
+    Ivy_Man_t *         pManFraig;      // the final AIG manager
+    // simulation information
+    int                 nSimWords;      // the number of words
+    char *              pSimWords;      // the simulation info
+    Ivy_FraigSim_t *    pSimStart;      // the list of simulation info for internal nodes
+    // counter example storage
+    int                 nPatWords;      // the number of words in the counter example
+    unsigned *          pPatWords;      // the counter example
+    int *               pPatScores;     // the scores of each pattern
+    // equivalence classes 
+    Ivy_FraigList_t     lClasses;       // equivalence classes
+    Ivy_FraigList_t     lCand;          // candidatates
+    int                 nPairs;         // the number of pairs of nodes
+    // equivalence checking
+    sat_solver *        pSat;           // SAT solver
+    int                 nSatVars;       // the number of variables currently used
+    Vec_Ptr_t *         vPiVars;        // the PIs of the cone used 
+    // other 
+    ProgressBar *       pProgress;
+    // statistics
+    int                 nSimRounds;
+    int                 nNodesMiter;
+    int                 nClassesZero;
+    int                 nClassesBeg;
+    int                 nClassesEnd;
+    int                 nPairsBeg;
+    int                 nPairsEnd;
+    int                 nSatCalls;
+    int                 nSatCallsSat;
+    int                 nSatCallsUnsat;
+    int                 nSatProof;
+    int                 nSatFails;
+    int                 nSatFailsReal;
+    // runtime
+    int                 timeSim;
+    int                 timeTrav;
+    int                 timeSat;
+    int                 timeSatUnsat;
+    int                 timeSatSat;
+    int                 timeSatFail;
+    int                 timeRef;
+    int                 timeTotal;
+    int                 time1;
+    int                 time2;
+};
+
+typedef struct Prove_ParamsStruct_t_      Prove_Params_t;
+struct Prove_ParamsStruct_t_
+{
+    // general parameters
+    int     fUseFraiging;          // enables fraiging
+    int     fUseRewriting;         // enables rewriting
+    int     fUseBdds;              // enables BDD construction when other methods fail
+    int     fVerbose;              // prints verbose stats
+    // iterations
+    int     nItersMax;             // the number of iterations
+    // mitering 
+    int     nMiteringLimitStart;   // starting mitering limit
+    float   nMiteringLimitMulti;   // multiplicative coefficient to increase the limit in each iteration
+    // rewriting 
+    int     nRewritingLimitStart;  // the number of rewriting iterations
+    float   nRewritingLimitMulti;  // multiplicative coefficient to increase the limit in each iteration
+    // fraiging 
+    int     nFraigingLimitStart;   // starting backtrack(conflict) limit
+    float   nFraigingLimitMulti;   // multiplicative coefficient to increase the limit in each iteration
+    // last-gasp BDD construction
+    int     nBddSizeLimit;         // the number of BDD nodes when construction is aborted
+    int     fBddReorder;           // enables dynamic BDD variable reordering
+    // last-gasp mitering
+    int     nMiteringLimitLast;    // final mitering limit
+    // global SAT solver limits
+    sint64  nTotalBacktrackLimit;  // global limit on the number of backtracks
+    sint64  nTotalInspectLimit;    // global limit on the number of clause inspects
+    // global resources applied
+    sint64  nTotalBacktracksMade;  // the total number of backtracks made
+    sint64  nTotalInspectsMade;    // the total number of inspects made
+};
+
+static inline Ivy_FraigSim_t * Ivy_ObjSim( Ivy_Obj_t * pObj )                            { return (Ivy_FraigSim_t *)pObj->pFanout;  }
+static inline Ivy_Obj_t * Ivy_ObjClassNodeLast( Ivy_Obj_t * pObj )                       { return pObj->pNextFan0;  }
+static inline Ivy_Obj_t * Ivy_ObjClassNodeRepr( Ivy_Obj_t * pObj )                       { return pObj->pNextFan0;  }
+static inline Ivy_Obj_t * Ivy_ObjClassNodeNext( Ivy_Obj_t * pObj )                       { return pObj->pNextFan1;  }
+static inline Ivy_Obj_t * Ivy_ObjNodeHashNext( Ivy_Obj_t * pObj )                        { return pObj->pPrevFan0;  }
+static inline Ivy_Obj_t * Ivy_ObjEquivListNext( Ivy_Obj_t * pObj )                       { return pObj->pPrevFan0;  }
+static inline Ivy_Obj_t * Ivy_ObjEquivListPrev( Ivy_Obj_t * pObj )                       { return pObj->pPrevFan1;  }
+static inline Ivy_Obj_t * Ivy_ObjFraig( Ivy_Obj_t * pObj )                               { return pObj->pEquiv;     }
+static inline int         Ivy_ObjSatNum( Ivy_Obj_t * pObj )                              { return (int)pObj->pNextFan0;         }
+static inline Vec_Ptr_t * Ivy_ObjFaninVec( Ivy_Obj_t * pObj )                            { return (Vec_Ptr_t *)pObj->pNextFan1; }
+
+static inline void        Ivy_ObjSetSim( Ivy_Obj_t * pObj, Ivy_FraigSim_t * pSim )       { pObj->pFanout = (Ivy_Obj_t *)pSim; }
+static inline void        Ivy_ObjSetClassNodeLast( Ivy_Obj_t * pObj, Ivy_Obj_t * pLast ) { pObj->pNextFan0 = pLast; }
+static inline void        Ivy_ObjSetClassNodeRepr( Ivy_Obj_t * pObj, Ivy_Obj_t * pRepr ) { pObj->pNextFan0 = pRepr; }
+static inline void        Ivy_ObjSetClassNodeNext( Ivy_Obj_t * pObj, Ivy_Obj_t * pNext ) { pObj->pNextFan1 = pNext; }
+static inline void        Ivy_ObjSetNodeHashNext( Ivy_Obj_t * pObj, Ivy_Obj_t * pNext )  { pObj->pPrevFan0 = pNext; }
+static inline void        Ivy_ObjSetEquivListNext( Ivy_Obj_t * pObj, Ivy_Obj_t * pNext ) { pObj->pPrevFan0 = pNext; }
+static inline void        Ivy_ObjSetEquivListPrev( Ivy_Obj_t * pObj, Ivy_Obj_t * pPrev ) { pObj->pPrevFan1 = pPrev; }
+static inline void        Ivy_ObjSetFraig( Ivy_Obj_t * pObj, Ivy_Obj_t * pNode )         { pObj->pEquiv    = pNode; }
+static inline void        Ivy_ObjSetSatNum( Ivy_Obj_t * pObj, int Num )                  { pObj->pNextFan0 = (Ivy_Obj_t *)Num;     }
+static inline void        Ivy_ObjSetFaninVec( Ivy_Obj_t * pObj, Vec_Ptr_t * vFanins )    { pObj->pNextFan1 = (Ivy_Obj_t *)vFanins; }
+
+static inline unsigned    Ivy_ObjRandomSim()                       { return (rand() << 24) ^ (rand() << 12) ^ rand(); }
+
+// iterate through equivalence classes
+#define Ivy_FraigForEachEquivClass( pList, pEnt )                 \
+    for ( pEnt = pList;                                           \
+          pEnt;                                                   \
+          pEnt = Ivy_ObjEquivListNext(pEnt) )
+#define Ivy_FraigForEachEquivClassSafe( pList, pEnt, pEnt2 )      \
+    for ( pEnt = pList,                                           \
+          pEnt2 = pEnt? Ivy_ObjEquivListNext(pEnt): NULL;         \
+          pEnt;                                                   \
+          pEnt = pEnt2,                                           \
+          pEnt2 = pEnt? Ivy_ObjEquivListNext(pEnt): NULL )
+// iterate through nodes in one class
+#define Ivy_FraigForEachClassNode( pClass, pEnt )                 \
+    for ( pEnt = pClass;                                          \
+          pEnt;                                                   \
+          pEnt = Ivy_ObjClassNodeNext(pEnt) )
+// iterate through nodes in the hash table
+#define Ivy_FraigForEachBinNode( pBin, pEnt )                     \
+    for ( pEnt = pBin;                                            \
+          pEnt;                                                   \
+          pEnt = Ivy_ObjNodeHashNext(pEnt) )
+
+static Ivy_FraigMan_t * Ivy_FraigStart( Ivy_Man_t * pManAig, Ivy_FraigParams_t * pParams );
+static Ivy_FraigMan_t * Ivy_FraigStartSimple( Ivy_Man_t * pManAig, Ivy_FraigParams_t * pParams );
+static Ivy_Man_t *   Ivy_FraigPerform_int( Ivy_Man_t * pManAig, Ivy_FraigParams_t * pParams, sint64 nBTLimitGlobal, sint64 nInsLimitGlobal, sint64 * pnSatConfs, sint64 * pnSatInspects );
+static void          Ivy_FraigPrint( Ivy_FraigMan_t * p );
+static void          Ivy_FraigStop( Ivy_FraigMan_t * p );
+static void          Ivy_FraigSimulate( Ivy_FraigMan_t * p );
+static void          Ivy_FraigSweep( Ivy_FraigMan_t * p );
+static Ivy_Obj_t *   Ivy_FraigAnd( Ivy_FraigMan_t * p, Ivy_Obj_t * pObjOld );
+static int           Ivy_FraigNodesAreEquiv( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj0, Ivy_Obj_t * pObj1 );
+static int           Ivy_FraigNodeIsConst( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj );
+static void          Ivy_FraigNodeAddToSolver( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj0, Ivy_Obj_t * pObj1 );
+static int           Ivy_FraigSetActivityFactors( Ivy_FraigMan_t * p, Ivy_Obj_t * pOld, Ivy_Obj_t * pNew );
+static void          Ivy_FraigAddToPatScores( Ivy_FraigMan_t * p, Ivy_Obj_t * pClass, Ivy_Obj_t * pClassNew );
+static int           Ivy_FraigMiterStatus( Ivy_Man_t * pMan );
+static void          Ivy_FraigMiterProve( Ivy_FraigMan_t * p );
+static void          Ivy_FraigMiterPrint( Ivy_Man_t * pNtk, char * pString, int clk, int fVerbose );
+static int *         Ivy_FraigCreateModel( Ivy_FraigMan_t * p );
+
+static int Ivy_FraigNodesAreEquivBdd( Ivy_Obj_t * pObj1, Ivy_Obj_t * pObj2 );
+
+static sint64 s_nBTLimitGlobal = 0;
+static sint64 s_nInsLimitGlobal = 0;
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the default solving parameters.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigParamsDefault( Ivy_FraigParams_t * pParams )
+{
+    memset( pParams, 0, sizeof(Ivy_FraigParams_t) );
+    pParams->nSimWords        =      32;  // the number of words in the simulation info
+    pParams->dSimSatur        =   0.005;  // the ratio of refined classes when saturation is reached
+    pParams->fPatScores       =       0;  // enables simulation pattern scoring
+    pParams->MaxScore         =      25;  // max score after which resimulation is used
+    pParams->fDoSparse        =       1;  // skips sparse functions
+//    pParams->dActConeRatio    =    0.05;  // the ratio of cone to be bumped
+//    pParams->dActConeBumpMax  =     5.0;  // the largest bump of activity
+    pParams->dActConeRatio    =     0.3;  // the ratio of cone to be bumped
+    pParams->dActConeBumpMax  =    10.0;  // the largest bump of activity
+
+    pParams->nBTLimitNode     =     100;  // conflict limit at a node
+    pParams->nBTLimitMiter    =  500000;  // conflict limit at an output
+//    pParams->nBTLimitGlobal   =       0;  // conflict limit global
+//    pParams->nInsLimitGlobal  =       0;  // inspection limit global
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs combinational equivalence checking for the miter.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigProve( Ivy_Man_t ** ppManAig, void * pPars )
+{
+    Prove_Params_t * pParams = pPars;
+    Ivy_FraigParams_t Params, * pIvyParams = &Params; 
+    Ivy_Man_t * pManAig, * pManTemp;
+    int RetValue, nIter, clk, timeStart = clock();//, Counter;
+    sint64 nSatConfs, nSatInspects;
+
+    // start the network and parameters
+    pManAig = *ppManAig;
+    Ivy_FraigParamsDefault( pIvyParams );
+    pIvyParams->fVerbose = pParams->fVerbose;
+    pIvyParams->fProve = 1;
+
+    if ( pParams->fVerbose )
+    {
+        printf( "RESOURCE LIMITS: Iterations = %d. Rewriting = %s. Fraiging = %s.\n",
+            pParams->nItersMax, pParams->fUseRewriting? "yes":"no", pParams->fUseFraiging? "yes":"no" );
+        printf( "Miter = %d (%3.1f).  Rwr = %d (%3.1f).  Fraig = %d (%3.1f).  Last = %d.\n", 
+            pParams->nMiteringLimitStart,  pParams->nMiteringLimitMulti, 
+            pParams->nRewritingLimitStart, pParams->nRewritingLimitMulti,
+            pParams->nFraigingLimitStart,  pParams->nFraigingLimitMulti, pParams->nMiteringLimitLast );
+    }
+
+    // if SAT only, solve without iteration
+    if ( !pParams->fUseRewriting && !pParams->fUseFraiging )
+    {
+        clk = clock();
+        pIvyParams->nBTLimitMiter = pParams->nMiteringLimitLast / Ivy_ManPoNum(pManAig);
+        pManAig = Ivy_FraigMiter( pManTemp = pManAig, pIvyParams );  Ivy_ManStop( pManTemp );
+        RetValue = Ivy_FraigMiterStatus( pManAig );
+        Ivy_FraigMiterPrint( pManAig, "SAT solving", clk, pParams->fVerbose );
+        *ppManAig = pManAig;
+        return RetValue;
+    }
+
+    if ( Ivy_ManNodeNum(pManAig) < 500 )
+    {
+        // run the first mitering
+        clk = clock();
+        pIvyParams->nBTLimitMiter = pParams->nMiteringLimitStart / Ivy_ManPoNum(pManAig);
+        pManAig = Ivy_FraigMiter( pManTemp = pManAig, pIvyParams );  Ivy_ManStop( pManTemp );
+        RetValue = Ivy_FraigMiterStatus( pManAig );
+        Ivy_FraigMiterPrint( pManAig, "SAT solving", clk, pParams->fVerbose );
+        if ( RetValue >= 0 )
+        {
+            *ppManAig = pManAig;
+            return RetValue;
+        }
+    }
+
+    // check the current resource limits
+    RetValue = -1;
+    for ( nIter = 0; nIter < pParams->nItersMax; nIter++ )
+    {
+        if ( pParams->fVerbose )
+        {
+            printf( "ITERATION %2d : Confs = %6d. FraigBTL = %3d. \n", nIter+1, 
+                 (int)(pParams->nMiteringLimitStart * pow(pParams->nMiteringLimitMulti,nIter)), 
+                 (int)(pParams->nFraigingLimitStart * pow(pParams->nFraigingLimitMulti,nIter)) );
+            fflush( stdout );
+        }
+
+        // try rewriting
+        if ( pParams->fUseRewriting )
+        { // bug in Ivy_NodeFindCutsAll() when leaves are identical!
+/*
+            clk = clock();
+            Counter = (int)(pParams->nRewritingLimitStart * pow(pParams->nRewritingLimitMulti,nIter));
+            pManAig = Ivy_ManRwsat( pManAig, 0 );  
+            RetValue = Ivy_FraigMiterStatus( pManAig );
+            Ivy_FraigMiterPrint( pManAig, "Rewriting  ", clk, pParams->fVerbose );
+*/
+        }
+        if ( RetValue >= 0 )
+            break;
+
+        // try fraiging followed by mitering
+        if ( pParams->fUseFraiging )
+        {
+            clk = clock();
+            pIvyParams->nBTLimitNode  = (int)(pParams->nFraigingLimitStart * pow(pParams->nFraigingLimitMulti,nIter));
+            pIvyParams->nBTLimitMiter = (int)(pParams->nMiteringLimitStart * pow(pParams->nMiteringLimitMulti,nIter)) / Ivy_ManPoNum(pManAig);
+            pManAig = Ivy_FraigPerform_int( pManTemp = pManAig, pIvyParams, pParams->nTotalBacktrackLimit, pParams->nTotalInspectLimit, &nSatConfs, &nSatInspects );  Ivy_ManStop( pManTemp );
+            RetValue = Ivy_FraigMiterStatus( pManAig );
+            Ivy_FraigMiterPrint( pManAig, "Fraiging   ", clk, pParams->fVerbose );
+        }
+        if ( RetValue >= 0 )
+            break;
+
+        // add to the number of backtracks and inspects
+        pParams->nTotalBacktracksMade += nSatConfs;
+        pParams->nTotalInspectsMade   += nSatInspects;
+        // check if global resource limit is reached
+        if ( (pParams->nTotalBacktrackLimit && pParams->nTotalBacktracksMade >= pParams->nTotalBacktrackLimit) ||
+             (pParams->nTotalInspectLimit   && pParams->nTotalInspectsMade   >= pParams->nTotalInspectLimit) )
+        {
+            printf( "Reached global limit on conflicts/inspects. Quitting.\n" );
+            *ppManAig = pManAig;
+            return -1;
+        }
+    }    
+
+    if ( RetValue < 0 )
+    {
+        if ( pParams->fVerbose )
+        {
+            printf( "Attempting SAT with conflict limit %d ...\n", pParams->nMiteringLimitLast );
+            fflush( stdout );
+        }
+        clk = clock();
+        pIvyParams->nBTLimitMiter = pParams->nMiteringLimitLast / Ivy_ManPoNum(pManAig);
+        if ( pParams->nTotalBacktrackLimit )
+            s_nBTLimitGlobal  = pParams->nTotalBacktrackLimit - pParams->nTotalBacktracksMade;
+        if ( pParams->nTotalInspectLimit )
+            s_nInsLimitGlobal = pParams->nTotalInspectLimit -   pParams->nTotalInspectsMade;        
+        pManAig = Ivy_FraigMiter( pManTemp = pManAig, pIvyParams );  Ivy_ManStop( pManTemp );
+        s_nBTLimitGlobal  = 0;
+        s_nInsLimitGlobal = 0;        
+        RetValue = Ivy_FraigMiterStatus( pManAig );
+        Ivy_FraigMiterPrint( pManAig, "SAT solving", clk, pParams->fVerbose );
+        // make sure that the sover never returns "undecided" when infinite resource limits are set
+        if( RetValue == -1 && pParams->nTotalInspectLimit == 0 &&
+            pParams->nTotalBacktrackLimit == 0 )
+        {
+            extern void Prove_ParamsPrint( Prove_Params_t * pParams );
+            Prove_ParamsPrint( pParams );
+            printf("ERROR: ABC has returned \"undecided\" in spite of no limits...\n");
+            exit(1);
+        }
+    }
+
+    // assign the model if it was proved by rewriting (const 1 miter)
+    if ( RetValue == 0 && pManAig->pData == NULL )
+    {
+        pManAig->pData = ALLOC( int, Ivy_ManPiNum(pManAig) );
+        memset( pManAig->pData, 0, sizeof(int) * Ivy_ManPiNum(pManAig) );
+    }
+    *ppManAig = pManAig;
+    return RetValue;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fraiging of the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Man_t * Ivy_FraigPerform_int( Ivy_Man_t * pManAig, Ivy_FraigParams_t * pParams, sint64 nBTLimitGlobal, sint64 nInsLimitGlobal, sint64 * pnSatConfs, sint64 * pnSatInspects )
+{ 
+    Ivy_FraigMan_t * p;
+    Ivy_Man_t * pManAigNew;
+    int clk;
+    if ( Ivy_ManNodeNum(pManAig) == 0 )
+        return Ivy_ManDup(pManAig);
+clk = clock();
+    assert( Ivy_ManLatchNum(pManAig) == 0 );
+    p = Ivy_FraigStart( pManAig, pParams );
+    // set global limits
+    p->nBTLimitGlobal  = nBTLimitGlobal;
+    p->nInsLimitGlobal = nInsLimitGlobal; 
+    
+    Ivy_FraigSimulate( p );
+    Ivy_FraigSweep( p );
+    pManAigNew = p->pManFraig;
+p->timeTotal = clock() - clk;
+    if ( pnSatConfs )
+        *pnSatConfs = p->pSat? p->pSat->stats.conflicts : 0;
+    if ( pnSatInspects )
+        *pnSatInspects = p->pSat? p->pSat->stats.inspects : 0;
+    Ivy_FraigStop( p );
+    return pManAigNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fraiging of the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Man_t * Ivy_FraigPerform( Ivy_Man_t * pManAig, Ivy_FraigParams_t * pParams )
+{
+    Ivy_FraigMan_t * p;
+    Ivy_Man_t * pManAigNew;
+    int clk;
+    if ( Ivy_ManNodeNum(pManAig) == 0 )
+        return Ivy_ManDup(pManAig);
+clk = clock();
+    assert( Ivy_ManLatchNum(pManAig) == 0 );
+    p = Ivy_FraigStart( pManAig, pParams );
+    Ivy_FraigSimulate( p );
+    Ivy_FraigSweep( p );
+    pManAigNew = p->pManFraig;
+p->timeTotal = clock() - clk;
+    Ivy_FraigStop( p );
+    return pManAigNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Applies brute-force SAT to the miter.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Man_t * Ivy_FraigMiter( Ivy_Man_t * pManAig, Ivy_FraigParams_t * pParams )
+{
+    Ivy_FraigMan_t * p;
+    Ivy_Man_t * pManAigNew;
+    Ivy_Obj_t * pObj;
+    int i, clk;
+clk = clock();
+    assert( Ivy_ManLatchNum(pManAig) == 0 );
+    p = Ivy_FraigStartSimple( pManAig, pParams );
+    // set global limits
+    p->nBTLimitGlobal  = s_nBTLimitGlobal;
+    p->nInsLimitGlobal = s_nInsLimitGlobal; 
+    // duplicate internal nodes
+    Ivy_ManForEachNode( p->pManAig, pObj, i )
+        pObj->pEquiv = Ivy_And( p->pManFraig, Ivy_ObjChild0Equiv(pObj), Ivy_ObjChild1Equiv(pObj) );
+    // try to prove each output of the miter
+    Ivy_FraigMiterProve( p );
+    // add the POs
+    Ivy_ManForEachPo( p->pManAig, pObj, i )
+        Ivy_ObjCreatePo( p->pManFraig, Ivy_ObjChild0Equiv(pObj) );
+    // clean the new manager
+    Ivy_ManForEachObj( p->pManFraig, pObj, i )
+    {
+        if ( Ivy_ObjFaninVec(pObj) )
+            Vec_PtrFree( Ivy_ObjFaninVec(pObj) );
+        pObj->pNextFan0 = pObj->pNextFan1 = NULL;
+    }
+    // remove dangling nodes 
+    Ivy_ManCleanup( p->pManFraig );
+    pManAigNew = p->pManFraig;
+p->timeTotal = clock() - clk;
+
+//printf( "Final nodes = %6d. ", Ivy_ManNodeNum(pManAigNew) );
+//PRT( "Time", p->timeTotal );
+    Ivy_FraigStop( p );
+    return pManAigNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the fraiging manager without simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_FraigMan_t * Ivy_FraigStartSimple( Ivy_Man_t * pManAig, Ivy_FraigParams_t * pParams )
+{
+    Ivy_FraigMan_t * p;
+    // allocat the fraiging manager
+    p = ALLOC( Ivy_FraigMan_t, 1 );
+    memset( p, 0, sizeof(Ivy_FraigMan_t) );
+    p->pParams   = pParams;
+    p->pManAig   = pManAig;
+    p->pManFraig = Ivy_ManStartFrom( pManAig );
+    p->vPiVars   = Vec_PtrAlloc( 100 );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the fraiging manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_FraigMan_t * Ivy_FraigStart( Ivy_Man_t * pManAig, Ivy_FraigParams_t * pParams )
+{
+    Ivy_FraigMan_t * p;
+    Ivy_FraigSim_t * pSims;
+    Ivy_Obj_t * pObj;
+    int i, k, EntrySize;
+    // clean the fanout representation
+    Ivy_ManForEachObj( pManAig, pObj, i )
+//        pObj->pEquiv = pObj->pFanout = pObj->pNextFan0 = pObj->pNextFan1 = pObj->pPrevFan0 = pObj->pPrevFan1 = NULL;
+        assert( !pObj->pEquiv && !pObj->pFanout );
+    // allocat the fraiging manager
+    p = ALLOC( Ivy_FraigMan_t, 1 );
+    memset( p, 0, sizeof(Ivy_FraigMan_t) );
+    p->pParams   = pParams;
+    p->pManAig   = pManAig;
+    p->pManFraig = Ivy_ManStartFrom( pManAig );
+    // allocate simulation info
+    p->nSimWords    = pParams->nSimWords;
+//    p->pSimWords    = ALLOC( unsigned, Ivy_ManObjNum(pManAig) * p->nSimWords ); 
+    EntrySize    = sizeof(Ivy_FraigSim_t) + sizeof(unsigned) * p->nSimWords;
+    p->pSimWords = (char *)malloc( Ivy_ManObjNum(pManAig) * EntrySize ); 
+    memset( p->pSimWords, 0, EntrySize );
+    k = 0;
+    Ivy_ManForEachObj( pManAig, pObj, i )
+    {
+        pSims = (Ivy_FraigSim_t *)(p->pSimWords + EntrySize * k++);
+        pSims->pNext = NULL;
+        if ( Ivy_ObjIsNode(pObj) )
+        {
+            if ( p->pSimStart == NULL )
+                p->pSimStart = pSims;
+            else
+                ((Ivy_FraigSim_t *)(p->pSimWords + EntrySize * (k-2)))->pNext = pSims;
+            pSims->pFanin0 = Ivy_ObjSim( Ivy_ObjFanin0(pObj) );
+            pSims->pFanin1 = Ivy_ObjSim( Ivy_ObjFanin1(pObj) );
+            pSims->Type = (Ivy_ObjFaninPhase(Ivy_ObjChild0(pObj)) << 2) | (Ivy_ObjFaninPhase(Ivy_ObjChild1(pObj)) << 1) | pObj->fPhase;
+        }
+        else
+        {
+            pSims->pFanin0 = NULL;
+            pSims->pFanin1 = NULL;
+            pSims->Type = 0;
+        }
+        Ivy_ObjSetSim( pObj, pSims );
+    }
+    assert( k == Ivy_ManObjNum(pManAig) );
+    // allocate storage for sim pattern
+    p->nPatWords = Ivy_BitWordNum( Ivy_ManPiNum(pManAig) );
+    p->pPatWords = ALLOC( unsigned, p->nPatWords ); 
+    p->pPatScores = ALLOC( int, 32 * p->nSimWords ); 
+    p->vPiVars   = Vec_PtrAlloc( 100 );
+    // set random number generator
+    srand( 0xABCABC );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the fraiging manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigStop( Ivy_FraigMan_t * p )
+{
+    if ( p->pParams->fVerbose )
+        Ivy_FraigPrint( p );
+    if ( p->vPiVars ) Vec_PtrFree( p->vPiVars );
+    if ( p->pSat ) sat_solver_delete( p->pSat );
+    FREE( p->pPatScores );
+    FREE( p->pPatWords );
+    FREE( p->pSimWords );
+    free( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints stats for the fraiging manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigPrint( Ivy_FraigMan_t * p )
+{
+    double nMemory;
+    nMemory = (double)Ivy_ManObjNum(p->pManAig)*p->nSimWords*sizeof(unsigned)/(1<<20);
+    printf( "SimWords = %d. Rounds = %d. Mem = %0.2f Mb.  ", p->nSimWords, p->nSimRounds, nMemory );
+    printf( "Classes: Beg = %d. End = %d.\n", p->nClassesBeg, p->nClassesEnd );
+//    printf( "Limits: BTNode = %d. BTMiter = %d.\n", p->pParams->nBTLimitNode, p->pParams->nBTLimitMiter );
+    printf( "Proof = %d. Counter-example = %d. Fail = %d. FailReal = %d. Zero = %d.\n", 
+        p->nSatProof, p->nSatCallsSat, p->nSatFails, p->nSatFailsReal, p->nClassesZero );
+    printf( "Final = %d. Miter = %d. Total = %d. Mux = %d. (Exor = %d.) SatVars = %d.\n", 
+        Ivy_ManNodeNum(p->pManFraig), p->nNodesMiter, Ivy_ManNodeNum(p->pManAig), 0, 0, p->nSatVars );
+    if ( p->pSat ) Sat_SolverPrintStats( stdout, p->pSat );
+    PRT( "AIG simulation  ", p->timeSim  );
+    PRT( "AIG traversal   ", p->timeTrav  );
+    PRT( "SAT solving     ", p->timeSat   );
+    PRT( "    Unsat       ", p->timeSatUnsat );
+    PRT( "    Sat         ", p->timeSatSat   );
+    PRT( "    Fail        ", p->timeSatFail  );
+    PRT( "Class refining  ", p->timeRef   );
+    PRT( "TOTAL RUNTIME   ", p->timeTotal );
+    if ( p->time1 ) { PRT( "time1           ", p->time1 ); }
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Assigns random patterns to the PI node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeAssignRandom( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj )
+{
+    Ivy_FraigSim_t * pSims;
+    int i;
+    assert( Ivy_ObjIsPi(pObj) );
+    pSims = Ivy_ObjSim(pObj);
+    for ( i = 0; i < p->nSimWords; i++ )
+        pSims->pData[i] = Ivy_ObjRandomSim();
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Assigns constant patterns to the PI node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeAssignConst( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj, int fConst1 )
+{
+    Ivy_FraigSim_t * pSims;
+    int i;
+    assert( Ivy_ObjIsPi(pObj) );
+    pSims = Ivy_ObjSim(pObj);
+    for ( i = 0; i < p->nSimWords; i++ )
+        pSims->pData[i] = fConst1? ~(unsigned)0 : 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Assings random simulation info for the PIs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigAssignRandom( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i;
+    Ivy_ManForEachPi( p->pManAig, pObj, i )
+        Ivy_NodeAssignRandom( p, pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Assings distance-1 simulation info for the PIs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigAssignDist1( Ivy_FraigMan_t * p, unsigned * pPat )
+{
+    Ivy_Obj_t * pObj;
+    int i, Limit;
+    Ivy_ManForEachPi( p->pManAig, pObj, i )
+    {
+        Ivy_NodeAssignConst( p, pObj, Ivy_InfoHasBit(pPat, i) );
+//        printf( "%d", Ivy_InfoHasBit(pPat, i) );
+    }
+//    printf( "\n" );
+
+    Limit = IVY_MIN( Ivy_ManPiNum(p->pManAig), p->nSimWords * 32 - 1 );
+    for ( i = 0; i < Limit; i++ )
+        Ivy_InfoXorBit( Ivy_ObjSim( Ivy_ManPi(p->pManAig,i) )->pData, i+1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if simulation info is composed of all zeros.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeHasZeroSim( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj )
+{
+    Ivy_FraigSim_t * pSims;
+    int i;
+    pSims = Ivy_ObjSim(pObj);
+    for ( i = 0; i < p->nSimWords; i++ )
+        if ( pSims->pData[i] )
+            return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if simulation info is composed of all zeros.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeComplementSim( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj )
+{
+    Ivy_FraigSim_t * pSims;
+    int i;
+    pSims = Ivy_ObjSim(pObj);
+    for ( i = 0; i < p->nSimWords; i++ )
+        pSims->pData[i] = ~pSims->pData[i];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if simulation infos are equal.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeCompareSims( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj0, Ivy_Obj_t * pObj1 )
+{
+    Ivy_FraigSim_t * pSims0, * pSims1;
+    int i;
+    pSims0 = Ivy_ObjSim(pObj0);
+    pSims1 = Ivy_ObjSim(pObj1);
+    for ( i = 0; i < p->nSimWords; i++ )
+        if ( pSims0->pData[i] != pSims1->pData[i] )
+            return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeSimulateSim( Ivy_FraigMan_t * p, Ivy_FraigSim_t * pSims )
+{
+    unsigned * pData, * pData0, * pData1;
+    int i;
+    pData  = pSims->pData;
+    pData0 = pSims->pFanin0->pData;
+    pData1 = pSims->pFanin1->pData;
+    switch( pSims->Type )
+    {
+    case 0:
+        for ( i = 0; i < p->nSimWords; i++ )
+            pData[i] = (pData0[i] & pData1[i]);
+        break;
+    case 1:
+        for ( i = 0; i < p->nSimWords; i++ )
+            pData[i] = ~(pData0[i] & pData1[i]);
+        break;
+    case 2:
+        for ( i = 0; i < p->nSimWords; i++ )
+            pData[i] = (pData0[i] & ~pData1[i]);
+        break;
+    case 3:
+        for ( i = 0; i < p->nSimWords; i++ )
+            pData[i] = (~pData0[i] | pData1[i]);
+        break;
+    case 4:
+        for ( i = 0; i < p->nSimWords; i++ )
+            pData[i] = (~pData0[i] & pData1[i]);
+        break;
+    case 5:
+        for ( i = 0; i < p->nSimWords; i++ )
+            pData[i] = (pData0[i] | ~pData1[i]);
+        break;
+    case 6:
+        for ( i = 0; i < p->nSimWords; i++ )
+            pData[i] = ~(pData0[i] | pData1[i]);
+        break;
+    case 7:
+        for ( i = 0; i < p->nSimWords; i++ )
+            pData[i] = (pData0[i] | pData1[i]);
+        break;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeSimulate( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj )
+{
+    Ivy_FraigSim_t * pSims, * pSims0, * pSims1;
+    int fCompl, fCompl0, fCompl1, i;
+    assert( !Ivy_IsComplement(pObj) );
+    // get hold of the simulation information
+    pSims  = Ivy_ObjSim(pObj);
+    pSims0 = Ivy_ObjSim(Ivy_ObjFanin0(pObj));
+    pSims1 = Ivy_ObjSim(Ivy_ObjFanin1(pObj));
+    // get complemented attributes of the children using their random info
+    fCompl  = pObj->fPhase;
+    fCompl0 = Ivy_ObjFaninPhase(Ivy_ObjChild0(pObj));
+    fCompl1 = Ivy_ObjFaninPhase(Ivy_ObjChild1(pObj));
+    // simulate
+    if ( fCompl0 && fCompl1 )
+    {
+        if ( fCompl )
+            for ( i = 0; i < p->nSimWords; i++ )
+                pSims->pData[i] = (pSims0->pData[i] | pSims1->pData[i]);
+        else
+            for ( i = 0; i < p->nSimWords; i++ )
+                pSims->pData[i] = ~(pSims0->pData[i] | pSims1->pData[i]);
+    }
+    else if ( fCompl0 && !fCompl1 )
+    {
+        if ( fCompl )
+            for ( i = 0; i < p->nSimWords; i++ )
+                pSims->pData[i] = (pSims0->pData[i] | ~pSims1->pData[i]);
+        else
+            for ( i = 0; i < p->nSimWords; i++ )
+                pSims->pData[i] = (~pSims0->pData[i] & pSims1->pData[i]);
+    }
+    else if ( !fCompl0 && fCompl1 )
+    {
+        if ( fCompl )
+            for ( i = 0; i < p->nSimWords; i++ )
+                pSims->pData[i] = (~pSims0->pData[i] | pSims1->pData[i]);
+        else
+            for ( i = 0; i < p->nSimWords; i++ )
+                pSims->pData[i] = (pSims0->pData[i] & ~pSims1->pData[i]);
+    }
+    else // if ( !fCompl0 && !fCompl1 )
+    {
+        if ( fCompl )
+            for ( i = 0; i < p->nSimWords; i++ )
+                pSims->pData[i] = ~(pSims0->pData[i] & pSims1->pData[i]);
+        else
+            for ( i = 0; i < p->nSimWords; i++ )
+                pSims->pData[i] = (pSims0->pData[i] & pSims1->pData[i]);
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes hash value using simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Ivy_NodeHash( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj )
+{
+    static int s_FPrimes[128] = { 
+        1009, 1049, 1093, 1151, 1201, 1249, 1297, 1361, 1427, 1459, 
+        1499, 1559, 1607, 1657, 1709, 1759, 1823, 1877, 1933, 1997, 
+        2039, 2089, 2141, 2213, 2269, 2311, 2371, 2411, 2467, 2543, 
+        2609, 2663, 2699, 2741, 2797, 2851, 2909, 2969, 3037, 3089, 
+        3169, 3221, 3299, 3331, 3389, 3461, 3517, 3557, 3613, 3671, 
+        3719, 3779, 3847, 3907, 3943, 4013, 4073, 4129, 4201, 4243, 
+        4289, 4363, 4441, 4493, 4549, 4621, 4663, 4729, 4793, 4871, 
+        4933, 4973, 5021, 5087, 5153, 5227, 5281, 5351, 5417, 5471, 
+        5519, 5573, 5651, 5693, 5749, 5821, 5861, 5923, 6011, 6073, 
+        6131, 6199, 6257, 6301, 6353, 6397, 6481, 6563, 6619, 6689, 
+        6737, 6803, 6863, 6917, 6977, 7027, 7109, 7187, 7237, 7309, 
+        7393, 7477, 7523, 7561, 7607, 7681, 7727, 7817, 7877, 7933, 
+        8011, 8039, 8059, 8081, 8093, 8111, 8123, 8147
+    };
+    Ivy_FraigSim_t * pSims;
+    unsigned uHash;
+    int i;
+    assert( p->nSimWords <= 128 );
+    uHash = 0;
+    pSims  = Ivy_ObjSim(pObj);
+    for ( i = 0; i < p->nSimWords; i++ )
+        uHash ^= pSims->pData[i] * s_FPrimes[i];
+    return uHash;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates AIG manager.]
+
+  Description [Assumes that the PI simulation info is attached.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigSimulateOne( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i, clk;
+clk = clock();
+    Ivy_ManForEachNode( p->pManAig, pObj, i )
+    {
+        Ivy_NodeSimulate( p, pObj );
+/*
+        if ( Ivy_ObjFraig(pObj) == NULL )
+            printf( "%3d --- -- %d  :  ", pObj->Id, pObj->fPhase );
+        else
+            printf( "%3d %3d %2d %d  :  ", pObj->Id, Ivy_Regular(Ivy_ObjFraig(pObj))->Id, Ivy_ObjSatNum(Ivy_Regular(Ivy_ObjFraig(pObj))), pObj->fPhase );
+        Extra_PrintBinary( stdout, Ivy_ObjSim(pObj), 30 );
+        printf( "\n" );
+*/
+    }
+p->timeSim += clock() - clk;
+p->nSimRounds++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates AIG manager.]
+
+  Description [Assumes that the PI simulation info is attached.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigSimulateOneSim( Ivy_FraigMan_t * p )
+{
+    Ivy_FraigSim_t * pSims;
+    int clk;
+clk = clock();
+    for ( pSims = p->pSimStart; pSims; pSims = pSims->pNext )
+        Ivy_NodeSimulateSim( p, pSims );
+p->timeSim += clock() - clk;
+p->nSimRounds++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node to the equivalence class.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeAddToClass( Ivy_Obj_t * pClass, Ivy_Obj_t * pObj )
+{
+    if ( Ivy_ObjClassNodeNext(pClass) == NULL )
+        Ivy_ObjSetClassNodeNext( pClass, pObj );
+    else
+        Ivy_ObjSetClassNodeNext( Ivy_ObjClassNodeLast(pClass), pObj );
+    Ivy_ObjSetClassNodeLast( pClass, pObj );
+    Ivy_ObjSetClassNodeRepr( pObj, pClass );
+    Ivy_ObjSetClassNodeNext( pObj, NULL );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds equivalence class to the list of classes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigAddClass( Ivy_FraigList_t * pList, Ivy_Obj_t * pClass )
+{
+    if ( pList->pHead == NULL )
+    {
+        pList->pHead = pClass;
+        pList->pTail = pClass;
+        Ivy_ObjSetEquivListPrev( pClass, NULL );
+        Ivy_ObjSetEquivListNext( pClass, NULL ); 
+    }
+    else
+    {
+        Ivy_ObjSetEquivListNext( pList->pTail, pClass ); 
+        Ivy_ObjSetEquivListPrev( pClass, pList->pTail );
+        Ivy_ObjSetEquivListNext( pClass, NULL ); 
+        pList->pTail = pClass;
+    }
+    pList->nItems++;
+}
+ 
+/**Function*************************************************************
+
+  Synopsis    [Updates the list of classes after base class has split.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigInsertClass( Ivy_FraigList_t * pList, Ivy_Obj_t * pBase, Ivy_Obj_t * pClass )
+{
+    Ivy_ObjSetEquivListPrev( pClass, pBase );
+    Ivy_ObjSetEquivListNext( pClass, Ivy_ObjEquivListNext(pBase) ); 
+    if ( Ivy_ObjEquivListNext(pBase) )
+        Ivy_ObjSetEquivListPrev( Ivy_ObjEquivListNext(pBase), pClass );
+    Ivy_ObjSetEquivListNext( pBase, pClass ); 
+    if ( pList->pTail == pBase )
+        pList->pTail = pClass;
+    pList->nItems++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Removes equivalence class from the list of classes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigRemoveClass( Ivy_FraigList_t * pList, Ivy_Obj_t * pClass )
+{
+    if ( pList->pHead == pClass )
+        pList->pHead = Ivy_ObjEquivListNext(pClass);
+    if ( pList->pTail == pClass )
+        pList->pTail = Ivy_ObjEquivListPrev(pClass);
+    if ( Ivy_ObjEquivListPrev(pClass) )
+        Ivy_ObjSetEquivListNext( Ivy_ObjEquivListPrev(pClass), Ivy_ObjEquivListNext(pClass) ); 
+    if ( Ivy_ObjEquivListNext(pClass) )
+        Ivy_ObjSetEquivListPrev( Ivy_ObjEquivListNext(pClass), Ivy_ObjEquivListPrev(pClass) );
+    Ivy_ObjSetEquivListNext( pClass, NULL ); 
+    Ivy_ObjSetEquivListPrev( pClass, NULL );
+    pClass->fMarkA = 0;
+    pList->nItems--;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Count the number of pairs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigCountPairsClasses( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t * pClass, * pNode;
+    int nPairs = 0, nNodes;
+    return nPairs;
+
+    Ivy_FraigForEachEquivClass( p->lClasses.pHead, pClass )
+    {
+        nNodes = 0;
+        Ivy_FraigForEachClassNode( pClass, pNode )
+            nNodes++;
+        nPairs += nNodes * (nNodes - 1) / 2;
+    }
+    return nPairs;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates initial simulation classes.]
+
+  Description [Assumes that simulation info is assigned.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigCreateClasses( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t ** pTable;
+    Ivy_Obj_t * pObj, * pConst1, * pBin, * pEntry;
+    int i, nTableSize;
+    unsigned Hash;
+    pConst1 = Ivy_ManConst1(p->pManAig);
+    // allocate the table
+    nTableSize = Ivy_ManObjNum(p->pManAig) / 2 + 13;
+    pTable = ALLOC( Ivy_Obj_t *, nTableSize ); 
+    memset( pTable, 0, sizeof(Ivy_Obj_t *) * nTableSize );
+    // collect nodes into the table
+    Ivy_ManForEachObj( p->pManAig, pObj, i )
+    {
+        if ( !Ivy_ObjIsPi(pObj) && !Ivy_ObjIsNode(pObj) )
+            continue;
+        Hash = Ivy_NodeHash( p, pObj );
+        if ( Hash == 0 && Ivy_NodeHasZeroSim( p, pObj ) )
+        {
+            Ivy_NodeAddToClass( pConst1, pObj );
+            continue;
+        }
+        // add the node to the table
+        pBin = pTable[Hash % nTableSize];
+        Ivy_FraigForEachBinNode( pBin, pEntry )
+            if ( Ivy_NodeCompareSims( p, pEntry, pObj ) )
+            {
+                Ivy_NodeAddToClass( pEntry, pObj );
+                break;
+            }
+        // check if the entry was added
+        if ( pEntry )
+            continue;
+        Ivy_ObjSetNodeHashNext( pObj, pBin );
+        pTable[Hash % nTableSize] = pObj;
+    }
+    // collect non-trivial classes
+    assert( p->lClasses.pHead == NULL );
+    Ivy_ManForEachObj( p->pManAig, pObj, i )
+    {
+        if ( !Ivy_ObjIsConst1(pObj) && !Ivy_ObjIsPi(pObj) && !Ivy_ObjIsNode(pObj) )
+            continue;
+        Ivy_ObjSetNodeHashNext( pObj, NULL );
+        if ( Ivy_ObjClassNodeRepr(pObj) == NULL )
+        {
+            assert( Ivy_ObjClassNodeNext(pObj) == NULL );
+            continue;
+        }
+        // recognize the head of the class
+        if ( Ivy_ObjClassNodeNext( Ivy_ObjClassNodeRepr(pObj) ) != NULL )
+            continue;
+        // clean the class representative and add it to the list
+        Ivy_ObjSetClassNodeRepr( pObj, NULL );
+        Ivy_FraigAddClass( &p->lClasses, pObj );
+    }
+    // free the table
+    free( pTable );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively refines the class after simulation.]
+
+  Description [Returns 1 if the class has changed.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigRefineClass_rec( Ivy_FraigMan_t * p, Ivy_Obj_t * pClass )
+{
+    Ivy_Obj_t * pClassNew, * pListOld, * pListNew, * pNode;
+    int RetValue = 0;
+    // check if there is refinement
+    pListOld = pClass;
+    Ivy_FraigForEachClassNode( Ivy_ObjClassNodeNext(pClass), pClassNew )
+    {
+        if ( !Ivy_NodeCompareSims(p, pClass, pClassNew) )
+        {
+            if ( p->pParams->fPatScores )
+                Ivy_FraigAddToPatScores( p, pClass, pClassNew );
+            break;
+        }
+        pListOld = pClassNew;
+    }
+    if ( pClassNew == NULL )
+        return 0;
+    // set representative of the new class
+    Ivy_ObjSetClassNodeRepr( pClassNew, NULL );
+    // start the new list
+    pListNew = pClassNew;
+    // go through the remaining nodes and sort them into two groups:
+    // (1) matches of the old node; (2) non-matches of the old node
+    Ivy_FraigForEachClassNode( Ivy_ObjClassNodeNext(pClassNew), pNode )
+        if ( Ivy_NodeCompareSims( p, pClass, pNode ) )
+        {
+            Ivy_ObjSetClassNodeNext( pListOld, pNode );
+            pListOld = pNode;
+        }
+        else
+        {
+            Ivy_ObjSetClassNodeNext( pListNew, pNode );
+            Ivy_ObjSetClassNodeRepr( pNode, pClassNew );
+            pListNew = pNode;
+        }
+    // finish both lists
+    Ivy_ObjSetClassNodeNext( pListNew, NULL );
+    Ivy_ObjSetClassNodeNext( pListOld, NULL );
+    // update the list of classes
+    Ivy_FraigInsertClass( &p->lClasses, pClass, pClassNew );
+    // if the old class is trivial, remove it
+    if ( Ivy_ObjClassNodeNext(pClass) == NULL )
+        Ivy_FraigRemoveClass( &p->lClasses, pClass );
+    // if the new class is trivial, remove it; otherwise, try to refine it
+    if ( Ivy_ObjClassNodeNext(pClassNew) == NULL )
+        Ivy_FraigRemoveClass( &p->lClasses, pClassNew );
+    else
+        RetValue = Ivy_FraigRefineClass_rec( p, pClassNew );
+    return RetValue + 1;
+}
+ 
+/**Function*************************************************************
+
+  Synopsis    [Creates the counter-example from the successful pattern.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigCheckOutputSimsSavePattern( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj )
+{ 
+    Ivy_FraigSim_t * pSims;
+    int i, k, BestPat, * pModel;
+    // find the word of the pattern
+    pSims = Ivy_ObjSim(pObj);
+    for ( i = 0; i < p->nSimWords; i++ )
+        if ( pSims->pData[i] )
+            break;
+    assert( i < p->nSimWords );
+    // find the bit of the pattern
+    for ( k = 0; k < 32; k++ )
+        if ( pSims->pData[i] & (1 << k) )
+            break;
+    assert( k < 32 );
+    // determine the best pattern
+    BestPat = i * 32 + k;
+    // fill in the counter-example data
+    pModel = ALLOC( int, Ivy_ManPiNum(p->pManFraig) );
+    Ivy_ManForEachPi( p->pManAig, pObj, i )
+    {
+        pModel[i] = Ivy_InfoHasBit(Ivy_ObjSim(pObj)->pData, BestPat);
+//        printf( "%d", pModel[i] );
+    }
+//    printf( "\n" );
+    // set the model
+    assert( p->pManFraig->pData == NULL );
+    p->pManFraig->pData = pModel;
+    return;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the one of the output is already non-constant 0.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigCheckOutputSims( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i;
+    // make sure the reference simulation pattern does not detect the bug
+    pObj = Ivy_ManPo( p->pManAig, 0 );
+    assert( Ivy_ObjFanin0(pObj)->fPhase == (unsigned)Ivy_ObjFaninC0(pObj) ); // Ivy_ObjFaninPhase(Ivy_ObjChild0(pObj)) == 0
+    Ivy_ManForEachPo( p->pManAig, pObj, i )
+    {
+        // complement simulation info
+//        if ( Ivy_ObjFanin0(pObj)->fPhase ^ Ivy_ObjFaninC0(pObj) ) // Ivy_ObjFaninPhase(Ivy_ObjChild0(pObj))
+//            Ivy_NodeComplementSim( p, Ivy_ObjFanin0(pObj) );
+        // check 
+        if ( !Ivy_NodeHasZeroSim( p, Ivy_ObjFanin0(pObj) ) )
+        {
+            // create the counter-example from this pattern
+            Ivy_FraigCheckOutputSimsSavePattern( p, Ivy_ObjFanin0(pObj) );
+            return 1;
+        }
+        // complement simulation info
+//        if ( Ivy_ObjFanin0(pObj)->fPhase ^ Ivy_ObjFaninC0(pObj) )
+//            Ivy_NodeComplementSim( p, Ivy_ObjFanin0(pObj) );
+    }
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Refines the classes after simulation.]
+
+  Description [Assumes that simulation info is assigned. Returns the
+  number of classes refined.]
+               
+  SideEffects [Large equivalence class of constant 0 may cause problems.]
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigRefineClasses( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t * pClass, * pClass2;
+    int clk, RetValue, Counter = 0;
+    // check if some outputs already became non-constant
+    // this is a special case when computation can be stopped!!!
+    if ( p->pParams->fProve )
+        Ivy_FraigCheckOutputSims( p );
+    if ( p->pManFraig->pData )
+        return 0;
+    // refine the classed
+clk = clock();
+    Ivy_FraigForEachEquivClassSafe( p->lClasses.pHead, pClass, pClass2 )
+    {
+        if ( pClass->fMarkA )
+            continue;
+        RetValue = Ivy_FraigRefineClass_rec( p, pClass );
+        Counter += ( RetValue > 0 );
+//if ( Ivy_ObjIsConst1(pClass) )
+//printf( "%d ", RetValue );
+//if ( Ivy_ObjIsConst1(pClass) )
+//    p->time1 += clock() - clk;
+    }
+p->timeRef += clock() - clk;
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Print the class.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigPrintClass( Ivy_Obj_t * pClass )
+{
+    Ivy_Obj_t * pObj;
+    printf( "Class {" );
+    Ivy_FraigForEachClassNode( pClass, pObj )
+        printf( " %d(%d)%c", pObj->Id, pObj->Level, pObj->fPhase? '+' : '-' );
+    printf( " }\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Count the number of elements in the class.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigCountClassNodes( Ivy_Obj_t * pClass )
+{
+    Ivy_Obj_t * pObj;
+    int Counter = 0;
+    Ivy_FraigForEachClassNode( pClass, pObj )
+        Counter++;
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints simulation classes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigPrintSimClasses( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t * pClass;
+    Ivy_FraigForEachEquivClass( p->lClasses.pHead, pClass )
+    {
+//        Ivy_FraigPrintClass( pClass );
+        printf( "%d ", Ivy_FraigCountClassNodes( pClass ) );
+    }
+//    printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Generated const 0 pattern.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigSavePattern0( Ivy_FraigMan_t * p )
+{
+    memset( p->pPatWords, 0, sizeof(unsigned) * p->nPatWords );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [[Generated const 1 pattern.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigSavePattern1( Ivy_FraigMan_t * p )
+{
+    memset( p->pPatWords, 0xff, sizeof(unsigned) * p->nPatWords );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Generates the counter-example satisfying the miter.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int * Ivy_FraigCreateModel( Ivy_FraigMan_t * p )
+{
+    int * pModel;
+    Ivy_Obj_t * pObj;
+    int i;
+    pModel = ALLOC( int, Ivy_ManPiNum(p->pManFraig) );
+    Ivy_ManForEachPi( p->pManFraig, pObj, i )
+        pModel[i] = ( p->pSat->model.ptr[Ivy_ObjSatNum(pObj)] == l_True );
+    return pModel;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Copy pattern from the solver into the internal storage.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigSavePattern( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i;
+    memset( p->pPatWords, 0, sizeof(unsigned) * p->nPatWords );
+    Ivy_ManForEachPi( p->pManFraig, pObj, i )
+//    Vec_PtrForEachEntry( p->vPiVars, pObj, i )
+        if ( p->pSat->model.ptr[Ivy_ObjSatNum(pObj)] == l_True )
+            Ivy_InfoSetBit( p->pPatWords, i );
+//            Ivy_InfoSetBit( p->pPatWords, pObj->Id - 1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Copy pattern from the solver into the internal storage.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigSavePattern2( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i;
+    memset( p->pPatWords, 0, sizeof(unsigned) * p->nPatWords );
+//    Ivy_ManForEachPi( p->pManFraig, pObj, i )
+    Vec_PtrForEachEntry( p->vPiVars, pObj, i )
+        if ( p->pSat->model.ptr[Ivy_ObjSatNum(pObj)] == l_True )
+//            Ivy_InfoSetBit( p->pPatWords, i );
+            Ivy_InfoSetBit( p->pPatWords, pObj->Id - 1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Copy pattern from the solver into the internal storage.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigSavePattern3( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i;
+    for ( i = 0; i < p->nPatWords; i++ )
+        p->pPatWords[i] = Ivy_ObjRandomSim();
+    Vec_PtrForEachEntry( p->vPiVars, pObj, i )
+        if ( Ivy_InfoHasBit( p->pPatWords, pObj->Id - 1 ) ^ (p->pSat->model.ptr[Ivy_ObjSatNum(pObj)] == l_True) )
+            Ivy_InfoXorBit( p->pPatWords, pObj->Id - 1 );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Performs simulation of the manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigSimulate( Ivy_FraigMan_t * p )
+{
+    int nChanges, nClasses;
+    // start the classes
+    Ivy_FraigAssignRandom( p );
+    Ivy_FraigSimulateOne( p );
+    Ivy_FraigCreateClasses( p );
+//printf( "Starting classes = %5d.   Pairs = %6d.\n", p->lClasses.nItems, Ivy_FraigCountPairsClasses(p) );
+    // refine classes by walking 0/1 patterns
+    Ivy_FraigSavePattern0( p );
+    Ivy_FraigAssignDist1( p, p->pPatWords );
+    Ivy_FraigSimulateOne( p );
+    nChanges = Ivy_FraigRefineClasses( p );
+    if ( p->pManFraig->pData )
+        return;
+//printf( "Refined classes  = %5d.   Changes = %4d.   Pairs = %6d.\n", p->lClasses.nItems, nChanges, Ivy_FraigCountPairsClasses(p) );
+    Ivy_FraigSavePattern1( p );
+    Ivy_FraigAssignDist1( p, p->pPatWords );
+    Ivy_FraigSimulateOne( p );
+    nChanges = Ivy_FraigRefineClasses( p );
+    if ( p->pManFraig->pData )
+        return;
+//printf( "Refined classes  = %5d.   Changes = %4d.   Pairs = %6d.\n", p->lClasses.nItems, nChanges, Ivy_FraigCountPairsClasses(p) );
+    // refine classes by random simulation
+    do {
+        Ivy_FraigAssignRandom( p );
+        Ivy_FraigSimulateOne( p );
+        nClasses = p->lClasses.nItems;
+        nChanges = Ivy_FraigRefineClasses( p );
+        if ( p->pManFraig->pData )
+            return;
+//printf( "Refined classes  = %5d.   Changes = %4d.   Pairs = %6d.\n", p->lClasses.nItems, nChanges, Ivy_FraigCountPairsClasses(p) );
+    } while ( (double)nChanges / nClasses > p->pParams->dSimSatur );
+//    Ivy_FraigPrintSimClasses( p );
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Cleans pattern scores.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigCleanPatScores( Ivy_FraigMan_t * p )
+{
+    int i, nLimit = p->nSimWords * 32;
+    for ( i = 0; i < nLimit; i++ )
+        p->pPatScores[i] = 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds to pattern scores.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigAddToPatScores( Ivy_FraigMan_t * p, Ivy_Obj_t * pClass, Ivy_Obj_t * pClassNew )
+{
+    Ivy_FraigSim_t * pSims0, * pSims1;
+    unsigned uDiff;
+    int i, w;
+    // get hold of the simulation information
+    pSims0 = Ivy_ObjSim(pClass);
+    pSims1 = Ivy_ObjSim(pClassNew);
+    // iterate through the differences and record the score
+    for ( w = 0; w < p->nSimWords; w++ )
+    {
+        uDiff = pSims0->pData[w] ^ pSims1->pData[w];
+        if ( uDiff == 0 )
+            continue;
+        for ( i = 0; i < 32; i++ )
+            if ( uDiff & ( 1 << i ) )
+                p->pPatScores[w*32+i]++;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Selects the best pattern.]
+
+  Description [Returns 1 if such pattern is found.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigSelectBestPat( Ivy_FraigMan_t * p )
+{
+    Ivy_FraigSim_t * pSims;
+    Ivy_Obj_t * pObj;
+    int i, nLimit = p->nSimWords * 32, MaxScore = 0, BestPat = -1;
+    for ( i = 1; i < nLimit; i++ )
+    {
+        if ( MaxScore < p->pPatScores[i] )
+        {
+            MaxScore = p->pPatScores[i];
+            BestPat = i;
+        }
+    }
+    if ( MaxScore == 0 )
+        return 0;
+//    if ( MaxScore > p->pParams->MaxScore )
+//    printf( "Max score is %3d.  ", MaxScore );
+    // copy the best pattern into the selected pattern
+    memset( p->pPatWords, 0, sizeof(unsigned) * p->nPatWords );
+    Ivy_ManForEachPi( p->pManAig, pObj, i )
+    {
+        pSims = Ivy_ObjSim(pObj);
+        if ( Ivy_InfoHasBit(pSims->pData, BestPat) )
+            Ivy_InfoSetBit(p->pPatWords, i);
+    }
+    return MaxScore;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Resimulates fraiging manager after finding a counter-example.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigResimulate( Ivy_FraigMan_t * p )
+{
+    int nChanges;
+    Ivy_FraigAssignDist1( p, p->pPatWords );
+    Ivy_FraigSimulateOne( p );
+    if ( p->pParams->fPatScores )
+        Ivy_FraigCleanPatScores( p );
+    nChanges = Ivy_FraigRefineClasses( p );
+    if ( p->pManFraig->pData )
+        return;
+    if ( nChanges < 1 )
+        printf( "Error: A counter-example did not refine classes!\n" );
+    assert( nChanges >= 1 );
+//printf( "Refined classes! = %5d.   Changes = %4d.\n", p->lClasses.nItems, nChanges );
+    if ( !p->pParams->fPatScores )
+        return;
+
+    // perform additional simulation using dist1 patterns derived from successful patterns
+    while ( Ivy_FraigSelectBestPat(p) > p->pParams->MaxScore )
+    {
+        Ivy_FraigAssignDist1( p, p->pPatWords );
+        Ivy_FraigSimulateOne( p );
+        Ivy_FraigCleanPatScores( p );
+        nChanges = Ivy_FraigRefineClasses( p );
+        if ( p->pManFraig->pData )
+            return;
+//printf( "Refined class!!! = %5d.   Changes = %4d.   Pairs = %6d.\n", p->lClasses.nItems, nChanges, Ivy_FraigCountPairsClasses(p) );
+        if ( nChanges == 0 )
+            break;
+    }
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the status of the miter.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigMiterPrint( Ivy_Man_t * pNtk, char * pString, int clk, int fVerbose )
+{
+    if ( !fVerbose )
+        return;
+    printf( "Nodes = %7d.  Levels = %4d.  ", Ivy_ManNodeNum(pNtk), Ivy_ManLevels(pNtk) );
+    PRT( pString, clock() - clk );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Reports the status of the miter.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigMiterStatus( Ivy_Man_t * pMan )
+{
+    Ivy_Obj_t * pObj, * pObjNew;
+    int i, CountConst0 = 0, CountNonConst0 = 0, CountUndecided = 0;
+    if ( pMan->pData )
+        return 0;
+    Ivy_ManForEachPo( pMan, pObj, i )
+    {
+        pObjNew = Ivy_ObjChild0(pObj);
+        // check if the output is constant 1
+        if ( pObjNew == pMan->pConst1 )
+        {
+            CountNonConst0++;
+            continue;
+        }
+        // check if the output is constant 0
+        if ( pObjNew == Ivy_Not(pMan->pConst1) )
+        {
+            CountConst0++;
+            continue;
+        }
+        // check if the output can be constant 0
+        if ( Ivy_Regular(pObjNew)->fPhase != (unsigned)Ivy_IsComplement(pObjNew) )
+        {
+            CountNonConst0++;
+            continue;
+        }
+        CountUndecided++;
+    }
+/*
+    if ( p->pParams->fVerbose )
+    {
+        printf( "Miter has %d outputs. ", Ivy_ManPoNum(p->pManAig) );
+        printf( "Const0 = %d.  ", CountConst0 );
+        printf( "NonConst0 = %d.  ", CountNonConst0 );
+        printf( "Undecided = %d.  ", CountUndecided );
+        printf( "\n" );
+    }
+*/
+    if ( CountNonConst0 )
+        return 0;
+    if ( CountUndecided )
+        return -1;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Tries to prove each output of the miter until encountering a sat output.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigMiterProve( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t * pObj, * pObjNew;
+    int i, RetValue, clk = clock();
+    int fVerbose = 0;
+    Ivy_ManForEachPo( p->pManAig, pObj, i )
+    {
+        if ( i && fVerbose )
+        {
+            PRT( "Time", clock() -clk );
+        }
+        pObjNew = Ivy_ObjChild0Equiv(pObj);
+        // check if the output is constant 1
+        if ( pObjNew == p->pManFraig->pConst1 )
+        {
+            if ( fVerbose )
+                printf( "Output %2d (out of %2d) is constant 1.  ", i, Ivy_ManPoNum(p->pManAig) );
+            // assing constant 0 model
+            p->pManFraig->pData = ALLOC( int, Ivy_ManPiNum(p->pManFraig) );
+            memset( p->pManFraig->pData, 0, sizeof(int) * Ivy_ManPiNum(p->pManFraig) );
+            break;
+        }
+        // check if the output is constant 0
+        if ( pObjNew == Ivy_Not(p->pManFraig->pConst1) )
+        {
+            if ( fVerbose )
+                printf( "Output %2d (out of %2d) is already constant 0.  ", i, Ivy_ManPoNum(p->pManAig) );
+            continue;
+        }
+        // check if the output can be constant 0
+        if ( Ivy_Regular(pObjNew)->fPhase != (unsigned)Ivy_IsComplement(pObjNew) )
+        {
+            if ( fVerbose )
+                printf( "Output %2d (out of %2d) cannot be constant 0.  ", i, Ivy_ManPoNum(p->pManAig) );
+            // assing constant 0 model
+            p->pManFraig->pData = ALLOC( int, Ivy_ManPiNum(p->pManFraig) );
+            memset( p->pManFraig->pData, 0, sizeof(int) * Ivy_ManPiNum(p->pManFraig) );
+            break;
+        }
+/*
+        // check the representative of this node
+        pRepr = Ivy_ObjClassNodeRepr(Ivy_ObjFanin0(pObj));
+        if ( Ivy_Regular(pRepr) != p->pManAig->pConst1 )
+            printf( "Representative is not constant 1.\n" );
+        else
+            printf( "Representative is constant 1.\n" );
+*/
+        // try to prove the output constant 0
+        RetValue = Ivy_FraigNodeIsConst( p, Ivy_Regular(pObjNew) );
+        if ( RetValue == 1 )  // proved equivalent
+        {
+            if ( fVerbose )
+                printf( "Output %2d (out of %2d) was proved constant 0.  ", i, Ivy_ManPoNum(p->pManAig) );
+            // set the constant miter
+            Ivy_ObjFanin0(pObj)->pEquiv = Ivy_NotCond( p->pManFraig->pConst1, !Ivy_ObjFaninC0(pObj) );
+            continue;
+        }
+        if ( RetValue == -1 ) // failed
+        {
+            if ( fVerbose )
+                printf( "Output %2d (out of %2d) has timed out at %d backtracks.  ", i, Ivy_ManPoNum(p->pManAig), p->pParams->nBTLimitMiter );
+            continue;
+        }
+        // proved satisfiable
+        if ( fVerbose )
+            printf( "Output %2d (out of %2d) was proved NOT a constant 0.  ", i, Ivy_ManPoNum(p->pManAig) );
+        // create the model
+        p->pManFraig->pData = Ivy_FraigCreateModel(p);
+        break;
+    }
+    if ( fVerbose )
+    {
+        PRT( "Time", clock() -clk );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fraiging for the internal nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigSweep( Ivy_FraigMan_t * p )
+{
+    Ivy_Obj_t * pObj;//, * pTemp;
+    int i, k = 0;
+p->nClassesZero = p->lClasses.pHead? (Ivy_ObjIsConst1(p->lClasses.pHead) ? Ivy_FraigCountClassNodes(p->lClasses.pHead) : 0) : 0;
+p->nClassesBeg  = p->lClasses.nItems;
+    // duplicate internal nodes
+    p->pProgress = Extra_ProgressBarStart( stdout, Ivy_ManNodeNum(p->pManAig) );
+    Ivy_ManForEachNode( p->pManAig, pObj, i )
+    {
+        Extra_ProgressBarUpdate( p->pProgress, k++, NULL );
+        // default to simple strashing if simulation detected a counter-example for a PO
+        if ( p->pManFraig->pData )
+            pObj->pEquiv = Ivy_And( p->pManFraig, Ivy_ObjChild0Equiv(pObj), Ivy_ObjChild1Equiv(pObj) );
+        else
+            pObj->pEquiv = Ivy_FraigAnd( p, pObj );
+        assert( pObj->pEquiv != NULL );
+//        pTemp = Ivy_Regular(pObj->pEquiv);
+//        assert( Ivy_Regular(pObj->pEquiv)->Type );
+    }
+    Extra_ProgressBarStop( p->pProgress );
+p->nClassesEnd = p->lClasses.nItems;
+    // try to prove the outputs of the miter
+    p->nNodesMiter = Ivy_ManNodeNum(p->pManFraig);
+//    Ivy_FraigMiterStatus( p->pManFraig );
+    if ( p->pParams->fProve && p->pManFraig->pData == NULL )
+        Ivy_FraigMiterProve( p );
+    // add the POs
+    Ivy_ManForEachPo( p->pManAig, pObj, i )
+        Ivy_ObjCreatePo( p->pManFraig, Ivy_ObjChild0Equiv(pObj) );
+    // clean the old manager
+    Ivy_ManForEachObj( p->pManAig, pObj, i )
+        pObj->pFanout = pObj->pNextFan0 = pObj->pNextFan1 = pObj->pPrevFan0 = pObj->pPrevFan1 = NULL;
+    // clean the new manager
+    Ivy_ManForEachObj( p->pManFraig, pObj, i )
+    {
+        if ( Ivy_ObjFaninVec(pObj) )
+            Vec_PtrFree( Ivy_ObjFaninVec(pObj) );
+        pObj->pNextFan0 = pObj->pNextFan1 = NULL;
+    }
+    // remove dangling nodes 
+    Ivy_ManCleanup( p->pManFraig );
+    // clean up the class marks
+    Ivy_FraigForEachEquivClass( p->lClasses.pHead, pObj )
+        pObj->fMarkA = 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fraiging for one node.]
+
+  Description [Returns the fraiged node.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_FraigAnd( Ivy_FraigMan_t * p, Ivy_Obj_t * pObjOld )
+{ 
+    Ivy_Obj_t * pObjNew, * pFanin0New, * pFanin1New, * pObjReprNew;
+    int RetValue;
+    // get the fraiged fanins
+    pFanin0New = Ivy_ObjChild0Equiv(pObjOld);
+    pFanin1New = Ivy_ObjChild1Equiv(pObjOld);
+    // get the candidate fraig node
+    pObjNew = Ivy_And( p->pManFraig, pFanin0New, pFanin1New );
+    // get representative of this class
+    if ( Ivy_ObjClassNodeRepr(pObjOld) == NULL || // this is a unique node
+         (!p->pParams->fDoSparse && Ivy_ObjClassNodeRepr(pObjOld) == p->pManAig->pConst1) ) // this is a sparse node
+    {
+        assert( Ivy_Regular(pFanin0New) != Ivy_Regular(pFanin1New) );
+        assert( pObjNew != Ivy_Regular(pFanin0New) );
+        assert( pObjNew != Ivy_Regular(pFanin1New) );
+        return pObjNew;
+    }
+    // get the fraiged representative
+    pObjReprNew = Ivy_ObjFraig(Ivy_ObjClassNodeRepr(pObjOld));
+    // if the fraiged nodes are the same return
+    if ( Ivy_Regular(pObjNew) == Ivy_Regular(pObjReprNew) )
+        return pObjNew;
+    assert( Ivy_Regular(pObjNew) != Ivy_ManConst1(p->pManFraig) );
+//    printf( "Node = %d. Repr = %d.\n", pObjOld->Id, Ivy_ObjClassNodeRepr(pObjOld)->Id );
+
+    // they are different (the counter-example is in p->pPatWords)
+    RetValue = Ivy_FraigNodesAreEquiv( p, Ivy_Regular(pObjReprNew), Ivy_Regular(pObjNew) );
+    if ( RetValue == 1 )  // proved equivalent
+    {
+        // mark the class as proved
+        if ( Ivy_ObjClassNodeNext(pObjOld) == NULL )
+            Ivy_ObjClassNodeRepr(pObjOld)->fMarkA = 1;
+        return Ivy_NotCond( pObjReprNew, pObjOld->fPhase ^ Ivy_ObjClassNodeRepr(pObjOld)->fPhase );
+    }
+    if ( RetValue == -1 ) // failed
+        return pObjNew;
+    // simulate the counter-example and return the new node
+    Ivy_FraigResimulate( p );
+    return pObjNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints variable activity.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigPrintActivity( Ivy_FraigMan_t * p )
+{
+    int i;
+    for ( i = 0; i < p->nSatVars; i++ )
+        printf( "%d %.3f  ", i, p->pSat->activity[i] );
+    printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Runs equivalence test for the two nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigNodesAreEquiv( Ivy_FraigMan_t * p, Ivy_Obj_t * pOld, Ivy_Obj_t * pNew )
+{
+    int pLits[4], RetValue, RetValue1, nBTLimit, clk, clk2 = clock();
+
+    // make sure the nodes are not complemented
+    assert( !Ivy_IsComplement(pNew) );
+    assert( !Ivy_IsComplement(pOld) );
+    assert( pNew != pOld );
+
+    // if at least one of the nodes is a failed node, perform adjustments:
+    // if the backtrack limit is small, simply skip this node
+    // if the backtrack limit is > 10, take the quare root of the limit
+    nBTLimit = p->pParams->nBTLimitNode;
+    if ( nBTLimit > 0 && (pOld->fFailTfo || pNew->fFailTfo) )
+    {
+        p->nSatFails++;
+        // fail immediately
+//        return -1;
+        if ( nBTLimit <= 10 )
+            return -1;
+        nBTLimit = (int)pow(nBTLimit, 0.7);
+    }
+    p->nSatCalls++;
+
+    // make sure the solver is allocated and has enough variables
+    if ( p->pSat == NULL )
+    {
+        p->pSat = sat_solver_new();
+        p->nSatVars = 1;
+        sat_solver_setnvars( p->pSat, 1000 );
+        // var 0 is reserved for const1 node - add the clause
+//        pLits[0] = toLit( 0 );
+//        sat_solver_addclause( p->pSat, pLits, pLits + 1 );
+    }
+
+    // if the nodes do not have SAT variables, allocate them
+    Ivy_FraigNodeAddToSolver( p, pOld, pNew );
+
+    // prepare variable activity
+    Ivy_FraigSetActivityFactors( p, pOld, pNew ); 
+
+    // solve under assumptions
+    // A = 1; B = 0     OR     A = 1; B = 1 
+clk = clock();
+    pLits[0] = toLitCond( Ivy_ObjSatNum(pOld), 0 );
+    pLits[1] = toLitCond( Ivy_ObjSatNum(pNew), pOld->fPhase == pNew->fPhase );
+//Sat_SolverWriteDimacs( p->pSat, "temp.cnf", pLits, pLits + 2, 1 );
+    RetValue1 = sat_solver_solve( p->pSat, pLits, pLits + 2, 
+        (sint64)nBTLimit, (sint64)0, 
+        p->nBTLimitGlobal, p->nInsLimitGlobal );
+p->timeSat += clock() - clk;
+    if ( RetValue1 == l_False )
+    {
+p->timeSatUnsat += clock() - clk;
+        pLits[0] = lit_neg( pLits[0] );
+        pLits[1] = lit_neg( pLits[1] );
+        RetValue = sat_solver_addclause( p->pSat, pLits, pLits + 2 );
+        assert( RetValue );
+        // continue solving the other implication
+        p->nSatCallsUnsat++;
+    }
+    else if ( RetValue1 == l_True )
+    {
+p->timeSatSat += clock() - clk;
+        Ivy_FraigSavePattern( p );
+        p->nSatCallsSat++;
+        return 0;
+    }
+    else // if ( RetValue1 == l_Undef )
+    {
+p->timeSatFail += clock() - clk;
+        // mark the node as the failed node
+        if ( pOld != p->pManFraig->pConst1 ) 
+            pOld->fFailTfo = 1;
+        pNew->fFailTfo = 1;
+        p->nSatFailsReal++;
+        return -1;
+    }
+
+    // if the old node was constant 0, we already know the answer
+    if ( pOld == p->pManFraig->pConst1 )
+    {
+        p->nSatProof++;
+        return 1;
+    }
+
+    // solve under assumptions
+    // A = 0; B = 1     OR     A = 0; B = 0 
+clk = clock();
+    pLits[0] = toLitCond( Ivy_ObjSatNum(pOld), 1 );
+    pLits[1] = toLitCond( Ivy_ObjSatNum(pNew), pOld->fPhase ^ pNew->fPhase );
+    RetValue1 = sat_solver_solve( p->pSat, pLits, pLits + 2, 
+        (sint64)nBTLimit, (sint64)0, 
+        p->nBTLimitGlobal, p->nInsLimitGlobal );
+p->timeSat += clock() - clk;
+    if ( RetValue1 == l_False )
+    {
+p->timeSatUnsat += clock() - clk;
+        pLits[0] = lit_neg( pLits[0] );
+        pLits[1] = lit_neg( pLits[1] );
+        RetValue = sat_solver_addclause( p->pSat, pLits, pLits + 2 );
+        assert( RetValue );
+        p->nSatCallsUnsat++;
+    }
+    else if ( RetValue1 == l_True )
+    {
+p->timeSatSat += clock() - clk;
+        Ivy_FraigSavePattern( p );
+        p->nSatCallsSat++;
+        return 0;
+    }
+    else // if ( RetValue1 == l_Undef )
+    {
+p->timeSatFail += clock() - clk;
+        // mark the node as the failed node
+        pOld->fFailTfo = 1;
+        pNew->fFailTfo = 1;
+        p->nSatFailsReal++;
+        return -1;
+    }
+/*
+    // check BDD proof
+    {
+        int RetVal;
+        PRT( "Sat", clock() - clk2 );
+        clk2 = clock();
+        RetVal = Ivy_FraigNodesAreEquivBdd( pOld, pNew );
+//        printf( "%d ", RetVal );
+        assert( RetVal );
+        PRT( "Bdd", clock() - clk2 );
+        printf( "\n" );
+    }
+*/
+    // return SAT proof
+    p->nSatProof++;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Runs equivalence test for one node.]
+
+  Description [Returns the fraiged node.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigNodeIsConst( Ivy_FraigMan_t * p, Ivy_Obj_t * pNew )
+{
+    int pLits[2], RetValue1, RetValue, clk;
+
+    // make sure the nodes are not complemented
+    assert( !Ivy_IsComplement(pNew) );
+    assert( pNew != p->pManFraig->pConst1 );
+    p->nSatCalls++;
+
+    // make sure the solver is allocated and has enough variables
+    if ( p->pSat == NULL )
+    {
+        p->pSat = sat_solver_new();
+        p->nSatVars = 1;
+        sat_solver_setnvars( p->pSat, 1000 );
+        // var 0 is reserved for const1 node - add the clause
+//        pLits[0] = toLit( 0 );
+//        sat_solver_addclause( p->pSat, pLits, pLits + 1 );
+    }
+
+    // if the nodes do not have SAT variables, allocate them
+    Ivy_FraigNodeAddToSolver( p, NULL, pNew );
+
+    // prepare variable activity
+    Ivy_FraigSetActivityFactors( p, NULL, pNew ); 
+
+    // solve under assumptions
+clk = clock();
+    pLits[0] = toLitCond( Ivy_ObjSatNum(pNew), pNew->fPhase );
+    RetValue1 = sat_solver_solve( p->pSat, pLits, pLits + 1, 
+        (sint64)p->pParams->nBTLimitMiter, (sint64)0, 
+        p->nBTLimitGlobal, p->nInsLimitGlobal );
+p->timeSat += clock() - clk;
+    if ( RetValue1 == l_False )
+    {
+p->timeSatUnsat += clock() - clk;
+        pLits[0] = lit_neg( pLits[0] );
+        RetValue = sat_solver_addclause( p->pSat, pLits, pLits + 1 );
+        assert( RetValue );
+        // continue solving the other implication
+        p->nSatCallsUnsat++;
+    }
+    else if ( RetValue1 == l_True )
+    {
+p->timeSatSat += clock() - clk;
+        if ( p->pPatWords )
+            Ivy_FraigSavePattern( p );
+        p->nSatCallsSat++;
+        return 0;
+    }
+    else // if ( RetValue1 == l_Undef )
+    {
+p->timeSatFail += clock() - clk;
+        // mark the node as the failed node
+        pNew->fFailTfo = 1;
+        p->nSatFailsReal++;
+        return -1;
+    }
+
+    // return SAT proof
+    p->nSatProof++;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Addes clauses to the solver.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigAddClausesMux( Ivy_FraigMan_t * p, Ivy_Obj_t * pNode )
+{
+    Ivy_Obj_t * pNodeI, * pNodeT, * pNodeE;
+    int pLits[4], RetValue, VarF, VarI, VarT, VarE, fCompT, fCompE;
+
+    assert( !Ivy_IsComplement( pNode ) );
+    assert( Ivy_ObjIsMuxType( pNode ) );
+    // get nodes (I = if, T = then, E = else)
+    pNodeI = Ivy_ObjRecognizeMux( pNode, &pNodeT, &pNodeE );
+    // get the variable numbers
+    VarF = Ivy_ObjSatNum(pNode);
+    VarI = Ivy_ObjSatNum(pNodeI);
+    VarT = Ivy_ObjSatNum(Ivy_Regular(pNodeT));
+    VarE = Ivy_ObjSatNum(Ivy_Regular(pNodeE));
+    // get the complementation flags
+    fCompT = Ivy_IsComplement(pNodeT);
+    fCompE = Ivy_IsComplement(pNodeE);
+
+    // f = ITE(i, t, e)
+
+    // i' + t' + f
+    // i' + t  + f'
+    // i  + e' + f
+    // i  + e  + f'
+
+    // create four clauses
+    pLits[0] = toLitCond(VarI, 1);
+    pLits[1] = toLitCond(VarT, 1^fCompT);
+    pLits[2] = toLitCond(VarF, 0);
+    RetValue = sat_solver_addclause( p->pSat, pLits, pLits + 3 );
+    assert( RetValue );
+    pLits[0] = toLitCond(VarI, 1);
+    pLits[1] = toLitCond(VarT, 0^fCompT);
+    pLits[2] = toLitCond(VarF, 1);
+    RetValue = sat_solver_addclause( p->pSat, pLits, pLits + 3 );
+    assert( RetValue );
+    pLits[0] = toLitCond(VarI, 0);
+    pLits[1] = toLitCond(VarE, 1^fCompE);
+    pLits[2] = toLitCond(VarF, 0);
+    RetValue = sat_solver_addclause( p->pSat, pLits, pLits + 3 );
+    assert( RetValue );
+    pLits[0] = toLitCond(VarI, 0);
+    pLits[1] = toLitCond(VarE, 0^fCompE);
+    pLits[2] = toLitCond(VarF, 1);
+    RetValue = sat_solver_addclause( p->pSat, pLits, pLits + 3 );
+    assert( RetValue );
+
+    // two additional clauses
+    // t' & e' -> f'
+    // t  & e  -> f 
+
+    // t  + e   + f'
+    // t' + e'  + f 
+
+    if ( VarT == VarE )
+    {
+//        assert( fCompT == !fCompE );
+        return;
+    }
+
+    pLits[0] = toLitCond(VarT, 0^fCompT);
+    pLits[1] = toLitCond(VarE, 0^fCompE);
+    pLits[2] = toLitCond(VarF, 1);
+    RetValue = sat_solver_addclause( p->pSat, pLits, pLits + 3 );
+    assert( RetValue );
+    pLits[0] = toLitCond(VarT, 1^fCompT);
+    pLits[1] = toLitCond(VarE, 1^fCompE);
+    pLits[2] = toLitCond(VarF, 0);
+    RetValue = sat_solver_addclause( p->pSat, pLits, pLits + 3 );
+    assert( RetValue );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Addes clauses to the solver.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigAddClausesSuper( Ivy_FraigMan_t * p, Ivy_Obj_t * pNode, Vec_Ptr_t * vSuper )
+{
+    Ivy_Obj_t * pFanin;
+    int * pLits, nLits, RetValue, i;
+    assert( !Ivy_IsComplement(pNode) );
+    assert( Ivy_ObjIsNode( pNode ) );
+    // create storage for literals
+    nLits = Vec_PtrSize(vSuper) + 1;
+    pLits = ALLOC( int, nLits );
+    // suppose AND-gate is A & B = C
+    // add !A => !C   or   A + !C
+    Vec_PtrForEachEntry( vSuper, pFanin, i )
+    {
+        pLits[0] = toLitCond(Ivy_ObjSatNum(Ivy_Regular(pFanin)), Ivy_IsComplement(pFanin));
+        pLits[1] = toLitCond(Ivy_ObjSatNum(pNode), 1);
+        RetValue = sat_solver_addclause( p->pSat, pLits, pLits + 2 );
+        assert( RetValue );
+    }
+    // add A & B => C   or   !A + !B + C
+    Vec_PtrForEachEntry( vSuper, pFanin, i )
+        pLits[i] = toLitCond(Ivy_ObjSatNum(Ivy_Regular(pFanin)), !Ivy_IsComplement(pFanin));
+    pLits[nLits-1] = toLitCond(Ivy_ObjSatNum(pNode), 0);
+    RetValue = sat_solver_addclause( p->pSat, pLits, pLits + nLits );
+    assert( RetValue );
+    free( pLits );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects the supergate.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigCollectSuper_rec( Ivy_Obj_t * pObj, Vec_Ptr_t * vSuper, int fFirst, int fUseMuxes )
+{
+    // if the new node is complemented or a PI, another gate begins
+    if ( Ivy_IsComplement(pObj) || Ivy_ObjIsPi(pObj) || (!fFirst && Ivy_ObjRefs(pObj) > 1) || 
+         (fUseMuxes && Ivy_ObjIsMuxType(pObj)) )
+    {
+        Vec_PtrPushUnique( vSuper, pObj );
+        return;
+    }
+    // go through the branches
+    Ivy_FraigCollectSuper_rec( Ivy_ObjChild0(pObj), vSuper, 0, fUseMuxes );
+    Ivy_FraigCollectSuper_rec( Ivy_ObjChild1(pObj), vSuper, 0, fUseMuxes );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects the supergate.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Ivy_FraigCollectSuper( Ivy_Obj_t * pObj, int fUseMuxes )
+{
+    Vec_Ptr_t * vSuper;
+    assert( !Ivy_IsComplement(pObj) );
+    assert( !Ivy_ObjIsPi(pObj) );
+    vSuper = Vec_PtrAlloc( 4 );
+    Ivy_FraigCollectSuper_rec( pObj, vSuper, 1, fUseMuxes );
+    return vSuper;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Updates the solver clause database.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigObjAddToFrontier( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj, Vec_Ptr_t * vFrontier )
+{
+    assert( !Ivy_IsComplement(pObj) );
+    if ( Ivy_ObjSatNum(pObj) )
+        return;
+    assert( Ivy_ObjSatNum(pObj) == 0 );
+    assert( Ivy_ObjFaninVec(pObj) == NULL );
+    if ( Ivy_ObjIsConst1(pObj) )
+        return;
+//printf( "Assigning node %d number %d\n", pObj->Id, p->nSatVars );
+    Ivy_ObjSetSatNum( pObj, p->nSatVars++ );
+    if ( Ivy_ObjIsNode(pObj) )
+        Vec_PtrPush( vFrontier, pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Updates the solver clause database.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_FraigNodeAddToSolver( Ivy_FraigMan_t * p, Ivy_Obj_t * pOld, Ivy_Obj_t * pNew )
+{ 
+    Vec_Ptr_t * vFrontier, * vFanins;
+    Ivy_Obj_t * pNode, * pFanin;
+    int i, k, fUseMuxes = 1;
+    assert( pOld || pNew );
+    // quit if CNF is ready
+    if ( (!pOld || Ivy_ObjFaninVec(pOld)) && (!pNew || Ivy_ObjFaninVec(pNew)) )
+        return;
+    // start the frontier
+    vFrontier = Vec_PtrAlloc( 100 );
+    if ( pOld ) Ivy_FraigObjAddToFrontier( p, pOld, vFrontier );
+    if ( pNew ) Ivy_FraigObjAddToFrontier( p, pNew, vFrontier );
+    // explore nodes in the frontier
+    Vec_PtrForEachEntry( vFrontier, pNode, i )
+    {
+        // create the supergate
+        assert( Ivy_ObjSatNum(pNode) );
+        assert( Ivy_ObjFaninVec(pNode) == NULL );
+        if ( fUseMuxes && Ivy_ObjIsMuxType(pNode) )
+        {
+            vFanins = Vec_PtrAlloc( 4 );
+            Vec_PtrPushUnique( vFanins, Ivy_ObjFanin0( Ivy_ObjFanin0(pNode) ) );
+            Vec_PtrPushUnique( vFanins, Ivy_ObjFanin0( Ivy_ObjFanin1(pNode) ) );
+            Vec_PtrPushUnique( vFanins, Ivy_ObjFanin1( Ivy_ObjFanin0(pNode) ) );
+            Vec_PtrPushUnique( vFanins, Ivy_ObjFanin1( Ivy_ObjFanin1(pNode) ) );
+            Vec_PtrForEachEntry( vFanins, pFanin, k )
+                Ivy_FraigObjAddToFrontier( p, Ivy_Regular(pFanin), vFrontier );
+            Ivy_FraigAddClausesMux( p, pNode );
+        }
+        else
+        {
+            vFanins = Ivy_FraigCollectSuper( pNode, fUseMuxes );
+            Vec_PtrForEachEntry( vFanins, pFanin, k )
+                Ivy_FraigObjAddToFrontier( p, Ivy_Regular(pFanin), vFrontier );
+            Ivy_FraigAddClausesSuper( p, pNode, vFanins );
+        }
+        assert( Vec_PtrSize(vFanins) > 1 );
+        Ivy_ObjSetFaninVec( pNode, vFanins );
+    }
+    Vec_PtrFree( vFrontier );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets variable activities in the cone.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigSetActivityFactors_rec( Ivy_FraigMan_t * p, Ivy_Obj_t * pObj, int LevelMin, int LevelMax )
+{
+    Vec_Ptr_t * vFanins;
+    Ivy_Obj_t * pFanin;
+    int i, Counter = 0;
+    assert( !Ivy_IsComplement(pObj) );
+    assert( Ivy_ObjSatNum(pObj) );
+    // skip visited variables
+    if ( Ivy_ObjIsTravIdCurrent(p->pManFraig, pObj) )
+        return 0;
+    Ivy_ObjSetTravIdCurrent(p->pManFraig, pObj);
+    // add the PI to the list
+    if ( pObj->Level <= (unsigned)LevelMin || Ivy_ObjIsPi(pObj) )
+        return 0;
+    // set the factor of this variable
+    // (LevelMax-LevelMin) / (pObj->Level-LevelMin) = p->pParams->dActConeBumpMax / ThisBump
+    p->pSat->factors[Ivy_ObjSatNum(pObj)] = p->pParams->dActConeBumpMax * (pObj->Level - LevelMin)/(LevelMax - LevelMin);
+    veci_push(&p->pSat->act_vars, Ivy_ObjSatNum(pObj));
+    // explore the fanins
+    vFanins = Ivy_ObjFaninVec( pObj );
+    Vec_PtrForEachEntry( vFanins, pFanin, i )
+        Counter += Ivy_FraigSetActivityFactors_rec( p, Ivy_Regular(pFanin), LevelMin, LevelMax );
+    return 1 + Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets variable activities in the cone.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigSetActivityFactors( Ivy_FraigMan_t * p, Ivy_Obj_t * pOld, Ivy_Obj_t * pNew )
+{
+    int clk, LevelMin, LevelMax;
+    assert( pOld || pNew );
+clk = clock(); 
+    // reset the active variables
+    veci_resize(&p->pSat->act_vars, 0);
+    // prepare for traversal
+    Ivy_ManIncrementTravId( p->pManFraig );
+    // determine the min and max level to visit
+    assert( p->pParams->dActConeRatio > 0 && p->pParams->dActConeRatio < 1 );
+    LevelMax = IVY_MAX( (pNew ? pNew->Level : 0), (pOld ? pOld->Level : 0) );
+    LevelMin = (int)(LevelMax * (1.0 - p->pParams->dActConeRatio));
+    // traverse
+    if ( pOld && !Ivy_ObjIsConst1(pOld) )
+        Ivy_FraigSetActivityFactors_rec( p, pOld, LevelMin, LevelMax );
+    if ( pNew && !Ivy_ObjIsConst1(pNew) )
+        Ivy_FraigSetActivityFactors_rec( p, pNew, LevelMin, LevelMax );
+//Ivy_FraigPrintActivity( p );
+p->timeTrav += clock() - clk;
+    return 1;
+}
+
+
+
+#include "cuddInt.h"
+
+/**Function*************************************************************
+
+  Synopsis    [Checks equivalence using BDDs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+DdNode * Ivy_FraigNodesAreEquivBdd_int( DdManager * dd, DdNode * bFunc, Vec_Ptr_t * vFront, int Level )
+{
+    DdNode ** pFuncs;
+    DdNode * bFuncNew;
+    Vec_Ptr_t * vTemp;
+    Ivy_Obj_t * pObj, * pFanin;
+    int i, NewSize;
+    // create new frontier
+    vTemp = Vec_PtrAlloc( 100 );
+    Vec_PtrForEachEntry( vFront, pObj, i )
+    {
+        if ( (int)pObj->Level != Level )
+        {
+            pObj->fMarkB = 1;
+            pObj->TravId = Vec_PtrSize(vTemp);
+            Vec_PtrPush( vTemp, pObj );
+            continue;
+        }
+
+        pFanin = Ivy_ObjFanin0(pObj);
+        if ( pFanin->fMarkB == 0 )
+        {
+            pFanin->fMarkB = 1;
+            pFanin->TravId = Vec_PtrSize(vTemp);
+            Vec_PtrPush( vTemp, pFanin );
+        }
+
+        pFanin = Ivy_ObjFanin1(pObj);
+        if ( pFanin->fMarkB == 0 )
+        {
+            pFanin->fMarkB = 1;
+            pFanin->TravId = Vec_PtrSize(vTemp);
+            Vec_PtrPush( vTemp, pFanin );
+        }
+    }
+    // collect the permutation
+    NewSize = IVY_MAX(dd->size, Vec_PtrSize(vTemp));
+    pFuncs = ALLOC( DdNode *, NewSize );
+    Vec_PtrForEachEntry( vFront, pObj, i )
+    {
+        if ( (int)pObj->Level != Level )
+            pFuncs[i] = Cudd_bddIthVar( dd, pObj->TravId );
+        else
+            pFuncs[i] = Cudd_bddAnd( dd, 
+                Cudd_NotCond( Cudd_bddIthVar(dd, Ivy_ObjFanin0(pObj)->TravId), Ivy_ObjFaninC0(pObj) ),
+                Cudd_NotCond( Cudd_bddIthVar(dd, Ivy_ObjFanin1(pObj)->TravId), Ivy_ObjFaninC1(pObj) ) );
+        Cudd_Ref( pFuncs[i] );
+    }
+    // add the remaining vars
+    assert( NewSize == dd->size );
+    for ( i = Vec_PtrSize(vFront); i < dd->size; i++ )
+    {
+        pFuncs[i] = Cudd_bddIthVar( dd, i );
+        Cudd_Ref( pFuncs[i] );
+    }
+
+    // create new
+    bFuncNew = Cudd_bddVectorCompose( dd, bFunc, pFuncs ); Cudd_Ref( bFuncNew );
+    // clean trav Id
+    Vec_PtrForEachEntry( vTemp, pObj, i )
+    {
+        pObj->fMarkB = 0;
+        pObj->TravId = 0;
+    }
+    // deref
+    for ( i = 0; i < dd->size; i++ )
+        Cudd_RecursiveDeref( dd, pFuncs[i] );
+    free( pFuncs );
+
+    free( vFront->pArray );
+    *vFront = *vTemp;
+
+    vTemp->nCap = vTemp->nSize = 0;
+    vTemp->pArray = NULL;
+    Vec_PtrFree( vTemp );
+
+    Cudd_Deref( bFuncNew );
+    return bFuncNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Checks equivalence using BDDs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_FraigNodesAreEquivBdd( Ivy_Obj_t * pObj1, Ivy_Obj_t * pObj2 )
+{
+    static DdManager * dd = NULL;
+    DdNode * bFunc, * bTemp;
+    Vec_Ptr_t * vFront;
+    Ivy_Obj_t * pObj;
+    int i, RetValue, Iter, Level;
+    // start the manager
+    if ( dd == NULL )
+        dd = Cudd_Init( 50, 0, CUDD_UNIQUE_SLOTS, CUDD_CACHE_SLOTS, 0 );
+    // create front
+    vFront = Vec_PtrAlloc( 100 );
+    Vec_PtrPush( vFront, pObj1 );
+    Vec_PtrPush( vFront, pObj2 );
+    // get the function
+    bFunc = Cudd_bddXor( dd, Cudd_bddIthVar(dd,0), Cudd_bddIthVar(dd,1) );  Cudd_Ref( bFunc );
+    bFunc = Cudd_NotCond( bFunc, pObj1->fPhase != pObj2->fPhase );
+    // try running BDDs
+    for ( Iter = 0; ; Iter++ )
+    {
+        // find max level
+        Level = 0;
+        Vec_PtrForEachEntry( vFront, pObj, i )
+            if ( Level < (int)pObj->Level )
+                Level = (int)pObj->Level;
+        if ( Level == 0 )
+            break;            
+        bFunc = Ivy_FraigNodesAreEquivBdd_int( dd, bTemp = bFunc, vFront, Level ); Cudd_Ref( bFunc );
+        Cudd_RecursiveDeref( dd, bTemp );
+        if ( bFunc == Cudd_ReadLogicZero(dd) ) // proved
+            {printf( "%d", Iter ); break;}
+        if ( Cudd_DagSize(bFunc) > 1000 )
+            {printf( "b" ); break;}
+        if ( dd->size > 120 )
+            {printf( "s" ); break;}
+        if ( Iter > 50 )
+            {printf( "i" ); break;}
+    }
+    if ( bFunc == Cudd_ReadLogicZero(dd) ) // unsat
+        RetValue = 1;
+    else if ( Level == 0 ) // sat
+        RetValue = 0;
+    else 
+        RetValue = -1; // spaceout/timeout
+    Cudd_RecursiveDeref( dd, bFunc );
+    Vec_PtrFree( vFront );
+    return RetValue;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyHaig.c b/src/aig/ivy/ivyHaig.c
new file mode 100644
index 00000000..87021600
--- /dev/null
+++ b/src/aig/ivy/ivyHaig.c
@@ -0,0 +1,530 @@
+/**CFile****************************************************************
+
+  FileName    [ivyHaig.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [HAIG management procedures.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyHaig.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+/* 
+    HAIGing rules in working AIG:
+    - Each node in the working AIG has a pointer to the corresponding node in HAIG 
+      (this node is not necessarily the representative of the equivalence class of HAIG nodes)
+    - This pointer is complemented if the AIG node and its corresponding HAIG node have different phase
+
+    Choice node rules in HAIG:
+    - Equivalent nodes are linked into a ring
+    - Exactly one node in the ring has fanouts (this node is called the representative)
+    - The pointer going from a node to the next node in the ring is complemented 
+      if the first node is complemented, compared to the representative node of the equivalence class
+    - (consequence of the above) The representative node always has non-complemented pointer to the next node
+    - New nodes are inserted into the ring immediately after the representative node
+*/
+
+// returns the representative node of the given HAIG node
+static inline Ivy_Obj_t * Ivy_HaigObjRepr( Ivy_Obj_t * pObj )
+{
+    Ivy_Obj_t * pTemp;
+    assert( !Ivy_IsComplement(pObj) );
+    // if the node has no equivalent node or has fanout, it is representative
+    if ( pObj->pEquiv == NULL || Ivy_ObjRefs(pObj) > 0 )
+        return pObj;
+    // the node belongs to a class and is not a representative
+    // complemented edge (pObj->pEquiv) tells if it is complemented w.r.t. the repr
+    for ( pTemp = Ivy_Regular(pObj->pEquiv); pTemp != pObj; pTemp = Ivy_Regular(pTemp->pEquiv) )
+        if ( Ivy_ObjRefs(pTemp) > 0 )
+            break;
+    // return the representative node
+    assert( Ivy_ObjRefs(pTemp) > 0 );
+    return Ivy_NotCond( pTemp, Ivy_IsComplement(pObj->pEquiv) );
+}
+
+// counts the number of nodes in the equivalence class
+static inline int Ivy_HaigObjCountClass( Ivy_Obj_t * pObj )
+{
+    Ivy_Obj_t * pTemp;
+    int Counter;
+    assert( !Ivy_IsComplement(pObj) );
+    assert( Ivy_ObjRefs(pObj) > 0 );
+    if ( pObj->pEquiv == NULL )
+        return 1;
+    assert( !Ivy_IsComplement(pObj->pEquiv) );
+    Counter = 1;
+    for ( pTemp = pObj->pEquiv; pTemp != pObj; pTemp = Ivy_Regular(pTemp->pEquiv) )
+        Counter++;
+    return Counter;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Starts HAIG for the manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManHaigStart( Ivy_Man_t * p, int fVerbose )
+{
+    Vec_Int_t * vLatches;
+    Ivy_Obj_t * pObj;
+    int i;
+    assert( p->pHaig == NULL );
+    p->pHaig = Ivy_ManDup( p );
+
+    if ( fVerbose )
+    {
+        printf( "Starting : " );
+        Ivy_ManPrintStats( p->pHaig );
+    }
+
+    // collect latches of design D and set their values to be DC
+    vLatches = Vec_IntAlloc( 100 );
+    Ivy_ManForEachLatch( p->pHaig, pObj, i )
+    {
+        pObj->Init = IVY_INIT_DC;
+        Vec_IntPush( vLatches, pObj->Id );
+    }
+    p->pHaig->pData = vLatches;
+/*
+    {
+        int x;
+        Ivy_ManShow( p, 0, NULL );
+        Ivy_ManShow( p->pHaig, 1, NULL );
+        x = 0;
+    }
+*/
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transfers the HAIG to the newly created manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManHaigTrasfer( Ivy_Man_t * p, Ivy_Man_t * pNew )
+{
+    Ivy_Obj_t * pObj;
+    int i;
+    assert( p->pHaig != NULL );
+    Ivy_ManConst1(pNew)->pEquiv = Ivy_ManConst1(p)->pEquiv;
+    Ivy_ManForEachPi( pNew, pObj, i )
+        pObj->pEquiv = Ivy_ManPi( p, i )->pEquiv;
+    pNew->pHaig = p->pHaig;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops HAIG for the manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManHaigStop( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i;
+    assert( p->pHaig != NULL );
+    Vec_IntFree( p->pHaig->pData );
+    Ivy_ManStop( p->pHaig );
+    p->pHaig = NULL;
+    // remove dangling pointers to the HAIG objects
+    Ivy_ManForEachObj( p, pObj, i )
+        pObj->pEquiv = NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates a new node in HAIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManHaigCreateObj( Ivy_Man_t * p, Ivy_Obj_t * pObj )
+{
+    Ivy_Obj_t * pEquiv0, * pEquiv1;
+    assert( p->pHaig != NULL );
+    assert( !Ivy_IsComplement(pObj) );
+    if ( Ivy_ObjType(pObj) == IVY_BUF )
+        pObj->pEquiv = Ivy_ObjChild0Equiv(pObj);
+    else if ( Ivy_ObjType(pObj) == IVY_LATCH )
+    {
+//        pObj->pEquiv = Ivy_Latch( p->pHaig, Ivy_ObjChild0Equiv(pObj), pObj->Init );
+        pEquiv0 = Ivy_ObjChild0Equiv(pObj);
+        pEquiv0 = Ivy_NotCond( Ivy_HaigObjRepr(Ivy_Regular(pEquiv0)), Ivy_IsComplement(pEquiv0) );
+        pObj->pEquiv = Ivy_Latch( p->pHaig, pEquiv0, pObj->Init );
+    }
+    else if ( Ivy_ObjType(pObj) == IVY_AND )
+    {
+//        pObj->pEquiv = Ivy_And( p->pHaig, Ivy_ObjChild0Equiv(pObj), Ivy_ObjChild1Equiv(pObj) );
+        pEquiv0 = Ivy_ObjChild0Equiv(pObj);
+        pEquiv0 = Ivy_NotCond( Ivy_HaigObjRepr(Ivy_Regular(pEquiv0)), Ivy_IsComplement(pEquiv0) );
+        pEquiv1 = Ivy_ObjChild1Equiv(pObj);
+        pEquiv1 = Ivy_NotCond( Ivy_HaigObjRepr(Ivy_Regular(pEquiv1)), Ivy_IsComplement(pEquiv1) );
+        pObj->pEquiv = Ivy_And( p->pHaig, pEquiv0, pEquiv1 );
+    }
+    else assert( 0 );
+    // make sure the node points to the representative
+//    pObj->pEquiv = Ivy_NotCond( Ivy_HaigObjRepr(Ivy_Regular(pObj->pEquiv)), Ivy_IsComplement(pObj->pEquiv) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Checks if the old node is in the TFI of the new node.]
+
+  Description [] 
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ObjIsInTfi_rec( Ivy_Obj_t * pObjNew, Ivy_Obj_t * pObjOld, int Levels )
+{
+    if ( pObjNew == pObjOld )
+        return 1;
+    if ( Levels == 0 || Ivy_ObjIsCi(pObjNew) || Ivy_ObjIsConst1(pObjNew) )
+        return 0;
+    if ( Ivy_ObjIsInTfi_rec( Ivy_ObjFanin0(pObjNew), pObjOld, Levels - 1 ) )
+        return 1;
+    if ( Ivy_ObjIsNode(pObjNew) && Ivy_ObjIsInTfi_rec( Ivy_ObjFanin1(pObjNew), pObjOld, Levels - 1 ) )
+        return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the pair of equivalent nodes in HAIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManHaigCreateChoice( Ivy_Man_t * p, Ivy_Obj_t * pObjOld, Ivy_Obj_t * pObjNew )
+{
+    Ivy_Obj_t * pObjOldHaig, * pObjNewHaig;
+    Ivy_Obj_t * pObjOldHaigR, * pObjNewHaigR;
+    int fCompl;
+//printf( "\nCreating choice for %d and %d in AIG\n", pObjOld->Id, Ivy_Regular(pObjNew)->Id );
+
+    assert( p->pHaig != NULL );
+    assert( !Ivy_IsComplement(pObjOld) );
+    // get pointers to the representatives of pObjOld and pObjNew
+    pObjOldHaig = pObjOld->pEquiv;
+    pObjNewHaig = Ivy_NotCond( Ivy_Regular(pObjNew)->pEquiv, Ivy_IsComplement(pObjNew) );
+    // get the classes
+    pObjOldHaig = Ivy_NotCond( Ivy_HaigObjRepr(Ivy_Regular(pObjOldHaig)), Ivy_IsComplement(pObjOldHaig) );
+    pObjNewHaig = Ivy_NotCond( Ivy_HaigObjRepr(Ivy_Regular(pObjNewHaig)), Ivy_IsComplement(pObjNewHaig) );
+    // get regular pointers
+    pObjOldHaigR = Ivy_Regular(pObjOldHaig);
+    pObjNewHaigR = Ivy_Regular(pObjNewHaig);
+    // check if there is phase difference between them
+    fCompl = (Ivy_IsComplement(pObjOldHaig) != Ivy_IsComplement(pObjNewHaig));
+    // if the class is the same, nothing to do
+    if ( pObjOldHaigR == pObjNewHaigR )
+        return;
+    // if the second node belongs to a class, do not merge classes (for the time being)
+    if ( Ivy_ObjRefs(pObjOldHaigR) == 0 || pObjNewHaigR->pEquiv != NULL || 
+        Ivy_ObjRefs(pObjNewHaigR) > 0 ) //|| Ivy_ObjIsInTfi_rec(pObjNewHaigR, pObjOldHaigR, 10) )
+    {
+/*
+        if ( pObjNewHaigR->pEquiv != NULL )
+            printf( "c" );
+        if ( Ivy_ObjRefs(pObjNewHaigR) > 0 )
+            printf( "f" );
+        printf( " " );
+*/
+        p->pHaig->nClassesSkip++;
+        return;
+    }
+
+    // add this node to the class of pObjOldHaig
+    assert( Ivy_ObjRefs(pObjOldHaigR) > 0 );
+    assert( !Ivy_IsComplement(pObjOldHaigR->pEquiv) );
+    if ( pObjOldHaigR->pEquiv == NULL )
+        pObjNewHaigR->pEquiv = Ivy_NotCond( pObjOldHaigR, fCompl );
+    else
+        pObjNewHaigR->pEquiv = Ivy_NotCond( pObjOldHaigR->pEquiv, fCompl );
+    pObjOldHaigR->pEquiv = pObjNewHaigR;
+//printf( "Setting choice node %d -> %d.\n", pObjOldHaigR->Id, pObjNewHaigR->Id );
+    // update the class of the new node
+//    Ivy_Regular(pObjNew)->pEquiv = Ivy_NotCond( pObjOldHaigR, fCompl ^ Ivy_IsComplement(pObjNew) );
+//printf( "Creating choice for %d and %d in HAIG\n", pObjOldHaigR->Id, pObjNewHaigR->Id );
+
+//    if ( pObjOldHaigR->Id == 13 )
+//    {
+//        Ivy_ManShow( p, 0 );
+//        Ivy_ManShow( p->pHaig, 1 );
+//    }
+//    if ( !Ivy_ManIsAcyclic( p->pHaig ) )
+//        printf( "HAIG contains a cycle\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Count the number of choices and choice nodes in HAIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManHaigCountChoices( Ivy_Man_t * p, int * pnChoices )
+{
+    Ivy_Obj_t * pObj;
+    int nChoices, nChoiceNodes, Counter, i;
+    assert( p->pHaig != NULL );
+    nChoices = nChoiceNodes = 0;
+    Ivy_ManForEachObj( p->pHaig, pObj, i )
+    {
+        if ( Ivy_ObjIsTerm(pObj) || i == 0 )
+            continue;
+        if ( Ivy_ObjRefs(pObj) == 0 )
+            continue;
+        Counter = Ivy_HaigObjCountClass( pObj );
+        nChoiceNodes += (int)(Counter > 1);
+        nChoices += Counter - 1;
+//        if ( Counter > 1 )
+//            printf( "Choice node %d %s\n", pObj->Id, Ivy_ObjIsLatch(pObj)? "(latch)": "" );
+    }
+    *pnChoices = nChoices;
+    return nChoiceNodes;
+} 
+
+/**Function*************************************************************
+
+  Synopsis    [Prints statistics of the HAIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManHaigPostprocess( Ivy_Man_t * p, int fVerbose )
+{
+    int nChoices, nChoiceNodes;
+
+    assert( p->pHaig != NULL );
+
+    if ( fVerbose )
+    {
+        printf( "Final    : " );
+        Ivy_ManPrintStats( p );
+        printf( "HAIG     : " );
+        Ivy_ManPrintStats( p->pHaig );
+
+        // print choice node stats
+        nChoiceNodes = Ivy_ManHaigCountChoices( p, &nChoices );
+        printf( "Total choice nodes = %d. Total choices = %d. Skipped classes = %d.\n", 
+            nChoiceNodes, nChoices, p->pHaig->nClassesSkip ); 
+    }
+
+    if ( Ivy_ManIsAcyclic( p->pHaig ) )
+    {
+        if ( fVerbose )
+            printf( "HAIG is acyclic\n" );
+    }
+    else
+        printf( "HAIG contains a cycle\n" );
+
+//    if ( fVerbose )
+//        Ivy_ManHaigSimulate( p );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Applies the simulation rules.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Ivy_Init_t Ivy_ManHaigSimulateAnd( Ivy_Init_t In0, Ivy_Init_t In1 )
+{
+    assert( In0 != IVY_INIT_NONE && In1 != IVY_INIT_NONE );
+    if ( In0 == IVY_INIT_DC || In1 == IVY_INIT_DC )
+        return IVY_INIT_DC;
+    if ( In0 == IVY_INIT_1 && In1 == IVY_INIT_1 )
+        return IVY_INIT_1;
+    return IVY_INIT_0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Applies the simulation rules.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Ivy_Init_t Ivy_ManHaigSimulateChoice( Ivy_Init_t In0, Ivy_Init_t In1 )
+{
+    assert( In0 != IVY_INIT_NONE && In1 != IVY_INIT_NONE );
+    if ( (In0 == IVY_INIT_0 && In1 == IVY_INIT_1) || (In0 == IVY_INIT_1 && In1 == IVY_INIT_0) )
+    {
+         printf( "Compatibility fails.\n" );
+         return IVY_INIT_0;
+    }
+    if ( In0 == IVY_INIT_DC && In1 == IVY_INIT_DC )
+        return IVY_INIT_DC;
+    if ( In0 != IVY_INIT_DC )
+        return In0;
+    return In1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulate HAIG using modified 3-valued simulation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManHaigSimulate( Ivy_Man_t * p )
+{
+    Vec_Int_t * vNodes, * vLatches, * vLatchesD;
+    Ivy_Obj_t * pObj, * pTemp;
+    Ivy_Init_t In0, In1;
+    int i, k, Counter;
+    int fVerbose = 0;
+
+    // check choices
+    Ivy_ManCheckChoices( p );
+
+    // switch to HAIG
+    assert( p->pHaig != NULL );
+    p = p->pHaig;
+
+if ( fVerbose )
+Ivy_ManForEachPi( p, pObj, i )
+printf( "Setting PI %d\n", pObj->Id );
+
+    // collect latches and nodes in the DFS order
+    vNodes = Ivy_ManDfsSeq( p, &vLatches );
+
+if ( fVerbose )
+Ivy_ManForEachNodeVec( p, vNodes, pObj, i )
+printf( "Collected node %d with fanins %d and %d\n", pObj->Id, Ivy_ObjFanin0(pObj)->Id, Ivy_ObjFanin1(pObj)->Id );
+
+    // set the PI values
+    Ivy_ManConst1(p)->Init = IVY_INIT_1;
+    Ivy_ManForEachPi( p, pObj, i )
+        pObj->Init = IVY_INIT_0;
+
+    // set the latch values
+    Ivy_ManForEachNodeVec( p, vLatches, pObj, i )
+        pObj->Init = IVY_INIT_DC;
+    // set the latches of D to be determinate
+    vLatchesD = p->pData;
+    Ivy_ManForEachNodeVec( p, vLatchesD, pObj, i )
+        pObj->Init = IVY_INIT_0;
+
+    // perform several rounds of simulation
+    for ( k = 0; k < 10; k++ )
+    {
+        // count the number of non-determinate values
+        Counter = 0;
+        Ivy_ManForEachNodeVec( p, vLatches, pObj, i )
+            Counter += ( pObj->Init == IVY_INIT_DC );
+        printf( "Iter %d : Non-determinate = %d\n", k, Counter );    
+        
+        // simulate the internal nodes
+        Ivy_ManForEachNodeVec( p, vNodes, pObj, i )
+        {
+if ( fVerbose )
+printf( "Processing node %d with fanins %d and %d\n", pObj->Id, Ivy_ObjFanin0(pObj)->Id, Ivy_ObjFanin1(pObj)->Id );
+            In0 = Ivy_InitNotCond( Ivy_ObjFanin0(pObj)->Init, Ivy_ObjFaninC0(pObj) );
+            In1 = Ivy_InitNotCond( Ivy_ObjFanin1(pObj)->Init, Ivy_ObjFaninC1(pObj) );
+            pObj->Init = Ivy_ManHaigSimulateAnd( In0, In1 );
+            // simulate the equivalence class if the node is a representative
+            if ( pObj->pEquiv && Ivy_ObjRefs(pObj) > 0 )
+            {
+if ( fVerbose )
+printf( "Processing choice node %d\n", pObj->Id );
+                In0 = pObj->Init;
+                assert( !Ivy_IsComplement(pObj->pEquiv) );
+                for ( pTemp = pObj->pEquiv; pTemp != pObj; pTemp = Ivy_Regular(pTemp->pEquiv) )
+                {
+if ( fVerbose )
+printf( "Processing secondary node %d\n", pTemp->Id );
+                    In1 = Ivy_InitNotCond( pTemp->Init, Ivy_IsComplement(pTemp->pEquiv) );
+                    In0 = Ivy_ManHaigSimulateChoice( In0, In1 );
+                }
+                pObj->Init = In0;
+            }
+        }
+
+        // simulate the latches
+        Ivy_ManForEachNodeVec( p, vLatches, pObj, i )
+        {
+            pObj->Level = Ivy_ObjFanin0(pObj)->Init;
+if ( fVerbose )
+printf( "Using latch %d with fanin %d\n", pObj->Id, Ivy_ObjFanin0(pObj)->Id );
+        }
+        Ivy_ManForEachNodeVec( p, vLatches, pObj, i )
+            pObj->Init = pObj->Level, pObj->Level = 0;
+    }
+    // free arrays
+    Vec_IntFree( vNodes );
+    Vec_IntFree( vLatches );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyMan.c b/src/aig/ivy/ivyMan.c
new file mode 100644
index 00000000..07faef85
--- /dev/null
+++ b/src/aig/ivy/ivyMan.c
@@ -0,0 +1,546 @@
+/**CFile****************************************************************
+
+  FileName    [ivyMan.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [AIG manager.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivy_.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the AIG manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Man_t * Ivy_ManStart()
+{
+    Ivy_Man_t * p;
+    // start the manager
+    p = ALLOC( Ivy_Man_t, 1 );
+    memset( p, 0, sizeof(Ivy_Man_t) );
+    // perform initializations
+    p->Ghost.Id   = -1;
+    p->nTravIds   =  1;
+    p->fCatchExor =  1;
+    // allocate arrays for nodes
+    p->vPis = Vec_PtrAlloc( 100 );
+    p->vPos = Vec_PtrAlloc( 100 );
+    p->vBufs = Vec_PtrAlloc( 100 );
+    p->vObjs = Vec_PtrAlloc( 100 );
+    // prepare the internal memory manager
+    Ivy_ManStartMemory( p );
+    // create the constant node
+    p->pConst1 = Ivy_ManFetchMemory( p );
+    p->pConst1->fPhase = 1;
+    Vec_PtrPush( p->vObjs, p->pConst1 );
+    p->nCreated = 1;
+    // start the table
+    p->nTableSize = 10007;
+    p->pTable = ALLOC( int, p->nTableSize );
+    memset( p->pTable, 0, sizeof(int) * p->nTableSize );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Duplicates the AIG manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Man_t * Ivy_ManStartFrom( Ivy_Man_t * p )
+{
+    Ivy_Man_t * pNew;
+    Ivy_Obj_t * pObj;
+    int i;
+    // create the new manager
+    pNew = Ivy_ManStart();
+    // create the PIs
+    Ivy_ManConst1(p)->pEquiv = Ivy_ManConst1(pNew);
+    Ivy_ManForEachPi( p, pObj, i )
+        pObj->pEquiv = Ivy_ObjCreatePi(pNew);
+    return pNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Duplicates the AIG manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Man_t * Ivy_ManDup( Ivy_Man_t * p )
+{
+    Vec_Int_t * vNodes, * vLatches;
+    Ivy_Man_t * pNew;
+    Ivy_Obj_t * pObj;
+    int i;
+    // collect latches and nodes in the DFS order
+    vNodes = Ivy_ManDfsSeq( p, &vLatches );
+    // create the new manager
+    pNew = Ivy_ManStart();
+    // create the PIs
+    Ivy_ManConst1(p)->pEquiv = Ivy_ManConst1(pNew);
+    Ivy_ManForEachPi( p, pObj, i )
+        pObj->pEquiv = Ivy_ObjCreatePi(pNew);
+    // create the fake PIs for latches
+    Ivy_ManForEachNodeVec( p, vLatches, pObj, i )
+        pObj->pEquiv = Ivy_ObjCreatePi(pNew);
+    // duplicate internal nodes
+    Ivy_ManForEachNodeVec( p, vNodes, pObj, i )
+        if ( Ivy_ObjIsBuf(pObj) )
+            pObj->pEquiv = Ivy_ObjChild0Equiv(pObj);
+        else
+            pObj->pEquiv = Ivy_And( pNew, Ivy_ObjChild0Equiv(pObj), Ivy_ObjChild1Equiv(pObj) );
+    // add the POs
+    Ivy_ManForEachPo( p, pObj, i )
+        Ivy_ObjCreatePo( pNew, Ivy_ObjChild0Equiv(pObj) );
+    // transform additional PI nodes into latches and connect them
+    Ivy_ManForEachNodeVec( p, vLatches, pObj, i )
+    {
+        assert( !Ivy_ObjFaninC0(pObj) );
+        pObj->pEquiv->Type = IVY_LATCH;
+        pObj->pEquiv->Init = pObj->Init;
+        Ivy_ObjConnect( pNew, pObj->pEquiv, Ivy_ObjChild0Equiv(pObj), NULL );
+    }
+    // shrink the arrays
+    Vec_PtrShrink( pNew->vPis, Ivy_ManPiNum(p) );
+    // update the counters of different objects
+    pNew->nObjs[IVY_PI] -= Ivy_ManLatchNum(p);
+    pNew->nObjs[IVY_LATCH] += Ivy_ManLatchNum(p);
+    // free arrays
+    Vec_IntFree( vNodes );
+    Vec_IntFree( vLatches );
+    // make sure structural hashing did not change anything
+    assert( Ivy_ManNodeNum(p)  == Ivy_ManNodeNum(pNew) );
+    assert( Ivy_ManLatchNum(p) == Ivy_ManLatchNum(pNew) );
+    // check the resulting network
+    if ( !Ivy_ManCheck(pNew) )
+        printf( "Ivy_ManMakeSeq(): The check has failed.\n" );
+    return pNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the AIG manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Man_t * Ivy_ManFrames( Ivy_Man_t * pMan, int nLatches, int nFrames, int fInit, Vec_Ptr_t ** pvMapping )
+{
+    Vec_Ptr_t * vMapping;
+    Ivy_Man_t * pNew;
+    Ivy_Obj_t * pObj;
+    int i, f, nPis, nPos, nIdMax;
+    assert( Ivy_ManLatchNum(pMan) == 0 );
+    assert( nFrames > 0 );
+    // prepare the mapping
+    nPis = Ivy_ManPiNum(pMan) - nLatches;
+    nPos = Ivy_ManPoNum(pMan) - nLatches;
+    nIdMax = Ivy_ManObjIdMax(pMan);
+    // create the new manager
+    pNew = Ivy_ManStart();
+    // set the starting values of latch inputs
+    for ( i = 0; i < nLatches; i++ )
+        Ivy_ManPo(pMan, nPos+i)->pEquiv = fInit? Ivy_Not(Ivy_ManConst1(pNew)) : Ivy_ObjCreatePi(pNew);
+    // add timeframes
+    vMapping = Vec_PtrStart( nIdMax * nFrames + 1 );
+    for ( f = 0; f < nFrames; f++ )
+    {
+        // create PIs
+        Ivy_ManConst1(pMan)->pEquiv = Ivy_ManConst1(pNew);
+        for ( i = 0; i < nPis; i++ )
+            Ivy_ManPi(pMan, i)->pEquiv = Ivy_ObjCreatePi(pNew);
+        // transfer values to latch outputs
+        for ( i = 0; i < nLatches; i++ )
+            Ivy_ManPi(pMan, nPis+i)->pEquiv = Ivy_ManPo(pMan, nPos+i)->pEquiv;
+        // perform strashing
+        Ivy_ManForEachNode( pMan, pObj, i )
+            pObj->pEquiv = Ivy_And( pNew, Ivy_ObjChild0Equiv(pObj), Ivy_ObjChild1Equiv(pObj) );
+        // create POs
+        for ( i = 0; i < nPos; i++ )
+            Ivy_ManPo(pMan, i)->pEquiv = Ivy_ObjCreatePo( pNew, Ivy_ObjChild0Equiv(Ivy_ManPo(pMan, i)) );
+        // set the results of latch inputs
+        for ( i = 0; i < nLatches; i++ )
+            Ivy_ManPo(pMan, nPos+i)->pEquiv = Ivy_ObjChild0Equiv(Ivy_ManPo(pMan, nPos+i));
+        // save the pointers in this frame
+        Ivy_ManForEachObj( pMan, pObj, i )
+            Vec_PtrWriteEntry( vMapping, f * nIdMax + i, pObj->pEquiv );
+    }
+    // connect latches
+    if ( !fInit )
+        for ( i = 0; i < nLatches; i++ )
+            Ivy_ObjCreatePo( pNew, Ivy_ManPo(pMan, nPos+i)->pEquiv );
+    // remove dangling nodes
+    Ivy_ManCleanup(pNew);
+    *pvMapping = vMapping;
+    // check the resulting network
+    if ( !Ivy_ManCheck(pNew) )
+        printf( "Ivy_ManFrames(): The check has failed.\n" );
+    return pNew;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the AIG manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManStop( Ivy_Man_t * p )
+{
+    if ( p->time1 ) { PRT( "Update lev  ", p->time1 ); }
+    if ( p->time2 ) { PRT( "Update levR ", p->time2 ); }
+//    Ivy_TableProfile( p );
+//    if ( p->vFanouts )  Ivy_ManStopFanout( p );
+    if ( p->vChunks )   Ivy_ManStopMemory( p );
+    if ( p->vRequired ) Vec_IntFree( p->vRequired );
+    if ( p->vPis )      Vec_PtrFree( p->vPis );
+    if ( p->vPos )      Vec_PtrFree( p->vPos );
+    if ( p->vBufs )     Vec_PtrFree( p->vBufs );
+    if ( p->vObjs )     Vec_PtrFree( p->vObjs );
+    free( p->pTable );
+    free( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Removes nodes without fanout.]
+
+  Description [Returns the number of dangling nodes removed.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManCleanup( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pNode;
+    int i, nNodesOld;
+    nNodesOld = Ivy_ManNodeNum(p);
+    Ivy_ManForEachObj( p, pNode, i )
+        if ( Ivy_ObjIsNode(pNode) || Ivy_ObjIsLatch(pNode) || Ivy_ObjIsBuf(pNode) )
+            if ( Ivy_ObjRefs(pNode) == 0 )
+                Ivy_ObjDelete_rec( p, pNode, 1 );
+//printf( "Cleanup removed %d nodes.\n", nNodesOld - Ivy_ManNodeNum(p) );
+    return nNodesOld - Ivy_ManNodeNum(p);
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Marks nodes reachable from the given one.]
+
+  Description [Returns the number of dangling nodes removed.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManCleanupSeq_rec( Ivy_Obj_t * pObj )
+{
+    if ( Ivy_ObjIsMarkA(pObj) )
+        return;
+    Ivy_ObjSetMarkA(pObj);
+    if ( pObj->pFanin0 != NULL )
+        Ivy_ManCleanupSeq_rec( Ivy_ObjFanin0(pObj) );
+    if ( pObj->pFanin1 != NULL )
+        Ivy_ManCleanupSeq_rec( Ivy_ObjFanin1(pObj) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Removes logic that does not feed into POs.]
+
+  Description [Returns the number of dangling nodes removed.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManCleanupSeq( Ivy_Man_t * p )
+{
+    Vec_Ptr_t * vNodes;
+    Ivy_Obj_t * pObj;
+    int i, RetValue;
+    // mark the constant and PIs
+    Ivy_ObjSetMarkA( Ivy_ManConst1(p) );
+    Ivy_ManForEachPi( p, pObj, i )
+        Ivy_ObjSetMarkA( pObj );
+    // mark nodes visited from POs
+    Ivy_ManForEachPo( p, pObj, i )
+        Ivy_ManCleanupSeq_rec( pObj );
+    // collect unmarked nodes
+    vNodes = Vec_PtrAlloc( 100 );
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        if ( Ivy_ObjIsMarkA(pObj) )
+            Ivy_ObjClearMarkA(pObj);
+        else
+            Vec_PtrPush( vNodes, pObj );
+    }
+    if ( Vec_PtrSize(vNodes) == 0 )
+    {
+        Vec_PtrFree( vNodes );
+//printf( "Sequential sweep cleaned out %d nodes.\n", 0 );
+        return 0;
+    }
+    // disconnect the marked objects
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+        Ivy_ObjDisconnect( p, pObj );
+    // remove the dangling objects
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+    {
+        assert( Ivy_ObjIsNode(pObj) || Ivy_ObjIsLatch(pObj) || Ivy_ObjIsBuf(pObj) );
+        assert( Ivy_ObjRefs(pObj) == 0 );
+        // update node counters of the manager
+        p->nObjs[pObj->Type]--;
+        p->nDeleted++;
+        // delete buffer from the array of buffers
+        if ( p->fFanout && Ivy_ObjIsBuf(pObj) )
+            Vec_PtrRemove( p->vBufs, pObj );
+        // free the node
+        Vec_PtrWriteEntry( p->vObjs, pObj->Id, NULL );
+        Ivy_ManRecycleMemory( p, pObj );
+    }
+    // return the number of nodes freed
+    RetValue = Vec_PtrSize(vNodes);
+    Vec_PtrFree( vNodes );
+//printf( "Sequential sweep cleaned out %d nodes.\n", RetValue );
+    return RetValue;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Checks if latches form self-loop.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManLatchIsSelfFeed_rec( Ivy_Obj_t * pLatch, Ivy_Obj_t * pLatchRoot )
+{
+    if ( !Ivy_ObjIsLatch(pLatch) && !Ivy_ObjIsBuf(pLatch) )
+        return 0;
+    if ( pLatch == pLatchRoot )
+        return 1;
+    return Ivy_ManLatchIsSelfFeed_rec( Ivy_ObjFanin0(pLatch), pLatchRoot );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Checks if latches form self-loop.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManLatchIsSelfFeed( Ivy_Obj_t * pLatch )
+{
+    if ( !Ivy_ObjIsLatch(pLatch) )
+        return 0;
+    return Ivy_ManLatchIsSelfFeed_rec( Ivy_ObjFanin0(pLatch), pLatch );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the number of dangling nodes removed.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     [] 
+
+***********************************************************************/
+int Ivy_ManPropagateBuffers( Ivy_Man_t * p, int fUpdateLevel )
+{
+    Ivy_Obj_t * pNode;
+    int LimitFactor = 100;
+    int NodeBeg = Ivy_ManNodeNum(p);
+    int nSteps;
+    for ( nSteps = 0; Vec_PtrSize(p->vBufs) > 0; nSteps++ )
+    {
+        pNode = Vec_PtrEntryLast(p->vBufs);
+        while ( Ivy_ObjIsBuf(pNode) )
+            pNode = Ivy_ObjReadFirstFanout( p, pNode );
+        // check if this buffer should remain
+        if ( Ivy_ManLatchIsSelfFeed(pNode) )
+        {
+            Vec_PtrPop(p->vBufs);
+            continue;
+        }
+//printf( "Propagating buffer %d with input %d and output %d\n", Ivy_ObjFaninId0(pNode), Ivy_ObjFaninId0(Ivy_ObjFanin0(pNode)), pNode->Id );
+//printf( "Latch num %d\n", Ivy_ManLatchNum(p) );
+        Ivy_NodeFixBufferFanins( p, pNode, fUpdateLevel );
+        if ( nSteps > NodeBeg * LimitFactor )
+        {
+            printf( "Structural hashing is not finished after %d forward latch moves.\n", NodeBeg * LimitFactor );
+            printf( "This circuit cannot be forward-retimed completely. Quitting.\n" );
+            break;
+        }
+    }
+//    printf( "Number of steps = %d. Nodes beg = %d. Nodes end = %d.\n", nSteps, NodeBeg, Ivy_ManNodeNum(p) );
+    return nSteps;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the AIG manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManPrintStats( Ivy_Man_t * p )
+{
+    printf( "PI/PO = %d/%d ", Ivy_ManPiNum(p), Ivy_ManPoNum(p) );
+    printf( "A = %7d. ",       Ivy_ManAndNum(p) );
+    printf( "L = %5d. ",       Ivy_ManLatchNum(p) );
+//    printf( "X = %d. ",       Ivy_ManExorNum(p) );
+//    printf( "B = %3d. ",       Ivy_ManBufNum(p) );
+    printf( "MaxID = %7d. ",   Ivy_ManObjIdMax(p) );
+//    printf( "Cre = %d. ",     p->nCreated );
+//    printf( "Del = %d. ",     p->nDeleted );
+    printf( "Lev = %3d. ",     Ivy_ManLatchNum(p)? -1 : Ivy_ManLevels(p) );
+    printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Converts a combinational AIG manager into a sequential one.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManMakeSeq( Ivy_Man_t * p, int nLatches, int * pInits )
+{
+    Ivy_Obj_t * pObj, * pLatch;
+    Ivy_Init_t Init;
+    int i;
+    if ( nLatches == 0 )
+        return;
+    assert( nLatches < Ivy_ManPiNum(p) && nLatches < Ivy_ManPoNum(p) );
+    assert( Ivy_ManPiNum(p) == Vec_PtrSize(p->vPis) );
+    assert( Ivy_ManPoNum(p) == Vec_PtrSize(p->vPos) );
+    assert( Vec_PtrSize( p->vBufs ) == 0 );
+    // create fanouts
+    if ( p->fFanout == 0 )
+        Ivy_ManStartFanout( p );
+    // collect the POs to be converted into latches
+    for ( i = 0; i < nLatches; i++ )
+    {
+        // get the latch value
+        Init = pInits? pInits[i] : IVY_INIT_0;
+        // create latch
+        pObj = Ivy_ManPo( p, Ivy_ManPoNum(p) - nLatches + i );
+        pLatch = Ivy_Latch( p, Ivy_ObjChild0(pObj), Init );
+        Ivy_ObjDisconnect( p, pObj );
+        // recycle the old PO object
+        Vec_PtrWriteEntry( p->vObjs, pObj->Id, NULL );
+        Ivy_ManRecycleMemory( p, pObj );
+        // convert the corresponding PI to a buffer and connect it to the latch
+        pObj = Ivy_ManPi( p, Ivy_ManPiNum(p) - nLatches + i );
+        pObj->Type = IVY_BUF;
+        Ivy_ObjConnect( p, pObj, pLatch, NULL );
+        // save the buffer
+        Vec_PtrPush( p->vBufs, pObj );
+    }
+    // shrink the arrays
+    Vec_PtrShrink( p->vPis, Ivy_ManPiNum(p) - nLatches );
+    Vec_PtrShrink( p->vPos, Ivy_ManPoNum(p) - nLatches );
+    // update the counters of different objects
+    p->nObjs[IVY_PI] -= nLatches;
+    p->nObjs[IVY_PO] -= nLatches;
+    p->nObjs[IVY_BUF] += nLatches;
+    p->nDeleted -= 2 * nLatches;
+    // remove dangling nodes
+    Ivy_ManCleanup(p);
+    Ivy_ManCleanupSeq(p);
+/* 
+    // check for dangling nodes
+    Ivy_ManForEachObj( p, pObj, i )
+        if ( !Ivy_ObjIsPi(pObj) && !Ivy_ObjIsPo(pObj) && !Ivy_ObjIsConst1(pObj) )
+        {
+            assert( Ivy_ObjRefs(pObj) > 0 );
+            assert( Ivy_ObjRefs(pObj) == Ivy_ObjFanoutNum(p, pObj) );
+        }
+*/
+    // perform hashing by propagating the buffers
+    Ivy_ManPropagateBuffers( p, 0 );
+    if ( Ivy_ManBufNum(p) )
+        printf( "The number of remaining buffers is %d.\n", Ivy_ManBufNum(p) );
+    // fix the levels
+    Ivy_ManResetLevels( p );
+    // check the resulting network
+    if ( !Ivy_ManCheck(p) )
+        printf( "Ivy_ManMakeSeq(): The check has failed.\n" );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyMem.c b/src/aig/ivy/ivyMem.c
new file mode 100644
index 00000000..2a96857c
--- /dev/null
+++ b/src/aig/ivy/ivyMem.c
@@ -0,0 +1,116 @@
+/**CFile****************************************************************
+
+  FileName    [ivyMem.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Memory management for the AIG nodes.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyMem.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+// memory management
+#define IVY_PAGE_SIZE      12        // page size containing 2^IVY_PAGE_SIZE nodes
+#define IVY_PAGE_MASK    4095        // page bitmask (2^IVY_PAGE_SIZE)-1
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the internal memory manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManStartMemory( Ivy_Man_t * p )
+{
+    p->vChunks = Vec_PtrAlloc( 128 );
+    p->vPages = Vec_PtrAlloc( 128 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the internal memory manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManStopMemory( Ivy_Man_t * p )
+{
+    void * pMemory;
+    int i;
+    Vec_PtrForEachEntry( p->vChunks, pMemory, i )
+        free( pMemory );
+    Vec_PtrFree( p->vChunks );
+    Vec_PtrFree( p->vPages );
+    p->pListFree = NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Allocates additional memory for the nodes.]
+
+  Description [Allocates IVY_PAGE_SIZE nodes. Aligns memory by 32 bytes. 
+  Records the pointer to the AIG manager in the -1 entry.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManAddMemory( Ivy_Man_t * p )
+{
+    char * pMemory;
+    int i, nBytes;
+    int EntrySizeMax = 128;
+    assert( sizeof(Ivy_Obj_t) <= EntrySizeMax );
+    assert( p->pListFree == NULL );
+//    assert( (Ivy_ManObjNum(p) & IVY_PAGE_MASK) == 0 );
+    // allocate new memory page
+    nBytes = sizeof(Ivy_Obj_t) * (1<<IVY_PAGE_SIZE) + EntrySizeMax;
+    pMemory = ALLOC( char, nBytes );
+    Vec_PtrPush( p->vChunks, pMemory );
+    // align memory at the 32-byte boundary
+    pMemory = pMemory + EntrySizeMax - (((int)pMemory) & (EntrySizeMax-1));
+    // remember the manager in the first entry
+    Vec_PtrPush( p->vPages, pMemory );
+    // break the memory down into nodes
+    p->pListFree = (Ivy_Obj_t *)pMemory;
+    for ( i = 1; i <= IVY_PAGE_MASK; i++ )
+    {
+        *((char **)pMemory) = pMemory + sizeof(Ivy_Obj_t);
+        pMemory += sizeof(Ivy_Obj_t);
+    }
+    *((char **)pMemory) = NULL;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyMulti.c b/src/aig/ivy/ivyMulti.c
new file mode 100644
index 00000000..a7970156
--- /dev/null
+++ b/src/aig/ivy/ivyMulti.c
@@ -0,0 +1,301 @@
+/**CFile****************************************************************
+
+  FileName    [ivyMulti.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Constructing multi-input AND/EXOR gates.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyMulti.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define IVY_EVAL_LIMIT    128
+
+typedef struct Ivy_Eva_t_ Ivy_Eva_t;
+struct Ivy_Eva_t_
+{
+    Ivy_Obj_t * pArg;     // the argument node
+    unsigned    Mask;     // the mask of covered nodes
+    int         Weight;   // the number of covered nodes
+};
+
+static void Ivy_MultiPrint( Ivy_Man_t * p, Ivy_Eva_t * pEvals, int nLeaves, int nEvals );
+static int Ivy_MultiCover( Ivy_Man_t * p, Ivy_Eva_t * pEvals, int nLeaves, int nEvals, int nLimit, Vec_Ptr_t * vSols );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Constructs a balanced tree while taking sharing into account.]
+
+  Description [Returns 1 if the implementation exists.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_MultiPlus( Ivy_Man_t * p, Vec_Ptr_t * vLeaves, Vec_Ptr_t * vCone, Ivy_Type_t Type, int nLimit, Vec_Ptr_t * vSols )
+{
+    static Ivy_Eva_t pEvals[IVY_EVAL_LIMIT];
+    Ivy_Eva_t * pEval, * pFan0, * pFan1;
+    Ivy_Obj_t * pObj, * pTemp;
+    int nEvals, nEvalsOld, i, k, x, nLeaves;
+    unsigned uMaskAll;
+
+    // consider special cases
+    nLeaves = Vec_PtrSize(vLeaves);
+    assert( nLeaves > 2 );
+    if ( nLeaves > 32 || nLeaves + Vec_PtrSize(vCone) > IVY_EVAL_LIMIT )
+        return 0;
+//    if ( nLeaves == 1 )
+//        return Vec_PtrEntry( vLeaves, 0 );
+//    if ( nLeaves == 2 )
+//        return Ivy_Oper( Vec_PtrEntry(vLeaves, 0), Vec_PtrEntry(vLeaves, 1), Type );
+
+    // set the leaf entries
+    uMaskAll = ((1 << nLeaves) - 1);
+    nEvals = 0;
+    Vec_PtrForEachEntry( vLeaves, pObj, i )
+    {
+        pEval = pEvals + nEvals;
+        pEval->pArg   = pObj;
+        pEval->Mask   = (1 << nEvals);
+        pEval->Weight = 1;
+        // mark the leaf
+        Ivy_Regular(pObj)->TravId = nEvals;
+        nEvals++;
+    }
+
+    // propagate masks through the cone
+    Vec_PtrForEachEntry( vCone, pObj, i )
+    {
+        pObj->TravId = nEvals + i;
+        if ( Ivy_ObjIsBuf(pObj) )
+            pEvals[pObj->TravId].Mask = pEvals[Ivy_ObjFanin0(pObj)->TravId].Mask;
+        else
+            pEvals[pObj->TravId].Mask = pEvals[Ivy_ObjFanin0(pObj)->TravId].Mask | pEvals[Ivy_ObjFanin1(pObj)->TravId].Mask;
+    }
+
+    // set the internal entries
+    Vec_PtrForEachEntry( vCone, pObj, i )
+    {
+        if ( i == Vec_PtrSize(vCone) - 1 )
+            break;
+        // skip buffers
+        if ( Ivy_ObjIsBuf(pObj) )
+            continue;
+        // skip nodes without external fanout
+        if ( Ivy_ObjRefs(pObj) == 0 )
+            continue;
+        assert( !Ivy_IsComplement(pObj) );
+        pEval = pEvals + nEvals;
+        pEval->pArg   = pObj;
+        pEval->Mask   = pEvals[pObj->TravId].Mask;
+        pEval->Weight = Extra_WordCountOnes(pEval->Mask);
+        // mark the node
+        pObj->TravId = nEvals;
+        nEvals++;
+    }
+
+    // find the available nodes
+    nEvalsOld = nEvals;
+    for ( i = 1; i < nEvals; i++ )
+    for ( k = 0; k < i; k++ )
+    {
+        pFan0 = pEvals + i;
+        pFan1 = pEvals + k;
+        pTemp = Ivy_TableLookup(p, Ivy_ObjCreateGhost(p, pFan0->pArg, pFan1->pArg, Type, IVY_INIT_NONE));
+        // skip nodes in the cone
+        if ( pTemp == NULL || pTemp->fMarkB )
+            continue;
+        // skip the leaves
+        for ( x = 0; x < nLeaves; x++ )
+            if ( pTemp == Ivy_Regular(vLeaves->pArray[x]) )
+                break;
+        if ( x < nLeaves )
+            continue;
+        pEval = pEvals + nEvals;
+        pEval->pArg   = pTemp;
+        pEval->Mask   = pFan0->Mask | pFan1->Mask;
+        pEval->Weight = (pFan0->Mask & pFan1->Mask) ? Extra_WordCountOnes(pEval->Mask) : pFan0->Weight + pFan1->Weight;
+        // save the argument
+        pObj->TravId = nEvals;
+        nEvals++;
+        // quit if the number of entries exceeded the limit
+        if ( nEvals == IVY_EVAL_LIMIT )
+            goto Outside;
+        // quit if we found an acceptable implementation
+        if ( pEval->Mask == uMaskAll )
+            goto Outside;
+    }
+Outside:
+
+//    Ivy_MultiPrint( pEvals, nLeaves, nEvals );
+    if ( !Ivy_MultiCover( p, pEvals, nLeaves, nEvals, nLimit, vSols ) )
+        return 0;
+    assert( Vec_PtrSize( vSols ) > 0 );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes how many uncovered ones this one covers.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_MultiPrint( Ivy_Man_t * p, Ivy_Eva_t * pEvals, int nLeaves, int nEvals )
+{
+    Ivy_Eva_t * pEval;
+    int i, k;
+    for ( i = nLeaves; i < nEvals; i++ )
+    {
+        pEval = pEvals + i;
+        printf( "%2d  (id = %5d)  : |", i-nLeaves, Ivy_ObjId(pEval->pArg) );
+        for ( k = 0; k < nLeaves; k++ )
+        {
+            if ( pEval->Mask & (1 << k) )
+                printf( "+" );
+            else
+                printf( " " );
+        }
+        printf( "|  Lev = %d.\n", Ivy_ObjLevel(pEval->pArg) );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes how many uncovered ones this one covers.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Ivy_MultiWeight( unsigned uMask, int nMaskOnes, unsigned uFound )
+{
+    assert( uMask & ~uFound );
+    if ( (uMask & uFound) == 0 )
+        return nMaskOnes;
+    return Extra_WordCountOnes( uMask & ~uFound );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Finds the cover.]
+
+  Description [Returns 1 if the cover is found.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_MultiCover( Ivy_Man_t * p, Ivy_Eva_t * pEvals, int nLeaves, int nEvals, int nLimit, Vec_Ptr_t * vSols )
+{
+    int fVerbose = 0;
+    Ivy_Eva_t * pEval, * pEvalBest;
+    unsigned uMaskAll, uFound, uTemp;
+    int i, k, BestK, WeightBest, WeightCur, LevelBest, LevelCur;
+    uMaskAll = (nLeaves == 32)? (~(unsigned)0) : ((1 << nLeaves) - 1);
+    uFound = 0;
+    // solve the covering problem
+    if ( fVerbose )
+    printf( "Solution:  " );
+    Vec_PtrClear( vSols );
+    for ( i = 0; i < nLimit; i++ )
+    {
+        BestK = -1;
+        for ( k = nEvals - 1; k >= 0; k-- )
+        {
+            pEval = pEvals + k;
+            if ( (pEval->Mask & ~uFound) == 0 )
+                continue;
+            if ( BestK == -1 )
+            {
+                BestK      = k;
+                pEvalBest  = pEval;
+                WeightBest = Ivy_MultiWeight( pEvalBest->Mask, pEvalBest->Weight, uFound );
+                LevelBest  = Ivy_ObjLevel( Ivy_Regular(pEvalBest->pArg) );
+                continue;
+            }
+            // compare BestK and the new one (k)
+            WeightCur = Ivy_MultiWeight( pEval->Mask, pEval->Weight, uFound );
+            LevelCur = Ivy_ObjLevel( Ivy_Regular(pEval->pArg) );
+            if ( WeightBest < WeightCur || 
+                (WeightBest == WeightCur && LevelBest > LevelCur) )
+            {
+                BestK      = k;
+                pEvalBest  = pEval;
+                WeightBest = WeightCur;
+                LevelBest  = LevelCur;
+            }
+        }
+        assert( BestK != -1 );
+        // if the cost is only 1, take the leaf
+        if ( WeightBest == 1 && BestK >= nLeaves )
+        {
+            uTemp = (pEvalBest->Mask & ~uFound);
+            for ( k = 0; k < nLeaves; k++ )
+                if ( uTemp & (1 << k) )
+                    break;
+            assert( k < nLeaves );
+            BestK     = k;
+            pEvalBest = pEvals + BestK;
+        }
+        if ( fVerbose )
+        {
+            if ( BestK < nLeaves )
+                printf( "L(%d) ", BestK );
+            else
+                printf( "%d ", BestK - nLeaves );
+        }
+        // update the found set
+        Vec_PtrPush( vSols, pEvalBest->pArg );
+        uFound |= pEvalBest->Mask;
+        if ( uFound == uMaskAll )
+            break;
+    }
+    if ( uFound == uMaskAll )
+    {
+        if ( fVerbose )
+            printf( "  Found \n\n" );
+        return 1;
+    }
+    else
+    {
+        if ( fVerbose )
+            printf( "  Not found \n\n" );
+        return 0;
+    }
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyMulti8.c b/src/aig/ivy/ivyMulti8.c
new file mode 100644
index 00000000..059d1500
--- /dev/null
+++ b/src/aig/ivy/ivyMulti8.c
@@ -0,0 +1,427 @@
+/**CFile****************************************************************
+
+  FileName    [ivyMulti.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Constructing multi-input AND/EXOR gates.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyMulti.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Ivy_Eval_t_ Ivy_Eval_t;
+struct Ivy_Eval_t_
+{
+    unsigned Mask   :  5;  // the mask of covered nodes
+    unsigned Weight :  3;  // the number of covered nodes
+    unsigned Cost   :  4;  // the number of overlapping nodes
+    unsigned Level  : 12;  // the level of this node
+    unsigned Fan0   :  4;  // the first fanin
+    unsigned Fan1   :  4;  // the second fanin
+};
+
+static Ivy_Obj_t * Ivy_MultiBuild_rec( Ivy_Eval_t * pEvals, int iNum, Ivy_Obj_t ** pArgs, int nArgs, Ivy_Type_t Type );
+static void        Ivy_MultiSort( Ivy_Obj_t ** pArgs, int nArgs );
+static int         Ivy_MultiPushUniqueOrderByLevel( Ivy_Obj_t ** pArray, int nArgs, Ivy_Obj_t * pNode );
+static Ivy_Obj_t * Ivy_MultiEval( Ivy_Obj_t ** pArgs, int nArgs, Ivy_Type_t Type );
+
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Constructs the well-balanced tree of gates.]
+
+  Description [Disregards levels and possible logic sharing.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Multi_rec( Ivy_Obj_t ** ppObjs, int nObjs, Ivy_Type_t Type )
+{
+    Ivy_Obj_t * pObj1, * pObj2;
+    if ( nObjs == 1 )
+        return ppObjs[0];
+    pObj1 = Ivy_Multi_rec( ppObjs,           nObjs/2,         Type );
+    pObj2 = Ivy_Multi_rec( ppObjs + nObjs/2, nObjs - nObjs/2, Type );
+    return Ivy_Oper( pObj1, pObj2, Type );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Constructs a balanced tree while taking sharing into account.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Multi( Ivy_Obj_t ** pArgsInit, int nArgs, Ivy_Type_t Type )
+{
+    static char NumBits[32] = {0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5};
+    static Ivy_Eval_t pEvals[15+15*14/2];
+    static Ivy_Obj_t * pArgs[16];
+    Ivy_Eval_t * pEva, * pEvaBest;
+    int nArgsNew, nEvals, i, k;
+    Ivy_Obj_t * pTemp;
+
+    // consider the case of one argument
+    assert( nArgs > 0 );
+    if ( nArgs == 1 )
+        return pArgsInit[0];
+    // consider the case of two arguments
+    if ( nArgs == 2 )
+        return Ivy_Oper( pArgsInit[0], pArgsInit[1], Type );
+
+//Ivy_MultiEval( pArgsInit, nArgs, Type ); printf( "\n" );
+
+    // set the initial ones
+    for ( i = 0; i < nArgs; i++ )
+    {
+        pArgs[i] = pArgsInit[i];
+        pEva = pEvals + i;
+        pEva->Mask   = (1 << i);
+        pEva->Weight = 1;
+        pEva->Cost   = 0; 
+        pEva->Level  = Ivy_Regular(pArgs[i])->Level; 
+        pEva->Fan0   = 0; 
+        pEva->Fan1   = 0; 
+    }
+
+    // find the available nodes
+    pEvaBest = pEvals;
+    nArgsNew = nArgs;
+    for ( i = 1; i < nArgsNew; i++ )
+    for ( k = 0; k < i; k++ )
+        if ( pTemp = Ivy_TableLookup(Ivy_ObjCreateGhost(pArgs[k], pArgs[i], Type, IVY_INIT_NONE)) )
+        {
+            pEva = pEvals + nArgsNew;
+            pEva->Mask   = pEvals[k].Mask | pEvals[i].Mask;
+            pEva->Weight = NumBits[pEva->Mask];
+            pEva->Cost   = pEvals[k].Cost + pEvals[i].Cost + NumBits[pEvals[k].Mask & pEvals[i].Mask]; 
+            pEva->Level  = 1 + IVY_MAX(pEvals[k].Level, pEvals[i].Level); 
+            pEva->Fan0   = k; 
+            pEva->Fan1   = i; 
+//            assert( pEva->Level == (unsigned)Ivy_ObjLevel(pTemp) );
+            // compare
+            if ( pEvaBest->Weight < pEva->Weight ||
+                 pEvaBest->Weight == pEva->Weight && pEvaBest->Cost > pEva->Cost ||
+                 pEvaBest->Weight == pEva->Weight && pEvaBest->Cost == pEva->Cost && pEvaBest->Level > pEva->Level )
+                 pEvaBest = pEva;
+            // save the argument
+            pArgs[nArgsNew++] = pTemp;
+            if ( nArgsNew == 15 )
+                goto Outside;
+        }
+Outside:
+
+//    printf( "Best = %d.\n", pEvaBest - pEvals );
+
+    // the case of no common nodes
+    if ( nArgsNew == nArgs )
+    {
+        Ivy_MultiSort( pArgs, nArgs );
+        return Ivy_MultiBalance_rec( pArgs, nArgs, Type );
+    }
+    // the case of one common node
+    if ( nArgsNew == nArgs + 1 )
+    {
+        assert( pEvaBest - pEvals == nArgs );
+        k = 0;
+        for ( i = 0; i < nArgs; i++ )
+            if ( i != (int)pEvaBest->Fan0 && i != (int)pEvaBest->Fan1 )
+                pArgs[k++] = pArgs[i];
+        pArgs[k++] = pArgs[nArgs];
+        assert( k == nArgs - 1 );
+        nArgs = k;
+        Ivy_MultiSort( pArgs, nArgs );
+        return Ivy_MultiBalance_rec( pArgs, nArgs, Type );
+    }
+    // the case when there is a node that covers everything
+    if ( (int)pEvaBest->Mask == ((1 << nArgs) - 1) )
+        return Ivy_MultiBuild_rec( pEvals, pEvaBest - pEvals, pArgs, nArgsNew, Type ); 
+
+    // evaluate node pairs
+    nEvals = nArgsNew;
+    for ( i = 1; i < nArgsNew; i++ )
+    for ( k = 0; k < i; k++ )
+    {
+        pEva = pEvals + nEvals;
+        pEva->Mask   = pEvals[k].Mask | pEvals[i].Mask;
+        pEva->Weight = NumBits[pEva->Mask];
+        pEva->Cost   = pEvals[k].Cost + pEvals[i].Cost + NumBits[pEvals[k].Mask & pEvals[i].Mask]; 
+        pEva->Level  = 1 + IVY_MAX(pEvals[k].Level, pEvals[i].Level); 
+        pEva->Fan0   = k; 
+        pEva->Fan1   = i; 
+        // compare
+        if ( pEvaBest->Weight < pEva->Weight ||
+             pEvaBest->Weight == pEva->Weight && pEvaBest->Cost > pEva->Cost ||
+             pEvaBest->Weight == pEva->Weight && pEvaBest->Cost == pEva->Cost && pEvaBest->Level > pEva->Level )
+             pEvaBest = pEva;
+        // save the argument
+        nEvals++;
+    }
+    assert( pEvaBest - pEvals >= nArgsNew );
+
+//    printf( "Used (%d, %d).\n", pEvaBest->Fan0, pEvaBest->Fan1 );
+
+    // get the best implementation
+    pTemp = Ivy_MultiBuild_rec( pEvals, pEvaBest - pEvals, pArgs, nArgsNew, Type );
+
+    // collect those not covered by EvaBest
+    k = 0;
+    for ( i = 0; i < nArgs; i++ )
+        if ( (pEvaBest->Mask & (1 << i)) == 0 )
+            pArgs[k++] = pArgs[i];
+    pArgs[k++] = pTemp;
+    assert( k == nArgs - (int)pEvaBest->Weight + 1 );
+    nArgs = k;
+    Ivy_MultiSort( pArgs, nArgs );
+    return Ivy_MultiBalance_rec( pArgs, nArgs, Type );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implements multi-input AND/EXOR operation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_MultiBuild_rec( Ivy_Eval_t * pEvals, int iNum, Ivy_Obj_t ** pArgs, int nArgs, Ivy_Type_t Type )
+{
+    Ivy_Obj_t * pNode0, * pNode1;
+    if ( iNum < nArgs )
+        return pArgs[iNum];
+    pNode0 = Ivy_MultiBuild_rec( pEvals, pEvals[iNum].Fan0, pArgs, nArgs, Type );
+    pNode1 = Ivy_MultiBuild_rec( pEvals, pEvals[iNum].Fan1, pArgs, nArgs, Type );
+    return Ivy_Oper( pNode0, pNode1, Type );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Selection-sorts the nodes in the decreasing over of level.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_MultiSort( Ivy_Obj_t ** pArgs, int nArgs )
+{
+    Ivy_Obj_t * pTemp;
+    int i, j, iBest;
+
+    for ( i = 0; i < nArgs-1; i++ )
+    {
+        iBest = i;
+        for ( j = i+1; j < nArgs; j++ )
+            if ( Ivy_Regular(pArgs[j])->Level > Ivy_Regular(pArgs[iBest])->Level )
+                iBest = j;
+        pTemp = pArgs[i]; 
+        pArgs[i] = pArgs[iBest]; 
+        pArgs[iBest] = pTemp;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Inserts a new node in the order by levels.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_MultiPushUniqueOrderByLevel( Ivy_Obj_t ** pArray, int nArgs, Ivy_Obj_t * pNode )
+{
+    Ivy_Obj_t * pNode1, * pNode2;
+    int i;
+    // try to find the node in the array
+    for ( i = 0; i < nArgs; i++ )
+        if ( pArray[i] == pNode )
+            return nArgs;
+    // put the node last
+    pArray[nArgs++] = pNode;
+    // find the place to put the new node
+    for ( i = nArgs-1; i > 0; i-- )
+    {
+        pNode1 = pArray[i  ];
+        pNode2 = pArray[i-1];
+        if ( Ivy_Regular(pNode1)->Level <= Ivy_Regular(pNode2)->Level )
+            break;
+        pArray[i  ] = pNode2;
+        pArray[i-1] = pNode1;
+    }
+    return nArgs;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Balances the array recursively.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_MultiBalance_rec( Ivy_Obj_t ** pArgs, int nArgs, Ivy_Type_t Type )
+{
+    Ivy_Obj_t * pNodeNew;
+    // consider the case of one argument
+    assert( nArgs > 0 );
+    if ( nArgs == 1 )
+        return pArgs[0];
+    // consider the case of two arguments
+    if ( nArgs == 2 )
+        return Ivy_Oper( pArgs[0], pArgs[1], Type );
+    // get the last two nodes
+    pNodeNew = Ivy_Oper( pArgs[nArgs-1], pArgs[nArgs-2], Type );
+    // add the new node
+    nArgs = Ivy_MultiPushUniqueOrderByLevel( pArgs, nArgs - 2, pNodeNew );
+    return Ivy_MultiBalance_rec( pArgs, nArgs, Type );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implements multi-input AND/EXOR operation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_MultiEval( Ivy_Obj_t ** pArgs, int nArgs, Ivy_Type_t Type )
+{
+    Ivy_Obj_t * pTemp;
+    int i, k;
+    int nArgsOld = nArgs;
+    for ( i = 0; i < nArgs; i++ )
+        printf( "%d[%d] ", i, Ivy_Regular(pArgs[i])->Level );
+    for ( i = 1; i < nArgs; i++ )
+        for ( k = 0; k < i; k++ )
+        {
+            pTemp = Ivy_TableLookup(Ivy_ObjCreateGhost(pArgs[k], pArgs[i], Type, IVY_INIT_NONE));
+            if ( pTemp != NULL )
+            {
+                printf( "%d[%d]=(%d,%d) ", nArgs, Ivy_Regular(pTemp)->Level, k, i );
+                pArgs[nArgs++] = pTemp;
+            }
+        }
+    printf( "     ((%d/%d))    ", nArgsOld, nArgs-nArgsOld );
+    return NULL;
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Old code.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Multi1( Ivy_Obj_t ** pArgs, int nArgs, Ivy_Type_t Type )
+{
+    Ivy_Obj_t * pArgsRef[5], * pTemp;
+    int i, k, m, nArgsNew, Counter = 0;
+ 
+    
+//Ivy_MultiEval( pArgs, nArgs, Type );  printf( "\n" );
+
+
+    assert( Type == IVY_AND || Type == IVY_EXOR );
+    assert( nArgs > 0 );
+    if ( nArgs == 1 )
+        return pArgs[0];
+
+    // find the nodes with more than one fanout
+    nArgsNew = 0;
+    for ( i = 0; i < nArgs; i++ )
+        if ( Ivy_ObjRefs( Ivy_Regular(pArgs[i]) ) > 0 )
+            pArgsRef[nArgsNew++] = pArgs[i];
+
+    // go through pairs
+    if ( nArgsNew >= 2 )
+    for ( i = 0; i < nArgsNew; i++ )
+    for ( k = i + 1; k < nArgsNew; k++ )
+        if ( pTemp = Ivy_TableLookup(Ivy_ObjCreateGhost(pArgsRef[i], pArgsRef[k], Type, IVY_INIT_NONE)) )
+            Counter++;
+//    printf( "%d", Counter );
+            
+    // go through pairs
+    if ( nArgsNew >= 2 )
+    for ( i = 0; i < nArgsNew; i++ )
+    for ( k = i + 1; k < nArgsNew; k++ )
+        if ( pTemp = Ivy_TableLookup(Ivy_ObjCreateGhost(pArgsRef[i], pArgsRef[k], Type, IVY_INIT_NONE)) )
+        {
+            nArgsNew = 0;
+            for ( m = 0; m < nArgs; m++ )
+                if ( pArgs[m] != pArgsRef[i] && pArgs[m] != pArgsRef[k] )
+                    pArgs[nArgsNew++] = pArgs[m];
+            pArgs[nArgsNew++] = pTemp;
+            assert( nArgsNew == nArgs - 1 );
+            return Ivy_Multi1( pArgs, nArgsNew, Type );
+        }
+    return Ivy_Multi_rec( pArgs, nArgs, Type );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Old code.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Multi2( Ivy_Obj_t ** pArgs, int nArgs, Ivy_Type_t Type )
+{
+    assert( Type == IVY_AND || Type == IVY_EXOR );
+    assert( nArgs > 0 );
+    return Ivy_Multi_rec( pArgs, nArgs, Type );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyObj.c b/src/aig/ivy/ivyObj.c
new file mode 100644
index 00000000..59dda19c
--- /dev/null
+++ b/src/aig/ivy/ivyObj.c
@@ -0,0 +1,476 @@
+/**CFile****************************************************************
+
+  FileName    [ivyObj.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Adding/removing objects.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyObj.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Create the new node assuming it does not exist.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_ObjCreatePi( Ivy_Man_t * p )
+{
+    return Ivy_ObjCreate( p, Ivy_ObjCreateGhost(p, NULL, NULL, IVY_PI, IVY_INIT_NONE) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Create the new node assuming it does not exist.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_ObjCreatePo( Ivy_Man_t * p, Ivy_Obj_t * pDriver )
+{
+    return Ivy_ObjCreate( p, Ivy_ObjCreateGhost(p, pDriver, NULL, IVY_PO, IVY_INIT_NONE) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Create the new node assuming it does not exist.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_ObjCreate( Ivy_Man_t * p, Ivy_Obj_t * pGhost )
+{
+    Ivy_Obj_t * pObj;
+    assert( !Ivy_IsComplement(pGhost) );
+    assert( Ivy_ObjIsGhost(pGhost) );
+    assert( Ivy_TableLookup(p, pGhost) == NULL );
+    // get memory for the new object
+    pObj = Ivy_ManFetchMemory( p );
+    assert( Ivy_ObjIsNone(pObj) );
+    pObj->Id = Vec_PtrSize(p->vObjs);
+    Vec_PtrPush( p->vObjs, pObj );
+    // add basic info (fanins, compls, type, init)
+    pObj->Type = pGhost->Type;
+    pObj->Init = pGhost->Init;
+    // add connections
+    Ivy_ObjConnect( p, pObj, pGhost->pFanin0, pGhost->pFanin1 );
+    // compute level
+    if ( Ivy_ObjIsNode(pObj) )
+        pObj->Level = Ivy_ObjLevelNew(pObj);
+    else if ( Ivy_ObjIsLatch(pObj) )
+        pObj->Level = 0;
+    else if ( Ivy_ObjIsOneFanin(pObj) )
+        pObj->Level = Ivy_ObjFanin0(pObj)->Level;
+    else if ( !Ivy_ObjIsPi(pObj) )
+        assert( 0 );
+    // create phase
+    if ( Ivy_ObjIsNode(pObj) )
+        pObj->fPhase = Ivy_ObjFaninPhase(Ivy_ObjChild0(pObj)) & Ivy_ObjFaninPhase(Ivy_ObjChild1(pObj));
+    else if ( Ivy_ObjIsOneFanin(pObj) )
+        pObj->fPhase = Ivy_ObjFaninPhase(Ivy_ObjChild0(pObj));
+    // set the fail TFO flag
+    if ( Ivy_ObjIsNode(pObj) )
+        pObj->fFailTfo = Ivy_ObjFanin0(pObj)->fFailTfo | Ivy_ObjFanin1(pObj)->fFailTfo;
+    // mark the fanins in a special way if the node is EXOR
+    if ( Ivy_ObjIsExor(pObj) )
+    {
+        Ivy_ObjFanin0(pObj)->fExFan = 1;
+        Ivy_ObjFanin1(pObj)->fExFan = 1;
+    }
+    // add PIs/POs to the arrays
+    if ( Ivy_ObjIsPi(pObj) )
+        Vec_PtrPush( p->vPis, pObj );
+    else if ( Ivy_ObjIsPo(pObj) )
+        Vec_PtrPush( p->vPos, pObj );
+//    else if ( Ivy_ObjIsBuf(pObj) )
+//        Vec_PtrPush( p->vBufs, pObj );
+    if ( p->vRequired && Vec_IntSize(p->vRequired) <= pObj->Id )
+        Vec_IntFillExtra( p->vRequired, 2 * Vec_IntSize(p->vRequired), 1000000 );
+    // update node counters of the manager
+    p->nObjs[Ivy_ObjType(pObj)]++;
+    p->nCreated++;
+
+//    printf( "Adding %sAIG node: ", p->pHaig==NULL? "H":" " );
+//    Ivy_ObjPrintVerbose( p, pObj, p->pHaig==NULL );
+//    printf( "\n" );
+
+    // if HAIG is defined, create a corresponding node
+    if ( p->pHaig )
+        Ivy_ManHaigCreateObj( p, pObj );
+    return pObj;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Connect the object to the fanin.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjConnect( Ivy_Man_t * p, Ivy_Obj_t * pObj, Ivy_Obj_t * pFan0, Ivy_Obj_t * pFan1 )
+{
+    assert( !Ivy_IsComplement(pObj) );
+    assert( Ivy_ObjIsPi(pObj) || Ivy_ObjIsOneFanin(pObj) || pFan1 != NULL );
+    // add the first fanin
+    pObj->pFanin0 = pFan0;
+    pObj->pFanin1 = pFan1;
+    // increment references of the fanins and add their fanouts
+    if ( Ivy_ObjFanin0(pObj) != NULL )
+    {
+        Ivy_ObjRefsInc( Ivy_ObjFanin0(pObj) );
+        if ( p->fFanout )
+            Ivy_ObjAddFanout( p, Ivy_ObjFanin0(pObj), pObj );
+    }
+    if ( Ivy_ObjFanin1(pObj) != NULL )
+    {
+        Ivy_ObjRefsInc( Ivy_ObjFanin1(pObj) );
+        if ( p->fFanout )
+            Ivy_ObjAddFanout( p, Ivy_ObjFanin1(pObj), pObj );
+    }
+    // add the node to the structural hash table
+    Ivy_TableInsert( p, pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Connect the object to the fanin.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjDisconnect( Ivy_Man_t * p, Ivy_Obj_t * pObj )
+{
+    assert( !Ivy_IsComplement(pObj) );
+    assert( Ivy_ObjIsPi(pObj) || Ivy_ObjIsOneFanin(pObj) || Ivy_ObjFanin1(pObj) != NULL );
+    // remove connections
+    if ( pObj->pFanin0 != NULL )
+    {
+        Ivy_ObjRefsDec(Ivy_ObjFanin0(pObj));
+        if ( p->fFanout )
+            Ivy_ObjDeleteFanout( p, Ivy_ObjFanin0(pObj), pObj );
+    }
+    if ( pObj->pFanin1 != NULL )
+    {
+        Ivy_ObjRefsDec(Ivy_ObjFanin1(pObj));
+        if ( p->fFanout )
+            Ivy_ObjDeleteFanout( p, Ivy_ObjFanin1(pObj), pObj );
+    }
+    assert( pObj->pNextFan0 == NULL );
+    assert( pObj->pNextFan1 == NULL );
+    assert( pObj->pPrevFan0 == NULL );
+    assert( pObj->pPrevFan1 == NULL );
+    // remove the node from the structural hash table
+    Ivy_TableDelete( p, pObj );
+    // add the first fanin
+    pObj->pFanin0 = NULL;
+    pObj->pFanin1 = NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Replaces the first fanin of the node by the new fanin.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjPatchFanin0( Ivy_Man_t * p, Ivy_Obj_t * pObj, Ivy_Obj_t * pFaninNew )
+{
+    Ivy_Obj_t * pFaninOld;
+    assert( !Ivy_IsComplement(pObj) );
+    pFaninOld = Ivy_ObjFanin0(pObj);
+    // decrement ref and remove fanout
+    Ivy_ObjRefsDec( pFaninOld );
+    if ( p->fFanout )
+        Ivy_ObjDeleteFanout( p, pFaninOld, pObj );
+    // update the fanin
+    pObj->pFanin0 = pFaninNew;
+    // increment ref and add fanout
+    Ivy_ObjRefsInc( Ivy_Regular(pFaninNew) );
+    if ( p->fFanout )
+        Ivy_ObjAddFanout( p, Ivy_Regular(pFaninNew), pObj );
+    // get rid of old fanin
+    if ( !Ivy_ObjIsPi(pFaninOld) && !Ivy_ObjIsConst1(pFaninOld) && Ivy_ObjRefs(pFaninOld) == 0 )
+        Ivy_ObjDelete_rec( p, pFaninOld, 1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Deletes the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjDelete( Ivy_Man_t * p, Ivy_Obj_t * pObj, int fFreeTop )
+{
+    assert( !Ivy_IsComplement(pObj) );
+    assert( Ivy_ObjRefs(pObj) == 0 || !fFreeTop );
+    // update node counters of the manager
+    p->nObjs[pObj->Type]--;
+    p->nDeleted++;
+    // remove connections
+    Ivy_ObjDisconnect( p, pObj );
+    // remove PIs/POs from the arrays
+    if ( Ivy_ObjIsPi(pObj) )
+        Vec_PtrRemove( p->vPis, pObj );
+    else if ( Ivy_ObjIsPo(pObj) )
+        Vec_PtrRemove( p->vPos, pObj );
+    else if ( p->fFanout && Ivy_ObjIsBuf(pObj) )
+        Vec_PtrRemove( p->vBufs, pObj );
+    // clean and recycle the entry
+    if ( fFreeTop )
+    {
+        // free the node
+        Vec_PtrWriteEntry( p->vObjs, pObj->Id, NULL );
+        Ivy_ManRecycleMemory( p, pObj );
+    }
+    else
+    {
+        int nRefsOld = pObj->nRefs;
+        Ivy_Obj_t * pFanout = pObj->pFanout;
+        Ivy_ObjClean( pObj );
+        pObj->pFanout = pFanout;
+        pObj->nRefs = nRefsOld;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Deletes the MFFC of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjDelete_rec( Ivy_Man_t * p, Ivy_Obj_t * pObj, int fFreeTop )
+{
+    Ivy_Obj_t * pFanin0, * pFanin1;
+    assert( !Ivy_IsComplement(pObj) );
+    assert( !Ivy_ObjIsNone(pObj) );
+    if ( Ivy_ObjIsConst1(pObj) || Ivy_ObjIsPi(pObj) )
+        return;
+    pFanin0 = Ivy_ObjFanin0(pObj);
+    pFanin1 = Ivy_ObjFanin1(pObj);
+    Ivy_ObjDelete( p, pObj, fFreeTop );
+    if ( pFanin0 && !Ivy_ObjIsNone(pFanin0) && Ivy_ObjRefs(pFanin0) == 0 )
+        Ivy_ObjDelete_rec( p, pFanin0, 1 );
+    if ( pFanin1 && !Ivy_ObjIsNone(pFanin1) && Ivy_ObjRefs(pFanin1) == 0 )
+        Ivy_ObjDelete_rec( p, pFanin1, 1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Replaces one object by another.]
+
+  Description [Both objects are currently in the manager. The new object
+  (pObjNew) should be used instead of the old object (pObjOld). If the 
+  new object is complemented or used, the buffer is added.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjReplace( Ivy_Man_t * p, Ivy_Obj_t * pObjOld, Ivy_Obj_t * pObjNew, int fDeleteOld, int fFreeTop, int fUpdateLevel )
+{
+    int nRefsOld;//, clk;
+    // the object to be replaced cannot be complemented
+    assert( !Ivy_IsComplement(pObjOld) );
+    // the object to be replaced cannot be a terminal
+    assert( Ivy_ObjIsNone(pObjOld) || !Ivy_ObjIsPi(pObjOld) );
+    // the object to be used cannot be a PO or assert
+    assert( !Ivy_ObjIsBuf(Ivy_Regular(pObjNew)) );
+    // the object cannot be the same
+    assert( pObjOld != Ivy_Regular(pObjNew) );
+//printf( "Replacing %d by %d.\n", Ivy_Regular(pObjOld)->Id, Ivy_Regular(pObjNew)->Id );
+
+    // if HAIG is defined, create the choice node
+    if ( p->pHaig )
+    {
+//        if ( pObjOld->Id == 31 )
+//        {
+//            Ivy_ManShow( p, 0 );
+//            Ivy_ManShow( p->pHaig, 1 );
+//        }
+        Ivy_ManHaigCreateChoice( p, pObjOld, pObjNew );
+    }
+    // if the new object is complemented or already used, add the buffer
+    if ( Ivy_IsComplement(pObjNew) || Ivy_ObjIsLatch(pObjNew) || Ivy_ObjRefs(pObjNew) > 0 || Ivy_ObjIsPi(pObjNew) || Ivy_ObjIsConst1(pObjNew) )
+        pObjNew = Ivy_ObjCreate( p, Ivy_ObjCreateGhost(p, pObjNew, NULL, IVY_BUF, IVY_INIT_NONE) );
+    assert( !Ivy_IsComplement(pObjNew) );
+    if ( fUpdateLevel )
+    {
+//clk = clock();
+        // if the new node's arrival time is different, recursively update arrival time of the fanouts
+        if ( p->fFanout && !Ivy_ObjIsBuf(pObjNew) && pObjOld->Level != pObjNew->Level )
+        {
+            assert( Ivy_ObjIsNode(pObjOld) );
+            pObjOld->Level = pObjNew->Level;
+            Ivy_ObjUpdateLevel_rec( p, pObjOld );
+        }
+//p->time1 += clock() - clk;
+        // if the new node's required time has changed, recursively update required time of the fanins
+//clk = clock();
+        if ( p->vRequired )
+        {
+            int ReqNew = Vec_IntEntry(p->vRequired, pObjOld->Id);
+            if ( ReqNew < Vec_IntEntry(p->vRequired, pObjNew->Id) )
+            {
+                Vec_IntWriteEntry( p->vRequired, pObjNew->Id, ReqNew );
+                Ivy_ObjUpdateLevelR_rec( p, pObjNew, ReqNew );
+            }
+        }
+//p->time2 += clock() - clk;
+    }
+    // delete the old object
+    if ( fDeleteOld )
+        Ivy_ObjDelete_rec( p, pObjOld, fFreeTop );
+    // make sure object is not pointing to itself
+    assert( Ivy_ObjFanin0(pObjNew) == NULL || pObjOld != Ivy_ObjFanin0(pObjNew) );
+    assert( Ivy_ObjFanin1(pObjNew) == NULL || pObjOld != Ivy_ObjFanin1(pObjNew) );
+    // make sure the old node has no fanin fanout pointers
+    if ( p->fFanout )
+    {
+        assert( pObjOld->pFanout != NULL );
+        assert( pObjNew->pFanout == NULL );
+        pObjNew->pFanout = pObjOld->pFanout;
+    }
+    // transfer the old object
+    assert( Ivy_ObjRefs(pObjNew) == 0 );
+    nRefsOld = pObjOld->nRefs;  
+    Ivy_ObjOverwrite( pObjOld, pObjNew );
+    pObjOld->nRefs = nRefsOld;
+    // patch the fanout of the fanins 
+    if ( p->fFanout )
+    {
+        Ivy_ObjPatchFanout( p, Ivy_ObjFanin0(pObjOld), pObjNew, pObjOld );
+        if ( Ivy_ObjFanin1(pObjOld) )
+        Ivy_ObjPatchFanout( p, Ivy_ObjFanin1(pObjOld), pObjNew, pObjOld );
+    }
+    // update the hash table
+    Ivy_TableUpdate( p, pObjNew, pObjOld->Id );
+    // recycle the object that was taken over by pObjOld
+    Vec_PtrWriteEntry( p->vObjs, pObjNew->Id, NULL );
+    Ivy_ManRecycleMemory( p, pObjNew );
+    // if the new node is the buffer propagate it
+    if ( p->fFanout && Ivy_ObjIsBuf(pObjOld) )
+        Vec_PtrPush( p->vBufs, pObjOld );
+//    Ivy_ManCheckFanouts( p );
+//    printf( "\n" );
+/*
+    if ( p->pHaig )
+    {
+        int x;
+        Ivy_ManShow( p, 0, NULL );
+        Ivy_ManShow( p->pHaig, 1, NULL );
+        x = 0;
+    }
+*/
+//    if ( Ivy_ManCheckFanoutNums(p) )
+//    {
+//        int x = 0;
+//    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Fixes buffer fanins.]
+
+  Description [This situation happens because NodeReplace is a lazy
+  procedure, which does not propagate the change to the fanouts but
+  instead records the change in the form of a buf/inv node.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_NodeFixBufferFanins( Ivy_Man_t * p, Ivy_Obj_t * pNode, int fUpdateLevel )
+{
+    Ivy_Obj_t * pFanReal0, * pFanReal1, * pResult;
+    if ( Ivy_ObjIsPo(pNode) )
+    {
+        if ( !Ivy_ObjIsBuf(Ivy_ObjFanin0(pNode)) )
+            return;
+        pFanReal0 = Ivy_ObjReal( Ivy_ObjChild0(pNode) );
+        Ivy_ObjPatchFanin0( p, pNode, pFanReal0 );
+//        Ivy_ManCheckFanouts( p );
+        return;
+    }
+    if ( !Ivy_ObjIsBuf(Ivy_ObjFanin0(pNode)) && !Ivy_ObjIsBuf(Ivy_ObjFanin1(pNode)) )
+        return;
+    // get the real fanins
+    pFanReal0 = Ivy_ObjReal( Ivy_ObjChild0(pNode) );
+    pFanReal1 = Ivy_ObjReal( Ivy_ObjChild1(pNode) );
+    // get the new node
+    if ( Ivy_ObjIsNode(pNode) )
+        pResult = Ivy_Oper( p, pFanReal0, pFanReal1, Ivy_ObjType(pNode) );
+    else if ( Ivy_ObjIsLatch(pNode) )
+        pResult = Ivy_Latch( p, pFanReal0, Ivy_ObjInit(pNode) );
+    else 
+        assert( 0 );
+
+//printf( "===== Replacing %d by %d.\n", pNode->Id, pResult->Id );
+//Ivy_ObjPrintVerbose( p, pNode, 0 );   printf( "\n" );
+//Ivy_ObjPrintVerbose( p, pResult, 0 ); printf( "\n" );
+
+    // perform the replacement
+    Ivy_ObjReplace( p, pNode, pResult, 1, 0, fUpdateLevel ); 
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyOper.c b/src/aig/ivy/ivyOper.c
new file mode 100644
index 00000000..8115ce4f
--- /dev/null
+++ b/src/aig/ivy/ivyOper.c
@@ -0,0 +1,293 @@
+/**CFile****************************************************************
+
+  FileName    [ivyOper.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [AIG operations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyOper.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+// procedure to detect an EXOR gate
+static inline int Ivy_ObjIsExorType( Ivy_Obj_t * p0, Ivy_Obj_t * p1, Ivy_Obj_t ** ppFan0, Ivy_Obj_t ** ppFan1 )
+{
+    if ( !Ivy_IsComplement(p0) || !Ivy_IsComplement(p1) )
+        return 0;
+    p0 = Ivy_Regular(p0);
+    p1 = Ivy_Regular(p1);
+    if ( !Ivy_ObjIsAnd(p0) || !Ivy_ObjIsAnd(p1) )
+        return 0;
+    if ( Ivy_ObjFanin0(p0) != Ivy_ObjFanin0(p1) || Ivy_ObjFanin1(p0) != Ivy_ObjFanin1(p1) )
+        return 0;
+    if ( Ivy_ObjFaninC0(p0) == Ivy_ObjFaninC0(p1) || Ivy_ObjFaninC1(p0) == Ivy_ObjFaninC1(p1) )
+        return 0;
+    *ppFan0 = Ivy_ObjChild0(p0);
+    *ppFan1 = Ivy_ObjChild1(p0);
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Perform one operation.]
+
+  Description [The argument nodes can be complemented.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Oper( Ivy_Man_t * p, Ivy_Obj_t * p0, Ivy_Obj_t * p1, Ivy_Type_t Type )
+{
+    if ( Type == IVY_AND )
+        return Ivy_And( p, p0, p1 );
+    if ( Type == IVY_EXOR )
+        return Ivy_Exor( p, p0, p1 );
+    assert( 0 );
+    return NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs canonicization step.]
+
+  Description [The argument nodes can be complemented.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_And( Ivy_Man_t * p, Ivy_Obj_t * p0, Ivy_Obj_t * p1 )
+{
+//    Ivy_Obj_t * pFan0, * pFan1;
+    // check trivial cases
+    if ( p0 == p1 )
+        return p0;
+    if ( p0 == Ivy_Not(p1) )
+        return Ivy_Not(p->pConst1);
+    if ( Ivy_Regular(p0) == p->pConst1 )
+        return p0 == p->pConst1 ? p1 : Ivy_Not(p->pConst1);
+    if ( Ivy_Regular(p1) == p->pConst1 )
+        return p1 == p->pConst1 ? p0 : Ivy_Not(p->pConst1);
+    // check if it can be an EXOR gate
+//    if ( Ivy_ObjIsExorType( p0, p1, &pFan0, &pFan1 ) )
+//        return Ivy_CanonExor( pFan0, pFan1 );
+    return Ivy_CanonAnd( p, p0, p1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs canonicization step.]
+
+  Description [The argument nodes can be complemented.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Exor( Ivy_Man_t * p, Ivy_Obj_t * p0, Ivy_Obj_t * p1 )
+{
+/*
+    // check trivial cases
+    if ( p0 == p1 )
+        return Ivy_Not(p->pConst1);
+    if ( p0 == Ivy_Not(p1) )
+        return p->pConst1;
+    if ( Ivy_Regular(p0) == p->pConst1 )
+        return Ivy_NotCond( p1, p0 == p->pConst1 );
+    if ( Ivy_Regular(p1) == p->pConst1 )
+        return Ivy_NotCond( p0, p1 == p->pConst1 );
+    // check the table
+    return Ivy_CanonExor( p, p0, p1 );
+*/
+    return Ivy_Or( p, Ivy_And(p, p0, Ivy_Not(p1)), Ivy_And(p, Ivy_Not(p0), p1) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implements Boolean OR.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Or( Ivy_Man_t * p, Ivy_Obj_t * p0, Ivy_Obj_t * p1 )
+{
+    return Ivy_Not( Ivy_And( p, Ivy_Not(p0), Ivy_Not(p1) ) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implements ITE operation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Mux( Ivy_Man_t * p, Ivy_Obj_t * pC, Ivy_Obj_t * p1, Ivy_Obj_t * p0 )
+{
+    Ivy_Obj_t * pTempA1, * pTempA2, * pTempB1, * pTempB2, * pTemp;
+    int Count0, Count1;
+    // consider trivial cases
+    if ( p0 == Ivy_Not(p1) )
+        return Ivy_Exor( p, pC, p0 );
+    // other cases can be added
+    // implement the first MUX (F = C * x1 + C' * x0)
+    pTempA1 = Ivy_TableLookup( p, Ivy_ObjCreateGhost(p, pC,          p1, IVY_AND, IVY_INIT_NONE) );
+    pTempA2 = Ivy_TableLookup( p, Ivy_ObjCreateGhost(p, Ivy_Not(pC), p0, IVY_AND, IVY_INIT_NONE) );
+    if ( pTempA1 && pTempA2 )
+    {
+        pTemp = Ivy_TableLookup( p, Ivy_ObjCreateGhost(p, Ivy_Not(pTempA1), Ivy_Not(pTempA2), IVY_AND, IVY_INIT_NONE) );
+        if ( pTemp ) return Ivy_Not(pTemp);
+    }
+    Count0 = (pTempA1 != NULL) + (pTempA2 != NULL);
+    // implement the second MUX (F' = C * x1' + C' * x0')
+    pTempB1 = Ivy_TableLookup( p, Ivy_ObjCreateGhost(p, pC,          Ivy_Not(p1), IVY_AND, IVY_INIT_NONE) );
+    pTempB2 = Ivy_TableLookup( p, Ivy_ObjCreateGhost(p, Ivy_Not(pC), Ivy_Not(p0), IVY_AND, IVY_INIT_NONE) );
+    if ( pTempB1 && pTempB2 )
+    {
+        pTemp = Ivy_TableLookup( p, Ivy_ObjCreateGhost(p, Ivy_Not(pTempB1), Ivy_Not(pTempB2), IVY_AND, IVY_INIT_NONE) );
+        if ( pTemp ) return pTemp;
+    }
+    Count1 = (pTempB1 != NULL) + (pTempB2 != NULL);
+    // compare and decide which one to implement
+    if ( Count0 >= Count1 )
+    {
+        pTempA1 = pTempA1? pTempA1 : Ivy_And(p, pC,          p1);
+        pTempA2 = pTempA2? pTempA2 : Ivy_And(p, Ivy_Not(pC), p0);
+        return Ivy_Or( p, pTempA1, pTempA2 );
+    }
+    pTempB1 = pTempB1? pTempB1 : Ivy_And(p, pC,          Ivy_Not(p1));
+    pTempB2 = pTempB2? pTempB2 : Ivy_And(p, Ivy_Not(pC), Ivy_Not(p0));
+    return Ivy_Not( Ivy_Or( p, pTempB1, pTempB2 ) );
+
+//    return Ivy_Or( Ivy_And(pC, p1), Ivy_And(Ivy_Not(pC), p0) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implements ITE operation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Maj( Ivy_Man_t * p, Ivy_Obj_t * pA, Ivy_Obj_t * pB, Ivy_Obj_t * pC )
+{
+    return Ivy_Or( p, Ivy_Or(p, Ivy_And(p, pA, pB), Ivy_And(p, pA, pC)), Ivy_And(p, pB, pC) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Constructs the well-balanced tree of gates.]
+
+  Description [Disregards levels and possible logic sharing.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Multi_rec( Ivy_Man_t * p, Ivy_Obj_t ** ppObjs, int nObjs, Ivy_Type_t Type )
+{
+    Ivy_Obj_t * pObj1, * pObj2;
+    if ( nObjs == 1 )
+        return ppObjs[0];
+    pObj1 = Ivy_Multi_rec( p, ppObjs,           nObjs/2,         Type );
+    pObj2 = Ivy_Multi_rec( p, ppObjs + nObjs/2, nObjs - nObjs/2, Type );
+    return Ivy_Oper( p, pObj1, pObj2, Type );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Old code.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Multi( Ivy_Man_t * p, Ivy_Obj_t ** pArgs, int nArgs, Ivy_Type_t Type )
+{
+    assert( Type == IVY_AND || Type == IVY_EXOR );
+    assert( nArgs > 0 );
+    return Ivy_Multi_rec( p, pArgs, nArgs, Type );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implements the miter.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Miter( Ivy_Man_t * p, Vec_Ptr_t * vPairs )
+{
+    int i;
+    assert( vPairs->nSize > 0 );
+    assert( vPairs->nSize % 2 == 0 );
+    // go through the cubes of the node's SOP
+    for ( i = 0; i < vPairs->nSize; i += 2 )
+        vPairs->pArray[i/2] = Ivy_Not( Ivy_Exor( p, vPairs->pArray[i], vPairs->pArray[i+1] ) );
+    vPairs->nSize = vPairs->nSize/2;
+    return Ivy_Not( Ivy_Multi_rec( p, (Ivy_Obj_t **)vPairs->pArray, vPairs->nSize, IVY_AND ) );
+}
+ 
+/**Function*************************************************************
+
+  Synopsis    [Performs canonicization step.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_Latch( Ivy_Man_t * p, Ivy_Obj_t * pObj, Ivy_Init_t Init )
+{
+    return Ivy_CanonLatch( p, pObj, Init );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyResyn.c b/src/aig/ivy/ivyResyn.c
new file mode 100644
index 00000000..f42d7464
--- /dev/null
+++ b/src/aig/ivy/ivyResyn.c
@@ -0,0 +1,196 @@
+/**CFile****************************************************************
+
+  FileName    [ivyResyn.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [AIG rewriting script.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyResyn.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Performs several passes of rewriting on the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Man_t * Ivy_ManResyn0( Ivy_Man_t * pMan, int fUpdateLevel, int fVerbose )
+{
+    int clk;
+    Ivy_Man_t * pTemp;
+
+if ( fVerbose ) { printf( "Original:\n" ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+clk = clock();
+    pMan = Ivy_ManBalance( pMan, fUpdateLevel );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Balance", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+//    Ivy_ManRewriteAlg( pMan, fUpdateLevel, 0 );
+clk = clock();
+    Ivy_ManRewritePre( pMan, fUpdateLevel, 0, 0 );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Rewrite", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+clk = clock();
+    pMan = Ivy_ManBalance( pTemp = pMan, fUpdateLevel );
+    Ivy_ManStop( pTemp );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Balance", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+    return pMan;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs several passes of rewriting on the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Man_t * Ivy_ManResyn( Ivy_Man_t * pMan, int fUpdateLevel, int fVerbose )
+{
+    int clk;
+    Ivy_Man_t * pTemp;
+
+if ( fVerbose ) { printf( "Original:\n" ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+clk = clock();
+    pMan = Ivy_ManBalance( pMan, fUpdateLevel );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Balance", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+//    Ivy_ManRewriteAlg( pMan, fUpdateLevel, 0 );
+clk = clock();
+    Ivy_ManRewritePre( pMan, fUpdateLevel, 0, 0 );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Rewrite", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+clk = clock();
+    pMan = Ivy_ManBalance( pTemp = pMan, fUpdateLevel );
+    Ivy_ManStop( pTemp );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Balance", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+//    Ivy_ManRewriteAlg( pMan, fUpdateLevel, 1 );
+clk = clock();
+    Ivy_ManRewritePre( pMan, fUpdateLevel, 1, 0 );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Rewrite", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+clk = clock();
+    pMan = Ivy_ManBalance( pTemp = pMan, fUpdateLevel );
+    Ivy_ManStop( pTemp );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Balance", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+//    Ivy_ManRewriteAlg( pMan, fUpdateLevel, 1 );
+clk = clock();
+    Ivy_ManRewritePre( pMan, fUpdateLevel, 1, 0 );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Rewrite", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+clk = clock();
+    pMan = Ivy_ManBalance( pTemp = pMan, fUpdateLevel );
+    Ivy_ManStop( pTemp );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Balance", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+    return pMan;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs several passes of rewriting on the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Man_t * Ivy_ManRwsat( Ivy_Man_t * pMan, int fVerbose )
+{
+    int clk;
+    Ivy_Man_t * pTemp;
+
+if ( fVerbose ) { printf( "Original:\n" ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+clk = clock();
+    Ivy_ManRewritePre( pMan, 0, 0, 0 );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Rewrite", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+clk = clock();
+    pMan = Ivy_ManBalance( pTemp = pMan, 0 );
+//    pMan = Ivy_ManDup( pTemp = pMan );
+    Ivy_ManStop( pTemp );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Balance", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+/*
+clk = clock();
+    Ivy_ManRewritePre( pMan, 0, 0, 0 );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Rewrite", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+
+clk = clock();
+    pMan = Ivy_ManBalance( pTemp = pMan, 0 );
+    Ivy_ManStop( pTemp );
+if ( fVerbose ) { printf( "\n" ); }
+if ( fVerbose ) { PRT( "Balance", clock() - clk ); }
+if ( fVerbose ) Ivy_ManPrintStats( pMan );
+*/
+    return pMan;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyRwr.c b/src/aig/ivy/ivyRwr.c
new file mode 100644
index 00000000..3f8720ba
--- /dev/null
+++ b/src/aig/ivy/ivyRwr.c
@@ -0,0 +1,609 @@
+/**CFile****************************************************************
+
+  FileName    [ivyRwt.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Rewriting based on precomputation.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyRwt.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+#include "deco.h"
+#include "rwt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static unsigned Ivy_NodeGetTruth( Ivy_Obj_t * pObj, int * pNums, int nNums );
+static int Ivy_NodeRewrite( Ivy_Man_t * pMan, Rwt_Man_t * p, Ivy_Obj_t * pNode, int fUpdateLevel, int fUseZeroCost );
+static Dec_Graph_t * Rwt_CutEvaluate( Ivy_Man_t * pMan, Rwt_Man_t * p, Ivy_Obj_t * pRoot, 
+    Vec_Ptr_t * vFaninsCur, int nNodesSaved, int LevelMax, int * pGainBest, unsigned uTruth );
+
+static int Ivy_GraphToNetworkCount( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Dec_Graph_t * pGraph, int NodeMax, int LevelMax );
+static void Ivy_GraphUpdateNetwork( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Dec_Graph_t * pGraph, int fUpdateLevel, int nGain );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Performs incremental rewriting of the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManRewritePre( Ivy_Man_t * p, int fUpdateLevel, int fUseZeroCost, int fVerbose )
+{
+    Rwt_Man_t * pManRwt;
+    Ivy_Obj_t * pNode;
+    int i, nNodes, nGain;
+    int clk, clkStart = clock();
+    // start the rewriting manager
+    pManRwt = Rwt_ManStart( 0 );
+    p->pData = pManRwt;
+    if ( pManRwt == NULL )
+        return 0; 
+    // create fanouts
+    if ( fUpdateLevel && p->fFanout == 0 )
+        Ivy_ManStartFanout( p );
+    // compute the reverse levels if level update is requested
+    if ( fUpdateLevel )
+        Ivy_ManRequiredLevels( p );
+    // set the number of levels
+//    p->nLevelMax = Ivy_ManLevels( p );
+    // resynthesize each node once
+    nNodes = Ivy_ManObjIdMax(p);
+    Ivy_ManForEachNode( p, pNode, i )
+    {
+        // fix the fanin buffer problem
+        Ivy_NodeFixBufferFanins( p, pNode, 1 );
+        if ( Ivy_ObjIsBuf(pNode) )
+            continue;
+        // stop if all nodes have been tried once
+        if ( i > nNodes )
+            break;
+        // for each cut, try to resynthesize it
+        nGain = Ivy_NodeRewrite( p, pManRwt, pNode, fUpdateLevel, fUseZeroCost );
+        if ( nGain > 0 || nGain == 0 && fUseZeroCost )
+        {
+            Dec_Graph_t * pGraph = Rwt_ManReadDecs(pManRwt);
+            int fCompl           = Rwt_ManReadCompl(pManRwt);
+/*
+            {
+                Ivy_Obj_t * pObj;
+                int i;
+                printf( "USING: (" );
+                Vec_PtrForEachEntry( Rwt_ManReadLeaves(pManRwt), pObj, i )
+                    printf( "%d ", Ivy_ObjFanoutNum(Ivy_Regular(pObj)) );
+                printf( ")   Gain = %d.\n", nGain );
+            }
+            if ( nGain > 0 )
+            { // print stats on the MFFC
+                extern void Ivy_NodeMffsConeSuppPrint( Ivy_Obj_t * pNode );
+                printf( "Node %6d : Gain = %4d  ", pNode->Id, nGain );
+                Ivy_NodeMffsConeSuppPrint( pNode );
+            }
+*/
+            // complement the FF if needed
+clk = clock();
+            if ( fCompl ) Dec_GraphComplement( pGraph );
+            Ivy_GraphUpdateNetwork( p, pNode, pGraph, fUpdateLevel, nGain );
+            if ( fCompl ) Dec_GraphComplement( pGraph );
+Rwt_ManAddTimeUpdate( pManRwt, clock() - clk );
+        }
+    }
+Rwt_ManAddTimeTotal( pManRwt, clock() - clkStart );
+    // print stats
+    if ( fVerbose )
+        Rwt_ManPrintStats( pManRwt );
+    // delete the managers
+    Rwt_ManStop( pManRwt );
+    p->pData = NULL;
+    // fix the levels
+    if ( fUpdateLevel )
+        Vec_IntFree( p->vRequired ), p->vRequired = NULL;
+    else
+        Ivy_ManResetLevels( p );
+    // check
+    if ( i = Ivy_ManCleanup(p) )
+        printf( "Cleanup after rewriting removed %d dangling nodes.\n", i );
+    if ( !Ivy_ManCheck(p) )
+        printf( "Ivy_ManRewritePre(): The check has failed.\n" );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs rewriting for one node.]
+
+  Description [This procedure considers all the cuts computed for the node
+  and tries to rewrite each of them using the "forest" of different AIG
+  structures precomputed and stored in the RWR manager. 
+  Determines the best rewriting and computes the gain in the number of AIG
+  nodes in the final network. In the end, p->vFanins contains information 
+  about the best cut that can be used for rewriting, while p->pGraph gives 
+  the decomposition dag (represented using decomposition graph data structure).
+  Returns gain in the number of nodes or -1 if node cannot be rewritten.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeRewrite( Ivy_Man_t * pMan, Rwt_Man_t * p, Ivy_Obj_t * pNode, int fUpdateLevel, int fUseZeroCost )
+{
+    int fVeryVerbose = 0;
+    Dec_Graph_t * pGraph;
+    Ivy_Store_t * pStore;
+    Ivy_Cut_t * pCut;
+    Ivy_Obj_t * pFanin;
+    unsigned uPhase, uTruthBest, uTruth;
+    char * pPerm;
+    int Required, nNodesSaved, nNodesSaveCur;
+    int i, c, GainCur, GainBest = -1;
+    int clk, clk2;
+
+    p->nNodesConsidered++;
+    // get the required times
+    Required = fUpdateLevel? Vec_IntEntry( pMan->vRequired, pNode->Id ) : 1000000;
+    // get the node's cuts
+clk = clock();
+    pStore = Ivy_NodeFindCutsAll( pMan, pNode, 5 );
+p->timeCut += clock() - clk;
+
+    // go through the cuts
+clk = clock();
+    for ( c = 1; c < pStore->nCuts; c++ )
+    {
+        pCut = pStore->pCuts + c;
+        // consider only 4-input cuts
+        if ( pCut->nSize != 4 )
+            continue;
+        // skip the cuts with buffers
+        for ( i = 0; i < (int)pCut->nSize; i++ )
+            if ( Ivy_ObjIsBuf( Ivy_ManObj(pMan, pCut->pArray[i]) ) )
+                break;
+        if ( i != pCut->nSize )
+        {
+            p->nCutsBad++;
+            continue;
+        }
+        p->nCutsGood++;
+        // get the fanin permutation
+clk2 = clock();
+        uTruth = 0xFFFF & Ivy_NodeGetTruth( pNode, pCut->pArray, pCut->nSize );  // truth table
+p->timeTruth += clock() - clk2;
+        pPerm = p->pPerms4[ p->pPerms[uTruth] ];
+        uPhase = p->pPhases[uTruth];
+        // collect fanins with the corresponding permutation/phase
+        Vec_PtrClear( p->vFaninsCur );
+        Vec_PtrFill( p->vFaninsCur, (int)pCut->nSize, 0 );
+        for ( i = 0; i < (int)pCut->nSize; i++ )
+        {
+            pFanin = Ivy_ManObj( pMan, pCut->pArray[pPerm[i]] );
+            assert( Ivy_ObjIsNode(pFanin) || Ivy_ObjIsCi(pFanin) );
+            pFanin = Ivy_NotCond(pFanin, ((uPhase & (1<<i)) > 0) );
+            Vec_PtrWriteEntry( p->vFaninsCur, i, pFanin );
+        }
+clk2 = clock();
+/*
+        printf( "Considering: (" );
+        Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+            printf( "%d ", Ivy_ObjFanoutNum(Ivy_Regular(pFanin)) );
+        printf( ")\n" );
+*/
+        // mark the fanin boundary 
+        Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+            Ivy_ObjRefsInc( Ivy_Regular(pFanin) );
+        // label MFFC with current ID
+        Ivy_ManIncrementTravId( pMan );
+        nNodesSaved = Ivy_ObjMffcLabel( pMan, pNode );
+        // unmark the fanin boundary
+        Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+            Ivy_ObjRefsDec( Ivy_Regular(pFanin) );
+p->timeMffc += clock() - clk2;
+
+        // evaluate the cut
+clk2 = clock();
+        pGraph = Rwt_CutEvaluate( pMan, p, pNode, p->vFaninsCur, nNodesSaved, Required, &GainCur, uTruth );
+p->timeEval += clock() - clk2;
+
+        // check if the cut is better than the current best one
+        if ( pGraph != NULL && GainBest < GainCur )
+        {
+            // save this form
+            nNodesSaveCur = nNodesSaved;
+            GainBest  = GainCur;
+            p->pGraph  = pGraph;
+            p->fCompl = ((uPhase & (1<<4)) > 0);
+            uTruthBest = uTruth;
+            // collect fanins in the
+            Vec_PtrClear( p->vFanins );
+            Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+                Vec_PtrPush( p->vFanins, pFanin );
+        }
+    }
+p->timeRes += clock() - clk;
+
+    if ( GainBest == -1 )
+        return -1;
+
+//    printf( "%d", nNodesSaveCur - GainBest );
+/*
+    if ( GainBest > 0 )
+    {
+        if ( Rwt_CutIsintean( pNode, p->vFanins ) )
+            printf( "b" );
+        else
+        {
+            printf( "Node %d : ", pNode->Id );
+            Vec_PtrForEachEntry( p->vFanins, pFanin, i )
+                printf( "%d ", Ivy_Regular(pFanin)->Id );
+            printf( "a" );
+        }
+    }
+*/
+/*
+    if ( GainBest > 0 )
+        if ( p->fCompl )
+            printf( "c" );
+        else
+            printf( "." );
+*/
+
+    // copy the leaves
+    Vec_PtrForEachEntry( p->vFanins, pFanin, i )
+        Dec_GraphNode(p->pGraph, i)->pFunc = pFanin;
+
+    p->nScores[p->pMap[uTruthBest]]++;
+    p->nNodesGained += GainBest;
+    if ( fUseZeroCost || GainBest > 0 )
+        p->nNodesRewritten++;
+
+    // report the progress
+    if ( fVeryVerbose && GainBest > 0 )
+    {
+        printf( "Node %6d :   ", Ivy_ObjId(pNode) );
+        printf( "Fanins = %d. ", p->vFanins->nSize );
+        printf( "Save = %d.  ", nNodesSaveCur );
+        printf( "Add = %d.  ",  nNodesSaveCur-GainBest );
+        printf( "GAIN = %d.  ", GainBest );
+        printf( "Cone = %d.  ", p->pGraph? Dec_GraphNodeNum(p->pGraph) : 0 );
+        printf( "Class = %d.  ", p->pMap[uTruthBest] );
+        printf( "\n" );
+    }
+    return GainBest;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the truth table.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Ivy_NodeGetTruth_rec( Ivy_Obj_t * pObj, int * pNums, int nNums )
+{
+    static unsigned uMasks[5] = { 0xAAAAAAAA, 0xCCCCCCCC, 0xF0F0F0F0, 0xFF00FF00, 0xFFFF0000 };
+    unsigned uTruth0, uTruth1;
+    int i;
+    for ( i = 0; i < nNums; i++ )
+        if ( pObj->Id == pNums[i] )
+            return uMasks[i];
+    assert( Ivy_ObjIsNode(pObj) || Ivy_ObjIsBuf(pObj) );
+    uTruth0 = Ivy_NodeGetTruth_rec( Ivy_ObjFanin0(pObj), pNums, nNums );
+    if ( Ivy_ObjFaninC0(pObj) )
+        uTruth0 = ~uTruth0;
+    if ( Ivy_ObjIsBuf(pObj) )
+        return uTruth0;
+    uTruth1 = Ivy_NodeGetTruth_rec( Ivy_ObjFanin1(pObj), pNums, nNums );
+    if ( Ivy_ObjFaninC1(pObj) )
+        uTruth1 = ~uTruth1;
+    return uTruth0 & uTruth1;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the truth table.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Ivy_NodeGetTruth( Ivy_Obj_t * pObj, int * pNums, int nNums )
+{
+    assert( nNums < 6 );
+    return Ivy_NodeGetTruth_rec( pObj, pNums, nNums );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Evaluates the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Graph_t * Rwt_CutEvaluate( Ivy_Man_t * pMan, Rwt_Man_t * p, Ivy_Obj_t * pRoot, Vec_Ptr_t * vFaninsCur, int nNodesSaved, int LevelMax, int * pGainBest, unsigned uTruth )
+{
+    Vec_Ptr_t * vSubgraphs;
+    Dec_Graph_t * pGraphBest, * pGraphCur;
+    Rwt_Node_t * pNode, * pFanin;
+    int nNodesAdded, GainBest, i, k;
+    // find the matching class of subgraphs
+    vSubgraphs = Vec_VecEntry( p->vClasses, p->pMap[uTruth] );
+    p->nSubgraphs += vSubgraphs->nSize;
+    // determine the best subgraph
+    GainBest = -1;
+    Vec_PtrForEachEntry( vSubgraphs, pNode, i )
+    {
+        // get the current graph
+        pGraphCur = (Dec_Graph_t *)pNode->pNext;
+        // copy the leaves
+        Vec_PtrForEachEntry( vFaninsCur, pFanin, k )
+            Dec_GraphNode(pGraphCur, k)->pFunc = pFanin;
+        // detect how many unlabeled nodes will be reused
+        nNodesAdded = Ivy_GraphToNetworkCount( pMan, pRoot, pGraphCur, nNodesSaved, LevelMax );
+        if ( nNodesAdded == -1 )
+            continue;
+        assert( nNodesSaved >= nNodesAdded );
+        // count the gain at this node
+        if ( GainBest < nNodesSaved - nNodesAdded )
+        {
+            GainBest   = nNodesSaved - nNodesAdded;
+            pGraphBest = pGraphCur;
+        }
+    }
+    if ( GainBest == -1 )
+        return NULL;
+    *pGainBest = GainBest;
+    return pGraphBest;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of new nodes added when using this graph.]
+
+  Description [AIG nodes for the fanins should be assigned to pNode->pFunc 
+  of the leaves of the graph before calling this procedure. 
+  Returns -1 if the number of nodes and levels exceeded the given limit or 
+  the number of levels exceeded the maximum allowed level.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_GraphToNetworkCount( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Dec_Graph_t * pGraph, int NodeMax, int LevelMax )
+{
+    Dec_Node_t * pNode, * pNode0, * pNode1;
+    Ivy_Obj_t * pAnd, * pAnd0, * pAnd1;
+    int i, Counter, LevelNew, LevelOld;
+    // check for constant function or a literal
+    if ( Dec_GraphIsConst(pGraph) || Dec_GraphIsVar(pGraph) )
+        return 0;
+    // set the levels of the leaves
+    Dec_GraphForEachLeaf( pGraph, pNode, i )
+        pNode->Level = Ivy_Regular(pNode->pFunc)->Level;
+    // compute the AIG size after adding the internal nodes
+    Counter = 0;
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        // get the children of this node
+        pNode0 = Dec_GraphNode( pGraph, pNode->eEdge0.Node );
+        pNode1 = Dec_GraphNode( pGraph, pNode->eEdge1.Node );
+        // get the AIG nodes corresponding to the children 
+        pAnd0 = pNode0->pFunc; 
+        pAnd1 = pNode1->pFunc; 
+        if ( pAnd0 && pAnd1 )
+        {
+            // if they are both present, find the resulting node
+            pAnd0 = Ivy_NotCond( pAnd0, pNode->eEdge0.fCompl );
+            pAnd1 = Ivy_NotCond( pAnd1, pNode->eEdge1.fCompl );
+            pAnd  = Ivy_TableLookup( p, Ivy_ObjCreateGhost(p, pAnd0, pAnd1, IVY_AND, IVY_INIT_NONE) );
+            // return -1 if the node is the same as the original root
+            if ( Ivy_Regular(pAnd) == pRoot )
+                return -1;
+        }
+        else
+            pAnd = NULL;
+        // count the number of added nodes
+        if ( pAnd == NULL || Ivy_ObjIsTravIdCurrent(p, Ivy_Regular(pAnd)) )
+        {
+            if ( ++Counter > NodeMax )
+                return -1;
+        }
+        // count the number of new levels
+        LevelNew = 1 + RWT_MAX( pNode0->Level, pNode1->Level );
+        if ( pAnd )
+        {
+            if ( Ivy_Regular(pAnd) == p->pConst1 )
+                LevelNew = 0;
+            else if ( Ivy_Regular(pAnd) == Ivy_Regular(pAnd0) )
+                LevelNew = (int)Ivy_Regular(pAnd0)->Level;
+            else if ( Ivy_Regular(pAnd) == Ivy_Regular(pAnd1) )
+                LevelNew = (int)Ivy_Regular(pAnd1)->Level;
+            LevelOld = (int)Ivy_Regular(pAnd)->Level;
+//            assert( LevelNew == LevelOld );
+        }
+        if ( LevelNew > LevelMax )
+            return -1;
+        pNode->pFunc = pAnd;
+        pNode->Level = LevelNew;
+    }
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transforms the decomposition graph into the AIG.]
+
+  Description [AIG nodes for the fanins should be assigned to pNode->pFunc
+  of the leaves of the graph before calling this procedure.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_GraphToNetwork( Ivy_Man_t * p, Dec_Graph_t * pGraph )
+{
+    Ivy_Obj_t * pAnd0, * pAnd1;
+    Dec_Node_t * pNode;
+    int i;
+    // check for constant function
+    if ( Dec_GraphIsConst(pGraph) )
+        return Ivy_NotCond( Ivy_ManConst1(p), Dec_GraphIsComplement(pGraph) );
+    // check for a literal
+    if ( Dec_GraphIsVar(pGraph) )
+        return Ivy_NotCond( Dec_GraphVar(pGraph)->pFunc, Dec_GraphIsComplement(pGraph) );
+    // build the AIG nodes corresponding to the AND gates of the graph
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        pAnd0 = Ivy_NotCond( Dec_GraphNode(pGraph, pNode->eEdge0.Node)->pFunc, pNode->eEdge0.fCompl ); 
+        pAnd1 = Ivy_NotCond( Dec_GraphNode(pGraph, pNode->eEdge1.Node)->pFunc, pNode->eEdge1.fCompl ); 
+        pNode->pFunc = Ivy_And( p, pAnd0, pAnd1 );
+    }
+    // complement the result if necessary
+    return Ivy_NotCond( pNode->pFunc, Dec_GraphIsComplement(pGraph) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Replaces MFFC of the node by the new factored form.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_GraphUpdateNetwork( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Dec_Graph_t * pGraph, int fUpdateLevel, int nGain )
+{
+    Ivy_Obj_t * pRootNew;
+    int nNodesNew, nNodesOld, Required;
+    Required = fUpdateLevel? Vec_IntEntry( p->vRequired, pRoot->Id ) : 1000000;
+    nNodesOld = Ivy_ManNodeNum(p);
+    // create the new structure of nodes
+    pRootNew = Ivy_GraphToNetwork( p, pGraph );
+    assert( (int)Ivy_Regular(pRootNew)->Level <= Required );
+//    if ( Ivy_Regular(pRootNew)->Level == Required )
+//        printf( "Difference %d.\n", Ivy_Regular(pRootNew)->Level - Required );
+    // remove the old nodes
+//    Ivy_AigReplace( pMan->pManFunc, pRoot, pRootNew, fUpdateLevel );
+/*
+    if ( Ivy_IsComplement(pRootNew) )
+        printf( "c" );
+    else
+        printf( "d" );
+    if ( Ivy_ObjRefs(Ivy_Regular(pRootNew)) > 0 )
+        printf( "%d", Ivy_ObjRefs(Ivy_Regular(pRootNew)) );
+    printf( " " );
+*/
+    Ivy_ObjReplace( p, pRoot, pRootNew, 1, 0, 1 );
+    // compare the gains
+    nNodesNew = Ivy_ManNodeNum(p);
+    assert( nGain <= nNodesOld - nNodesNew );
+    // propagate the buffer
+    Ivy_ManPropagateBuffers( p, 1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Replaces MFFC of the node by the new factored form.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_GraphUpdateNetwork3( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Dec_Graph_t * pGraph, int fUpdateLevel, int nGain )
+{
+    Ivy_Obj_t * pRootNew, * pFanin;
+    int nNodesNew, nNodesOld, i, nRefsOld;
+    nNodesOld = Ivy_ManNodeNum(p);
+
+//printf( "Before = %d. ", Ivy_ManNodeNum(p) );
+    // mark the cut
+    Vec_PtrForEachEntry( ((Rwt_Man_t *)p->pData)->vFanins, pFanin, i )
+        Ivy_ObjRefsInc( Ivy_Regular(pFanin) );
+    // deref the old cone
+    nRefsOld = pRoot->nRefs;  
+    pRoot->nRefs = 0;
+    Ivy_ObjDelete_rec( p, pRoot, 0 );
+    pRoot->nRefs = nRefsOld;
+    // unmark the cut
+    Vec_PtrForEachEntry( ((Rwt_Man_t *)p->pData)->vFanins, pFanin, i )
+        Ivy_ObjRefsDec( Ivy_Regular(pFanin) );
+//printf( "Deref = %d. ", Ivy_ManNodeNum(p) );
+ 
+    // create the new structure of nodes
+    pRootNew = Ivy_GraphToNetwork( p, pGraph );
+//printf( "Create = %d. ", Ivy_ManNodeNum(p) );
+    // remove the old nodes
+//    Ivy_AigReplace( pMan->pManFunc, pRoot, pRootNew, fUpdateLevel );
+/*
+    if ( Ivy_IsComplement(pRootNew) )
+        printf( "c" );
+    else
+        printf( "d" );
+    if ( Ivy_ObjRefs(Ivy_Regular(pRootNew)) > 0 )
+        printf( "%d", Ivy_ObjRefs(Ivy_Regular(pRootNew)) );
+    printf( " " );
+*/
+    Ivy_ObjReplace( p, pRoot, pRootNew, 0, 0, 1 );
+//printf( "Replace = %d. ", Ivy_ManNodeNum(p) );
+
+    // delete remaining dangling nodes
+    Vec_PtrForEachEntry( ((Rwt_Man_t *)p->pData)->vFanins, pFanin, i )
+    {
+        pFanin = Ivy_Regular(pFanin);
+        if ( !Ivy_ObjIsNone(pFanin) && Ivy_ObjRefs(pFanin) == 0 )
+            Ivy_ObjDelete_rec( p, pFanin, 1 );
+    }
+//printf( "Deref = %d. ", Ivy_ManNodeNum(p) );
+//printf( "\n" );
+
+    // compare the gains
+    nNodesNew = Ivy_ManNodeNum(p);
+    assert( nGain <= nNodesOld - nNodesNew );
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyRwrAlg.c b/src/aig/ivy/ivyRwrAlg.c
new file mode 100644
index 00000000..fc48deb0
--- /dev/null
+++ b/src/aig/ivy/ivyRwrAlg.c
@@ -0,0 +1,408 @@
+/**CFile****************************************************************
+
+  FileName    [ivyRwrAlg.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Algebraic AIG rewriting.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyRwrAlg.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static int Ivy_ManFindAlgCut( Ivy_Obj_t * pRoot, Vec_Ptr_t * vFront, Vec_Ptr_t * vLeaves, Vec_Ptr_t * vCone );
+static Ivy_Obj_t * Ivy_NodeRewriteAlg( Ivy_Obj_t * pObj, Vec_Ptr_t * vFront, Vec_Ptr_t * vLeaves, Vec_Ptr_t * vCone, Vec_Ptr_t * vSols, int LevelR, int fUseZeroCost );
+static int Ivy_NodeCountMffc( Ivy_Obj_t * pNode );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Algebraic AIG rewriting.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManRewriteAlg( Ivy_Man_t * p, int fUpdateLevel, int fUseZeroCost )
+{
+    Vec_Int_t * vRequired;
+    Vec_Ptr_t * vFront, * vLeaves, * vCone, * vSol;
+    Ivy_Obj_t * pObj, * pResult;
+    int i, RetValue, LevelR, nNodesOld;
+    int CountUsed, CountUndo;
+    vRequired = fUpdateLevel? Ivy_ManRequiredLevels( p ) : NULL;
+    vFront    = Vec_PtrAlloc( 100 );
+    vLeaves   = Vec_PtrAlloc( 100 );
+    vCone     = Vec_PtrAlloc( 100 );
+    vSol      = Vec_PtrAlloc( 100 );
+    // go through the nodes in the topological order
+    CountUsed = CountUndo = 0;
+    nNodesOld = Ivy_ManObjIdNext(p);
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        assert( !Ivy_ObjIsBuf(pObj) );
+        if ( i >= nNodesOld )
+            break;
+        // skip no-nodes and MUX roots
+        if ( !Ivy_ObjIsNode(pObj) || Ivy_ObjIsExor(pObj) || Ivy_ObjIsMuxType(pObj) )
+            continue;
+//        if ( pObj->Id > 297 ) // 296 --- 297 
+//            break;
+        if ( pObj->Id == 297 )
+        {
+            int x = 0;
+        }
+        // get the largest algebraic cut
+        RetValue = Ivy_ManFindAlgCut( pObj, vFront, vLeaves, vCone );
+        // the case of a trivial tree cut
+        if ( RetValue == 1 )
+            continue;
+        // the case of constant 0 cone
+        if ( RetValue == -1 )
+        {
+            Ivy_ObjReplace( pObj, Ivy_ManConst0(p), 1, 0, 1 ); 
+            continue;
+        }
+        assert( Vec_PtrSize(vLeaves) > 2 );
+        // get the required level for this node
+        LevelR = vRequired? Vec_IntEntry(vRequired, pObj->Id) : 1000000;
+        // create a new cone
+        pResult = Ivy_NodeRewriteAlg( pObj, vFront, vLeaves, vCone, vSol, LevelR, fUseZeroCost );
+        if ( pResult == NULL || pResult == pObj )
+            continue;
+        assert( Vec_PtrSize(vSol) == 1 || !Ivy_IsComplement(pResult) );
+        if ( Ivy_ObjLevel(Ivy_Regular(pResult)) > LevelR && Ivy_ObjRefs(Ivy_Regular(pResult)) == 0 )
+            Ivy_ObjDelete_rec(Ivy_Regular(pResult), 1), CountUndo++;
+        else
+            Ivy_ObjReplace( pObj, pResult, 1, 0, 1 ), CountUsed++; 
+    }
+    printf( "Used = %d. Undo = %d.\n", CountUsed, CountUndo );
+    Vec_PtrFree( vFront );
+    Vec_PtrFree( vCone );
+    Vec_PtrFree( vSol );
+    if ( vRequired ) Vec_IntFree( vRequired );
+    if ( i = Ivy_ManCleanup(p) )
+        printf( "Cleanup after rewriting removed %d dangling nodes.\n", i );
+    if ( !Ivy_ManCheck(p) )
+        printf( "Ivy_ManRewriteAlg(): The check has failed.\n" );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Analizes one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_NodeRewriteAlg( Ivy_Obj_t * pObj, Vec_Ptr_t * vFront, Vec_Ptr_t * vLeaves, Vec_Ptr_t * vCone, Vec_Ptr_t * vSols, int LevelR, int fUseZeroCost )
+{
+    int fVerbose = 0;
+    Ivy_Obj_t * pTemp;
+    int k, Counter, nMffc, RetValue;
+
+    if ( fVerbose )
+    {
+        if ( Ivy_ObjIsExor(pObj) )
+            printf( "x " );
+        else
+            printf( "  " );
+    }
+
+/*       
+    printf( "%d ", Vec_PtrSize(vFront) );
+    printf( "( " );
+    Vec_PtrForEachEntry( vFront, pTemp, k )
+        printf( "%d ", Ivy_ObjRefs(Ivy_Regular(pTemp)) );
+    printf( ")\n" );
+*/
+    // collect nodes in the cone
+    if ( Ivy_ObjIsExor(pObj) )
+        Ivy_ManCollectCone( pObj, vFront, vCone );
+    else
+        Ivy_ManCollectCone( pObj, vLeaves, vCone );
+
+    // deref nodes in the cone
+    Vec_PtrForEachEntry( vCone, pTemp, k )
+    {
+        Ivy_ObjRefsDec( Ivy_ObjFanin0(pTemp) );
+        Ivy_ObjRefsDec( Ivy_ObjFanin1(pTemp) );
+        pTemp->fMarkB = 1;
+    }
+
+    // count the MFFC size
+    Vec_PtrForEachEntry( vFront, pTemp, k )
+        Ivy_Regular(pTemp)->fMarkA = 1;
+    nMffc = Ivy_NodeCountMffc( pObj );
+    Vec_PtrForEachEntry( vFront, pTemp, k )
+        Ivy_Regular(pTemp)->fMarkA = 0;
+
+    if ( fVerbose )
+    {
+    Counter = 0;
+    Vec_PtrForEachEntry( vCone, pTemp, k )
+        Counter += (Ivy_ObjRefs(pTemp) > 0);
+    printf( "%5d : Leaves = %2d. Cone = %2d. ConeRef = %2d.   Mffc = %d.   Lev = %d.  LevR = %d.\n", 
+        pObj->Id, Vec_PtrSize(vFront), Vec_PtrSize(vCone), Counter-1, nMffc, Ivy_ObjLevel(pObj), LevelR );
+    }
+/*
+    printf( "Leaves:" );
+    Vec_PtrForEachEntry( vLeaves, pTemp, k )
+        printf( " %d%s", Ivy_Regular(pTemp)->Id, Ivy_IsComplement(pTemp)? "\'" : "" );
+    printf( "\n" );
+    printf( "Cone:\n" );
+    Vec_PtrForEachEntry( vCone, pTemp, k )
+        printf( " %5d = %d%s %d%s\n", pTemp->Id,
+            Ivy_ObjFaninId0(pTemp), Ivy_ObjFaninC0(pTemp)? "\'" : "",
+            Ivy_ObjFaninId1(pTemp), Ivy_ObjFaninC1(pTemp)? "\'" : "" );
+*/
+
+    RetValue = Ivy_MultiPlus( vLeaves, vCone, Ivy_ObjType(pObj), nMffc + fUseZeroCost, vSols );
+
+    // ref nodes in the cone
+    Vec_PtrForEachEntry( vCone, pTemp, k )
+    {
+        Ivy_ObjRefsInc( Ivy_ObjFanin0(pTemp) );
+        Ivy_ObjRefsInc( Ivy_ObjFanin1(pTemp) );
+        pTemp->fMarkA = 0;
+        pTemp->fMarkB = 0;
+    }
+
+    if ( !RetValue )
+        return NULL;
+
+    if ( Vec_PtrSize( vSols ) == 1 )
+        return Vec_PtrEntry( vSols, 0 );
+    return Ivy_NodeBalanceBuildSuper( vSols, Ivy_ObjType(pObj), 1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Comparison for node pointers.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeCountMffc_rec( Ivy_Obj_t * pNode )
+{
+    if ( Ivy_ObjRefs(pNode) > 0 || Ivy_ObjIsCi(pNode) || pNode->fMarkA )
+        return 0;
+    assert( pNode->fMarkB );
+    pNode->fMarkA = 1;
+//    printf( "%d ", pNode->Id );
+    if ( Ivy_ObjIsBuf(pNode) )
+        return Ivy_NodeCountMffc_rec( Ivy_ObjFanin0(pNode) );
+    return 1 + Ivy_NodeCountMffc_rec( Ivy_ObjFanin0(pNode) ) + Ivy_NodeCountMffc_rec( Ivy_ObjFanin1(pNode) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Comparison for node pointers.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeCountMffc( Ivy_Obj_t * pNode )
+{
+    assert( pNode->fMarkB );
+    return 1 + Ivy_NodeCountMffc_rec( Ivy_ObjFanin0(pNode) ) + Ivy_NodeCountMffc_rec( Ivy_ObjFanin1(pNode) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Comparison for node pointers.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManFindAlgCutCompare( Ivy_Obj_t ** pp1, Ivy_Obj_t ** pp2 )
+{
+    if ( *pp1 < *pp2 )
+        return -1;
+    if ( *pp1 > *pp2 )
+        return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computing one algebraic cut.]
+
+  Description [Returns 1 if the tree-leaves of this node where traversed 
+  and found to have no external references (and have not been collected). 
+  Returns 0 if the tree-leaves have external references and are collected.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManFindAlgCut_rec( Ivy_Obj_t * pObj, Ivy_Type_t Type, Vec_Ptr_t * vFront, Vec_Ptr_t * vCone )
+{
+    int RetValue0, RetValue1;
+    Ivy_Obj_t * pObjR = Ivy_Regular(pObj);
+    assert( !Ivy_ObjIsBuf(pObjR) );
+    assert( Type != IVY_EXOR || !Ivy_IsComplement(pObj) );
+
+    // make sure the node is not visited twice in different polarities
+    if ( Ivy_IsComplement(pObj) )
+    { // if complemented, mark B
+        if ( pObjR->fMarkA )
+            return -1;
+        pObjR->fMarkB = 1;
+    }
+    else
+    { // if non-complicated, mark A
+        if ( pObjR->fMarkB )
+            return -1;
+        pObjR->fMarkA = 1;
+    }
+    Vec_PtrPush( vCone, pObjR );
+
+    // if the node is the end of the tree, return
+    if ( Ivy_IsComplement(pObj) || Ivy_ObjType(pObj) != Type )
+    {
+        if ( Ivy_ObjRefs(pObjR) == 1 )
+            return 1;
+        assert( Ivy_ObjRefs(pObjR) > 1 );
+        Vec_PtrPush( vFront, pObj );
+        return 0;
+    }
+
+    // branch on the node
+    assert( !Ivy_IsComplement(pObj) );
+    assert( Ivy_ObjIsNode(pObj) );
+    // what if buffer has more than one fanout???
+    RetValue0 = Ivy_ManFindAlgCut_rec( Ivy_ObjReal( Ivy_ObjChild0(pObj) ), Type, vFront, vCone );
+    RetValue1 = Ivy_ManFindAlgCut_rec( Ivy_ObjReal( Ivy_ObjChild1(pObj) ), Type, vFront, vCone );
+    if ( RetValue0 == -1 || RetValue1 == -1 )
+        return -1;
+
+    // the case when both have no external references
+    if ( RetValue0 && RetValue1 )
+    {
+        if ( Ivy_ObjRefs(pObj) == 1 )
+            return 1;
+        assert( Ivy_ObjRefs(pObj) > 1 );
+        Vec_PtrPush( vFront, pObj );
+        return 0;
+    }
+    // the case when one of them has external references
+    if ( RetValue0 )
+        Vec_PtrPush( vFront, Ivy_ObjReal( Ivy_ObjChild0(pObj) ) );
+    if ( RetValue1 )
+        Vec_PtrPush( vFront, Ivy_ObjReal( Ivy_ObjChild1(pObj) ) );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computing one algebraic cut.]
+
+  Description [Algebraic cut stops when we hit (a) CI, (b) complemented edge,
+  (c) boundary of different gates. Returns 1 if this is a pure tree.
+  Returns -1 if the contant 0 is detected. Return 0 if the array can be used.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManFindAlgCut( Ivy_Obj_t * pRoot, Vec_Ptr_t * vFront, Vec_Ptr_t * vLeaves, Vec_Ptr_t * vCone )
+{
+    Ivy_Obj_t * pObj, * pPrev;
+    int RetValue, i;
+    assert( !Ivy_IsComplement(pRoot) );
+    assert( Ivy_ObjIsNode(pRoot) );
+    // clear the frontier and collect the nodes
+    Vec_PtrClear( vCone );
+    Vec_PtrClear( vFront );
+    Vec_PtrClear( vLeaves );
+    RetValue = Ivy_ManFindAlgCut_rec( pRoot, Ivy_ObjType(pRoot), vFront, vCone );
+    // clean the marks
+    Vec_PtrForEachEntry( vCone, pObj, i )
+        pObj->fMarkA = pObj->fMarkB = 0;
+    // quit if the same node is found in both polarities
+    if ( RetValue == -1 )
+        return -1;
+    // return if the node is the root of a tree
+    if ( RetValue == 1 )
+        return 1;
+    // return if the cut is composed of two nodes
+    if ( Vec_PtrSize(vFront) <= 2 )
+        return 1;
+    // sort the entries in increasing order
+    Vec_PtrSort( vFront, Ivy_ManFindAlgCutCompare );
+    // remove duplicates from vFront and save the nodes in vLeaves
+    pPrev = Vec_PtrEntry(vFront, 0);
+    Vec_PtrPush( vLeaves, pPrev );
+    Vec_PtrForEachEntryStart( vFront, pObj, i, 1 )
+    {
+        // compare current entry and the previous entry
+        if ( pObj == pPrev )
+        {
+            if ( Ivy_ObjIsExor(pRoot) ) // A <+> A = 0
+            {
+                // vLeaves are no longer structural support of pRoot!!!
+                Vec_PtrPop(vLeaves);  
+                pPrev = Vec_PtrSize(vLeaves) == 0 ? NULL : Vec_PtrEntryLast(vLeaves);
+            }
+            continue;
+        }
+        if ( pObj == Ivy_Not(pPrev) )
+        {
+            assert( Ivy_ObjIsAnd(pRoot) );
+            return -1;
+        }
+        pPrev = pObj;
+        Vec_PtrPush( vLeaves, pObj );
+    }
+    if ( Vec_PtrSize(vLeaves) == 0 )
+        return -1;
+    if ( Vec_PtrSize(vLeaves) <= 2 )
+        return 1;
+    return 0;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivySeq.c b/src/aig/ivy/ivySeq.c
new file mode 100644
index 00000000..0ee29fee
--- /dev/null
+++ b/src/aig/ivy/ivySeq.c
@@ -0,0 +1,1134 @@
+/**CFile****************************************************************
+
+  FileName    [ivySeq.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+ 
+  Revision    [$Id: ivySeq.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+#include "deco.h"
+#include "rwt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static int Ivy_NodeRewriteSeq( Ivy_Man_t * pMan, Rwt_Man_t * p, Ivy_Obj_t * pNode, int fUseZeroCost );
+static void Ivy_GraphPrepare( Dec_Graph_t * pGraph, Ivy_Cut_t * pCut, Vec_Ptr_t * vFanins, char * pPerm );
+static unsigned Ivy_CutGetTruth( Ivy_Man_t * p, Ivy_Obj_t * pObj, int * pNums, int nNums );
+static Dec_Graph_t * Rwt_CutEvaluateSeq( Ivy_Man_t * pMan, Rwt_Man_t * p, Ivy_Obj_t * pRoot, Ivy_Cut_t * pCut, char * pPerm, Vec_Ptr_t * vFaninsCur, int nNodesSaved, int * pGainBest, unsigned uTruth );
+static int Ivy_GraphToNetworkSeqCountSeq( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Dec_Graph_t * pGraph, int NodeMax );
+static Ivy_Obj_t * Ivy_GraphToNetworkSeq( Ivy_Man_t * p, Dec_Graph_t * pGraph );
+static void Ivy_GraphUpdateNetworkSeq( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Dec_Graph_t * pGraph, int nGain );
+static Ivy_Store_t * Ivy_CutComputeForNode( Ivy_Man_t * p, Ivy_Obj_t * pObj, int nLeaves );
+
+static inline int Ivy_CutHashValue( int NodeId )  { return 1 << (NodeId % 31); }
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+//int nMoves;
+//int nMovesS;
+//int nClauses;
+//int timeInv;
+
+/**Function*************************************************************
+
+  Synopsis    [Performs incremental rewriting of the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManRewriteSeq( Ivy_Man_t * p, int fUseZeroCost, int fVerbose )
+{ 
+    Rwt_Man_t * pManRwt;
+    Ivy_Obj_t * pNode;
+    int i, nNodes, nGain;
+    int clk, clkStart = clock();
+
+    // set the DC latch values
+    Ivy_ManForEachLatch( p, pNode, i )
+        pNode->Init = IVY_INIT_DC;
+    // start the rewriting manager
+    pManRwt = Rwt_ManStart( 0 );
+    p->pData = pManRwt;
+    if ( pManRwt == NULL )
+        return 0; 
+    // create fanouts
+    if ( p->fFanout == 0 )
+        Ivy_ManStartFanout( p );
+    // resynthesize each node once
+    nNodes = Ivy_ManObjIdMax(p);
+    Ivy_ManForEachNode( p, pNode, i )
+    {
+        assert( !Ivy_ObjIsBuf(pNode) );
+        assert( !Ivy_ObjIsBuf(Ivy_ObjFanin0(pNode)) );
+        assert( !Ivy_ObjIsBuf(Ivy_ObjFanin1(pNode)) );
+        // fix the fanin buffer problem
+//        Ivy_NodeFixBufferFanins( p, pNode );
+//        if ( Ivy_ObjIsBuf(pNode) )
+//            continue;
+        // stop if all nodes have been tried once
+        if ( i > nNodes ) 
+            break;
+        // for each cut, try to resynthesize it
+        nGain = Ivy_NodeRewriteSeq( p, pManRwt, pNode, fUseZeroCost );
+        if ( nGain > 0 || nGain == 0 && fUseZeroCost )
+        {
+            Dec_Graph_t * pGraph = Rwt_ManReadDecs(pManRwt);
+            int fCompl           = Rwt_ManReadCompl(pManRwt);
+            // complement the FF if needed
+clk = clock();
+            if ( fCompl ) Dec_GraphComplement( pGraph );
+            Ivy_GraphUpdateNetworkSeq( p, pNode, pGraph, nGain );
+            if ( fCompl ) Dec_GraphComplement( pGraph );
+Rwt_ManAddTimeUpdate( pManRwt, clock() - clk );
+        }
+    }
+Rwt_ManAddTimeTotal( pManRwt, clock() - clkStart );
+    // print stats
+    if ( fVerbose )
+        Rwt_ManPrintStats( pManRwt );
+    // delete the managers
+    Rwt_ManStop( pManRwt );
+    p->pData = NULL;
+    // fix the levels
+    Ivy_ManResetLevels( p );
+//    if ( Ivy_ManCheckFanoutNums(p) )
+//        printf( "Ivy_ManRewritePre(): The check has failed.\n" );
+    // check
+    if ( !Ivy_ManCheck(p) )
+        printf( "Ivy_ManRewritePre(): The check has failed.\n" );
+    return 1;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Performs rewriting for one node.]
+
+  Description [This procedure considers all the cuts computed for the node
+  and tries to rewrite each of them using the "forest" of different AIG
+  structures precomputed and stored in the RWR manager. 
+  Determines the best rewriting and computes the gain in the number of AIG
+  nodes in the final network. In the end, p->vFanins contains information 
+  about the best cut that can be used for rewriting, while p->pGraph gives 
+  the decomposition dag (represented using decomposition graph data structure).
+  Returns gain in the number of nodes or -1 if node cannot be rewritten.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_NodeRewriteSeq( Ivy_Man_t * pMan, Rwt_Man_t * p, Ivy_Obj_t * pNode, int fUseZeroCost )
+{
+    int fVeryVerbose = 0;
+    Dec_Graph_t * pGraph;
+    Ivy_Store_t * pStore;
+    Ivy_Cut_t * pCut;
+    Ivy_Obj_t * pFanin;//, * pFanout;
+    Vec_Ptr_t * vFanout;
+    unsigned uPhase, uTruthBest, uTruth;//, nNewClauses;
+    char * pPerm;
+    int nNodesSaved, nNodesSaveCur;
+    int i, c, GainCur, GainBest = -1;
+    int clk, clk2;//, clk3;
+
+    p->nNodesConsidered++;
+    // get the node's cuts
+clk = clock();
+    pStore = Ivy_CutComputeForNode( pMan, pNode, 5 );
+p->timeCut += clock() - clk;
+
+    // go through the cuts
+clk = clock();
+    vFanout = Vec_PtrAlloc( 100 );
+    for ( c = 1; c < pStore->nCuts; c++ )
+    {
+        pCut = pStore->pCuts + c;
+        // consider only 4-input cuts
+        if ( pCut->nSize != 4 )
+            continue;
+        // skip the cuts with buffers
+        for ( i = 0; i < (int)pCut->nSize; i++ )
+            if ( Ivy_ObjIsBuf( Ivy_ManObj(pMan, Ivy_LeafId(pCut->pArray[i])) ) )
+                break;
+        if ( i != pCut->nSize )
+        {
+            p->nCutsBad++;
+            continue;
+        }
+        p->nCutsGood++;
+        // get the fanin permutation
+clk2 = clock();
+        uTruth = 0xFFFF & Ivy_CutGetTruth( pMan, pNode, pCut->pArray, pCut->nSize );  // truth table
+p->timeTruth += clock() - clk2;
+        pPerm = p->pPerms4[ p->pPerms[uTruth] ];
+        uPhase = p->pPhases[uTruth];
+        // collect fanins with the corresponding permutation/phase
+        Vec_PtrClear( p->vFaninsCur );
+        Vec_PtrFill( p->vFaninsCur, (int)pCut->nSize, 0 );
+        for ( i = 0; i < (int)pCut->nSize; i++ )
+        {
+            pFanin = Ivy_ManObj( pMan, Ivy_LeafId( pCut->pArray[pPerm[i]] ) );
+            assert( Ivy_ObjIsNode(pFanin) || Ivy_ObjIsCi(pFanin) || Ivy_ObjIsConst1(pFanin) );
+            pFanin = Ivy_NotCond(pFanin, ((uPhase & (1<<i)) > 0) );
+            Vec_PtrWriteEntry( p->vFaninsCur, i, pFanin );
+        }
+clk2 = clock();
+        // mark the fanin boundary 
+        Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+            Ivy_ObjRefsInc( Ivy_Regular(pFanin) );
+        // label MFFC with current ID
+        Ivy_ManIncrementTravId( pMan );
+        nNodesSaved = Ivy_ObjMffcLabel( pMan, pNode );
+        // label fanouts with the current ID
+//        Ivy_ObjForEachFanout( pMan, pNode, vFanout, pFanout, i )
+//            Ivy_ObjSetTravIdCurrent( pMan, pFanout );
+        // unmark the fanin boundary
+        Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+            Ivy_ObjRefsDec( Ivy_Regular(pFanin) );
+p->timeMffc += clock() - clk2;
+
+        // evaluate the cut
+clk2 = clock();
+        pGraph = Rwt_CutEvaluateSeq( pMan, p, pNode, pCut, pPerm, p->vFaninsCur, nNodesSaved, &GainCur, uTruth );
+p->timeEval += clock() - clk2;
+
+
+        // check if the cut is better than the current best one
+        if ( pGraph != NULL && GainBest < GainCur )
+        {
+            // save this form
+            nNodesSaveCur = nNodesSaved;
+            GainBest   = GainCur;
+            p->pGraph  = pGraph;
+            p->pCut    = pCut;
+            p->pPerm   = pPerm;
+            p->fCompl  = ((uPhase & (1<<4)) > 0);
+            uTruthBest = uTruth;
+            // collect fanins in the
+            Vec_PtrClear( p->vFanins );
+            Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+                Vec_PtrPush( p->vFanins, pFanin );
+        }
+    }
+    Vec_PtrFree( vFanout );
+p->timeRes += clock() - clk;
+
+    if ( GainBest == -1 )
+        return -1;
+/*
+    {
+    Ivy_Cut_t * pCut = p->pCut;
+    printf( "Node %5d. Using cut : {", Ivy_ObjId(pNode) );
+    for ( i = 0; i < pCut->nSize; i++ )
+        printf( " %d(%d)", Ivy_LeafId(pCut->pArray[i]), Ivy_LeafLat(pCut->pArray[i]) );
+    printf( " }\n" );
+    }
+*/
+
+//clk3 = clock();
+//nNewClauses = Ivy_CutTruthPrint( pMan, p->pCut, uTruth );
+//timeInv += clock() - clk;
+
+//    nClauses += nNewClauses;
+//    nMoves++;
+//    if ( nNewClauses > 0 )
+//        nMovesS++;
+
+    // copy the leaves
+    Ivy_GraphPrepare( p->pGraph, p->pCut, p->vFanins, p->pPerm );
+
+    p->nScores[p->pMap[uTruthBest]]++;
+    p->nNodesGained += GainBest;
+    if ( fUseZeroCost || GainBest > 0 )
+        p->nNodesRewritten++;
+
+/*
+    if ( GainBest > 0 )
+    {
+        Ivy_Cut_t * pCut = p->pCut;
+        printf( "Node %5d. Using cut : {", Ivy_ObjId(pNode) );
+        for ( i = 0; i < pCut->nSize; i++ )
+            printf( " %5d(%2d)", Ivy_LeafId(pCut->pArray[i]), Ivy_LeafLat(pCut->pArray[i]) );
+        printf( " }\n" );
+    }
+*/
+
+    // report the progress
+    if ( fVeryVerbose && GainBest > 0 )
+    {
+        printf( "Node %6d :   ", Ivy_ObjId(pNode) );
+        printf( "Fanins = %d. ", p->vFanins->nSize );
+        printf( "Save = %d.  ", nNodesSaveCur );
+        printf( "Add = %d.  ",  nNodesSaveCur-GainBest );
+        printf( "GAIN = %d.  ", GainBest );
+        printf( "Cone = %d.  ", p->pGraph? Dec_GraphNodeNum(p->pGraph) : 0 );
+        printf( "Class = %d.  ", p->pMap[uTruthBest] );
+        printf( "\n" );
+    }
+    return GainBest;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Evaluates the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Graph_t * Rwt_CutEvaluateSeq( Ivy_Man_t * pMan, Rwt_Man_t * p, Ivy_Obj_t * pRoot, Ivy_Cut_t * pCut, char * pPerm, Vec_Ptr_t * vFaninsCur, int nNodesSaved, int * pGainBest, unsigned uTruth )
+{
+    Vec_Ptr_t * vSubgraphs;
+    Dec_Graph_t * pGraphBest, * pGraphCur;
+    Rwt_Node_t * pNode;
+    int nNodesAdded, GainBest, i;
+    // find the matching class of subgraphs
+    vSubgraphs = Vec_VecEntry( p->vClasses, p->pMap[uTruth] );
+    p->nSubgraphs += vSubgraphs->nSize;
+    // determine the best subgraph
+    GainBest = -1;
+    Vec_PtrForEachEntry( vSubgraphs, pNode, i )
+    {
+        // get the current graph
+        pGraphCur = (Dec_Graph_t *)pNode->pNext;
+
+//        if ( pRoot->Id == 8648 )
+//        Dec_GraphPrint( stdout, pGraphCur, NULL, NULL );
+        // copy the leaves
+//        Vec_PtrForEachEntry( vFaninsCur, pFanin, k )
+//            Dec_GraphNode(pGraphCur, k)->pFunc = pFanin;
+        Ivy_GraphPrepare( pGraphCur, pCut, vFaninsCur, pPerm );
+
+        // detect how many unlabeled nodes will be reused
+        nNodesAdded = Ivy_GraphToNetworkSeqCountSeq( pMan, pRoot, pGraphCur, nNodesSaved );
+        if ( nNodesAdded == -1 )
+            continue;
+        assert( nNodesSaved >= nNodesAdded );
+        // count the gain at this node
+        if ( GainBest < nNodesSaved - nNodesAdded )
+        {
+            GainBest   = nNodesSaved - nNodesAdded;
+            pGraphBest = pGraphCur;
+        }
+    }
+    if ( GainBest == -1 )
+        return NULL;
+    *pGainBest = GainBest;
+    return pGraphBest;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_GraphPrepare( Dec_Graph_t * pGraph, Ivy_Cut_t * pCut, Vec_Ptr_t * vFanins, char * pPerm )
+{
+    Dec_Node_t * pNode, * pNode0, * pNode1;
+    int i;
+    assert( Dec_GraphLeaveNum(pGraph) == pCut->nSize );
+    assert( Vec_PtrSize(vFanins) == pCut->nSize );
+    // label the leaves with latch numbers
+    Dec_GraphForEachLeaf( pGraph, pNode, i )
+    {
+        pNode->pFunc = Vec_PtrEntry( vFanins, i );
+        pNode->nLat2 = Ivy_LeafLat( pCut->pArray[pPerm[i]] );
+    }
+    // propagate latches through the nodes
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        // get the children of this node
+        pNode0 = Dec_GraphNode( pGraph, pNode->eEdge0.Node );
+        pNode1 = Dec_GraphNode( pGraph, pNode->eEdge1.Node );
+        // distribute the latches
+        pNode->nLat2 = IVY_MIN( pNode0->nLat2, pNode1->nLat2 );
+        pNode->nLat0 = pNode0->nLat2 - pNode->nLat2;
+        pNode->nLat1 = pNode1->nLat2 - pNode->nLat2;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of new nodes added when using this graph.]
+
+  Description [AIG nodes for the fanins should be assigned to pNode->pFunc 
+  of the leaves of the graph before calling this procedure. 
+  Returns -1 if the number of nodes and levels exceeded the given limit or 
+  the number of levels exceeded the maximum allowed level.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_GraphToNetworkSeqCountSeq( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Dec_Graph_t * pGraph, int NodeMax )
+{
+    Dec_Node_t * pNode, * pNode0, * pNode1;
+    Ivy_Obj_t * pAnd, * pAnd0, * pAnd1;
+    int i, k, Counter, fCompl;
+    // check for constant function or a literal
+    if ( Dec_GraphIsConst(pGraph) || Dec_GraphIsVar(pGraph) )
+        return 0;
+    // compute the AIG size after adding the internal nodes
+    Counter = 0;
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        // get the children of this node
+        pNode0 = Dec_GraphNode( pGraph, pNode->eEdge0.Node );
+        pNode1 = Dec_GraphNode( pGraph, pNode->eEdge1.Node );
+        // get the AIG nodes corresponding to the children 
+        pAnd0 = pNode0->pFunc; 
+        pAnd1 = pNode1->pFunc; 
+        // skip the latches
+        for ( k = 0; pAnd0 && k < (int)pNode->nLat0; k++ )
+        {
+            fCompl = Ivy_IsComplement(pAnd0);
+            pAnd0 = Ivy_TableLookup( p, Ivy_ObjCreateGhost(p, Ivy_Regular(pAnd0), NULL, IVY_LATCH, IVY_INIT_DC) );
+            if ( pAnd0 )
+                pAnd0 = Ivy_NotCond( pAnd0, fCompl );
+        }
+        for ( k = 0; pAnd1 && k < (int)pNode->nLat1; k++ )
+        {
+            fCompl = Ivy_IsComplement(pAnd1);
+            pAnd1 = Ivy_TableLookup( p, Ivy_ObjCreateGhost(p, Ivy_Regular(pAnd1), NULL, IVY_LATCH, IVY_INIT_DC) );
+            if ( pAnd1 )
+                pAnd1 = Ivy_NotCond( pAnd1, fCompl );
+        }
+        // get the new node
+        if ( pAnd0 && pAnd1 )
+        {
+            // if they are both present, find the resulting node
+            pAnd0 = Ivy_NotCond( pAnd0, pNode->eEdge0.fCompl );
+            pAnd1 = Ivy_NotCond( pAnd1, pNode->eEdge1.fCompl );
+            assert( !Ivy_ObjIsLatch(Ivy_Regular(pAnd0)) || !Ivy_ObjIsLatch(Ivy_Regular(pAnd1)) );
+            if ( Ivy_Regular(pAnd0) == Ivy_Regular(pAnd1) || Ivy_ObjIsConst1(Ivy_Regular(pAnd0)) || Ivy_ObjIsConst1(Ivy_Regular(pAnd1)) )
+                pAnd = Ivy_And( p, pAnd0, pAnd1 );
+            else
+                pAnd = Ivy_TableLookup( p, Ivy_ObjCreateGhost(p, pAnd0, pAnd1, IVY_AND, IVY_INIT_NONE) );
+            // return -1 if the node is the same as the original root
+            if ( Ivy_Regular(pAnd) == pRoot )
+                return -1;
+        }
+        else
+            pAnd = NULL;
+        // count the number of added nodes
+        if ( pAnd == NULL || Ivy_ObjIsTravIdCurrent(p, Ivy_Regular(pAnd)) )
+        {
+            if ( ++Counter > NodeMax )
+                return -1;
+        }
+        pNode->pFunc = pAnd;
+    }
+    return Counter;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Transforms the decomposition graph into the AIG.]
+
+  Description [AIG nodes for the fanins should be assigned to pNode->pFunc
+  of the leaves of the graph before calling this procedure.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_GraphToNetworkSeq( Ivy_Man_t * p, Dec_Graph_t * pGraph )
+{
+    Ivy_Obj_t * pAnd0, * pAnd1;
+    Dec_Node_t * pNode;
+    int i, k;
+    // check for constant function
+    if ( Dec_GraphIsConst(pGraph) )
+        return Ivy_NotCond( Ivy_ManConst1(p), Dec_GraphIsComplement(pGraph) );
+    // check for a literal
+    if ( Dec_GraphIsVar(pGraph) )
+    {
+        // get the variable node
+        pNode = Dec_GraphVar(pGraph);
+        // add the remaining latches
+        for ( k = 0; k < (int)pNode->nLat2; k++ )
+            pNode->pFunc = Ivy_Latch( p, pNode->pFunc, IVY_INIT_DC );
+        return Ivy_NotCond( pNode->pFunc, Dec_GraphIsComplement(pGraph) );
+    }
+    // build the AIG nodes corresponding to the AND gates of the graph
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        pAnd0 = Ivy_NotCond( Dec_GraphNode(pGraph, pNode->eEdge0.Node)->pFunc, pNode->eEdge0.fCompl ); 
+        pAnd1 = Ivy_NotCond( Dec_GraphNode(pGraph, pNode->eEdge1.Node)->pFunc, pNode->eEdge1.fCompl ); 
+        // add the latches
+        for ( k = 0; k < (int)pNode->nLat0; k++ )
+            pAnd0 = Ivy_Latch( p, pAnd0, IVY_INIT_DC );
+        for ( k = 0; k < (int)pNode->nLat1; k++ )
+            pAnd1 = Ivy_Latch( p, pAnd1, IVY_INIT_DC );
+        // create the node
+        pNode->pFunc = Ivy_And( p, pAnd0, pAnd1 );
+    }
+    // add the remaining latches
+    for ( k = 0; k < (int)pNode->nLat2; k++ )
+        pNode->pFunc = Ivy_Latch( p, pNode->pFunc, IVY_INIT_DC );
+    // complement the result if necessary
+    return Ivy_NotCond( pNode->pFunc, Dec_GraphIsComplement(pGraph) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Replaces MFFC of the node by the new factored form.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_GraphUpdateNetworkSeq( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Dec_Graph_t * pGraph, int nGain )
+{
+    Ivy_Obj_t * pRootNew;
+    int nNodesNew, nNodesOld;
+    nNodesOld = Ivy_ManNodeNum(p);
+    // create the new structure of nodes
+    pRootNew = Ivy_GraphToNetworkSeq( p, pGraph );
+    Ivy_ObjReplace( p, pRoot, pRootNew, 1, 0, 0 );
+    // compare the gains
+    nNodesNew = Ivy_ManNodeNum(p);
+    assert( nGain <= nNodesOld - nNodesNew );
+    // propagate the buffer
+    Ivy_ManPropagateBuffers( p, 0 );
+}
+
+
+
+
+
+
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the truth table.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Ivy_CutGetTruth_rec( Ivy_Man_t * p, int Leaf, int * pNums, int nNums )
+{
+    static unsigned uMasks[5] = { 0xAAAAAAAA, 0xCCCCCCCC, 0xF0F0F0F0, 0xFF00FF00, 0xFFFF0000 };
+    unsigned uTruth0, uTruth1;
+    Ivy_Obj_t * pObj;
+    int i;
+    for ( i = 0; i < nNums; i++ )
+        if ( Leaf == pNums[i] )
+            return uMasks[i];
+    pObj = Ivy_ManObj( p, Ivy_LeafId(Leaf) );
+    if ( Ivy_ObjIsLatch(pObj) )
+    {
+        assert( !Ivy_ObjFaninC0(pObj) );
+        Leaf = Ivy_LeafCreate( Ivy_ObjFaninId0(pObj), Ivy_LeafLat(Leaf) + 1 );
+        return Ivy_CutGetTruth_rec( p, Leaf, pNums, nNums );
+    }
+    assert( Ivy_ObjIsNode(pObj) || Ivy_ObjIsBuf(pObj) );
+    Leaf = Ivy_LeafCreate( Ivy_ObjFaninId0(pObj), Ivy_LeafLat(Leaf) );
+    uTruth0 = Ivy_CutGetTruth_rec( p, Leaf, pNums, nNums );
+    if ( Ivy_ObjFaninC0(pObj) )
+        uTruth0 = ~uTruth0;
+    if ( Ivy_ObjIsBuf(pObj) )
+        return uTruth0;
+    Leaf = Ivy_LeafCreate( Ivy_ObjFaninId1(pObj), Ivy_LeafLat(Leaf) );
+    uTruth1 = Ivy_CutGetTruth_rec( p, Leaf, pNums, nNums );
+    if ( Ivy_ObjFaninC1(pObj) )
+        uTruth1 = ~uTruth1;
+    return uTruth0 & uTruth1;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the truth table.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Ivy_CutGetTruth( Ivy_Man_t * p, Ivy_Obj_t * pObj, int * pNums, int nNums )
+{
+    assert( Ivy_ObjIsNode(pObj) );
+    assert( nNums < 6 );
+    return Ivy_CutGetTruth_rec( p, Ivy_LeafCreate(pObj->Id, 0), pNums, nNums );
+}
+
+
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the cut can be constructed; 0 otherwise.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Ivy_CutPrescreen( Ivy_Cut_t * pCut, int Id0, int Id1 )
+{
+    int i;
+    if ( pCut->nSize < pCut->nSizeMax )
+        return 1;
+    for ( i = 0; i < pCut->nSize; i++ )
+        if ( pCut->pArray[i] == Id0 || pCut->pArray[i] == Id1 )
+            return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Derives new cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Ivy_CutDeriveNew2( Ivy_Cut_t * pCut, Ivy_Cut_t * pCutNew, int IdOld, int IdNew0, int IdNew1 )
+{
+    unsigned uHash = 0;
+    int i, k;
+    assert( pCut->nSize > 0 );
+    assert( IdNew0 < IdNew1 );
+    for ( i = k = 0; i < pCut->nSize; i++ )
+    {
+        if ( pCut->pArray[i] == IdOld )
+            continue;
+        if ( IdNew0 >= 0 )
+        {
+            if ( IdNew0 <= pCut->pArray[i] )
+            {
+                if ( IdNew0 < pCut->pArray[i] )
+                {
+                    if ( k == pCut->nSizeMax )
+                        return 0;
+                    pCutNew->pArray[ k++ ] = IdNew0;
+                    uHash |= Ivy_CutHashValue( IdNew0 );
+                }
+                IdNew0 = -1;
+            }
+        }
+        if ( IdNew1 >= 0 )
+        {
+            if ( IdNew1 <= pCut->pArray[i] )
+            {
+                if ( IdNew1 < pCut->pArray[i] )
+                {
+                    if ( k == pCut->nSizeMax )
+                        return 0;
+                    pCutNew->pArray[ k++ ] = IdNew1;
+                    uHash |= Ivy_CutHashValue( IdNew1 );
+                }
+                IdNew1 = -1;
+            }
+        }
+        if ( k == pCut->nSizeMax )
+            return 0;
+        pCutNew->pArray[ k++ ] = pCut->pArray[i];
+        uHash |= Ivy_CutHashValue( pCut->pArray[i] );
+    }
+    if ( IdNew0 >= 0 )
+    {
+        if ( k == pCut->nSizeMax )
+            return 0;
+        pCutNew->pArray[ k++ ] = IdNew0;
+        uHash |= Ivy_CutHashValue( IdNew0 );
+    }
+    if ( IdNew1 >= 0 )
+    {
+        if ( k == pCut->nSizeMax )
+            return 0;
+        pCutNew->pArray[ k++ ] = IdNew1;
+        uHash |= Ivy_CutHashValue( IdNew1 );
+    }
+    pCutNew->nSize = k;
+    pCutNew->uHash = uHash;
+    assert( pCutNew->nSize <= pCut->nSizeMax );
+    for ( i = 1; i < pCutNew->nSize; i++ )
+        assert( pCutNew->pArray[i-1] < pCutNew->pArray[i] );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Derives new cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Ivy_CutDeriveNew( Ivy_Cut_t * pCut, Ivy_Cut_t * pCutNew, int IdOld, int IdNew0, int IdNew1 )
+{
+    unsigned uHash = 0;
+    int i, k; 
+    assert( pCut->nSize > 0 );
+    assert( IdNew0 < IdNew1 );
+    for ( i = k = 0; i < pCut->nSize; i++ )
+    {
+        if ( pCut->pArray[i] == IdOld )
+            continue;
+        if ( IdNew0 <= pCut->pArray[i] )
+        {
+            if ( IdNew0 < pCut->pArray[i] )
+            {
+                pCutNew->pArray[ k++ ] = IdNew0;
+                uHash |= Ivy_CutHashValue( IdNew0 );
+            }
+            IdNew0 = 0x7FFFFFFF;
+        }
+        if ( IdNew1 <= pCut->pArray[i] )
+        {
+            if ( IdNew1 < pCut->pArray[i] )
+            {
+                pCutNew->pArray[ k++ ] = IdNew1;
+                uHash |= Ivy_CutHashValue( IdNew1 );
+            }
+            IdNew1 = 0x7FFFFFFF;
+        }
+        pCutNew->pArray[ k++ ] = pCut->pArray[i];
+        uHash |= Ivy_CutHashValue( pCut->pArray[i] );
+    }
+    if ( IdNew0 < 0x7FFFFFFF )
+    {
+        pCutNew->pArray[ k++ ] = IdNew0;
+        uHash |= Ivy_CutHashValue( IdNew0 );
+    }
+    if ( IdNew1 < 0x7FFFFFFF )
+    {
+        pCutNew->pArray[ k++ ] = IdNew1;
+        uHash |= Ivy_CutHashValue( IdNew1 );
+    }
+    pCutNew->nSize = k;
+    pCutNew->uHash = uHash;
+    assert( pCutNew->nSize <= pCut->nSizeMax );
+//    for ( i = 1; i < pCutNew->nSize; i++ )
+//        assert( pCutNew->pArray[i-1] < pCutNew->pArray[i] );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Find the hash value of the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline unsigned Ivy_NodeCutHash( Ivy_Cut_t * pCut )
+{
+    int i;
+    pCut->uHash = 0;
+    for ( i = 0; i < pCut->nSize; i++ )
+        pCut->uHash |= (1 << (pCut->pArray[i] % 31));
+    return pCut->uHash;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Derives new cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Ivy_CutDeriveNew3( Ivy_Cut_t * pCut, Ivy_Cut_t * pCutNew, int IdOld, int IdNew0, int IdNew1 )
+{
+    int i, k; 
+    assert( pCut->nSize > 0 );
+    assert( IdNew0 < IdNew1 );
+    for ( i = k = 0; i < pCut->nSize; i++ )
+    {
+        if ( pCut->pArray[i] == IdOld )
+            continue;
+        if ( IdNew0 <= pCut->pArray[i] )
+        {
+            if ( IdNew0 < pCut->pArray[i] )
+                pCutNew->pArray[ k++ ] = IdNew0;
+            IdNew0 = 0x7FFFFFFF;
+        }
+        if ( IdNew1 <= pCut->pArray[i] )
+        {
+            if ( IdNew1 < pCut->pArray[i] )
+                pCutNew->pArray[ k++ ] = IdNew1;
+            IdNew1 = 0x7FFFFFFF;
+        }
+        pCutNew->pArray[ k++ ] = pCut->pArray[i];
+    }
+    if ( IdNew0 < 0x7FFFFFFF )
+        pCutNew->pArray[ k++ ] = IdNew0;
+    if ( IdNew1 < 0x7FFFFFFF )
+        pCutNew->pArray[ k++ ] = IdNew1;
+    pCutNew->nSize = k;
+    assert( pCutNew->nSize <= pCut->nSizeMax );
+    Ivy_NodeCutHash( pCutNew );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if pDom is contained in pCut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Ivy_CutCheckDominance( Ivy_Cut_t * pDom, Ivy_Cut_t * pCut )
+{
+    int i, k;
+    for ( i = 0; i < pDom->nSize; i++ )
+    {
+        assert( i==0 || pDom->pArray[i-1] < pDom->pArray[i] );
+        for ( k = 0; k < pCut->nSize; k++ )
+            if ( pDom->pArray[i] == pCut->pArray[k] )
+                break;
+        if ( k == pCut->nSize ) // node i in pDom is not contained in pCut
+            return 0;
+    }
+    // every node in pDom is contained in pCut
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Check if the cut exists.]
+
+  Description [Returns 1 if the cut exists.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_CutFindOrAddFilter( Ivy_Store_t * pCutStore, Ivy_Cut_t * pCutNew )
+{
+    Ivy_Cut_t * pCut;
+    int i, k;
+    assert( pCutNew->uHash );
+    // try to find the cut
+    for ( i = 0; i < pCutStore->nCuts; i++ )
+    {
+        pCut = pCutStore->pCuts + i;
+        if ( pCut->nSize == 0 )
+            continue;
+        if ( pCut->nSize == pCutNew->nSize )
+        {
+            if ( pCut->uHash == pCutNew->uHash )
+            {
+                for ( k = 0; k < pCutNew->nSize; k++ )
+                    if ( pCut->pArray[k] != pCutNew->pArray[k] )
+                        break;
+                if ( k == pCutNew->nSize )
+                    return 1;
+            }
+            continue;
+        }
+        if ( pCut->nSize < pCutNew->nSize )
+        {
+            // skip the non-contained cuts
+            if ( (pCut->uHash & pCutNew->uHash) != pCut->uHash )
+                continue;
+            // check containment seriously
+            if ( Ivy_CutCheckDominance( pCut, pCutNew ) )
+                return 1;
+            continue;
+        }
+        // check potential containment of other cut
+
+        // skip the non-contained cuts
+        if ( (pCut->uHash & pCutNew->uHash) != pCutNew->uHash )
+            continue;
+        // check containment seriously
+        if ( Ivy_CutCheckDominance( pCutNew, pCut ) )
+        {
+            // remove the current cut
+            pCut->nSize = 0;
+        }
+    }
+    assert( pCutStore->nCuts < pCutStore->nCutsMax );
+    // add the cut
+    pCut = pCutStore->pCuts + pCutStore->nCuts++;
+    *pCut = *pCutNew;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compresses the cut representation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_CutCompactAll( Ivy_Store_t * pCutStore )
+{
+    Ivy_Cut_t * pCut;
+    int i, k;
+    pCutStore->nCutsM = 0;
+    for ( i = k = 0; i < pCutStore->nCuts; i++ )
+    {
+        pCut = pCutStore->pCuts + i;
+        if ( pCut->nSize == 0 )
+            continue;
+        if ( pCut->nSize < pCut->nSizeMax )
+            pCutStore->nCutsM++;
+        pCutStore->pCuts[k++] = *pCut;
+    }
+    pCutStore->nCuts = k;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Print the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_CutPrintForNode( Ivy_Cut_t * pCut )
+{
+    int i;
+    assert( pCut->nSize > 0 );
+    printf( "%d : {", pCut->nSize );
+    for ( i = 0; i < pCut->nSize; i++ )
+        printf( " %d", pCut->pArray[i] );
+    printf( " }\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_CutPrintForNodes( Ivy_Store_t * pCutStore )
+{
+    int i;
+    printf( "Node %d\n", pCutStore->pCuts[0].pArray[0] );
+    for ( i = 0; i < pCutStore->nCuts; i++ )
+        Ivy_CutPrintForNode( pCutStore->pCuts + i );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     [] 
+
+***********************************************************************/
+static inline int Ivy_CutReadLeaf( Ivy_Obj_t * pFanin )
+{
+    int nLats, iLeaf;
+    assert( !Ivy_IsComplement(pFanin) );
+    if ( !Ivy_ObjIsLatch(pFanin) )
+        return Ivy_LeafCreate( pFanin->Id, 0 );
+    iLeaf = Ivy_CutReadLeaf(Ivy_ObjFanin0(pFanin));
+    nLats = Ivy_LeafLat(iLeaf);
+    assert( nLats < IVY_LEAF_MASK );
+    return 1 + iLeaf;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Store_t * Ivy_CutComputeForNode( Ivy_Man_t * p, Ivy_Obj_t * pObj, int nLeaves )
+{
+    static Ivy_Store_t CutStore, * pCutStore = &CutStore;
+    Ivy_Cut_t CutNew, * pCutNew = &CutNew, * pCut;
+    Ivy_Man_t * pMan = p;
+    Ivy_Obj_t * pLeaf;
+    int i, k, Temp, nLats, iLeaf0, iLeaf1;
+
+    assert( nLeaves <= IVY_CUT_INPUT );
+
+    // start the structure
+    pCutStore->nCuts = 0;
+    pCutStore->nCutsMax = IVY_CUT_LIMIT;
+    // start the trivial cut
+    pCutNew->uHash = 0;
+    pCutNew->nSize = 1;
+    pCutNew->nSizeMax = nLeaves;
+    pCutNew->pArray[0] = Ivy_LeafCreate( pObj->Id, 0 );
+    pCutNew->uHash = Ivy_CutHashValue( pCutNew->pArray[0] );
+    // add the trivial cut
+    pCutStore->pCuts[pCutStore->nCuts++] = *pCutNew;
+    assert( pCutStore->nCuts == 1 );
+
+    // explore the cuts
+    for ( i = 0; i < pCutStore->nCuts; i++ )
+    {
+        // expand this cut
+        pCut = pCutStore->pCuts + i;
+        if ( pCut->nSize == 0 )
+            continue;
+        for ( k = 0; k < pCut->nSize; k++ )
+        {
+            pLeaf = Ivy_ManObj( p, Ivy_LeafId(pCut->pArray[k]) );
+            if ( Ivy_ObjIsCi(pLeaf) || Ivy_ObjIsConst1(pLeaf) )
+                continue;
+            assert( Ivy_ObjIsNode(pLeaf) );
+            nLats = Ivy_LeafLat(pCut->pArray[k]);
+
+            // get the fanins fanins
+            iLeaf0 = Ivy_CutReadLeaf( Ivy_ObjFanin0(pLeaf) );
+            iLeaf1 = Ivy_CutReadLeaf( Ivy_ObjFanin1(pLeaf) );
+            assert( nLats + Ivy_LeafLat(iLeaf0) < IVY_LEAF_MASK && nLats + Ivy_LeafLat(iLeaf1) < IVY_LEAF_MASK );
+            iLeaf0 = nLats + iLeaf0;
+            iLeaf1 = nLats + iLeaf1;
+            if ( !Ivy_CutPrescreen( pCut, iLeaf0, iLeaf1 ) )
+                continue;
+            // the given cut exist
+            if ( iLeaf0 > iLeaf1 )
+                Temp = iLeaf0, iLeaf0 = iLeaf1, iLeaf1 = Temp;
+            // create the new cut
+            if ( !Ivy_CutDeriveNew( pCut, pCutNew, pCut->pArray[k], iLeaf0, iLeaf1 ) )
+                continue;
+            // add the cut
+            Ivy_CutFindOrAddFilter( pCutStore, pCutNew );
+            if ( pCutStore->nCuts == IVY_CUT_LIMIT )
+                break;
+        }
+        if ( pCutStore->nCuts == IVY_CUT_LIMIT )
+            break;
+    }
+    if ( pCutStore->nCuts == IVY_CUT_LIMIT )
+        pCutStore->fSatur = 1;
+    else
+        pCutStore->fSatur = 0;
+//    printf( "%d ", pCutStore->nCuts );
+    Ivy_CutCompactAll( pCutStore );
+//    printf( "%d \n", pCutStore->nCuts );
+//    Ivy_CutPrintForNodes( pCutStore );
+    return pCutStore;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_CutComputeAll( Ivy_Man_t * p, int nInputs )
+{
+    Ivy_Store_t * pStore;
+    Ivy_Obj_t * pObj;
+    int i, nCutsTotal, nCutsTotalM, nNodeTotal, nNodeOver;
+    int clk = clock();
+    if ( nInputs > IVY_CUT_INPUT )
+    {
+        printf( "Cannot compute cuts for more than %d inputs.\n", IVY_CUT_INPUT );
+        return;
+    }
+    nNodeTotal = nNodeOver = 0;
+    nCutsTotal = nCutsTotalM = -Ivy_ManNodeNum(p);
+    Ivy_ManForEachObj( p, pObj, i )
+    {
+        if ( !Ivy_ObjIsNode(pObj) )
+            continue;
+        pStore = Ivy_CutComputeForNode( p, pObj, nInputs );
+        nCutsTotal  += pStore->nCuts;
+        nCutsTotalM += pStore->nCutsM;
+        nNodeOver   += pStore->fSatur;
+        nNodeTotal++;
+    }
+    printf( "All = %6d. Minus = %6d. Triv = %6d.   Node = %6d. Satur = %6d.  ", 
+        nCutsTotal, nCutsTotalM, Ivy_ManPiNum(p) + Ivy_ManNodeNum(p), nNodeTotal, nNodeOver );
+    PRT( "Time", clock() - clk );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyShow.c b/src/aig/ivy/ivyShow.c
new file mode 100644
index 00000000..cd726e43
--- /dev/null
+++ b/src/aig/ivy/ivyShow.c
@@ -0,0 +1,338 @@
+/**CFile****************************************************************
+
+  FileName    [ivyShow.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Visualization of HAIG.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyShow.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static void Ivy_WriteDotAig( Ivy_Man_t * pMan, char * pFileName, int fHaig, Vec_Ptr_t * vBold );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManShow( Ivy_Man_t * pMan, int fHaig, Vec_Ptr_t * vBold )
+{
+    extern void Abc_ShowFile( char * FileNameDot );
+    static Counter = 0;
+    char FileNameDot[200];
+    FILE * pFile;
+    // create the file name
+//    Ivy_ShowGetFileName( pMan->pName, FileNameDot );
+    sprintf( FileNameDot, "temp%02d.dot", Counter++ );
+    // check that the file can be opened
+    if ( (pFile = fopen( FileNameDot, "w" )) == NULL )
+    {
+        fprintf( stdout, "Cannot open the intermediate file \"%s\".\n", FileNameDot );
+        return;
+    }
+    fclose( pFile );
+    // generate the file
+    Ivy_WriteDotAig( pMan, FileNameDot, fHaig, vBold );
+    // visualize the file 
+    Abc_ShowFile( FileNameDot );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Writes the graph structure of AIG for DOT.]
+
+  Description [Useful for graph visualization using tools such as GraphViz: 
+  http://www.graphviz.org/]
+  
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_WriteDotAig( Ivy_Man_t * pMan, char * pFileName, int fHaig, Vec_Ptr_t * vBold )
+{
+    FILE * pFile;
+    Ivy_Obj_t * pNode, * pTemp, * pPrev;
+    int LevelMax, Level, i;
+
+    if ( Ivy_ManNodeNum(pMan) > 200 )
+    {
+        fprintf( stdout, "Cannot visualize AIG with more than 200 nodes.\n" );
+        return;
+    }
+    if ( (pFile = fopen( pFileName, "w" )) == NULL )
+    {
+        fprintf( stdout, "Cannot open the intermediate file \"%s\".\n", pFileName );
+        return;
+    }
+
+    // mark the nodes
+    if ( vBold )
+        Vec_PtrForEachEntry( vBold, pNode, i )
+            pNode->fMarkB = 1;
+
+    // compute levels
+    LevelMax = 1 + Ivy_ManSetLevels( pMan, fHaig );
+
+    // write the DOT header
+    fprintf( pFile, "# %s\n",  "AIG structure generated by IVY package" );
+    fprintf( pFile, "\n" );
+    fprintf( pFile, "digraph AIG {\n" );
+    fprintf( pFile, "size = \"7.5,10\";\n" );
+//  fprintf( pFile, "ranksep = 0.5;\n" );
+//  fprintf( pFile, "nodesep = 0.5;\n" );
+    fprintf( pFile, "center = true;\n" );
+//  fprintf( pFile, "orientation = landscape;\n" );
+//  fprintf( pFile, "edge [fontsize = 10];\n" );
+//  fprintf( pFile, "edge [dir = none];\n" );
+    fprintf( pFile, "edge [dir = back];\n" );
+    fprintf( pFile, "\n" );
+
+    // labels on the left of the picture
+    fprintf( pFile, "{\n" );
+    fprintf( pFile, "  node [shape = plaintext];\n" );
+    fprintf( pFile, "  edge [style = invis];\n" );
+    fprintf( pFile, "  LevelTitle1 [label=\"\"];\n" );
+    fprintf( pFile, "  LevelTitle2 [label=\"\"];\n" );
+    // generate node names with labels
+    for ( Level = LevelMax; Level >= 0; Level-- )
+    {
+        // the visible node name
+        fprintf( pFile, "  Level%d", Level );
+        fprintf( pFile, " [label = " );
+        // label name
+        fprintf( pFile, "\"" );
+        fprintf( pFile, "\"" );
+        fprintf( pFile, "];\n" );
+    }
+
+    // genetate the sequence of visible/invisible nodes to mark levels
+    fprintf( pFile, "  LevelTitle1 ->  LevelTitle2 ->" );
+    for ( Level = LevelMax; Level >= 0; Level-- )
+    {
+        // the visible node name
+        fprintf( pFile, "  Level%d",  Level );
+        // the connector
+        if ( Level != 0 )
+            fprintf( pFile, " ->" );
+        else
+            fprintf( pFile, ";" );
+    }
+    fprintf( pFile, "\n" );
+    fprintf( pFile, "}" );
+    fprintf( pFile, "\n" );
+    fprintf( pFile, "\n" );
+
+    // generate title box on top
+    fprintf( pFile, "{\n" );
+    fprintf( pFile, "  rank = same;\n" );
+    fprintf( pFile, "  LevelTitle1;\n" );
+    fprintf( pFile, "  title1 [shape=plaintext,\n" );
+    fprintf( pFile, "          fontsize=20,\n" );
+    fprintf( pFile, "          fontname = \"Times-Roman\",\n" );
+    fprintf( pFile, "          label=\"" );
+    fprintf( pFile, "%s", "AIG structure visualized by ABC" );
+    fprintf( pFile, "\\n" );
+    fprintf( pFile, "Benchmark \\\"%s\\\". ", "aig" );
+    fprintf( pFile, "Time was %s. ",  Extra_TimeStamp() );
+    fprintf( pFile, "\"\n" );
+    fprintf( pFile, "         ];\n" );
+    fprintf( pFile, "}" );
+    fprintf( pFile, "\n" );
+    fprintf( pFile, "\n" );
+
+    // generate statistics box
+    fprintf( pFile, "{\n" );
+    fprintf( pFile, "  rank = same;\n" );
+    fprintf( pFile, "  LevelTitle2;\n" );
+    fprintf( pFile, "  title2 [shape=plaintext,\n" );
+    fprintf( pFile, "          fontsize=18,\n" );
+    fprintf( pFile, "          fontname = \"Times-Roman\",\n" );
+    fprintf( pFile, "          label=\"" );
+    fprintf( pFile, "The set contains %d logic nodes and spans %d levels.", Ivy_ManNodeNum(pMan), LevelMax );
+    fprintf( pFile, "\\n" );
+    fprintf( pFile, "\"\n" );
+    fprintf( pFile, "         ];\n" );
+    fprintf( pFile, "}" );
+    fprintf( pFile, "\n" );
+    fprintf( pFile, "\n" );
+
+    // generate the COs
+    fprintf( pFile, "{\n" );
+    fprintf( pFile, "  rank = same;\n" );
+    // the labeling node of this level
+    fprintf( pFile, "  Level%d;\n",  LevelMax );
+    // generate the CO nodes
+    Ivy_ManForEachCo( pMan, pNode, i )
+    {
+        if ( fHaig || pNode->pEquiv == NULL )
+            fprintf( pFile, "  Node%d%s [label = \"%d%s\"", pNode->Id, 
+                (Ivy_ObjIsLatch(pNode)? "_in":""), pNode->Id, (Ivy_ObjIsLatch(pNode)? "_in":"") );
+        else
+            fprintf( pFile, "  Node%d%s [label = \"%d%s(%d%s)\"", pNode->Id, 
+                (Ivy_ObjIsLatch(pNode)? "_in":""), pNode->Id, (Ivy_ObjIsLatch(pNode)? "_in":""), 
+                    Ivy_Regular(pNode->pEquiv)->Id, Ivy_IsComplement(pNode->pEquiv)? "\'":"" );
+        fprintf( pFile, ", shape = %s", (Ivy_ObjIsLatch(pNode)? "box":"invtriangle") );
+        fprintf( pFile, ", color = coral, fillcolor = coral" );
+        fprintf( pFile, "];\n" );
+    }
+    fprintf( pFile, "}" );
+    fprintf( pFile, "\n" );
+    fprintf( pFile, "\n" );
+
+    // generate nodes of each rank
+    for ( Level = LevelMax - 1; Level > 0; Level-- )
+    {
+        fprintf( pFile, "{\n" );
+        fprintf( pFile, "  rank = same;\n" );
+        // the labeling node of this level
+        fprintf( pFile, "  Level%d;\n",  Level );
+        Ivy_ManForEachObj( pMan, pNode, i )
+        {
+            if ( (int)pNode->Level != Level )
+                continue;
+            if ( fHaig || pNode->pEquiv == NULL )
+                fprintf( pFile, "  Node%d [label = \"%d\"", pNode->Id, pNode->Id );
+            else 
+                fprintf( pFile, "  Node%d [label = \"%d(%d%s)\"", pNode->Id, pNode->Id, 
+                    Ivy_Regular(pNode->pEquiv)->Id, Ivy_IsComplement(pNode->pEquiv)? "\'":"" );
+            fprintf( pFile, ", shape = ellipse" );
+            if ( vBold && pNode->fMarkB )
+                fprintf( pFile, ", style = filled" );
+            fprintf( pFile, "];\n" );
+        }
+        fprintf( pFile, "}" );
+        fprintf( pFile, "\n" );
+        fprintf( pFile, "\n" );
+    }
+
+    // generate the CI nodes
+    fprintf( pFile, "{\n" );
+    fprintf( pFile, "  rank = same;\n" );
+    // the labeling node of this level
+    fprintf( pFile, "  Level%d;\n",  0 );
+    // generate constant node
+    if ( Ivy_ObjRefs(Ivy_ManConst1(pMan)) > 0 )
+    {
+        pNode = Ivy_ManConst1(pMan);
+        // check if the costant node is present
+        fprintf( pFile, "  Node%d [label = \"Const1\"", pNode->Id );
+        fprintf( pFile, ", shape = ellipse" );
+        fprintf( pFile, ", color = coral, fillcolor = coral" );
+        fprintf( pFile, "];\n" );
+    }
+    // generate the CI nodes
+    Ivy_ManForEachCi( pMan, pNode, i )
+    {
+        if ( fHaig || pNode->pEquiv == NULL )
+            fprintf( pFile, "  Node%d%s [label = \"%d%s\"", pNode->Id, 
+                (Ivy_ObjIsLatch(pNode)? "_out":""), pNode->Id, (Ivy_ObjIsLatch(pNode)? "_out":"") );
+        else
+            fprintf( pFile, "  Node%d%s [label = \"%d%s(%d%s)\"", pNode->Id, 
+                (Ivy_ObjIsLatch(pNode)? "_out":""), pNode->Id, (Ivy_ObjIsLatch(pNode)? "_out":""), 
+                    Ivy_Regular(pNode->pEquiv)->Id, Ivy_IsComplement(pNode->pEquiv)? "\'":"" );
+        fprintf( pFile, ", shape = %s", (Ivy_ObjIsLatch(pNode)? "box":"triangle") );
+        fprintf( pFile, ", color = coral, fillcolor = coral" );
+        fprintf( pFile, "];\n" );
+    }
+    fprintf( pFile, "}" );
+    fprintf( pFile, "\n" );
+    fprintf( pFile, "\n" );
+
+    // generate invisible edges from the square down
+    fprintf( pFile, "title1 -> title2 [style = invis];\n" );
+    Ivy_ManForEachCo( pMan, pNode, i )
+        fprintf( pFile, "title2 -> Node%d%s [style = invis];\n", pNode->Id, (Ivy_ObjIsLatch(pNode)? "_in":"") );
+
+    // generate edges
+    Ivy_ManForEachObj( pMan, pNode, i )
+    {
+        if ( !Ivy_ObjIsNode(pNode) && !Ivy_ObjIsCo(pNode) && !Ivy_ObjIsBuf(pNode) )
+            continue;
+        // generate the edge from this node to the next
+        fprintf( pFile, "Node%d%s",  pNode->Id, (Ivy_ObjIsLatch(pNode)? "_in":"") );
+        fprintf( pFile, " -> " );
+        fprintf( pFile, "Node%d%s",  Ivy_ObjFaninId0(pNode), (Ivy_ObjIsLatch(Ivy_ObjFanin0(pNode))? "_out":"") );
+        fprintf( pFile, " [" );
+        fprintf( pFile, "style = %s", Ivy_ObjFaninC0(pNode)? "dotted" : "bold" );
+//        if ( Ivy_NtkIsSeq(pNode->pMan) && Seq_ObjFaninL0(pNode) > 0 )
+//        fprintf( pFile, ", label = \"%s\"", Seq_ObjFaninGetInitPrintable(pNode,0) );
+        fprintf( pFile, "]" );
+        fprintf( pFile, ";\n" );
+        if ( !Ivy_ObjIsNode(pNode) )
+            continue;
+        // generate the edge from this node to the next
+        fprintf( pFile, "Node%d",  pNode->Id );
+        fprintf( pFile, " -> " );
+        fprintf( pFile, "Node%d%s",  Ivy_ObjFaninId1(pNode), (Ivy_ObjIsLatch(Ivy_ObjFanin1(pNode))? "_out":"") );
+        fprintf( pFile, " [" );
+        fprintf( pFile, "style = %s", Ivy_ObjFaninC1(pNode)? "dotted" : "bold" );
+//        if ( Ivy_NtkIsSeq(pNode->pMan) && Seq_ObjFaninL1(pNode) > 0 )
+//        fprintf( pFile, ", label = \"%s\"", Seq_ObjFaninGetInitPrintable(pNode,1) );
+        fprintf( pFile, "]" );
+        fprintf( pFile, ";\n" );
+        // generate the edges between the equivalent nodes
+        if ( fHaig && pNode->pEquiv && Ivy_ObjRefs(pNode) > 0 )
+        {
+            pPrev = pNode;
+            for ( pTemp = pNode->pEquiv; pTemp != pNode; pTemp = Ivy_Regular(pTemp->pEquiv) )
+            {
+                fprintf( pFile, "Node%d",  pPrev->Id );
+                fprintf( pFile, " -> " );
+                fprintf( pFile, "Node%d",  pTemp->Id );
+                fprintf( pFile, " [style = %s]", Ivy_IsComplement(pTemp->pEquiv)? "dotted" : "bold" );
+                fprintf( pFile, ";\n" );
+                pPrev = pTemp;
+            }
+            // connect the last node with the first
+            fprintf( pFile, "Node%d",  pPrev->Id );
+            fprintf( pFile, " -> " );
+            fprintf( pFile, "Node%d",  pNode->Id );
+            fprintf( pFile, " [style = %s]", Ivy_IsComplement(pPrev->pEquiv)? "dotted" : "bold" );
+            fprintf( pFile, ";\n" );
+        }
+    }
+
+    fprintf( pFile, "}" );
+    fprintf( pFile, "\n" );
+    fprintf( pFile, "\n" );
+    fclose( pFile );
+
+    // unmark nodes
+    if ( vBold )
+        Vec_PtrForEachEntry( vBold, pNode, i )
+            pNode->fMarkB = 0;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyTable.c b/src/aig/ivy/ivyTable.c
new file mode 100644
index 00000000..2ac0ae49
--- /dev/null
+++ b/src/aig/ivy/ivyTable.c
@@ -0,0 +1,301 @@
+/**CFile****************************************************************
+
+  FileName    [ivyTable.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Structural hashing table.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006. ]
+
+  Revision    [$Id: ivyTable.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+// hashing the node
+static unsigned Ivy_Hash( Ivy_Obj_t * pObj, int TableSize ) 
+{
+    unsigned Key = Ivy_ObjIsExor(pObj) * 1699;
+    Key ^= Ivy_ObjFaninId0(pObj) * 7937;
+    Key ^= Ivy_ObjFaninId1(pObj) * 2971;
+    Key ^= Ivy_ObjFaninC0(pObj) * 911;
+    Key ^= Ivy_ObjFaninC1(pObj) * 353;
+    Key ^= Ivy_ObjInit(pObj) * 911;
+    return Key % TableSize;
+}
+
+// returns the place where this node is stored (or should be stored)
+static int * Ivy_TableFind( Ivy_Man_t * p, Ivy_Obj_t * pObj )
+{
+    int i;
+    assert( Ivy_ObjIsHash(pObj) );
+    for ( i = Ivy_Hash(pObj, p->nTableSize); p->pTable[i]; i = (i+1) % p->nTableSize )
+        if ( p->pTable[i] == pObj->Id )
+            break;
+    return p->pTable + i;
+}
+
+static void         Ivy_TableResize( Ivy_Man_t * p );
+static unsigned int Cudd_PrimeAig( unsigned int  p );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+ 
+/**Function*************************************************************
+
+  Synopsis    [Checks if node with the given attributes is in the hash table.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_TableLookup( Ivy_Man_t * p, Ivy_Obj_t * pObj )
+{
+    Ivy_Obj_t * pEntry;
+    int i;
+    assert( !Ivy_IsComplement(pObj) );
+    if ( !Ivy_ObjIsHash(pObj) )
+        return NULL;
+    assert( Ivy_ObjIsLatch(pObj) || Ivy_ObjFaninId0(pObj) > 0 );
+    assert( Ivy_ObjFaninId1(pObj) == 0 || Ivy_ObjFaninId0(pObj) < Ivy_ObjFaninId1(pObj) );
+    if ( Ivy_ObjFanin0(pObj)->nRefs == 0 || (Ivy_ObjChild1(pObj) && Ivy_ObjFanin1(pObj)->nRefs == 0) )
+        return NULL;
+    for ( i = Ivy_Hash(pObj, p->nTableSize); p->pTable[i]; i = (i+1) % p->nTableSize )
+    {
+        pEntry = Ivy_ManObj( p, p->pTable[i] );
+        if ( Ivy_ObjChild0(pEntry) == Ivy_ObjChild0(pObj) && 
+             Ivy_ObjChild1(pEntry) == Ivy_ObjChild1(pObj) && 
+             Ivy_ObjInit(pEntry) == Ivy_ObjInit(pObj) && 
+             Ivy_ObjType(pEntry) == Ivy_ObjType(pObj) )
+            return pEntry;
+    }
+    return NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the node to the hash table.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_TableInsert( Ivy_Man_t * p, Ivy_Obj_t * pObj )
+{
+    int * pPlace;
+    assert( !Ivy_IsComplement(pObj) );
+    if ( !Ivy_ObjIsHash(pObj) )
+        return;
+    if ( (pObj->Id & 63) == 0 )
+    {
+        if ( p->nTableSize < 2 * Ivy_ManHashObjNum(p) )
+            Ivy_TableResize( p );
+    }
+    pPlace = Ivy_TableFind( p, pObj );
+    assert( *pPlace == 0 );
+    *pPlace = pObj->Id;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Deletes the node from the hash table.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_TableDelete( Ivy_Man_t * p, Ivy_Obj_t * pObj )
+{
+    Ivy_Obj_t * pEntry;
+    int i, * pPlace;
+    assert( !Ivy_IsComplement(pObj) );
+    if ( !Ivy_ObjIsHash(pObj) )
+        return;
+    pPlace = Ivy_TableFind( p, pObj );
+    assert( *pPlace == pObj->Id ); // node should be in the table
+    *pPlace = 0;
+    // rehash the adjacent entries
+    i = pPlace - p->pTable;
+    for ( i = (i+1) % p->nTableSize; p->pTable[i]; i = (i+1) % p->nTableSize )
+    {
+        pEntry = Ivy_ManObj( p, p->pTable[i] );
+        p->pTable[i] = 0;
+        Ivy_TableInsert( p, pEntry );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Updates the table to point to the new node.]
+
+  Description [If the old node (pObj) is in the table, updates the table
+  to point to an object with different ID (ObjIdNew). The table should
+  not contain an object with ObjIdNew (this is currently not checked).]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_TableUpdate( Ivy_Man_t * p, Ivy_Obj_t * pObj, int ObjIdNew )
+{
+    int * pPlace;
+    assert( !Ivy_IsComplement(pObj) );
+    if ( !Ivy_ObjIsHash(pObj) )
+        return;
+    pPlace = Ivy_TableFind( p, pObj );
+    assert( *pPlace == pObj->Id ); // node should be in the table
+    *pPlace = ObjIdNew; 
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Count the number of nodes in the table.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_TableCountEntries( Ivy_Man_t * p )
+{
+    int i, Counter = 0;
+    for ( i = 0; i < p->nTableSize; i++ )
+        Counter += (p->pTable[i] != 0);
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Resizes the table.]
+
+  Description [Typically this procedure should not be called.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_TableResize( Ivy_Man_t * p )
+{
+    int * pTableOld, * pPlace;
+    int nTableSizeOld, Counter, nEntries, e, clk;
+clk = clock();
+    // save the old table
+    pTableOld = p->pTable;
+    nTableSizeOld = p->nTableSize;
+    // get the new table
+    p->nTableSize = Cudd_PrimeAig( 5 * Ivy_ManHashObjNum(p) ); 
+    p->pTable = ALLOC( int, p->nTableSize );
+    memset( p->pTable, 0, sizeof(int) * p->nTableSize );
+    // rehash the entries from the old table
+    Counter = 0;
+    for ( e = 0; e < nTableSizeOld; e++ )
+    {
+        if ( pTableOld[e] == 0 )
+            continue;
+        Counter++;
+        // get the place where this entry goes in the table table
+        pPlace = Ivy_TableFind( p, Ivy_ManObj(p, pTableOld[e]) );
+        assert( *pPlace == 0 ); // should not be in the table
+        *pPlace = pTableOld[e];
+    }
+    nEntries = Ivy_ManHashObjNum(p);
+//    assert( Counter == nEntries );
+//    printf( "Increasing the structural table size from %6d to %6d. ", nTableSizeOld, p->nTableSize );
+//    PRT( "Time", clock() - clk );
+    // replace the table and the parameters
+    free( pTableOld );
+}
+
+/**Function********************************************************************
+
+  Synopsis    [Profiles the hash table.]
+
+  Description []
+
+  SideEffects []
+
+  SeeAlso     []
+
+******************************************************************************/
+void Ivy_TableProfile( Ivy_Man_t * p )
+{
+    int i, Counter = 0;
+    for ( i = 0; i < p->nTableSize; i++ )
+    {
+        if ( p->pTable[i] )
+            Counter++;
+        else if ( Counter )
+        {
+            printf( "%d ", Counter );
+            Counter = 0;
+        }
+    }
+}
+
+/**Function********************************************************************
+
+  Synopsis    [Returns the next prime &gt;= p.]
+
+  Description [Copied from CUDD, for stand-aloneness.]
+
+  SideEffects [None]
+
+  SeeAlso     []
+
+******************************************************************************/
+unsigned int Cudd_PrimeAig( unsigned int  p)
+{
+    int i,pn;
+
+    p--;
+    do {
+        p++;
+        if (p&1) {
+        pn = 1;
+        i = 3;
+        while ((unsigned) (i * i) <= p) {
+        if (p % i == 0) {
+            pn = 0;
+            break;
+        }
+        i += 2;
+        }
+    } else {
+        pn = 0;
+    }
+    } while (!pn);
+    return(p);
+
+} /* end of Cudd_Prime */
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivyUtil.c b/src/aig/ivy/ivyUtil.c
new file mode 100644
index 00000000..ab62a276
--- /dev/null
+++ b/src/aig/ivy/ivyUtil.c
@@ -0,0 +1,818 @@
+/**CFile****************************************************************
+
+  FileName    [ivyUtil.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    [Various procedures.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivyUtil.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Increments the current traversal ID of the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManIncrementTravId( Ivy_Man_t * p )
+{
+    if ( p->nTravIds >= (1<<30)-1 - 1000 )
+        Ivy_ManCleanTravId( p );
+    p->nTravIds++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the DFS ordering of the nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManCleanTravId( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i;
+    p->nTravIds = 1;
+    Ivy_ManForEachObj( p, pObj, i )
+        pObj->TravId = 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes truth table of the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManCollectCut_rec( Ivy_Man_t * p, Ivy_Obj_t * pNode, Vec_Int_t * vNodes )
+{
+    if ( pNode->fMarkA )
+        return;
+    pNode->fMarkA = 1;
+    assert( Ivy_ObjIsAnd(pNode) || Ivy_ObjIsExor(pNode) );
+    Ivy_ManCollectCut_rec( p, Ivy_ObjFanin0(pNode), vNodes );
+    Ivy_ManCollectCut_rec( p, Ivy_ObjFanin1(pNode), vNodes );
+    Vec_IntPush( vNodes, pNode->Id );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes truth table of the cut.]
+
+  Description [Does not modify the array of leaves. Uses array vTruth to store 
+  temporary truth tables. The returned pointer should be used immediately.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManCollectCut( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Vec_Int_t * vLeaves, Vec_Int_t * vNodes )
+{
+    int i, Leaf;
+    // collect and mark the leaves
+    Vec_IntClear( vNodes );
+    Vec_IntForEachEntry( vLeaves, Leaf, i )
+    {
+        Vec_IntPush( vNodes, Leaf );
+        Ivy_ManObj(p, Leaf)->fMarkA = 1;
+    }
+    // collect and mark the nodes
+    Ivy_ManCollectCut_rec( p, pRoot, vNodes );
+    // clean the nodes
+    Vec_IntForEachEntry( vNodes, Leaf, i )
+        Ivy_ManObj(p, Leaf)->fMarkA = 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the pointer to the truth table.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned * Ivy_ObjGetTruthStore( int ObjNum, Vec_Int_t * vTruth )
+{
+   return ((unsigned *)Vec_IntArray(vTruth)) + 8 * ObjNum;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes truth table of the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManCutTruthOne( Ivy_Man_t * p, Ivy_Obj_t * pNode, Vec_Int_t * vTruth, int nWords )
+{
+    unsigned * pTruth, * pTruth0, * pTruth1;
+    int i;
+    pTruth  = Ivy_ObjGetTruthStore( pNode->TravId, vTruth );
+    pTruth0 = Ivy_ObjGetTruthStore( Ivy_ObjFanin0(pNode)->TravId, vTruth );
+    pTruth1 = Ivy_ObjGetTruthStore( Ivy_ObjFanin1(pNode)->TravId, vTruth );
+    if ( Ivy_ObjIsExor(pNode) )
+        for ( i = 0; i < nWords; i++ )
+            pTruth[i] = pTruth0[i] ^ pTruth1[i];
+    else if ( !Ivy_ObjFaninC0(pNode) && !Ivy_ObjFaninC1(pNode) )
+        for ( i = 0; i < nWords; i++ )
+            pTruth[i] = pTruth0[i] & pTruth1[i];
+    else if ( !Ivy_ObjFaninC0(pNode) && Ivy_ObjFaninC1(pNode) )
+        for ( i = 0; i < nWords; i++ )
+            pTruth[i] = pTruth0[i] & ~pTruth1[i];
+    else if ( Ivy_ObjFaninC0(pNode) && !Ivy_ObjFaninC1(pNode) )
+        for ( i = 0; i < nWords; i++ )
+            pTruth[i] = ~pTruth0[i] & pTruth1[i];
+    else // if ( Ivy_ObjFaninC0(pNode) && Ivy_ObjFaninC1(pNode) )
+        for ( i = 0; i < nWords; i++ )
+            pTruth[i] = ~pTruth0[i] & ~pTruth1[i];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes truth table of the cut.]
+
+  Description [Does not modify the array of leaves. Uses array vTruth to store 
+  temporary truth tables. The returned pointer should be used immediately.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned * Ivy_ManCutTruth( Ivy_Man_t * p, Ivy_Obj_t * pRoot, Vec_Int_t * vLeaves, Vec_Int_t * vNodes, Vec_Int_t * vTruth )
+{
+    static unsigned uTruths[8][8] = { // elementary truth tables
+        { 0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA },
+        { 0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC },
+        { 0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0 },
+        { 0xFF00FF00,0xFF00FF00,0xFF00FF00,0xFF00FF00,0xFF00FF00,0xFF00FF00,0xFF00FF00,0xFF00FF00 },
+        { 0xFFFF0000,0xFFFF0000,0xFFFF0000,0xFFFF0000,0xFFFF0000,0xFFFF0000,0xFFFF0000,0xFFFF0000 }, 
+        { 0x00000000,0xFFFFFFFF,0x00000000,0xFFFFFFFF,0x00000000,0xFFFFFFFF,0x00000000,0xFFFFFFFF }, 
+        { 0x00000000,0x00000000,0xFFFFFFFF,0xFFFFFFFF,0x00000000,0x00000000,0xFFFFFFFF,0xFFFFFFFF }, 
+        { 0x00000000,0x00000000,0x00000000,0x00000000,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF } 
+    };
+    int i, Leaf;
+    // collect the cut
+    Ivy_ManCollectCut( p, pRoot, vLeaves, vNodes );
+    // set the node numbers
+    Vec_IntForEachEntry( vNodes, Leaf, i )
+        Ivy_ManObj(p, Leaf)->TravId = i;
+    // alloc enough memory
+    Vec_IntClear( vTruth );
+    Vec_IntGrow( vTruth, 8 * Vec_IntSize(vNodes) );
+    // set the elementary truth tables
+    Vec_IntForEachEntry( vLeaves, Leaf, i )
+        memcpy( Ivy_ObjGetTruthStore(i, vTruth), uTruths[i], 8 * sizeof(unsigned) );
+    // compute truths for other nodes
+    Vec_IntForEachEntryStart( vNodes, Leaf, i, Vec_IntSize(vLeaves) )
+        Ivy_ManCutTruthOne( p, Ivy_ManObj(p, Leaf), vTruth, 8 );
+    return Ivy_ObjGetTruthStore( pRoot->TravId, vTruth );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collect the latches.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Ivy_ManLatches( Ivy_Man_t * p )
+{
+    Vec_Int_t * vLatches;
+    Ivy_Obj_t * pObj;
+    int i;
+    vLatches = Vec_IntAlloc( Ivy_ManLatchNum(p) );
+    Ivy_ManForEachLatch( p, pObj, i )
+        Vec_IntPush( vLatches, pObj->Id );
+    return vLatches;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collect the latches.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManLevels( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i, LevelMax = 0;
+    Ivy_ManForEachPo( p, pObj, i )
+        LevelMax = IVY_MAX( LevelMax, (int)Ivy_ObjFanin0(pObj)->Level );
+    return LevelMax;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collect the latches.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ManResetLevels_rec( Ivy_Obj_t * pObj )
+{
+    if ( pObj->Level || Ivy_ObjIsCi(pObj) || Ivy_ObjIsConst1(pObj) )
+        return pObj->Level;
+    if ( Ivy_ObjIsBuf(pObj) )
+        return pObj->Level = Ivy_ManResetLevels_rec( Ivy_ObjFanin0(pObj) );
+    assert( Ivy_ObjIsNode(pObj) );
+    Ivy_ManResetLevels_rec( Ivy_ObjFanin0(pObj) );
+    Ivy_ManResetLevels_rec( Ivy_ObjFanin1(pObj) );
+    return pObj->Level = Ivy_ObjLevelNew( pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collect the latches.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManResetLevels( Ivy_Man_t * p )
+{
+    Ivy_Obj_t * pObj;
+    int i;
+    Ivy_ManForEachObj( p, pObj, i )
+        pObj->Level = 0;
+    Ivy_ManForEachCo( p, pObj, i )
+        Ivy_ManResetLevels_rec( Ivy_ObjFanin0(pObj) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [References/references the node and returns MFFC size.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ObjRefDeref( Ivy_Man_t * p, Ivy_Obj_t * pNode, int fReference, int fLabel )
+{
+    Ivy_Obj_t * pNode0, * pNode1;
+    int Counter;
+    // label visited nodes
+    if ( fLabel )
+        Ivy_ObjSetTravIdCurrent( p, pNode );
+    // skip the CI
+    if ( Ivy_ObjIsPi(pNode) )
+        return 0;
+    assert( Ivy_ObjIsNode(pNode) || Ivy_ObjIsBuf(pNode) || Ivy_ObjIsLatch(pNode) );
+    // process the internal node
+    pNode0 = Ivy_ObjFanin0(pNode);
+    pNode1 = Ivy_ObjFanin1(pNode);
+    Counter = Ivy_ObjIsNode(pNode);
+    if ( fReference )
+    {
+        if ( pNode0->nRefs++ == 0 )
+            Counter += Ivy_ObjRefDeref( p, pNode0, fReference, fLabel );
+        if ( pNode1 && pNode1->nRefs++ == 0 )
+            Counter += Ivy_ObjRefDeref( p, pNode1, fReference, fLabel );
+    }
+    else
+    {
+        assert( pNode0->nRefs > 0 );
+        assert( pNode1 == NULL || pNode1->nRefs > 0 );
+        if ( --pNode0->nRefs == 0 )
+            Counter += Ivy_ObjRefDeref( p, pNode0, fReference, fLabel );
+        if ( pNode1 && --pNode1->nRefs == 0 )
+            Counter += Ivy_ObjRefDeref( p, pNode1, fReference, fLabel );
+    }
+    return Counter;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Labels MFFC with the current label.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ObjMffcLabel( Ivy_Man_t * p, Ivy_Obj_t * pNode )
+{
+    int nConeSize1, nConeSize2;
+    assert( !Ivy_IsComplement( pNode ) );
+    assert( Ivy_ObjIsNode( pNode ) );
+    nConeSize1 = Ivy_ObjRefDeref( p, pNode, 0, 1 ); // dereference
+    nConeSize2 = Ivy_ObjRefDeref( p, pNode, 1, 0 ); // reference
+    assert( nConeSize1 == nConeSize2 );
+    assert( nConeSize1 > 0 );
+    return nConeSize1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively updates fanout levels.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjUpdateLevel_rec( Ivy_Man_t * p, Ivy_Obj_t * pObj )
+{
+    Ivy_Obj_t * pFanout;
+    Vec_Ptr_t * vFanouts;
+    int i, LevelNew;
+    assert( p->fFanout );
+    assert( Ivy_ObjIsNode(pObj) );
+    vFanouts = Vec_PtrAlloc( 10 );
+    Ivy_ObjForEachFanout( p, pObj, vFanouts, pFanout, i )
+    {
+        if ( Ivy_ObjIsCo(pFanout) )
+        {
+//            assert( (int)Ivy_ObjFanin0(pFanout)->Level <= p->nLevelMax );
+            continue;
+        }
+        LevelNew = Ivy_ObjLevelNew( pFanout );
+        if ( (int)pFanout->Level == LevelNew )
+            continue;
+        pFanout->Level = LevelNew;
+        Ivy_ObjUpdateLevel_rec( p, pFanout );
+    }
+    Vec_PtrFree( vFanouts );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compute the new required level.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ObjLevelRNew( Ivy_Man_t * p, Ivy_Obj_t * pObj )
+{
+    Ivy_Obj_t * pFanout;
+    Vec_Ptr_t * vFanouts;
+    int i, Required, LevelNew = 1000000;
+    assert( p->fFanout && p->vRequired );
+    vFanouts = Vec_PtrAlloc( 10 );
+    Ivy_ObjForEachFanout( p, pObj, vFanouts, pFanout, i )
+    {
+        Required = Vec_IntEntry(p->vRequired, pFanout->Id);
+        LevelNew = IVY_MIN( LevelNew, Required );
+    }
+    Vec_PtrFree( vFanouts );
+    return LevelNew - 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively updates fanout levels.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjUpdateLevelR_rec( Ivy_Man_t * p, Ivy_Obj_t * pObj, int ReqNew )
+{
+    Ivy_Obj_t * pFanin;
+    if ( Ivy_ObjIsConst1(pObj) || Ivy_ObjIsCi(pObj) )
+        return;
+    assert( Ivy_ObjIsNode(pObj) || Ivy_ObjIsBuf(pObj) );
+    // process the first fanin
+    pFanin = Ivy_ObjFanin0(pObj);
+    if ( Vec_IntEntry(p->vRequired, pFanin->Id) > ReqNew - 1 )
+    {
+        Vec_IntWriteEntry( p->vRequired, pFanin->Id, ReqNew - 1 );
+        Ivy_ObjUpdateLevelR_rec( p, pFanin, ReqNew - 1 );
+    }
+    if ( Ivy_ObjIsBuf(pObj) )
+        return;
+    // process the second fanin
+    pFanin = Ivy_ObjFanin1(pObj);
+    if ( Vec_IntEntry(p->vRequired, pFanin->Id) > ReqNew - 1 )
+    {
+        Vec_IntWriteEntry( p->vRequired, pFanin->Id, ReqNew - 1 );
+        Ivy_ObjUpdateLevelR_rec( p, pFanin, ReqNew - 1 );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the node is the root of MUX or EXOR/NEXOR.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_ObjIsMuxType( Ivy_Obj_t * pNode )
+{
+    Ivy_Obj_t * pNode0, * pNode1;
+    // check that the node is regular
+    assert( !Ivy_IsComplement(pNode) );
+    // if the node is not AND, this is not MUX
+    if ( !Ivy_ObjIsAnd(pNode) )
+        return 0;
+    // if the children are not complemented, this is not MUX
+    if ( !Ivy_ObjFaninC0(pNode) || !Ivy_ObjFaninC1(pNode) )
+        return 0;
+    // get children
+    pNode0 = Ivy_ObjFanin0(pNode);
+    pNode1 = Ivy_ObjFanin1(pNode);
+    // if the children are not ANDs, this is not MUX
+    if ( !Ivy_ObjIsAnd(pNode0) || !Ivy_ObjIsAnd(pNode1) )
+        return 0;
+    // otherwise the node is MUX iff it has a pair of equal grandchildren
+    return (Ivy_ObjFaninId0(pNode0) == Ivy_ObjFaninId0(pNode1) && (Ivy_ObjFaninC0(pNode0) ^ Ivy_ObjFaninC0(pNode1))) || 
+           (Ivy_ObjFaninId0(pNode0) == Ivy_ObjFaninId1(pNode1) && (Ivy_ObjFaninC0(pNode0) ^ Ivy_ObjFaninC1(pNode1))) ||
+           (Ivy_ObjFaninId1(pNode0) == Ivy_ObjFaninId0(pNode1) && (Ivy_ObjFaninC1(pNode0) ^ Ivy_ObjFaninC0(pNode1))) ||
+           (Ivy_ObjFaninId1(pNode0) == Ivy_ObjFaninId1(pNode1) && (Ivy_ObjFaninC1(pNode0) ^ Ivy_ObjFaninC1(pNode1)));
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recognizes what nodes are control and data inputs of a MUX.]
+
+  Description [If the node is a MUX, returns the control variable C.
+  Assigns nodes T and E to be the then and else variables of the MUX. 
+  Node C is never complemented. Nodes T and E can be complemented.
+  This function also recognizes EXOR/NEXOR gates as MUXes.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_ObjRecognizeMux( Ivy_Obj_t * pNode, Ivy_Obj_t ** ppNodeT, Ivy_Obj_t ** ppNodeE )
+{
+    Ivy_Obj_t * pNode0, * pNode1;
+    assert( !Ivy_IsComplement(pNode) );
+    assert( Ivy_ObjIsMuxType(pNode) );
+    // get children
+    pNode0 = Ivy_ObjFanin0(pNode);
+    pNode1 = Ivy_ObjFanin1(pNode);
+    // find the control variable
+//    if ( pNode1->p1 == Fraig_Not(pNode2->p1) )
+    if ( Ivy_ObjFaninId0(pNode0) == Ivy_ObjFaninId0(pNode1) && (Ivy_ObjFaninC0(pNode0) ^ Ivy_ObjFaninC0(pNode1)) )
+    {
+//        if ( Fraig_IsComplement(pNode1->p1) )
+        if ( Ivy_ObjFaninC0(pNode0) )
+        { // pNode2->p1 is positive phase of C
+            *ppNodeT = Ivy_Not(Ivy_ObjChild1(pNode1));//pNode2->p2);
+            *ppNodeE = Ivy_Not(Ivy_ObjChild1(pNode0));//pNode1->p2);
+            return Ivy_ObjChild0(pNode1);//pNode2->p1;
+        }
+        else
+        { // pNode1->p1 is positive phase of C
+            *ppNodeT = Ivy_Not(Ivy_ObjChild1(pNode0));//pNode1->p2);
+            *ppNodeE = Ivy_Not(Ivy_ObjChild1(pNode1));//pNode2->p2);
+            return Ivy_ObjChild0(pNode0);//pNode1->p1;
+        }
+    }
+//    else if ( pNode1->p1 == Fraig_Not(pNode2->p2) )
+    else if ( Ivy_ObjFaninId0(pNode0) == Ivy_ObjFaninId1(pNode1) && (Ivy_ObjFaninC0(pNode0) ^ Ivy_ObjFaninC1(pNode1)) )
+    {
+//        if ( Fraig_IsComplement(pNode1->p1) )
+        if ( Ivy_ObjFaninC0(pNode0) )
+        { // pNode2->p2 is positive phase of C
+            *ppNodeT = Ivy_Not(Ivy_ObjChild0(pNode1));//pNode2->p1);
+            *ppNodeE = Ivy_Not(Ivy_ObjChild1(pNode0));//pNode1->p2);
+            return Ivy_ObjChild1(pNode1);//pNode2->p2;
+        }
+        else
+        { // pNode1->p1 is positive phase of C
+            *ppNodeT = Ivy_Not(Ivy_ObjChild1(pNode0));//pNode1->p2);
+            *ppNodeE = Ivy_Not(Ivy_ObjChild0(pNode1));//pNode2->p1);
+            return Ivy_ObjChild0(pNode0);//pNode1->p1;
+        }
+    }
+//    else if ( pNode1->p2 == Fraig_Not(pNode2->p1) )
+    else if ( Ivy_ObjFaninId1(pNode0) == Ivy_ObjFaninId0(pNode1) && (Ivy_ObjFaninC1(pNode0) ^ Ivy_ObjFaninC0(pNode1)) )
+    {
+//        if ( Fraig_IsComplement(pNode1->p2) )
+        if ( Ivy_ObjFaninC1(pNode0) )
+        { // pNode2->p1 is positive phase of C
+            *ppNodeT = Ivy_Not(Ivy_ObjChild1(pNode1));//pNode2->p2);
+            *ppNodeE = Ivy_Not(Ivy_ObjChild0(pNode0));//pNode1->p1);
+            return Ivy_ObjChild0(pNode1);//pNode2->p1;
+        }
+        else
+        { // pNode1->p2 is positive phase of C
+            *ppNodeT = Ivy_Not(Ivy_ObjChild0(pNode0));//pNode1->p1);
+            *ppNodeE = Ivy_Not(Ivy_ObjChild1(pNode1));//pNode2->p2);
+            return Ivy_ObjChild1(pNode0);//pNode1->p2;
+        }
+    }
+//    else if ( pNode1->p2 == Fraig_Not(pNode2->p2) )
+    else if ( Ivy_ObjFaninId1(pNode0) == Ivy_ObjFaninId1(pNode1) && (Ivy_ObjFaninC1(pNode0) ^ Ivy_ObjFaninC1(pNode1)) )
+    {
+//        if ( Fraig_IsComplement(pNode1->p2) )
+        if ( Ivy_ObjFaninC1(pNode0) )
+        { // pNode2->p2 is positive phase of C
+            *ppNodeT = Ivy_Not(Ivy_ObjChild0(pNode1));//pNode2->p1);
+            *ppNodeE = Ivy_Not(Ivy_ObjChild0(pNode0));//pNode1->p1);
+            return Ivy_ObjChild1(pNode1);//pNode2->p2;
+        }
+        else
+        { // pNode1->p2 is positive phase of C
+            *ppNodeT = Ivy_Not(Ivy_ObjChild0(pNode0));//pNode1->p1);
+            *ppNodeE = Ivy_Not(Ivy_ObjChild0(pNode1));//pNode2->p1);
+            return Ivy_ObjChild1(pNode0);//pNode1->p2;
+        }
+    }
+    assert( 0 ); // this is not MUX
+    return NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the real fanin.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Ivy_ObjReal( Ivy_Obj_t * pObj )
+{
+    Ivy_Obj_t * pFanin;
+    if ( pObj == NULL || !Ivy_ObjIsBuf( Ivy_Regular(pObj) ) )
+        return pObj;
+    pFanin = Ivy_ObjReal( Ivy_ObjChild0(Ivy_Regular(pObj)) );
+    return Ivy_NotCond( pFanin, Ivy_IsComplement(pObj) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints node in HAIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ObjPrintVerbose( Ivy_Man_t * p, Ivy_Obj_t * pObj, int fHaig )
+{
+    Ivy_Obj_t * pTemp;
+    int fShowFanouts = 0;
+    assert( !Ivy_IsComplement(pObj) );
+    printf( "Node %5d : ", Ivy_ObjId(pObj) );
+    if ( Ivy_ObjIsConst1(pObj) )
+        printf( "constant 1" );
+    else if ( Ivy_ObjIsPi(pObj) )
+        printf( "PI" );
+    else if ( Ivy_ObjIsPo(pObj) )
+        printf( "PO" );
+    else if ( Ivy_ObjIsLatch(pObj) )
+        printf( "latch (%d%s)", Ivy_ObjFanin0(pObj)->Id, (Ivy_ObjFaninC0(pObj)? "\'" : " ") );
+    else if ( Ivy_ObjIsBuf(pObj) )
+        printf( "buffer (%d%s)", Ivy_ObjFanin0(pObj)->Id, (Ivy_ObjFaninC0(pObj)? "\'" : " ") );
+    else
+        printf( "AND( %5d%s, %5d%s )", 
+            Ivy_ObjFanin0(pObj)->Id, (Ivy_ObjFaninC0(pObj)? "\'" : " "), 
+            Ivy_ObjFanin1(pObj)->Id, (Ivy_ObjFaninC1(pObj)? "\'" : " ") );
+    printf( " (refs = %3d)", Ivy_ObjRefs(pObj) );
+    if ( fShowFanouts )
+    {
+        Vec_Ptr_t * vFanouts;
+        Ivy_Obj_t * pFanout;
+        int i;
+        vFanouts = Vec_PtrAlloc( 10 );
+        printf( "\nFanouts:\n" );
+        Ivy_ObjForEachFanout( p, pObj, vFanouts, pFanout, i )
+        {
+            printf( "    " );
+            printf( "Node %5d : ", Ivy_ObjId(pFanout) );
+            if ( Ivy_ObjIsPo(pFanout) )
+                printf( "PO" );
+            else if ( Ivy_ObjIsLatch(pFanout) )
+                printf( "latch (%d%s)", Ivy_ObjFanin0(pFanout)->Id, (Ivy_ObjFaninC0(pFanout)? "\'" : " ") );
+            else if ( Ivy_ObjIsBuf(pFanout) )
+                printf( "buffer (%d%s)", Ivy_ObjFanin0(pFanout)->Id, (Ivy_ObjFaninC0(pFanout)? "\'" : " ") );
+            else
+                printf( "AND( %5d%s, %5d%s )", 
+                    Ivy_ObjFanin0(pFanout)->Id, (Ivy_ObjFaninC0(pFanout)? "\'" : " "), 
+                    Ivy_ObjFanin1(pFanout)->Id, (Ivy_ObjFaninC1(pFanout)? "\'" : " ") );
+            printf( "\n" );
+        }
+        Vec_PtrFree( vFanouts );
+        return;
+    }
+    if ( !fHaig )
+    {
+        if ( pObj->pEquiv == NULL )
+            printf( " HAIG node not given" );
+        else
+            printf( " HAIG node = %d%s", Ivy_Regular(pObj->pEquiv)->Id, (Ivy_IsComplement(pObj->pEquiv)? "\'" : " ") );
+        return;
+    }
+    if ( pObj->pEquiv == NULL )
+        return;
+    // there are choices
+    if ( Ivy_ObjRefs(pObj) > 0 )
+    {
+        // print equivalence class
+        printf( "  { %5d ", pObj->Id );
+        assert( !Ivy_IsComplement(pObj->pEquiv) );
+        for ( pTemp = pObj->pEquiv; pTemp != pObj; pTemp = Ivy_Regular(pTemp->pEquiv) )
+            printf( " %5d%s", pTemp->Id, (Ivy_IsComplement(pTemp->pEquiv)? "\'" : " ") );
+        printf( " }" );
+        return;
+    }
+    // this is a secondary node
+    for ( pTemp = Ivy_Regular(pObj->pEquiv); Ivy_ObjRefs(pTemp) == 0; pTemp = Ivy_Regular(pTemp->pEquiv) );
+    assert( Ivy_ObjRefs(pTemp) > 0 );
+    printf( "  class of %d", pTemp->Id );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints node in HAIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ivy_ManPrintVerbose( Ivy_Man_t * p, int fHaig )
+{
+    Vec_Int_t * vNodes;
+    Ivy_Obj_t * pObj;
+    int i;
+    printf( "PIs: " );
+    Ivy_ManForEachPi( p, pObj, i )
+        printf( " %d", pObj->Id );
+    printf( "\n" );
+    printf( "POs: " );
+    Ivy_ManForEachPo( p, pObj, i )
+        printf( " %d", pObj->Id );
+    printf( "\n" );
+    printf( "Latches: " );
+    Ivy_ManForEachLatch( p, pObj, i )
+        printf( " %d=%d%s", pObj->Id, Ivy_ObjFanin0(pObj)->Id, (Ivy_ObjFaninC0(pObj)? "\'" : " ") );
+    printf( "\n" );
+    vNodes = Ivy_ManDfsSeq( p, NULL );
+    Ivy_ManForEachNodeVec( p, vNodes, pObj, i )
+        Ivy_ObjPrintVerbose( p, pObj, fHaig ), printf( "\n" );
+    printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs incremental rewriting of the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_CutTruthPrint2( Ivy_Man_t * p, Ivy_Cut_t * pCut, unsigned uTruth )
+{
+    int i;
+    printf( "Trying cut : {" );
+    for ( i = 0; i < pCut->nSize; i++ )
+        printf( " %6d(%d)", Ivy_LeafId(pCut->pArray[i]), Ivy_LeafLat(pCut->pArray[i]) );
+    printf( " }   " );
+    Extra_PrintBinary( stdout, &uTruth, 16 );  printf( "\n" );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs incremental rewriting of the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ivy_CutTruthPrint( Ivy_Man_t * p, Ivy_Cut_t * pCut, unsigned uTruth )
+{
+    Vec_Ptr_t * vArray;
+    Ivy_Obj_t * pObj, * pFanout;
+    int nLatches = 0;
+    int nPresent = 0;
+    int i, k;
+    int fVerbose = 0;
+
+    if ( fVerbose )
+        printf( "Trying cut : {" );
+    for ( i = 0; i < pCut->nSize; i++ )
+    {
+        if ( fVerbose )
+            printf( " %6d(%d)", Ivy_LeafId(pCut->pArray[i]), Ivy_LeafLat(pCut->pArray[i]) );
+        nLatches += Ivy_LeafLat(pCut->pArray[i]);
+    }
+    if ( fVerbose )
+        printf( " }   " );
+    if ( fVerbose )
+        printf( "Latches = %d. ", nLatches );
+
+    // check if there are latches on the fanout edges
+    vArray = Vec_PtrAlloc( 100 );
+    for ( i = 0; i < pCut->nSize; i++ )
+    {
+        pObj = Ivy_ManObj( p, Ivy_LeafId(pCut->pArray[i]) );
+        Ivy_ObjForEachFanout( p, pObj, vArray, pFanout, k )
+        {
+            if ( Ivy_ObjIsLatch(pFanout) )
+            {
+                nPresent++;
+                break;
+            }
+        }
+    }
+    Vec_PtrSize( vArray );
+    if ( fVerbose )
+    {
+        printf( "Present = %d. ", nPresent );
+        if ( nLatches > nPresent )
+            printf( "Clauses = %d. ", 2*(nLatches - nPresent) );
+        printf( "\n" );
+    }
+    return ( nLatches > nPresent ) ? 2*(nLatches - nPresent) : 0;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/ivy_.c b/src/aig/ivy/ivy_.c
new file mode 100644
index 00000000..65689689
--- /dev/null
+++ b/src/aig/ivy/ivy_.c
@@ -0,0 +1,48 @@
+/**CFile****************************************************************
+
+  FileName    [ivy_.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [And-Inverter Graph package.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - May 11, 2006.]
+
+  Revision    [$Id: ivy_.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ivy/module.make b/src/aig/ivy/module.make
new file mode 100644
index 00000000..daef43df
--- /dev/null
+++ b/src/aig/ivy/module.make
@@ -0,0 +1,22 @@
+SRC +=    src/aig/ivy/ivyBalance.c \
+    src/aig/ivy/ivyCanon.c \
+    src/aig/ivy/ivyCheck.c \
+    src/aig/ivy/ivyCut.c \
+    src/aig/ivy/ivyCutTrav.c \
+    src/aig/ivy/ivyDfs.c \
+    src/aig/ivy/ivyDsd.c \
+    src/aig/ivy/ivyFanout.c \
+    src/aig/ivy/ivyFastMap.c \
+    src/aig/ivy/ivyFraig.c \
+    src/aig/ivy/ivyHaig.c \
+    src/aig/ivy/ivyMan.c \
+    src/aig/ivy/ivyMem.c \
+    src/aig/ivy/ivyMulti.c \
+    src/aig/ivy/ivyObj.c \
+    src/aig/ivy/ivyOper.c \
+    src/aig/ivy/ivyResyn.c \
+    src/aig/ivy/ivyRwr.c \
+    src/aig/ivy/ivySeq.c \
+    src/aig/ivy/ivyShow.c \
+    src/aig/ivy/ivyTable.c \
+    src/aig/ivy/ivyUtil.c