Version abc70726

7 files changed, 306 insertions, 171 deletions

diff --git a/src/aig/fra/fra.h b/src/aig/fra/fra.h
index 7f2df105..127882ea 100644
--- a/src/aig/fra/fra.h
+++ b/src/aig/fra/fra.h
@@ -60,6 +60,7 @@ struct Fra_Par_t_
     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              fChoicing;         // enables choicing
     int              fSpeculate;        // use speculative reduction
     int              fProve;            // prove the miter outputs
     int              fVerbose;          // verbose output
@@ -101,6 +102,7 @@ struct Fra_Man_t_
     // various data members
     Aig_Obj_t **     pMemFraig;         // memory allocated for points to the fraig nodes
     Aig_Obj_t **     pMemRepr;          // memory allocated for points to the node representatives
+    Aig_Obj_t **     pMemReprFra;       // memory allocated for points to the node representatives in the FRAIG
     Vec_Ptr_t **     pMemFanins;        // the arrays of fanins
     int *            pMemSatNums;       // the array of SAT numbers
     int              nSizeAlloc;        // allocated size of the arrays
@@ -118,7 +120,9 @@ struct Fra_Man_t_
     int              nSatProof;
     int              nSatFails;
     int              nSatFailsReal;
-    int              nSpeculs;         
+    int              nSpeculs;   
+    int              nChoices;
+    int              nChoicesFake;
     // runtime
     int              timeSim;
     int              timeTrav;
@@ -141,11 +145,13 @@ static inline unsigned     Fra_ObjRandomSim()               { return (rand() <<
 
 static inline Aig_Obj_t *  Fra_ObjFraig( Aig_Obj_t * pObj )                              { return ((Fra_Man_t *)pObj->pData)->pMemFraig[pObj->Id];       }
 static inline Aig_Obj_t *  Fra_ObjRepr( Aig_Obj_t * pObj )                               { return ((Fra_Man_t *)pObj->pData)->pMemRepr[pObj->Id];        }
+static inline Aig_Obj_t *  Fra_ObjReprFra( Aig_Obj_t * pObj )                            { return ((Fra_Man_t *)pObj->pData)->pMemReprFra[pObj->Id];     }
 static inline Vec_Ptr_t *  Fra_ObjFaninVec( Aig_Obj_t * pObj )                           { return ((Fra_Man_t *)pObj->pData)->pMemFanins[pObj->Id];      }
 static inline int          Fra_ObjSatNum( Aig_Obj_t * pObj )                             { return ((Fra_Man_t *)pObj->pData)->pMemSatNums[pObj->Id];     }
 
 static inline void         Fra_ObjSetFraig( Aig_Obj_t * pObj, Aig_Obj_t * pNode )        { ((Fra_Man_t *)pObj->pData)->pMemFraig[pObj->Id]   = pNode;    }
 static inline void         Fra_ObjSetRepr( Aig_Obj_t * pObj, Aig_Obj_t * pNode )         { ((Fra_Man_t *)pObj->pData)->pMemRepr[pObj->Id]    = pNode;    }
+static inline void         Fra_ObjSetReprFra( Aig_Obj_t * pObj, Aig_Obj_t * pNode )      { ((Fra_Man_t *)pObj->pData)->pMemReprFra[pObj->Id] = pNode;    }
 static inline void         Fra_ObjSetFaninVec( Aig_Obj_t * pObj, Vec_Ptr_t * vFanins )   { ((Fra_Man_t *)pObj->pData)->pMemFanins[pObj->Id]  = vFanins;  }
 static inline void         Fra_ObjSetSatNum( Aig_Obj_t * pObj, int Num )                 { ((Fra_Man_t *)pObj->pData)->pMemSatNums[pObj->Id] = Num;      }
 
@@ -160,8 +166,6 @@ static inline Aig_Obj_t *  Fra_ObjChild1Fra( Aig_Obj_t * pObj ) { assert( !Aig_I
 ///                    FUNCTION DECLARATIONS                         ///
 ////////////////////////////////////////////////////////////////////////
 
-/*=== fraAnd.c ========================================================*/
-extern void                Fra_Sweep( Fra_Man_t * p );
 /*=== fraClass.c ========================================================*/
 extern void                Fra_PrintClasses( Fra_Man_t * p );
 extern void                Fra_CreateClasses( Fra_Man_t * p );
@@ -170,7 +174,10 @@ extern int                 Fra_RefineClasses1( Fra_Man_t * p );
 /*=== fraCnf.c ========================================================*/
 extern void                Fra_NodeAddToSolver( Fra_Man_t * p, Aig_Obj_t * pOld, Aig_Obj_t * pNew );
 /*=== fraCore.c ========================================================*/
-extern Aig_Man_t *         Fra_Perform( Aig_Man_t * pManAig, Fra_Par_t * pParams );
+extern Aig_Man_t *         Fra_Perform( Aig_Man_t * pManAig, Fra_Par_t * pPars );
+extern Aig_Man_t *         Fra_Choice( Aig_Man_t * pManAig );
+/*=== fraDfs.c ========================================================*/
+extern int                 Fra_CheckTfi( Fra_Man_t * p, Aig_Obj_t * pNew, Aig_Obj_t * pOld );
 /*=== fraMan.c ========================================================*/
 extern void                Fra_ParamsDefault( Fra_Par_t * pParams );
 extern Fra_Man_t *         Fra_ManStart( Aig_Man_t * pManAig, Fra_Par_t * pParams );
diff --git a/src/aig/fra/fraAnd.c b/src/aig/fra/fraAnd.c
deleted file mode 100644
index 36b4ccc3..00000000
--- a/src/aig/fra/fraAnd.c
+++ /dev/null
@@ -1,156 +0,0 @@
-/**CFile****************************************************************
-
-  FileName    [fraAnd.c]
-
-  SystemName  [ABC: Logic synthesis and verification system.]
-
-  PackageName [Fraig FRAIG package.]
-
-  Synopsis    []
-
-  Author      [Alan Mishchenko]
-  
-  Affiliation [UC Berkeley]
-
-  Date        [Ver. 1.0. Started - June 30, 2007.]
-
-  Revision    [$Id: fraAnd.c,v 1.00 2007/06/30 00:00:00 alanmi Exp $]
-
-***********************************************************************/
-
-#include "fra.h"
-
-////////////////////////////////////////////////////////////////////////
-///                        DECLARATIONS                              ///
-////////////////////////////////////////////////////////////////////////
-
-////////////////////////////////////////////////////////////////////////
-///                     FUNCTION DEFINITIONS                         ///
-////////////////////////////////////////////////////////////////////////
-
-
-/**Function*************************************************************
-
-  Synopsis    [Performs fraiging for one node.]
-
-  Description [Returns the fraiged node.]
-               
-  SideEffects []
-
-  SeeAlso     []
-
-***********************************************************************/
-Aig_Obj_t * Fra_And( Fra_Man_t * p, Aig_Obj_t * pObjOld )
-{ 
-    Aig_Obj_t * pObjOldRepr, * pObjFraig, * pFanin0Fraig, * pFanin1Fraig, * pObjOldReprFraig;
-    int RetValue;
-    assert( !Aig_IsComplement(pObjOld) );
-    assert( Aig_ObjIsNode(pObjOld) );
-    // get the fraiged fanins
-    pFanin0Fraig = Fra_ObjChild0Fra(pObjOld);
-    pFanin1Fraig = Fra_ObjChild1Fra(pObjOld);
-    // get the fraiged node
-    pObjFraig = Aig_And( p->pManFraig, pFanin0Fraig, pFanin1Fraig );
-    if ( Aig_ObjIsConst1(Aig_Regular(pObjFraig)) )
-        return pObjFraig;
-    Aig_Regular(pObjFraig)->pData = p;
-    // get representative of this class
-    pObjOldRepr = Fra_ObjRepr(pObjOld);
-    if ( pObjOldRepr == NULL || // this is a unique node
-       (!p->pPars->fDoSparse && pObjOldRepr == Aig_ManConst1(p->pManAig)) ) // this is a sparse node
-    {
-        assert( Aig_Regular(pFanin0Fraig) != Aig_Regular(pFanin1Fraig) );
-        assert( Aig_Regular(pObjFraig) != Aig_Regular(pFanin0Fraig) );
-        assert( Aig_Regular(pObjFraig) != Aig_Regular(pFanin1Fraig) );
-        return pObjFraig;
-    }
-    // get the fraiged representative
-    pObjOldReprFraig = Fra_ObjFraig(pObjOldRepr);
-    // if the fraiged nodes are the same, return
-    if ( Aig_Regular(pObjFraig) == Aig_Regular(pObjOldReprFraig) )
-        return pObjFraig;
-    assert( Aig_Regular(pObjFraig) != Aig_ManConst1(p->pManFraig) );
-//    printf( "Node = %d. Repr = %d.\n", pObjOld->Id, pObjOldRepr->Id );
-
-    // if they are proved different, the c-ex will be in p->pPatWords
-    RetValue = Fra_NodesAreEquiv( p, Aig_Regular(pObjOldReprFraig), Aig_Regular(pObjFraig) );
-    if ( RetValue == 1 )  // proved equivalent
-    {
-//        pObjOld->fMarkA = 1;
-        return Aig_NotCond( pObjOldReprFraig, pObjOld->fPhase ^ pObjOldRepr->fPhase );
-    }
-    if ( RetValue == -1 ) // failed
-    {
-        Aig_Obj_t * ppNodes[2] = { Aig_Regular(pObjOldReprFraig), Aig_Regular(pObjFraig) };
-        Vec_Ptr_t * vNodes;
-
-        if ( !p->pPars->fSpeculate )
-            return pObjFraig;
-        // substitute the node
-//        pObjOld->fMarkB = 1;
-        p->nSpeculs++;
-
-        vNodes = Aig_ManDfsNodes( p->pManFraig, ppNodes, 2 );
-        printf( "%d ", Vec_PtrSize(vNodes) );
-        Vec_PtrFree( vNodes );
-
-        return Aig_NotCond( pObjOldReprFraig, pObjOld->fPhase ^ pObjOldRepr->fPhase );
-    }
-//    printf( "Disproved %d and %d.\n", pObjOldRepr->Id, pObjOld->Id );
-    // simulate the counter-example and return the Fraig node
-//    printf( "Representaive before = %d.\n", Fra_ObjRepr(pObjOld)? Fra_ObjRepr(pObjOld)->Id : -1 );
-    Fra_Resimulate( p );
-//    printf( "Representaive after  = %d.\n", Fra_ObjRepr(pObjOld)? Fra_ObjRepr(pObjOld)->Id : -1 );
-    assert( Fra_ObjRepr(pObjOld) != pObjOldRepr );
-    return pObjFraig;
-}
-
-/**Function*************************************************************
-
-  Synopsis    [Performs fraiging for the internal nodes.]
-
-  Description []
-               
-  SideEffects []
-
-  SeeAlso     []
-
-***********************************************************************/
-void Fra_Sweep( Fra_Man_t * p )
-{
-    Aig_Obj_t * pObj, * pObjNew;
-    int i, k = 0;
-p->nClassesZero = Vec_PtrSize(p->vClasses1);
-p->nClassesBeg  = Vec_PtrSize(p->vClasses) + (int)(Vec_PtrSize(p->vClasses1) > 0);
-    // duplicate internal nodes
-//    p->pProgress = Extra_ProgressBarStart( stdout, Aig_ManNodeNum(p->pManAig) );
-    Aig_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 )
-            pObjNew = Aig_And( p->pManFraig, Fra_ObjChild0Fra(pObj), Fra_ObjChild1Fra(pObj) );
-        else
-            pObjNew = Fra_And( p, pObj ); // pObjNew can be complemented
-        Fra_ObjSetFraig( pObj, pObjNew );
-        assert( Fra_ObjFraig(pObj) != NULL );
-    }
-//    Extra_ProgressBarStop( p->pProgress );
-p->nClassesEnd = Vec_PtrSize(p->vClasses) + (int)(Vec_PtrSize(p->vClasses1) > 0);
-    // try to prove the outputs of the miter
-    p->nNodesMiter = Aig_ManNodeNum(p->pManFraig);
-//    Fra_MiterStatus( p->pManFraig );
-//    if ( p->pPars->fProve && p->pManFraig->pData == NULL )
-//        Fra_MiterProve( p );
-    // add the POs
-    Aig_ManForEachPo( p->pManAig, pObj, i )
-        Aig_ObjCreatePo( p->pManFraig, Fra_ObjChild0Fra(pObj) );
-    // remove dangling nodes 
-    Aig_ManCleanup( p->pManFraig );
-}
-
-////////////////////////////////////////////////////////////////////////
-///                       END OF FILE                                ///
-////////////////////////////////////////////////////////////////////////
-
-
diff --git a/src/aig/fra/fraCore.c b/src/aig/fra/fraCore.c
index 9e1a9a1a..ca2d0fb4 100644
--- a/src/aig/fra/fraCore.c
+++ b/src/aig/fra/fraCore.c
@@ -30,6 +30,177 @@
 
 /**Function*************************************************************
 
+  Synopsis    [Performs fraiging for one node.]
+
+  Description [Returns the fraiged node.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Aig_Obj_t * Fra_And( Fra_Man_t * p, Aig_Obj_t * pObjOld )
+{ 
+    Aig_Obj_t * pObjOldRepr, * pObjFraig, * pFanin0Fraig, * pFanin1Fraig, * pObjOldReprFraig;
+    int RetValue;
+    assert( !Aig_IsComplement(pObjOld) );
+    assert( Aig_ObjIsNode(pObjOld) );
+    // get the fraiged fanins
+    pFanin0Fraig = Fra_ObjChild0Fra(pObjOld);
+    pFanin1Fraig = Fra_ObjChild1Fra(pObjOld);
+    // get the fraiged node
+    pObjFraig = Aig_And( p->pManFraig, pFanin0Fraig, pFanin1Fraig );
+    if ( Aig_ObjIsConst1(Aig_Regular(pObjFraig)) )
+        return pObjFraig;
+    Aig_Regular(pObjFraig)->pData = p;
+    // get representative of this class
+    pObjOldRepr = Fra_ObjRepr(pObjOld);
+    if ( pObjOldRepr == NULL || // this is a unique node
+       (!p->pPars->fDoSparse && pObjOldRepr == Aig_ManConst1(p->pManAig)) ) // this is a sparse node
+    {
+        assert( Aig_Regular(pFanin0Fraig) != Aig_Regular(pFanin1Fraig) );
+        assert( Aig_Regular(pObjFraig) != Aig_Regular(pFanin0Fraig) );
+        assert( Aig_Regular(pObjFraig) != Aig_Regular(pFanin1Fraig) );
+        return pObjFraig;
+    }
+    // get the fraiged representative
+    pObjOldReprFraig = Fra_ObjFraig(pObjOldRepr);
+    // if the fraiged nodes are the same, return
+    if ( Aig_Regular(pObjFraig) == Aig_Regular(pObjOldReprFraig) )
+        return pObjFraig;
+    assert( Aig_Regular(pObjFraig) != Aig_ManConst1(p->pManFraig) );
+//    printf( "Node = %d. Repr = %d.\n", pObjOld->Id, pObjOldRepr->Id );
+
+    // if they are proved different, the c-ex will be in p->pPatWords
+    RetValue = Fra_NodesAreEquiv( p, Aig_Regular(pObjOldReprFraig), Aig_Regular(pObjFraig) );
+    if ( RetValue == 1 )  // proved equivalent
+    {
+//        pObjOld->fMarkA = 1;
+        if ( p->pPars->fChoicing && !Fra_CheckTfi( p, Aig_Regular(pObjFraig), Aig_Regular(pObjOldReprFraig) ) )
+        {
+//            Fra_ObjSetReprFra( Aig_Regular(pObjFraig), Aig_Regular(pObjOldReprFraig) );
+            Aig_Obj_t * pObjNew = Aig_Regular(pObjFraig);
+            Aig_Obj_t * pObjOld = Aig_Regular(pObjOldReprFraig);
+            Aig_Obj_t * pTemp;
+            assert( pObjNew != pObjOld );
+            for ( pTemp = Fra_ObjReprFra(pObjOld); pTemp; pTemp = Fra_ObjReprFra(pTemp) )
+                if ( pTemp == pObjNew )
+                    break;
+            if ( pTemp == NULL )
+            {
+                Fra_ObjSetReprFra( pObjNew, Fra_ObjReprFra(pObjOld) );
+                Fra_ObjSetReprFra( pObjOld, pObjNew );
+                assert( pObjOld != Fra_ObjReprFra(pObjOld) );
+                assert( pObjNew != Fra_ObjReprFra(pObjNew) );
+                p->nChoices++;
+
+                assert( pObjOld->Id < pObjNew->Id );
+            }
+            else
+                p->nChoicesFake++;
+        }
+        return Aig_NotCond( pObjOldReprFraig, pObjOld->fPhase ^ pObjOldRepr->fPhase );
+    }
+    if ( RetValue == -1 ) // failed
+    {
+        static int Counter = 0;
+        char FileName[20];
+        Aig_Man_t * pTemp;
+        Aig_Obj_t * pObj;
+        int i;
+
+        Aig_Obj_t * ppNodes[2] = { Aig_Regular(pObjOldReprFraig), Aig_Regular(pObjFraig) };
+//        Vec_Ptr_t * vNodes;
+
+        if ( !p->pPars->fSpeculate )
+            return pObjFraig;
+        // substitute the node
+//        pObjOld->fMarkB = 1;
+        p->nSpeculs++;
+
+        pTemp = Aig_ManExtractMiter( p->pManFraig, ppNodes, 2 );
+        sprintf( FileName, "aig\\%03d.blif", ++Counter );
+        Aig_ManDumpBlif( pTemp, FileName );
+        printf( "Speculation cone with %d nodes was written into file \"%s\".\n", Aig_ManNodeNum(pTemp), FileName );
+        Aig_ManStop( pTemp );
+
+        Aig_ManForEachObj( p->pManFraig, pObj, i )
+            pObj->pData = p;
+
+//        vNodes = Aig_ManDfsNodes( p->pManFraig, ppNodes, 2 );
+//        printf( "Cone=%d ", Vec_PtrSize(vNodes) );
+//        Vec_PtrFree( vNodes );
+
+        return Aig_NotCond( pObjOldReprFraig, pObjOld->fPhase ^ pObjOldRepr->fPhase );
+    }
+//    printf( "Disproved %d and %d.\n", pObjOldRepr->Id, pObjOld->Id );
+    // simulate the counter-example and return the Fraig node
+//    printf( "Representaive before = %d.\n", Fra_ObjRepr(pObjOld)? Fra_ObjRepr(pObjOld)->Id : -1 );
+    Fra_Resimulate( p );
+//    printf( "Representaive after  = %d.\n", Fra_ObjRepr(pObjOld)? Fra_ObjRepr(pObjOld)->Id : -1 );
+    assert( Fra_ObjRepr(pObjOld) != pObjOldRepr );
+    return pObjFraig;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fraiging for the internal nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fra_Sweep( Fra_Man_t * p )
+{
+    ProgressBar * pProgress;
+    Aig_Obj_t * pObj, * pObjNew;
+    int i, k = 0;
+p->nClassesZero = Vec_PtrSize(p->vClasses1);
+p->nClassesBeg  = Vec_PtrSize(p->vClasses) + (int)(Vec_PtrSize(p->vClasses1) > 0);
+    // duplicate internal nodes
+    pProgress = Extra_ProgressBarStart( stdout, Aig_ManObjIdMax(p->pManAig) );
+    Aig_ManForEachNode( p->pManAig, pObj, i )
+    {
+        Extra_ProgressBarUpdate( pProgress, i, NULL );
+        // default to simple strashing if simulation detected a counter-example for a PO
+        if ( p->pManFraig->pData )
+            pObjNew = Aig_And( p->pManFraig, Fra_ObjChild0Fra(pObj), Fra_ObjChild1Fra(pObj) );
+        else
+            pObjNew = Fra_And( p, pObj ); // pObjNew can be complemented
+        Fra_ObjSetFraig( pObj, pObjNew );
+        assert( Fra_ObjFraig(pObj) != NULL );
+    }
+    Extra_ProgressBarStop( pProgress );
+p->nClassesEnd = Vec_PtrSize(p->vClasses) + (int)(Vec_PtrSize(p->vClasses1) > 0);
+    // try to prove the outputs of the miter
+    p->nNodesMiter = Aig_ManNodeNum(p->pManFraig);
+//    Fra_MiterStatus( p->pManFraig );
+//    if ( p->pPars->fProve && p->pManFraig->pData == NULL )
+//        Fra_MiterProve( p );
+    // add the POs
+    Aig_ManForEachPo( p->pManAig, pObj, i )
+        Aig_ObjCreatePo( p->pManFraig, Fra_ObjChild0Fra(pObj) );
+    // postprocess
+    Aig_ManCleanMarkB( p->pManFraig );
+    if ( p->pPars->fChoicing )
+    {
+        // transfer the representative info
+        p->pManFraig->pReprs = p->pMemReprFra;
+        p->pMemReprFra = NULL;
+//        printf( "The number of choices = %d. Fake choices = %d.\n", p->nChoices, p->nChoicesFake );
+    }
+    else
+    {
+        // remove dangling nodes 
+        Aig_ManCleanup( p->pManFraig );
+    }
+}
+
+/**Function*************************************************************
+
   Synopsis    [Performs fraiging of the AIG.]
 
   Description []
@@ -57,6 +228,30 @@ p->timeTotal = clock() - clk;
     return pManAigNew;
 }
 
+/**Function*************************************************************
+
+  Synopsis    [Performs choicing of the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Aig_Man_t * Fra_Choice( Aig_Man_t * pManAig )
+{
+    Fra_Par_t Pars, * pPars = &Pars; 
+    Fra_ParamsDefault( pPars );
+    pPars->nBTLimitNode = 1000;
+    pPars->fVerbose     = 0;
+    pPars->fProve       = 0;
+    pPars->fDoSparse    = 1;
+    pPars->fSpeculate   = 0;
+    pPars->fChoicing    = 1;
+    return Fra_Perform( pManAig, pPars );
+}
+
 ////////////////////////////////////////////////////////////////////////
 ///                       END OF FILE                                ///
 ////////////////////////////////////////////////////////////////////////
diff --git a/src/aig/fra/fraDfs.c b/src/aig/fra/fraDfs.c
new file mode 100644
index 00000000..cd0985e0
--- /dev/null
+++ b/src/aig/fra/fraDfs.c
@@ -0,0 +1,87 @@
+/**CFile****************************************************************
+
+  FileName    [fraDfs.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fraig FRAIG package.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 30, 2007.]
+
+  Revision    [$Id: fraDfs.c,v 1.00 2007/06/30 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fra.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if pOld is in the TFI of pNew.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fra_CheckTfi_rec( Fra_Man_t * p, Aig_Obj_t * pNode, Aig_Obj_t * pOld )
+{
+    // check the trivial cases
+    if ( pNode == NULL )
+        return 0;
+//    if ( pNode->Id < pOld->Id ) // cannot use because of choicesof pNode
+//        return 0;
+    if ( pNode == pOld )
+        return 1;
+    // skip the visited node
+    if ( Aig_ObjIsTravIdCurrent(p->pManFraig, pNode) )
+        return 0;
+    Aig_ObjSetTravIdCurrent(p->pManFraig, pNode);
+    // check the children
+    if ( Fra_CheckTfi_rec( p, Aig_ObjFanin0(pNode), pOld ) )
+        return 1;
+    if ( Fra_CheckTfi_rec( p, Aig_ObjFanin1(pNode), pOld ) )
+        return 1;
+    // check equivalent nodes
+    return Fra_CheckTfi_rec( p, Fra_ObjReprFra(pNode), pOld );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if pOld is in the TFI of pNew.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fra_CheckTfi( Fra_Man_t * p, Aig_Obj_t * pNew, Aig_Obj_t * pOld )
+{
+    assert( !Aig_IsComplement(pNew) );
+    assert( !Aig_IsComplement(pOld) );
+    Aig_ManIncrementTravId( p->pManFraig );
+    return Fra_CheckTfi_rec( p, pNew, pOld );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/fra/fraMan.c b/src/aig/fra/fraMan.c
index 78246a8c..0e583d6c 100644
--- a/src/aig/fra/fraMan.c
+++ b/src/aig/fra/fraMan.c
@@ -97,6 +97,8 @@ Fra_Man_t * Fra_ManStart( Aig_Man_t * pManAig, Fra_Par_t * pPars )
     memset( p->pMemFraig, 0, p->nSizeAlloc * sizeof(Aig_Obj_t *) );
     p->pMemRepr  = ALLOC( Aig_Obj_t *, p->nSizeAlloc );
     memset( p->pMemRepr, 0, p->nSizeAlloc * sizeof(Aig_Obj_t *) );
+    p->pMemReprFra  = ALLOC( Aig_Obj_t *, p->nSizeAlloc );
+    memset( p->pMemReprFra, 0, p->nSizeAlloc * sizeof(Aig_Obj_t *) );
     p->pMemFanins  = ALLOC( Vec_Ptr_t *, p->nSizeAlloc );
     memset( p->pMemFanins, 0, p->nSizeAlloc * sizeof(Vec_Ptr_t *) );
     p->pMemSatNums  = ALLOC( int, p->nSizeAlloc );
@@ -166,6 +168,7 @@ void Fra_ManStop( Fra_Man_t * p )
     FREE( p->pMemSatNums );
     FREE( p->pMemFanins );
     FREE( p->pMemRepr );
+    FREE( p->pMemReprFra );
     FREE( p->pMemFraig );
     FREE( p->pMemClasses );
     FREE( p->pPatScores );
diff --git a/src/aig/fra/fraSat.c b/src/aig/fra/fraSat.c
index 66b1ba5a..8ab10c40 100644
--- a/src/aig/fra/fraSat.c
+++ b/src/aig/fra/fraSat.c
@@ -54,8 +54,7 @@ int Fra_NodesAreEquiv( Fra_Man_t * p, Aig_Obj_t * pOld, Aig_Obj_t * pNew )
     // 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->pPars->nBTLimitNode;
-/*
-    if ( nBTLimit > 0 && (pOld->fFailTfo || pNew->fFailTfo) )
+    if ( !p->pPars->fSpeculate && (nBTLimit > 0 && (pOld->fMarkB || pNew->fMarkB)) )
     {
         p->nSatFails++;
         // fail immediately
@@ -64,7 +63,7 @@ int Fra_NodesAreEquiv( Fra_Man_t * p, Aig_Obj_t * pOld, Aig_Obj_t * pNew )
             return -1;
         nBTLimit = (int)pow(nBTLimit, 0.7);
     }
-*/
+
     p->nSatCalls++;
 
     // make sure the solver is allocated and has enough variables
@@ -112,9 +111,9 @@ p->timeSatSat += clock() - clk;
     {
 p->timeSatFail += clock() - clk;
         // mark the node as the failed node
-//        if ( pOld != p->pManFraig->pConst1 ) 
-//            pOld->fFailTfo = 1;
-//        pNew->fFailTfo = 1;
+        if ( pOld != p->pManFraig->pConst1 ) 
+            pOld->fMarkB = 1;
+        pNew->fMarkB = 1;
         p->nSatFailsReal++;
         return -1;
     }
@@ -155,8 +154,8 @@ p->timeSatSat += clock() - clk;
     {
 p->timeSatFail += clock() - clk;
         // mark the node as the failed node
-//        pOld->fFailTfo = 1;
-//        pNew->fFailTfo = 1;
+        pOld->fMarkB = 1;
+        pNew->fMarkB = 1;
         p->nSatFailsReal++;
         return -1;
     }
@@ -240,7 +239,7 @@ p->timeSatSat += clock() - clk;
     {
 p->timeSatFail += clock() - clk;
         // mark the node as the failed node
-//        pNew->fFailTfo = 1;
+        pNew->fMarkB = 1;
         p->nSatFailsReal++;
         return -1;
     }
diff --git a/src/aig/fra/module.make b/src/aig/fra/module.make
index 934fbdac..df690700 100644
--- a/src/aig/fra/module.make
+++ b/src/aig/fra/module.make
@@ -1,7 +1,7 @@
-SRC +=    src/aig/fra/fraAnd.c \
-    src/aig/fra/fraClass.c \
+SRC +=    src/aig/fra/fraClass.c \
     src/aig/fra/fraCnf.c \
     src/aig/fra/fraCore.c \
+    src/aig/fra/fraDfs.c \
     src/aig/fra/fraMan.c \
     src/aig/fra/fraSat.c \
     src/aig/fra/fraSim.c