Experiments with circuit-based SAT.

1 files changed, 1132 insertions, 0 deletions

diff --git a/src/aig/gia/giaCSat2.c b/src/aig/gia/giaCSat2.c
new file mode 100644
index 00000000..14633b08
--- /dev/null
+++ b/src/aig/gia/giaCSat2.c
@@ -0,0 +1,1132 @@
+/**CFile****************************************************************
+
+  FileName    [giaCSat.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Scalable AIG package.]
+
+  Synopsis    [A simple circuit-based solver.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: giaCSat.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "gia.h"
+
+ABC_NAMESPACE_IMPL_START
+
+
+//#define gia_assert(exp)     ((void)0)
+//#define gia_assert(exp)     (assert(exp))
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Cbs2_Par_t_ Cbs2_Par_t;
+struct Cbs2_Par_t_
+{
+    // conflict limits
+    int           nBTLimit;     // limit on the number of conflicts
+    int           nJustLimit;   // limit on the size of justification queue
+    // current parameters
+    int           nBTThis;      // number of conflicts
+    int           nBTThisNc;    // number of conflicts
+    int           nJustThis;    // max size of the frontier
+    int           nBTTotal;     // total number of conflicts
+    int           nJustTotal;   // total size of the frontier
+    // decision heuristics
+    int           fUseHighest;  // use node with the highest ID
+    int           fUseLowest;   // use node with the highest ID
+    int           fUseMaxFF;    // use node with the largest fanin fanout
+    // other
+    int           fVerbose;
+};
+
+typedef struct Cbs2_Que_t_ Cbs2_Que_t;
+struct Cbs2_Que_t_
+{
+    int           iHead;        // beginning of the queue
+    int           iTail;        // end of the queue
+    int           nSize;        // allocated size
+    Gia_Obj_t **  pData;        // nodes stored in the queue
+};
+ 
+typedef struct Cbs2_Man_t_ Cbs2_Man_t;
+struct Cbs2_Man_t_
+{
+    Cbs2_Par_t    Pars;         // parameters
+    Gia_Man_t *   pAig;         // AIG manager
+    Cbs2_Que_t    pProp;        // propagation queue
+    Cbs2_Que_t    pJust;        // justification queue
+    Cbs2_Que_t    pClauses;     // clause queue
+    Gia_Obj_t **  pIter;        // iterator through clause vars
+    Vec_Int_t *   vLevReas;     // levels and decisions
+    Vec_Int_t *   vModel;       // satisfying assignment
+    Vec_Ptr_t *   vTemp;        // temporary storage
+    // SAT calls statistics
+    int           nSatUnsat;    // the number of proofs
+    int           nSatSat;      // the number of failure
+    int           nSatUndec;    // the number of timeouts
+    int           nSatTotal;    // the number of calls
+    // conflicts
+    int           nConfUnsat;   // conflicts in unsat problems
+    int           nConfSat;     // conflicts in sat problems
+    int           nConfUndec;   // conflicts in undec problems
+    // runtime stats
+    abctime       timeSatUnsat; // unsat
+    abctime       timeSatSat;   // sat
+    abctime       timeSatUndec; // undecided
+    abctime       timeTotal;    // total runtime
+};
+
+static inline int   Cbs2_VarIsAssigned( Gia_Obj_t * pVar )      { return pVar->fMark0;                        }
+static inline void  Cbs2_VarAssign( Gia_Obj_t * pVar )          { assert(!pVar->fMark0); pVar->fMark0 = 1;    }
+static inline void  Cbs2_VarUnassign( Gia_Obj_t * pVar )        { assert(pVar->fMark0);  pVar->fMark0 = 0; pVar->fMark1 = 0; pVar->Value = ~0; }
+static inline int   Cbs2_VarValue( Gia_Obj_t * pVar )           { assert(pVar->fMark0);  return pVar->fMark1; }
+static inline void  Cbs2_VarSetValue( Gia_Obj_t * pVar, int v ) { assert(pVar->fMark0);  pVar->fMark1 = v;    }
+static inline int   Cbs2_VarIsJust( Gia_Obj_t * pVar )          { return Gia_ObjIsAnd(pVar) && !Cbs2_VarIsAssigned(Gia_ObjFanin0(pVar)) && !Cbs2_VarIsAssigned(Gia_ObjFanin1(pVar)); } 
+static inline int   Cbs2_VarFanin0Value( Gia_Obj_t * pVar )     { return !Cbs2_VarIsAssigned(Gia_ObjFanin0(pVar)) ? 2 : (Cbs2_VarValue(Gia_ObjFanin0(pVar)) ^ Gia_ObjFaninC0(pVar)); }
+static inline int   Cbs2_VarFanin1Value( Gia_Obj_t * pVar )     { return !Cbs2_VarIsAssigned(Gia_ObjFanin1(pVar)) ? 2 : (Cbs2_VarValue(Gia_ObjFanin1(pVar)) ^ Gia_ObjFaninC1(pVar)); }
+
+static inline int         Cbs2_VarDecLevel( Cbs2_Man_t * p, Gia_Obj_t * pVar )  { assert( pVar->Value != ~0 ); return Vec_IntEntry(p->vLevReas, 3*pVar->Value);          }
+static inline Gia_Obj_t * Cbs2_VarReason0( Cbs2_Man_t * p, Gia_Obj_t * pVar )   { assert( pVar->Value != ~0 ); return pVar + Vec_IntEntry(p->vLevReas, 3*pVar->Value+1); }
+static inline Gia_Obj_t * Cbs2_VarReason1( Cbs2_Man_t * p, Gia_Obj_t * pVar )   { assert( pVar->Value != ~0 ); return pVar + Vec_IntEntry(p->vLevReas, 3*pVar->Value+2); }
+static inline int         Cbs2_ClauseDecLevel( Cbs2_Man_t * p, int hClause )    { return Cbs2_VarDecLevel( p, p->pClauses.pData[hClause] );                               }
+
+#define Cbs2_QueForEachEntry( Que, pObj, i )                         \
+    for ( i = (Que).iHead; (i < (Que).iTail) && ((pObj) = (Que).pData[i]); i++ )
+
+#define Cbs2_ClauseForEachVar( p, hClause, pObj )                    \
+    for ( (p)->pIter = (p)->pClauses.pData + hClause; (pObj = *pIter); (p)->pIter++ )
+#define Cbs2_ClauseForEachVar1( p, hClause, pObj )                   \
+    for ( (p)->pIter = (p)->pClauses.pData+hClause+1; (pObj = *pIter); (p)->pIter++ )
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Sets default values of the parameters.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cbs2_SetDefaultParams( Cbs2_Par_t * pPars )
+{
+    memset( pPars, 0, sizeof(Cbs2_Par_t) );
+    pPars->nBTLimit    =  1000;   // limit on the number of conflicts
+    pPars->nJustLimit  =   100;   // limit on the size of justification queue
+    pPars->fUseHighest =     1;   // use node with the highest ID
+    pPars->fUseLowest  =     0;   // use node with the highest ID
+    pPars->fUseMaxFF   =     0;   // use node with the largest fanin fanout
+    pPars->fVerbose    =     1;   // print detailed statistics
+}
+void Cbs2_ManSetConflictNum( Cbs2_Man_t * p, int Num )
+{
+    p->Pars.nBTLimit = Num;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cbs2_Man_t * Cbs2_ManAlloc( Gia_Man_t * pGia )
+{
+    Cbs2_Man_t * p;
+    p = ABC_CALLOC( Cbs2_Man_t, 1 );
+    p->pProp.nSize = p->pJust.nSize = p->pClauses.nSize = 10000;
+    p->pProp.pData = ABC_ALLOC( Gia_Obj_t *, p->pProp.nSize );
+    p->pJust.pData = ABC_ALLOC( Gia_Obj_t *, p->pJust.nSize );
+    p->pClauses.pData = ABC_ALLOC( Gia_Obj_t *, p->pClauses.nSize );
+    p->pClauses.iHead = p->pClauses.iTail = 1;
+    p->vModel   = Vec_IntAlloc( 1000 );
+    p->vLevReas = Vec_IntAlloc( 1000 );
+    p->vTemp    = Vec_PtrAlloc( 1000 );
+    p->pAig     = pGia;
+    Cbs2_SetDefaultParams( &p->Pars );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cbs2_ManStop( Cbs2_Man_t * p )
+{
+    Vec_IntFree( p->vLevReas );
+    Vec_IntFree( p->vModel );
+    Vec_PtrFree( p->vTemp );
+    ABC_FREE( p->pClauses.pData );
+    ABC_FREE( p->pProp.pData );
+    ABC_FREE( p->pJust.pData );
+    ABC_FREE( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns satisfying assignment.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Cbs2_ReadModel( Cbs2_Man_t * p )
+{
+    return p->vModel;
+}
+
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the solver is out of limits.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs2_ManCheckLimits( Cbs2_Man_t * p )
+{
+    return p->Pars.nJustThis > p->Pars.nJustLimit || p->Pars.nBTThis > p->Pars.nBTLimit;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Saves the satisfying assignment as an array of literals.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs2_ManSaveModel( Cbs2_Man_t * p, Vec_Int_t * vCex )
+{
+    Gia_Obj_t * pVar;
+    int i;
+    Vec_IntClear( vCex );
+    p->pProp.iHead = 0;
+    Cbs2_QueForEachEntry( p->pProp, pVar, i )
+        if ( Gia_ObjIsCi(pVar) )
+//            Vec_IntPush( vCex, Abc_Var2Lit(Gia_ObjId(p->pAig,pVar), !Cbs2_VarValue(pVar)) );
+            Vec_IntPush( vCex, Abc_Var2Lit(Gia_ObjCioId(pVar), !Cbs2_VarValue(pVar)) );
+} 
+static inline void Cbs2_ManSaveModelAll( Cbs2_Man_t * p, Vec_Int_t * vCex )
+{
+    Gia_Obj_t * pVar;
+    int i;
+    Vec_IntClear( vCex );
+    p->pProp.iHead = 0;
+    Cbs2_QueForEachEntry( p->pProp, pVar, i )
+        Vec_IntPush( vCex, Abc_Var2Lit(Gia_ObjId(p->pAig,pVar), !Cbs2_VarValue(pVar)) );
+} 
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs2_QueIsEmpty( Cbs2_Que_t * p )
+{
+    return p->iHead == p->iTail;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs2_QuePush( Cbs2_Que_t * p, Gia_Obj_t * pObj )
+{
+    if ( p->iTail == p->nSize )
+    {
+        p->nSize *= 2;
+        p->pData = ABC_REALLOC( Gia_Obj_t *, p->pData, p->nSize ); 
+    }
+    p->pData[p->iTail++] = pObj;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the object in the queue.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs2_QueHasNode( Cbs2_Que_t * p, Gia_Obj_t * pObj )
+{
+    Gia_Obj_t * pTemp;
+    int i;
+    Cbs2_QueForEachEntry( *p, pTemp, i )
+        if ( pTemp == pObj )
+            return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs2_QueStore( Cbs2_Que_t * p, int * piHeadOld, int * piTailOld )
+{
+    int i;
+    *piHeadOld = p->iHead;
+    *piTailOld = p->iTail;
+    for ( i = *piHeadOld; i < *piTailOld; i++ )
+        Cbs2_QuePush( p, p->pData[i] );
+    p->iHead = *piTailOld;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs2_QueRestore( Cbs2_Que_t * p, int iHeadOld, int iTailOld )
+{
+    p->iHead = iHeadOld;
+    p->iTail = iTailOld;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Finalized the clause.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs2_QueFinish( Cbs2_Que_t * p )
+{
+    int iHeadOld = p->iHead;
+    assert( p->iHead < p->iTail );
+    Cbs2_QuePush( p, NULL );
+    p->iHead = p->iTail;
+    return iHeadOld;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Max number of fanins fanouts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs2_VarFaninFanoutMax( Cbs2_Man_t * p, Gia_Obj_t * pObj )
+{
+    int Count0, Count1;
+    assert( !Gia_IsComplement(pObj) );
+    assert( Gia_ObjIsAnd(pObj) );
+    Count0 = Gia_ObjRefNum( p->pAig, Gia_ObjFanin0(pObj) );
+    Count1 = Gia_ObjRefNum( p->pAig, Gia_ObjFanin1(pObj) );
+    return Abc_MaxInt( Count0, Count1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Find variable with the highest ID.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Gia_Obj_t * Cbs2_ManDecideHighest( Cbs2_Man_t * p )
+{
+    Gia_Obj_t * pObj, * pObjMax = NULL;
+    int i;
+    Cbs2_QueForEachEntry( p->pJust, pObj, i )
+        if ( pObjMax == NULL || pObjMax < pObj )
+            pObjMax = pObj;
+    return pObjMax;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Find variable with the lowest ID.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Gia_Obj_t * Cbs2_ManDecideLowest( Cbs2_Man_t * p )
+{
+    Gia_Obj_t * pObj, * pObjMin = NULL;
+    int i;
+    Cbs2_QueForEachEntry( p->pJust, pObj, i )
+        if ( pObjMin == NULL || pObjMin > pObj )
+            pObjMin = pObj;
+    return pObjMin;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Find variable with the maximum number of fanin fanouts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Gia_Obj_t * Cbs2_ManDecideMaxFF( Cbs2_Man_t * p )
+{
+    Gia_Obj_t * pObj, * pObjMax = NULL;
+    int i, iMaxFF = 0, iCurFF;
+    assert( p->pAig->pRefs != NULL );
+    Cbs2_QueForEachEntry( p->pJust, pObj, i )
+    {
+        iCurFF = Cbs2_VarFaninFanoutMax( p, pObj );
+        assert( iCurFF > 0 );
+        if ( iMaxFF < iCurFF )
+        {
+            iMaxFF = iCurFF;
+            pObjMax = pObj;
+        }
+    }
+    return pObjMax; 
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs2_ManCancelUntil( Cbs2_Man_t * p, int iBound )
+{
+    Gia_Obj_t * pVar;
+    int i;
+    assert( iBound <= p->pProp.iTail );
+    p->pProp.iHead = iBound;
+    Cbs2_QueForEachEntry( p->pProp, pVar, i )
+        Cbs2_VarUnassign( pVar );
+    p->pProp.iTail = iBound;
+    Vec_IntShrink( p->vLevReas, 3*iBound );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Assigns the variables a value.]
+
+  Description [Returns 1 if conflict; 0 if no conflict.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs2_ManAssign( Cbs2_Man_t * p, Gia_Obj_t * pObj, int Level, Gia_Obj_t * pRes0, Gia_Obj_t * pRes1 )
+{
+    Gia_Obj_t * pObjR = Gia_Regular(pObj);
+    assert( Gia_ObjIsCand(pObjR) );
+    assert( !Cbs2_VarIsAssigned(pObjR) );
+    Cbs2_VarAssign( pObjR );
+    Cbs2_VarSetValue( pObjR, !Gia_IsComplement(pObj) );
+    assert( pObjR->Value == ~0 );
+    pObjR->Value = p->pProp.iTail;
+    Cbs2_QuePush( &p->pProp, pObjR );
+    Vec_IntPush( p->vLevReas, Level );
+    Vec_IntPush( p->vLevReas, pRes0 ? pRes0-pObjR : 0 );
+    Vec_IntPush( p->vLevReas, pRes1 ? pRes1-pObjR : 0 );
+    assert( Vec_IntSize(p->vLevReas) == 3 * p->pProp.iTail );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns clause size.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs2_ManClauseSize( Cbs2_Man_t * p, int hClause )
+{
+    Cbs2_Que_t * pQue = &(p->pClauses);
+    Gia_Obj_t ** pIter;
+    for ( pIter = pQue->pData + hClause; *pIter; pIter++ );
+    return pIter - pQue->pData - hClause ;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints conflict clause.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs2_ManPrintClause( Cbs2_Man_t * p, int Level, int hClause )
+{
+    Cbs2_Que_t * pQue = &(p->pClauses);
+    Gia_Obj_t * pObj;
+    int i;
+    assert( Cbs2_QueIsEmpty( pQue ) );
+    printf( "Level %2d : ", Level );
+    for ( i = hClause; (pObj = pQue->pData[i]); i++ )
+        printf( "%d=%d(%d) ", Gia_ObjId(p->pAig, pObj), Cbs2_VarValue(pObj), Cbs2_VarDecLevel(p, pObj) );
+    printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints conflict clause.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs2_ManPrintClauseNew( Cbs2_Man_t * p, int Level, int hClause )
+{
+    Cbs2_Que_t * pQue = &(p->pClauses);
+    Gia_Obj_t * pObj;
+    int i;
+    assert( Cbs2_QueIsEmpty( pQue ) );
+    printf( "Level %2d : ", Level );
+    for ( i = hClause; (pObj = pQue->pData[i]); i++ )
+        printf( "%c%d ", Cbs2_VarValue(pObj)? '+':'-', Gia_ObjId(p->pAig, pObj) );
+    printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns conflict clause.]
+
+  Description [Performs conflict analysis.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs2_ManDeriveReason( Cbs2_Man_t * p, int Level )
+{
+    Cbs2_Que_t * pQue = &(p->pClauses);
+    Gia_Obj_t * pObj, * pReason;
+    int i, k, iLitLevel;
+    assert( pQue->pData[pQue->iHead] == NULL );
+    assert( pQue->iHead + 1 < pQue->iTail );
+/*
+    for ( i = pQue->iHead + 1; i < pQue->iTail; i++ )
+    {
+        pObj = pQue->pData[i];
+        assert( pObj->fMark0 == 1 );
+    }
+*/
+    // compact literals
+    Vec_PtrClear( p->vTemp );
+    for ( i = k = pQue->iHead + 1; i < pQue->iTail; i++ )
+    {
+        pObj = pQue->pData[i];
+        if ( !pObj->fMark0 ) // unassigned - seen again
+            continue;
+        // assigned - seen first time
+        pObj->fMark0 = 0;
+        Vec_PtrPush( p->vTemp, pObj );
+        // check decision level
+        iLitLevel = Cbs2_VarDecLevel( p, pObj );
+        if ( iLitLevel < Level )
+        {
+            pQue->pData[k++] = pObj;
+            continue;
+        }
+        assert( iLitLevel == Level );
+        pReason = Cbs2_VarReason0( p, pObj );
+        if ( pReason == pObj ) // no reason
+        {
+            //assert( pQue->pData[pQue->iHead] == NULL );
+            pQue->pData[pQue->iHead] = pObj;
+            continue;
+        }
+        Cbs2_QuePush( pQue, pReason );
+        pReason = Cbs2_VarReason1( p, pObj );
+        if ( pReason != pObj ) // second reason
+            Cbs2_QuePush( pQue, pReason );
+    }
+    assert( pQue->pData[pQue->iHead] != NULL );
+    pQue->iTail = k;
+    // clear the marks
+    Vec_PtrForEachEntry( Gia_Obj_t *, p->vTemp, pObj, i )
+        pObj->fMark0 = 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns conflict clause.]
+
+  Description [Performs conflict analysis.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs2_ManAnalyze( Cbs2_Man_t * p, int Level, Gia_Obj_t * pVar, Gia_Obj_t * pFan0, Gia_Obj_t * pFan1 )
+{
+    Cbs2_Que_t * pQue = &(p->pClauses);
+    assert( Cbs2_VarIsAssigned(pVar) );
+    assert( Cbs2_VarIsAssigned(pFan0) );
+    assert( pFan1 == NULL || Cbs2_VarIsAssigned(pFan1) );
+    assert( Cbs2_QueIsEmpty( pQue ) );
+    Cbs2_QuePush( pQue, NULL );
+    Cbs2_QuePush( pQue, pVar );
+    Cbs2_QuePush( pQue, pFan0 );
+    if ( pFan1 )
+        Cbs2_QuePush( pQue, pFan1 );
+    Cbs2_ManDeriveReason( p, Level );
+    return Cbs2_QueFinish( pQue );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Performs resolution of two clauses.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs2_ManResolve( Cbs2_Man_t * p, int Level, int hClause0, int hClause1 )
+{
+    Cbs2_Que_t * pQue = &(p->pClauses);
+    Gia_Obj_t * pObj;
+    int i, LevelMax = -1, LevelCur;
+    assert( pQue->pData[hClause0] != NULL );
+    assert( pQue->pData[hClause0] == pQue->pData[hClause1] );
+/*
+    for ( i = hClause0 + 1; (pObj = pQue->pData[i]); i++ )
+        assert( pObj->fMark0 == 1 );
+    for ( i = hClause1 + 1; (pObj = pQue->pData[i]); i++ )
+        assert( pObj->fMark0 == 1 );
+*/
+    assert( Cbs2_QueIsEmpty( pQue ) );
+    Cbs2_QuePush( pQue, NULL );
+    for ( i = hClause0 + 1; (pObj = pQue->pData[i]); i++ )
+    {
+        if ( !pObj->fMark0 ) // unassigned - seen again
+            continue;
+        // assigned - seen first time
+        pObj->fMark0 = 0;
+        Cbs2_QuePush( pQue, pObj );
+        LevelCur = Cbs2_VarDecLevel( p, pObj );
+        if ( LevelMax < LevelCur )
+            LevelMax = LevelCur;
+    }
+    for ( i = hClause1 + 1; (pObj = pQue->pData[i]); i++ )
+    {
+        if ( !pObj->fMark0 ) // unassigned - seen again
+            continue;
+        // assigned - seen first time
+        pObj->fMark0 = 0;
+        Cbs2_QuePush( pQue, pObj );
+        LevelCur = Cbs2_VarDecLevel( p, pObj );
+        if ( LevelMax < LevelCur )
+            LevelMax = LevelCur;
+    }
+    for ( i = pQue->iHead + 1; i < pQue->iTail; i++ )
+        pQue->pData[i]->fMark0 = 1;
+    Cbs2_ManDeriveReason( p, LevelMax );
+    return Cbs2_QueFinish( pQue );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Propagates a variable.]
+
+  Description [Returns clause handle if conflict; 0 if no conflict.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs2_ManPropagateOne( Cbs2_Man_t * p, Gia_Obj_t * pVar, int Level )
+{
+    int Value0, Value1;
+    assert( !Gia_IsComplement(pVar) );
+    assert( Cbs2_VarIsAssigned(pVar) );
+    if ( Gia_ObjIsCi(pVar) )
+        return 0;
+    assert( Gia_ObjIsAnd(pVar) );
+    Value0 = Cbs2_VarFanin0Value(pVar);
+    Value1 = Cbs2_VarFanin1Value(pVar);
+    if ( Cbs2_VarValue(pVar) )
+    { // value is 1
+        if ( Value0 == 0 || Value1 == 0 ) // one is 0
+        {
+            if ( Value0 == 0 && Value1 != 0 )
+                return Cbs2_ManAnalyze( p, Level, pVar, Gia_ObjFanin0(pVar), NULL );
+            if ( Value0 != 0 && Value1 == 0 )
+                return Cbs2_ManAnalyze( p, Level, pVar, Gia_ObjFanin1(pVar), NULL );
+            assert( Value0 == 0 && Value1 == 0 );
+            return Cbs2_ManAnalyze( p, Level, pVar, Gia_ObjFanin0(pVar), Gia_ObjFanin1(pVar) );
+        }
+        if ( Value0 == 2 ) // first is unassigned
+            Cbs2_ManAssign( p, Gia_ObjChild0(pVar), Level, pVar, NULL );
+        if ( Value1 == 2 ) // first is unassigned
+            Cbs2_ManAssign( p, Gia_ObjChild1(pVar), Level, pVar, NULL );
+        return 0;
+    }
+    // value is 0
+    if ( Value0 == 0 || Value1 == 0 ) // one is 0
+        return 0;
+    if ( Value0 == 1 && Value1 == 1 ) // both are 1
+        return Cbs2_ManAnalyze( p, Level, pVar, Gia_ObjFanin0(pVar), Gia_ObjFanin1(pVar) );
+    if ( Value0 == 1 || Value1 == 1 ) // one is 1 
+    {
+        if ( Value0 == 2 ) // first is unassigned
+            Cbs2_ManAssign( p, Gia_Not(Gia_ObjChild0(pVar)), Level, pVar, Gia_ObjFanin1(pVar) );
+        if ( Value1 == 2 ) // second is unassigned
+            Cbs2_ManAssign( p, Gia_Not(Gia_ObjChild1(pVar)), Level, pVar, Gia_ObjFanin0(pVar) );
+        return 0;
+    }
+    assert( Cbs2_VarIsJust(pVar) );
+    assert( !Cbs2_QueHasNode( &p->pJust, pVar ) );
+    Cbs2_QuePush( &p->pJust, pVar );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Propagates a variable.]
+
+  Description [Returns 1 if conflict; 0 if no conflict.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs2_ManPropagateTwo( Cbs2_Man_t * p, Gia_Obj_t * pVar, int Level )
+{
+    int Value0, Value1;
+    assert( !Gia_IsComplement(pVar) );
+    assert( Gia_ObjIsAnd(pVar) );
+    assert( Cbs2_VarIsAssigned(pVar) );
+    assert( !Cbs2_VarValue(pVar) );
+    Value0 = Cbs2_VarFanin0Value(pVar);
+    Value1 = Cbs2_VarFanin1Value(pVar);
+    // value is 0
+    if ( Value0 == 0 || Value1 == 0 ) // one is 0
+        return 0;
+    if ( Value0 == 1 && Value1 == 1 ) // both are 1
+        return Cbs2_ManAnalyze( p, Level, pVar, Gia_ObjFanin0(pVar), Gia_ObjFanin1(pVar) );
+    assert( Value0 == 1 || Value1 == 1 );
+    if ( Value0 == 2 ) // first is unassigned
+        Cbs2_ManAssign( p, Gia_Not(Gia_ObjChild0(pVar)), Level, pVar, Gia_ObjFanin1(pVar) );
+    if ( Value1 == 2 ) // first is unassigned
+        Cbs2_ManAssign( p, Gia_Not(Gia_ObjChild1(pVar)), Level, pVar, Gia_ObjFanin0(pVar) );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Propagates all variables.]
+
+  Description [Returns 1 if conflict; 0 if no conflict.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cbs2_ManPropagate( Cbs2_Man_t * p, int Level )
+{
+    int hClause;
+    Gia_Obj_t * pVar;
+    int i, k;
+    while ( 1 )
+    {
+        Cbs2_QueForEachEntry( p->pProp, pVar, i )
+        {
+            if ( (hClause = Cbs2_ManPropagateOne( p, pVar, Level )) )
+                return hClause;
+        }
+        p->pProp.iHead = p->pProp.iTail;
+        k = p->pJust.iHead;
+        Cbs2_QueForEachEntry( p->pJust, pVar, i )
+        {
+            if ( Cbs2_VarIsJust( pVar ) )
+                p->pJust.pData[k++] = pVar;
+            else if ( (hClause = Cbs2_ManPropagateTwo( p, pVar, Level )) )
+                return hClause;
+        }
+        if ( k == p->pJust.iTail )
+            break;
+        p->pJust.iTail = k;
+    }
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Solve the problem recursively.]
+
+  Description [Returns learnt clause if unsat, NULL if sat or undecided.]
+               
+  SideEffects []
+
+  SeeAlso     []
+ 
+***********************************************************************/
+int Cbs2_ManSolve_rec( Cbs2_Man_t * p, int Level )
+{ 
+    Cbs2_Que_t * pQue = &(p->pClauses);
+    Gia_Obj_t * pVar = NULL, * pDecVar;
+    int hClause, hLearn0, hLearn1;
+    int iPropHead, iJustHead, iJustTail;
+    // propagate assignments
+    assert( !Cbs2_QueIsEmpty(&p->pProp) );
+    if ( (hClause = Cbs2_ManPropagate( p, Level )) )
+        return hClause;
+    // check for satisfying assignment
+    assert( Cbs2_QueIsEmpty(&p->pProp) );
+    if ( Cbs2_QueIsEmpty(&p->pJust) )
+        return 0;
+    // quit using resource limits
+    p->Pars.nJustThis = Abc_MaxInt( p->Pars.nJustThis, p->pJust.iTail - p->pJust.iHead );
+    if ( Cbs2_ManCheckLimits( p ) )
+        return 0;
+    // remember the state before branching
+    iPropHead = p->pProp.iHead;
+    Cbs2_QueStore( &p->pJust, &iJustHead, &iJustTail );
+    // find the decision variable
+    if ( p->Pars.fUseHighest )
+        pVar = Cbs2_ManDecideHighest( p );
+    else if ( p->Pars.fUseLowest )
+        pVar = Cbs2_ManDecideLowest( p );
+    else if ( p->Pars.fUseMaxFF )
+        pVar = Cbs2_ManDecideMaxFF( p );
+    else assert( 0 );
+    assert( Cbs2_VarIsJust( pVar ) );
+    // chose decision variable using fanout count
+    if ( Gia_ObjRefNum(p->pAig, Gia_ObjFanin0(pVar)) > Gia_ObjRefNum(p->pAig, Gia_ObjFanin1(pVar)) )
+        pDecVar = Gia_Not(Gia_ObjChild0(pVar));
+    else
+        pDecVar = Gia_Not(Gia_ObjChild1(pVar));
+//    pDecVar = Gia_NotCond( Gia_Regular(pDecVar), Gia_Regular(pDecVar)->fPhase );
+//    pDecVar = Gia_Not(pDecVar);
+    // decide on first fanin
+    Cbs2_ManAssign( p, pDecVar, Level+1, NULL, NULL );
+    if ( !(hLearn0 = Cbs2_ManSolve_rec( p, Level+1 )) )
+        return 0;
+    if ( pQue->pData[hLearn0] != Gia_Regular(pDecVar) )
+        return hLearn0;
+    Cbs2_ManCancelUntil( p, iPropHead );
+    Cbs2_QueRestore( &p->pJust, iJustHead, iJustTail );
+    // decide on second fanin
+    Cbs2_ManAssign( p, Gia_Not(pDecVar), Level+1, NULL, NULL );
+    if ( !(hLearn1 = Cbs2_ManSolve_rec( p, Level+1 )) )
+        return 0;
+    if ( pQue->pData[hLearn1] != Gia_Regular(pDecVar) )
+        return hLearn1;
+    hClause = Cbs2_ManResolve( p, Level, hLearn0, hLearn1 );
+//    Cbs2_ManPrintClauseNew( p, Level, hClause );
+//    if ( Level > Cbs2_ClauseDecLevel(p, hClause) )
+//        p->Pars.nBTThisNc++;
+    p->Pars.nBTThis++;
+    return hClause;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Looking for a satisfying assignment of the node.]
+
+  Description [Assumes that each node has flag pObj->fMark0 set to 0.
+  Returns 1 if unsatisfiable, 0 if satisfiable, and -1 if undecided.
+  The node may be complemented. ]
+               
+  SideEffects [The two procedures differ in the CEX format.]
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cbs2_ManSolve( Cbs2_Man_t * p, Gia_Obj_t * pObj )
+{
+    int RetValue = 0;
+    assert( !p->pProp.iHead && !p->pProp.iTail );
+    assert( !p->pJust.iHead && !p->pJust.iTail );
+    assert( p->pClauses.iHead == 1 && p->pClauses.iTail == 1 );
+    p->Pars.nBTThis = p->Pars.nJustThis = p->Pars.nBTThisNc = 0;
+    Cbs2_ManAssign( p, pObj, 0, NULL, NULL );
+    if ( !Cbs2_ManSolve_rec(p, 0) && !Cbs2_ManCheckLimits(p) )
+        Cbs2_ManSaveModel( p, p->vModel );
+    else
+        RetValue = 1;
+    Cbs2_ManCancelUntil( p, 0 );
+    p->pJust.iHead = p->pJust.iTail = 0;
+    p->pClauses.iHead = p->pClauses.iTail = 1;
+    p->Pars.nBTTotal += p->Pars.nBTThis;
+    p->Pars.nJustTotal = Abc_MaxInt( p->Pars.nJustTotal, p->Pars.nJustThis );
+    if ( Cbs2_ManCheckLimits( p ) )
+        RetValue = -1;
+    return RetValue;
+}
+int Cbs2_ManSolve2( Cbs2_Man_t * p, Gia_Obj_t * pObj, Gia_Obj_t * pObj2 )
+{
+    int RetValue = 0;
+    assert( !p->pProp.iHead && !p->pProp.iTail );
+    assert( !p->pJust.iHead && !p->pJust.iTail );
+    assert( p->pClauses.iHead == 1 && p->pClauses.iTail == 1 );
+    p->Pars.nBTThis = p->Pars.nJustThis = p->Pars.nBTThisNc = 0;
+    Cbs2_ManAssign( p, pObj, 0, NULL, NULL );
+    if ( pObj2 ) 
+    Cbs2_ManAssign( p, pObj2, 0, NULL, NULL );
+    if ( !Cbs2_ManSolve_rec(p, 0) && !Cbs2_ManCheckLimits(p) )
+        Cbs2_ManSaveModelAll( p, p->vModel );
+    else
+        RetValue = 1;
+    Cbs2_ManCancelUntil( p, 0 );
+    p->pJust.iHead = p->pJust.iTail = 0;
+    p->pClauses.iHead = p->pClauses.iTail = 1;
+    p->Pars.nBTTotal += p->Pars.nBTThis;
+    p->Pars.nJustTotal = Abc_MaxInt( p->Pars.nJustTotal, p->Pars.nJustThis );
+    if ( Cbs2_ManCheckLimits( p ) )
+        RetValue = -1;
+    return RetValue;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints statistics of the manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cbs2_ManSatPrintStats( Cbs2_Man_t * p )
+{
+    printf( "CO = %8d  ", Gia_ManCoNum(p->pAig) );
+    printf( "AND = %8d  ", Gia_ManAndNum(p->pAig) );
+    printf( "Conf = %6d  ", p->Pars.nBTLimit );
+    printf( "JustMax = %5d  ", p->Pars.nJustLimit );
+    printf( "\n" );
+    printf( "Unsat calls %6d  (%6.2f %%)   Ave conf = %8.1f   ", 
+        p->nSatUnsat, p->nSatTotal? 100.0*p->nSatUnsat/p->nSatTotal :0.0, p->nSatUnsat? 1.0*p->nConfUnsat/p->nSatUnsat :0.0 );
+    ABC_PRTP( "Time", p->timeSatUnsat, p->timeTotal );
+    printf( "Sat   calls %6d  (%6.2f %%)   Ave conf = %8.1f   ", 
+        p->nSatSat,   p->nSatTotal? 100.0*p->nSatSat/p->nSatTotal :0.0, p->nSatSat? 1.0*p->nConfSat/p->nSatSat : 0.0 );
+    ABC_PRTP( "Time", p->timeSatSat,   p->timeTotal );
+    printf( "Undef calls %6d  (%6.2f %%)   Ave conf = %8.1f   ", 
+        p->nSatUndec, p->nSatTotal? 100.0*p->nSatUndec/p->nSatTotal :0.0, p->nSatUndec? 1.0*p->nConfUndec/p->nSatUndec : 0.0 );
+    ABC_PRTP( "Time", p->timeSatUndec, p->timeTotal );
+    ABC_PRT( "Total time", p->timeTotal );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Procedure to test the new SAT solver.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Cbs2_ManSolveMiterNc( Gia_Man_t * pAig, int nConfs, Vec_Str_t ** pvStatus, int fVerbose )
+{
+    extern void Gia_ManCollectTest( Gia_Man_t * pAig );
+    extern void Cec_ManSatAddToStore( Vec_Int_t * vCexStore, Vec_Int_t * vCex, int Out );
+    Cbs2_Man_t * p; 
+    Vec_Int_t * vCex, * vVisit, * vCexStore;
+    Vec_Str_t * vStatus;
+    Gia_Obj_t * pRoot; 
+    int i, status;
+    abctime clk, clkTotal = Abc_Clock();
+    assert( Gia_ManRegNum(pAig) == 0 );
+//    Gia_ManCollectTest( pAig );
+    // prepare AIG
+    Gia_ManCreateRefs( pAig );
+    Gia_ManCleanMark0( pAig );
+    Gia_ManCleanMark1( pAig );
+    Gia_ManFillValue( pAig ); // maps nodes into trail ids
+    Gia_ManSetPhase( pAig ); // maps nodes into trail ids
+    // create logic network
+    p = Cbs2_ManAlloc( pAig );
+    p->Pars.nBTLimit = nConfs;
+    // create resulting data-structures
+    vStatus   = Vec_StrAlloc( Gia_ManPoNum(pAig) );
+    vCexStore = Vec_IntAlloc( 10000 );
+    vVisit    = Vec_IntAlloc( 100 );
+    vCex      = Cbs2_ReadModel( p );
+    // solve for each output
+    Gia_ManForEachCo( pAig, pRoot, i )
+    {
+//        printf( "\n" );
+
+        Vec_IntClear( vCex );
+        if ( Gia_ObjIsConst0(Gia_ObjFanin0(pRoot)) )
+        {
+            if ( Gia_ObjFaninC0(pRoot) )
+            {
+//                printf( "Constant 1 output of SRM!!!\n" );
+                Cec_ManSatAddToStore( vCexStore, vCex, i ); // trivial counter-example
+                Vec_StrPush( vStatus, 0 );
+            }
+            else
+            {
+//                printf( "Constant 0 output of SRM!!!\n" );
+                Vec_StrPush( vStatus, 1 );
+            }
+            continue;
+        }
+        clk = Abc_Clock();
+        p->Pars.fUseHighest = 1;
+        p->Pars.fUseLowest  = 0;
+        status = Cbs2_ManSolve( p, Gia_ObjChild0(pRoot) );
+//        printf( "\n" );
+/*
+        if ( status == -1 )
+        {
+            p->Pars.fUseHighest = 0;
+            p->Pars.fUseLowest  = 1;
+            status = Cbs2_ManSolve( p, Gia_ObjChild0(pRoot) );
+        }
+*/
+        Vec_StrPush( vStatus, (char)status );
+        if ( status == -1 )
+        {
+            p->nSatUndec++;
+            p->nConfUndec += p->Pars.nBTThis;
+            Cec_ManSatAddToStore( vCexStore, NULL, i ); // timeout
+            p->timeSatUndec += Abc_Clock() - clk;
+            continue;
+        }
+        if ( status == 1 )
+        {
+            p->nSatUnsat++;
+            p->nConfUnsat += p->Pars.nBTThis;
+            p->timeSatUnsat += Abc_Clock() - clk;
+            continue;
+        }
+        p->nSatSat++;
+        p->nConfSat += p->Pars.nBTThis;
+//        Gia_SatVerifyPattern( pAig, pRoot, vCex, vVisit );
+        Cec_ManSatAddToStore( vCexStore, vCex, i );
+        p->timeSatSat += Abc_Clock() - clk;
+    }
+    Vec_IntFree( vVisit );
+    p->nSatTotal = Gia_ManPoNum(pAig);
+    p->timeTotal = Abc_Clock() - clkTotal;
+    if ( fVerbose )
+        Cbs2_ManSatPrintStats( p );
+//    printf( "RecCalls = %8d.  RecClause = %8d.  RecNonChro = %8d.\n", p->nRecCall, p->nRecClause, p->nRecNonChro );
+    Cbs2_ManStop( p );
+    *pvStatus = vStatus;
+
+//    printf( "Total number of cex literals = %d. (Ave = %d)\n", 
+//         Vec_IntSize(vCexStore)-2*p->nSatUndec-2*p->nSatSat, 
+//        (Vec_IntSize(vCexStore)-2*p->nSatUndec-2*p->nSatSat)/p->nSatSat );
+    return vCexStore;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
+ABC_NAMESPACE_IMPL_END
+