Experiments with SAT sweeping.

2 files changed, 863 insertions, 0 deletions

diff --git a/src/proof/cec/cecSat.c b/src/proof/cec/cecSat.c
new file mode 100644
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+++ b/src/proof/cec/cecSat.c
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+/**CFile****************************************************************
+
+  FileName    [cecSat.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Combinational equivalence checking.]
+
+  Synopsis    [Detection of structural isomorphism.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cecSat.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "aig/gia/gia.h"
+#include "misc/util/utilTruth.h"
+#include "sat/satoko/satoko.h"
+#include "sat/satoko/solver.h"
+
+ABC_NAMESPACE_IMPL_START
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+// sweeping manager
+typedef struct Cec2_Par_t_ Cec2_Par_t;
+struct Cec2_Par_t_
+{
+    int              nSimWords;     // simulation words
+    int              nSimRounds;    // simulation rounds
+    int              nConfLimit;    // SAT solver conflict limit
+    int              fIsMiter;      // this is a miter
+    int              fVeryVerbose;  // verbose stats
+    int              fVerbose;      // verbose stats
+};
+
+// SAT solving manager
+typedef struct Cec2_Man_t_ Cec2_Man_t;
+struct Cec2_Man_t_
+{
+    Cec2_Par_t *     pPars;          // parameters
+    Gia_Man_t *      pAig;           // user's AIG
+    Gia_Man_t *      pNew;           // internal AIG
+    // SAT solving
+    satoko_t *       pSat;           // SAT solver
+    Vec_Ptr_t *      vFrontier;      // CNF construction
+    Vec_Ptr_t *      vFanins;        // CNF construction
+    Vec_Wrd_t *      vSims;          // CI simulation info
+    Vec_Int_t *      vNodesNew;      // nodes
+    Vec_Int_t *      vObjSatPairs;   // nodes
+};
+
+static inline int    Cec2_ObjSatId( Gia_Man_t * p, Gia_Obj_t * pObj )             { return Gia_ObjCopyArray(p, Gia_ObjId(p, pObj));                                                     }
+static inline int    Cec2_ObjSetSatId( Gia_Man_t * p, Gia_Obj_t * pObj, int Num ) { assert(Cec2_ObjSatId(p, pObj) == -1); Gia_ObjSetCopyArray(p, Gia_ObjId(p, pObj), Num); return Num;  }
+static inline void   Cec2_ObjCleanSatId( Gia_Man_t * p, Gia_Obj_t * pObj )        { assert(Cec2_ObjSatId(p, pObj) != -1); Gia_ObjSetCopyArray(p, Gia_ObjId(p, pObj), -1);               }
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Sets parameter defaults.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cec2_SetDefaultParams( Cec2_Par_t * p )
+{
+    memset( p, 0, sizeof(Cec2_Par_t) );
+    p->nSimWords      =       8;    // simulation words
+    p->nSimRounds     =       4;    // simulation rounds
+    p->nConfLimit     =    1000;    // conflict limit at a node
+    p->fIsMiter       =       0;    // this is a miter
+    p->fVeryVerbose   =       0;    // verbose stats
+    p->fVerbose       =       1;    // verbose stats
+}  
+
+/**Function*************************************************************
+
+  Synopsis    [Adds clauses to the solver.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cec2_AddClausesMux( Gia_Man_t * p, Gia_Obj_t * pNode, satoko_t * pSat )
+{
+    int fPolarFlip = 0;
+    Gia_Obj_t * pNodeI, * pNodeT, * pNodeE;
+    int pLits[4], RetValue, VarF, VarI, VarT, VarE, fCompT, fCompE;
+
+    assert( !Gia_IsComplement( pNode ) );
+    assert( pNode->fMark0 );
+    // get nodes (I = if, T = then, E = else)
+    pNodeI = Gia_ObjRecognizeMux( pNode, &pNodeT, &pNodeE );
+    // get the variable numbers
+    VarF = Cec2_ObjSatId(p, pNode);
+    VarI = Cec2_ObjSatId(p, pNodeI);
+    VarT = Cec2_ObjSatId(p, Gia_Regular(pNodeT));
+    VarE = Cec2_ObjSatId(p, Gia_Regular(pNodeE));
+    // get the complementation flags
+    fCompT = Gia_IsComplement(pNodeT);
+    fCompE = Gia_IsComplement(pNodeE);
+
+    // f = ITE(i, t, e)
+
+    // i' + t' + f
+    // i' + t  + f'
+    // i  + e' + f
+    // i  + e  + f'
+
+    // create four clauses
+    pLits[0] = Abc_Var2Lit(VarI, 1);
+    pLits[1] = Abc_Var2Lit(VarT, 1^fCompT);
+    pLits[2] = Abc_Var2Lit(VarF, 0);
+    if ( fPolarFlip )
+    {
+        if ( pNodeI->fPhase )               pLits[0] = Abc_LitNot( pLits[0] );
+        if ( Gia_Regular(pNodeT)->fPhase )  pLits[1] = Abc_LitNot( pLits[1] );
+        if ( pNode->fPhase )                pLits[2] = Abc_LitNot( pLits[2] );
+    }
+    RetValue = satoko_add_clause( pSat, pLits, 3 );
+    assert( RetValue );
+    pLits[0] = Abc_Var2Lit(VarI, 1);
+    pLits[1] = Abc_Var2Lit(VarT, 0^fCompT);
+    pLits[2] = Abc_Var2Lit(VarF, 1);
+    if ( fPolarFlip )
+    {
+        if ( pNodeI->fPhase )               pLits[0] = Abc_LitNot( pLits[0] );
+        if ( Gia_Regular(pNodeT)->fPhase )  pLits[1] = Abc_LitNot( pLits[1] );
+        if ( pNode->fPhase )                pLits[2] = Abc_LitNot( pLits[2] );
+    }
+    RetValue = satoko_add_clause( pSat, pLits, 3 );
+    assert( RetValue );
+    pLits[0] = Abc_Var2Lit(VarI, 0);
+    pLits[1] = Abc_Var2Lit(VarE, 1^fCompE);
+    pLits[2] = Abc_Var2Lit(VarF, 0);
+    if ( fPolarFlip )
+    {
+        if ( pNodeI->fPhase )               pLits[0] = Abc_LitNot( pLits[0] );
+        if ( Gia_Regular(pNodeE)->fPhase )  pLits[1] = Abc_LitNot( pLits[1] );
+        if ( pNode->fPhase )                pLits[2] = Abc_LitNot( pLits[2] );
+    }
+    RetValue = satoko_add_clause( pSat, pLits, 3 );
+    assert( RetValue );
+    pLits[0] = Abc_Var2Lit(VarI, 0);
+    pLits[1] = Abc_Var2Lit(VarE, 0^fCompE);
+    pLits[2] = Abc_Var2Lit(VarF, 1);
+    if ( fPolarFlip )
+    {
+        if ( pNodeI->fPhase )               pLits[0] = Abc_LitNot( pLits[0] );
+        if ( Gia_Regular(pNodeE)->fPhase )  pLits[1] = Abc_LitNot( pLits[1] );
+        if ( pNode->fPhase )                pLits[2] = Abc_LitNot( pLits[2] );
+    }
+    RetValue = satoko_add_clause( pSat, 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] = Abc_Var2Lit(VarT, 0^fCompT);
+    pLits[1] = Abc_Var2Lit(VarE, 0^fCompE);
+    pLits[2] = Abc_Var2Lit(VarF, 1);
+    if ( fPolarFlip )
+    {
+        if ( Gia_Regular(pNodeT)->fPhase )  pLits[0] = Abc_LitNot( pLits[0] );
+        if ( Gia_Regular(pNodeE)->fPhase )  pLits[1] = Abc_LitNot( pLits[1] );
+        if ( pNode->fPhase )                pLits[2] = Abc_LitNot( pLits[2] );
+    }
+    RetValue = satoko_add_clause( pSat, pLits, 3 );
+    assert( RetValue );
+    pLits[0] = Abc_Var2Lit(VarT, 1^fCompT);
+    pLits[1] = Abc_Var2Lit(VarE, 1^fCompE);
+    pLits[2] = Abc_Var2Lit(VarF, 0);
+    if ( fPolarFlip )
+    {
+        if ( Gia_Regular(pNodeT)->fPhase )  pLits[0] = Abc_LitNot( pLits[0] );
+        if ( Gia_Regular(pNodeE)->fPhase )  pLits[1] = Abc_LitNot( pLits[1] );
+        if ( pNode->fPhase )                pLits[2] = Abc_LitNot( pLits[2] );
+    }
+    RetValue = satoko_add_clause( pSat, pLits, 3 );
+    assert( RetValue );
+}
+void Cec2_AddClausesSuper( Gia_Man_t * p, Gia_Obj_t * pNode, Vec_Ptr_t * vSuper, satoko_t * pSat )
+{
+    int fPolarFlip = 0;
+    Gia_Obj_t * pFanin;
+    int * pLits, nLits, RetValue, i;
+    assert( !Gia_IsComplement(pNode) );
+    assert( Gia_ObjIsAnd( pNode ) );
+    // create storage for literals
+    nLits = Vec_PtrSize(vSuper) + 1;
+    pLits = ABC_ALLOC( int, nLits );
+    // suppose AND-gate is A & B = C
+    // add !A => !C   or   A + !C
+    Vec_PtrForEachEntry( Gia_Obj_t *, vSuper, pFanin, i )
+    {
+        pLits[0] = Abc_Var2Lit(Cec2_ObjSatId(p, Gia_Regular(pFanin)), Gia_IsComplement(pFanin));
+        pLits[1] = Abc_Var2Lit(Cec2_ObjSatId(p, pNode), 1);
+        if ( fPolarFlip )
+        {
+            if ( Gia_Regular(pFanin)->fPhase )  pLits[0] = Abc_LitNot( pLits[0] );
+            if ( pNode->fPhase )                pLits[1] = Abc_LitNot( pLits[1] );
+        }
+        RetValue = satoko_add_clause( pSat, pLits, 2 );
+        assert( RetValue );
+    }
+    // add A & B => C   or   !A + !B + C
+    Vec_PtrForEachEntry( Gia_Obj_t *, vSuper, pFanin, i )
+    {
+        pLits[i] = Abc_Var2Lit(Cec2_ObjSatId(p, Gia_Regular(pFanin)), !Gia_IsComplement(pFanin));
+        if ( fPolarFlip )
+        {
+            if ( Gia_Regular(pFanin)->fPhase )  pLits[i] = Abc_LitNot( pLits[i] );
+        }
+    }
+    pLits[nLits-1] = Abc_Var2Lit(Cec2_ObjSatId(p, pNode), 0);
+    if ( fPolarFlip )
+    {
+        if ( pNode->fPhase )  pLits[nLits-1] = Abc_LitNot( pLits[nLits-1] );
+    }
+    RetValue = satoko_add_clause( pSat, pLits, nLits );
+    assert( RetValue );
+    ABC_FREE( pLits );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds clauses and returns CNF variable of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cec2_CollectSuper_rec( Gia_Obj_t * pObj, Vec_Ptr_t * vSuper, int fFirst, int fUseMuxes )
+{
+    // if the new node is complemented or a PI, another gate begins
+    if ( Gia_IsComplement(pObj) || Gia_ObjIsCi(pObj) || 
+         (!fFirst && Gia_ObjValue(pObj) > 1) || 
+         (fUseMuxes && pObj->fMark0) )
+    {
+        Vec_PtrPushUnique( vSuper, pObj );
+        return;
+    }
+    // go through the branches
+    Cec2_CollectSuper_rec( Gia_ObjChild0(pObj), vSuper, 0, fUseMuxes );
+    Cec2_CollectSuper_rec( Gia_ObjChild1(pObj), vSuper, 0, fUseMuxes );
+}
+void Cec2_CollectSuper( Gia_Obj_t * pObj, int fUseMuxes, Vec_Ptr_t * vSuper )
+{
+    assert( !Gia_IsComplement(pObj) );
+    assert( !Gia_ObjIsCi(pObj) );
+    Vec_PtrClear( vSuper );
+    Cec2_CollectSuper_rec( pObj, vSuper, 1, fUseMuxes );
+}
+void Cec2_ObjAddToFrontier( Gia_Man_t * p, Gia_Obj_t * pObj, Vec_Ptr_t * vFrontier, satoko_t * pSat )
+{
+    assert( !Gia_IsComplement(pObj) );
+    assert( !Gia_ObjIsConst0(pObj) );
+    if ( Cec2_ObjSatId(p, pObj) >= 0 )
+        return;
+    assert( Cec2_ObjSatId(p, pObj) == -1 );
+    Cec2_ObjSetSatId( p, pObj, satoko_add_variable(pSat, 0) );
+    if ( Gia_ObjIsAnd(pObj) )
+        Vec_PtrPush( vFrontier, pObj );
+}
+int Cec2_ObjGetCnfVar( Cec2_Man_t * p, int iObj )
+{ 
+    Gia_Obj_t * pNode, * pFanin;
+    Gia_Obj_t * pObj = Gia_ManObj(p->pNew, iObj);
+    int i, k, fUseMuxes = 1;
+    // quit if CNF is ready
+    if ( Cec2_ObjSatId(p->pNew,pObj) >= 0 )
+        return Cec2_ObjSatId(p->pNew,pObj);
+    assert( iObj > 0 );
+    if ( Gia_ObjIsCi(pObj) )
+        return Cec2_ObjSetSatId( p->pNew, pObj, satoko_add_variable(p->pSat, 0) );
+    assert( Gia_ObjIsAnd(pObj) );
+    // start the frontier
+    Vec_PtrClear( p->vFrontier );
+    Cec2_ObjAddToFrontier( p->pNew, pObj, p->vFrontier, p->pSat );
+    // explore nodes in the frontier
+    Vec_PtrForEachEntry( Gia_Obj_t *, p->vFrontier, pNode, i )
+    {
+        // create the supergate
+        assert( Cec2_ObjSatId(p->pNew,pNode) >= 0 );
+        if ( fUseMuxes && pNode->fMark0 )
+        {
+            Vec_PtrClear( p->vFanins );
+            Vec_PtrPushUnique( p->vFanins, Gia_ObjFanin0( Gia_ObjFanin0(pNode) ) );
+            Vec_PtrPushUnique( p->vFanins, Gia_ObjFanin0( Gia_ObjFanin1(pNode) ) );
+            Vec_PtrPushUnique( p->vFanins, Gia_ObjFanin1( Gia_ObjFanin0(pNode) ) );
+            Vec_PtrPushUnique( p->vFanins, Gia_ObjFanin1( Gia_ObjFanin1(pNode) ) );
+            Vec_PtrForEachEntry( Gia_Obj_t *, p->vFanins, pFanin, k )
+                Cec2_ObjAddToFrontier( p->pNew, Gia_Regular(pFanin), p->vFrontier, p->pSat );
+            Cec2_AddClausesMux( p->pNew, pNode, p->pSat );
+        }
+        else
+        {
+            Cec2_CollectSuper( pNode, fUseMuxes, p->vFanins );
+            Vec_PtrForEachEntry( Gia_Obj_t *, p->vFanins, pFanin, k )
+                Cec2_ObjAddToFrontier( p->pNew, Gia_Regular(pFanin), p->vFrontier, p->pSat );
+            Cec2_AddClausesSuper( p->pNew, pNode, p->vFanins, p->pSat );
+        }
+        assert( Vec_PtrSize(p->vFanins) > 1 );
+    }
+    return Cec2_ObjSatId(p->pNew,pObj);
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Internal simulation APIs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline word * Cec2_ObjSim( Gia_Man_t * p, int iObj )
+{
+    return Vec_WrdEntryP( p->vSims, p->nSimWords * iObj );
+}
+static inline void Cec2_ObjSimSetPiBit( Gia_Man_t * p, int iObj, int Bit )
+{
+    word * pSim = Cec2_ObjSim( p, iObj );
+    p->iPatsPi = (p->iPatsPi == 64 * p->nSimWords - 1) ? 1 : p->iPatsPi + 1;
+    assert( p->iPatsPi > 0 && p->iPatsPi < 64 * p->nSimWords );
+    if ( Abc_InfoHasBit( (unsigned*)pSim, p->iPatsPi ) != Bit )
+        Abc_InfoXorBit( (unsigned*)pSim, p->iPatsPi );
+}
+static inline void Cec2_ObjSimRo( Gia_Man_t * p, int iObj )
+{
+    int w;
+    word * pSimRo = Cec2_ObjSim( p, iObj );
+    word * pSimRi = Cec2_ObjSim( p, Gia_ObjRoToRiId(p, iObj) );
+    for ( w = 0; w < p->nSimWords; w++ )
+        pSimRo[w] = pSimRi[w];
+}
+static inline void Cec2_ObjSimCo( Gia_Man_t * p, int iObj )
+{
+    int w;
+    Gia_Obj_t * pObj = Gia_ManObj( p, iObj );
+    word * pSimCo  = Cec2_ObjSim( p, iObj );
+    word * pSimDri = Cec2_ObjSim( p, Gia_ObjFaninId0(pObj, iObj) );
+    if ( Gia_ObjFaninC0(pObj) )
+        for ( w = 0; w < p->nSimWords; w++ )
+            pSimCo[w] = ~pSimDri[w];
+    else
+        for ( w = 0; w < p->nSimWords; w++ )
+            pSimCo[w] =  pSimDri[w];
+}
+static inline void Cec2_ObjSimAnd( Gia_Man_t * p, int iObj )
+{
+    int w;
+    Gia_Obj_t * pObj = Gia_ManObj( p, iObj );
+    word * pSim  = Cec2_ObjSim( p, iObj );
+    word * pSim0 = Cec2_ObjSim( p, Gia_ObjFaninId0(pObj, iObj) );
+    word * pSim1 = Cec2_ObjSim( p, Gia_ObjFaninId1(pObj, iObj) );
+    if ( Gia_ObjFaninC0(pObj) && Gia_ObjFaninC1(pObj) )
+        for ( w = 0; w < p->nSimWords; w++ )
+            pSim[w] = ~pSim0[w] & ~pSim1[w];
+    else if ( Gia_ObjFaninC0(pObj) && !Gia_ObjFaninC1(pObj) )
+        for ( w = 0; w < p->nSimWords; w++ )
+            pSim[w] = ~pSim0[w] & pSim1[w];
+    else if ( !Gia_ObjFaninC0(pObj) && Gia_ObjFaninC1(pObj) )
+        for ( w = 0; w < p->nSimWords; w++ )
+            pSim[w] = pSim0[w] & ~pSim1[w];
+    else
+        for ( w = 0; w < p->nSimWords; w++ )
+            pSim[w] = pSim0[w] & pSim1[w];
+}
+static inline int Cec2_ObjSimEqual( Gia_Man_t * p, int iObj0, int iObj1 )
+{
+    int w;
+    word * pSim0 = Cec2_ObjSim( p, iObj0 );
+    word * pSim1 = Cec2_ObjSim( p, iObj1 );
+    if ( (pSim0[0] & 1) == (pSim1[0] & 1) )
+    {
+        for ( w = 0; w < p->nSimWords; w++ )
+            if ( pSim0[w] != pSim1[w] )
+                return 0;
+        return 1;
+    }
+    else
+    {
+        for ( w = 0; w < p->nSimWords; w++ )
+            if ( pSim0[w] != ~pSim1[w] )
+                return 0;
+        return 1;
+    }
+}
+static inline void Cec2_ObjSimPi( Gia_Man_t * p, int iObj )
+{
+    int w;
+    word * pSim = Cec2_ObjSim( p, iObj );
+    for ( w = 0; w < p->nSimWords; w++ )
+        pSim[w] = Gia_ManRandomW( 0 );
+    pSim[0] <<= 1;
+}
+void Cec2_ManSimulateCis( Gia_Man_t * p )
+{
+    int i, Id;
+    Gia_ManForEachCiId( p, Id, i )
+        Cec2_ObjSimPi( p, Id );
+    p->iPatsPi = 1;
+}
+Abc_Cex_t * Cec2_ManDeriveCex( Gia_Man_t * p, int iOut, int iPat )
+{
+    Abc_Cex_t * pCex;
+    int i, Id;
+    pCex = Abc_CexAlloc( 0, Gia_ManCiNum(p), 1 );
+    pCex->iPo = iOut;
+    if ( iPat == -1 )
+        return pCex;
+    Gia_ManForEachCiId( p, Id, i )
+        if ( Abc_InfoHasBit((unsigned *)Cec2_ObjSim(p, Id), iPat) )
+            Abc_InfoSetBit( pCex->pData, i );
+    return pCex;
+}
+int Cec2_ManSimulateCos( Gia_Man_t * p )
+{
+    int i, Id;
+    // check outputs and generate CEX if they fail
+    Gia_ManForEachCoId( p, Id, i )
+    {
+        Cec2_ObjSimCo( p, Id );
+        if ( Cec2_ObjSimEqual(p, Id, 0) )
+            continue;
+        p->pCexSeq = Cec2_ManDeriveCex( p, i, Abc_TtFindFirstBit2(Cec2_ObjSim(p, Id), p->nSimWords) );
+        return 0;
+    }
+    return 1;
+}
+void Cec2_ManSaveCis( Gia_Man_t * p )
+{
+    int w, i, Id;
+    assert( p->vSimsPi != NULL );
+    for ( w = 0; w < p->nSimWords; w++ )
+        Gia_ManForEachCiId( p, Id, i )
+            Vec_WrdPush( p->vSimsPi, Cec2_ObjSim(p, Id)[w] );
+}
+void Cec2_ManSimulate( Gia_Man_t * p )
+{
+    extern void Cec2_ManSimClassRefineOne( Gia_Man_t * p, int iRepr );
+    Gia_Obj_t * pObj; int i;
+    Cec2_ManSaveCis( p );
+    Gia_ManForEachAnd( p, pObj, i )
+        Cec2_ObjSimAnd( p, i );
+    if ( p->pReprs == NULL )
+        return;
+    Gia_ManForEachClass0( p, i )
+        Cec2_ManSimClassRefineOne( p, i );
+}
+void Cec2_ManSimAlloc( Gia_Man_t * p, int nWords )
+{
+    Vec_WrdFreeP( &p->vSims );
+    Vec_WrdFreeP( &p->vSimsPi );
+    p->vSims   = Vec_WrdStart( Gia_ManObjNum(p) * nWords );
+    p->vSimsPi = Vec_WrdAlloc( Gia_ManCiNum(p) * nWords * 4 ); // storage for CI patterns
+    p->nSimWords = nWords;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computes hash key of the simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cec2_ManSimHashKey( word * pSim, int nSims, int nTableSize )
+{
+    static int s_Primes[16] = { 
+        1291, 1699, 1999, 2357, 2953, 3313, 3907, 4177, 
+        4831, 5147, 5647, 6343, 6899, 7103, 7873, 8147 };
+    unsigned uHash = 0, * pSimU = (unsigned *)pSim;
+    int i, nSimsU = 2 * nSims;
+    if ( pSimU[0] & 1 )
+        for ( i = 0; i < nSimsU; i++ )
+            uHash ^= ~pSimU[i] * s_Primes[i & 0xf];
+    else
+        for ( i = 0; i < nSimsU; i++ )
+            uHash ^= pSimU[i] * s_Primes[i & 0xf];
+    return (int)(uHash % nTableSize);
+
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creating initial equivalence classes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cec2_ManSimClassRefineOne( Gia_Man_t * p, int iRepr )
+{
+    int iObj, iPrev = iRepr, iPrev2, iRepr2;
+    Gia_ClassForEachObj1( p, iRepr, iRepr2 )
+        if ( Cec2_ObjSimEqual(p, iRepr, iRepr2) )
+            iPrev = iRepr2;
+        else
+            break;
+    if ( iRepr2 <= 0 ) // no refinement
+        return;
+    // relink remaining nodes of the class
+    // nodes that are equal to iRepr, remain in the class of iRepr
+    // nodes that are not equal to iRepr, move to the class of iRepr2
+    Gia_ObjSetRepr( p, iRepr2, GIA_VOID );
+    iPrev2 = iRepr2;
+    for ( iObj = Gia_ObjNext(p, iRepr2); iObj > 0; iObj = Gia_ObjNext(p, iObj) )
+    {
+        if ( Cec2_ObjSimEqual(p, iRepr, iObj) ) // remains with iRepr
+        {
+            Gia_ObjSetNext( p, iPrev, iObj );
+            iPrev = iObj;
+        }
+        else // moves to iRepr2
+        {
+            Gia_ObjSetRepr( p, iObj, iRepr2 );
+            Gia_ObjSetNext( p, iPrev2, iObj );
+            iPrev2 = iObj;
+        }
+    }
+    Gia_ObjSetNext( p, iPrev, -1 );
+    Gia_ObjSetNext( p, iPrev2, -1 );
+}
+void Cec2_ManCreateClasses( Gia_Man_t * p )
+{
+    Gia_Obj_t * pObj;
+    int nWords = p->nSimWords;
+    int * pTable, nTableSize, i, Key;
+    // allocate representation
+    assert( p->pReprs == NULL );
+    p->pReprs = ABC_CALLOC( Gia_Rpr_t, Gia_ManObjNum(p) );
+    p->pNexts = ABC_FALLOC( int, Gia_ManObjNum(p) );
+    // hash each node by its simulation info
+    nTableSize = Abc_PrimeCudd( Gia_ManObjNum(p) );
+    pTable = ABC_FALLOC( int, nTableSize );
+    Gia_ManForEachObj( p, pObj, i )
+    {
+        p->pReprs[i].iRepr = GIA_VOID;
+        if ( Gia_ObjIsCo(pObj) )
+            continue;
+        Key = Cec2_ManSimHashKey( Cec2_ObjSim(p, i), nWords, nTableSize );
+        assert( Key >= 0 && Key < nTableSize );
+        if ( pTable[Key] == -1 )
+            pTable[Key] = i;
+        else
+            Gia_ObjSetRepr( p, i, pTable[Key] );
+    }
+    // create classes
+    for ( i = Gia_ManObjNum(p) - 1; i >= 0; i-- )
+    {
+        int iRepr = Gia_ObjRepr(p, i);
+        if ( iRepr == GIA_VOID )
+            continue;
+        Gia_ObjSetNext( p, i, Gia_ObjNext(p, iRepr) );
+        Gia_ObjSetNext( p, iRepr, i );
+    }
+    ABC_FREE( pTable );
+    Gia_ManForEachClass0( p, i )
+        Cec2_ManSimClassRefineOne( p, i );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cec2_Man_t * Cec2_ManCreate( Gia_Man_t * pAig, Cec2_Par_t * pPars )
+{
+    Cec2_Man_t * p;
+    Gia_Obj_t * pObj; int i;
+    assert( Gia_ManRegNum(pAig) == 0 );
+    p = ABC_CALLOC( Cec2_Man_t, 1 );
+    memset( p, 0, sizeof(Cec2_Man_t) );
+    p->pPars        = pPars;
+    p->pAig         = pAig;
+    // create new manager
+    p->pNew         = Gia_ManStart( Gia_ManObjNum(pAig) );
+    Gia_ManFillValue( pAig );
+    Gia_ManConst0(pAig)->Value = 0;
+    Gia_ManForEachCi( pAig, pObj, i )
+        pObj->Value = Gia_ManAppendCi( p->pNew );
+    Gia_ManHashAlloc( p->pNew );
+    Vec_IntFill( &p->pNew->vCopies, Gia_ManObjNum(p->pNew), -1 );
+    // SAT solving
+    p->pSat         = satoko_create();
+    p->vFrontier    = Vec_PtrAlloc( 1000 );
+    p->vFanins      = Vec_PtrAlloc( 100 );
+    p->vNodesNew    = Vec_IntAlloc( 100 );
+    p->vObjSatPairs = Vec_IntAlloc( 100 );
+    // remember pointer to the solver in the AIG manager
+    pAig->pData     = p->pSat;
+    return p;
+}
+void Cec2_ManDestroy( Cec2_Man_t * p )
+{
+    Vec_WrdFreeP( &p->pAig->vSims );
+    //Vec_WrdFreeP( &p->pAig->vSimsPi );
+    Gia_ManCleanMark01( p->pAig );
+    satoko_destroy( p->pSat );
+    Gia_ManStopP( &p->pNew );
+    Vec_PtrFreeP( &p->vFrontier );
+    Vec_PtrFreeP( &p->vFanins );
+    Vec_IntFreeP( &p->vNodesNew );
+    Vec_IntFreeP( &p->vObjSatPairs );
+    ABC_FREE( p );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Internal simulation APIs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cec2_ManCollect_rec( Cec2_Man_t * p, int iObj )
+{
+    Gia_Obj_t * pObj;
+    if ( Gia_ObjIsTravIdCurrentId(p->pNew, iObj) )
+        return;
+    Gia_ObjSetTravIdCurrentId(p->pNew, iObj);
+    pObj = Gia_ManObj( p->pNew, iObj );
+    if ( Cec2_ObjSatId(p->pNew, pObj) >= 0 )
+        Vec_IntPush( p->vNodesNew, iObj );
+    if ( !iObj )
+        return;
+    if ( Gia_ObjIsAnd(pObj) )
+    {
+        Cec2_ManCollect_rec( p, Gia_ObjFaninId0(pObj, iObj) );
+        Cec2_ManCollect_rec( p, Gia_ObjFaninId1(pObj, iObj) );
+    }
+    else
+    {
+        assert( Cec2_ObjSatId(p->pNew, pObj) >= 0 );
+        Vec_IntPushTwo( p->vObjSatPairs, Gia_ManCiIdToId(p->pAig, Gia_ObjCioId(pObj)), Cec2_ObjSatId(p->pNew, pObj) ); // SAT var
+    }
+}
+int Cec2_ManSolveTwo( Cec2_Man_t * p, int iObj0, int iObj1, int fPhase )
+{
+    Gia_Obj_t * pObj;
+    int status, i, iVar0, iVar1;
+    if (iObj1 < iObj0) 
+        iObj1 ^= iObj0, iObj0 ^= iObj1, iObj1 ^= iObj0;
+    assert( iObj0 < iObj1 );
+    assert( solver_varnum(p->pSat) == 0 );
+    if ( !iObj0 )
+        Cec2_ObjSetSatId( p->pNew, Gia_ManConst0(p->pNew), satoko_add_variable(p->pSat, 0) );
+    iVar0 = Cec2_ObjGetCnfVar( p, iObj0 );
+    iVar1 = Cec2_ObjGetCnfVar( p, iObj1 );
+    // collect inputs and internal nodes
+    Vec_IntClear( p->vNodesNew );
+    Vec_IntClear( p->vObjSatPairs );
+    Gia_ManIncrementTravId( p->pNew );
+    Cec2_ManCollect_rec( p, iObj0 );
+    Cec2_ManCollect_rec( p, iObj1 );
+    // solve direct
+    satoko_assump_push( p->pSat, Abc_Var2Lit(iVar0, 1) );
+    satoko_assump_push( p->pSat, Abc_Var2Lit(iVar1, fPhase) );
+    status = satoko_solve( p->pSat );
+    satoko_assump_pop( p->pSat );
+    satoko_assump_pop( p->pSat );
+    if ( status == SATOKO_UNSAT && iObj0 > 0 )
+    {
+        // solve reverse
+        satoko_assump_push( p->pSat, Abc_Var2Lit(iVar0, 0) );
+        satoko_assump_push( p->pSat, Abc_Var2Lit(iVar1, !fPhase) );
+        status = satoko_solve( p->pSat );
+        satoko_assump_pop( p->pSat );
+        satoko_assump_pop( p->pSat );
+    }
+    Gia_ManForEachObjVec( p->vNodesNew, p->pNew, pObj, i )
+        Cec2_ObjCleanSatId( p->pNew, pObj );
+    return status;
+}
+int Cec2_ManSweepNode( Cec2_Man_t * p, int iObj )
+{
+    int i, IdAig, IdSat, status, RetValue = 1;
+    Gia_Obj_t * pObj = Gia_ManObj( p->pAig, iObj );
+    Gia_Obj_t * pRepr = Gia_ObjReprObj( p->pAig, iObj );
+    int fCompl = Abc_LitIsCompl(pObj->Value) ^ Abc_LitIsCompl(pRepr->Value) ^ pObj->fPhase ^ pRepr->fPhase;
+    status = Cec2_ManSolveTwo( p, Abc_Lit2Var(pRepr->Value), Abc_Lit2Var(pObj->Value), fCompl );
+    if ( status == SATOKO_SAT )
+    {
+        Vec_IntForEachEntryDouble( p->vObjSatPairs, IdAig, IdSat, i )
+            Cec2_ObjSimSetPiBit( p->pAig, IdAig, var_value(p->pSat, IdSat) == LIT_TRUE );
+        RetValue = 0;
+    }
+    else if ( status == SATOKO_UNSAT )
+    {
+        pObj->Value = Abc_LitNotCond( pRepr->Value, fCompl );
+        Gia_ObjSetProved( p->pAig, iObj );
+    }
+    else 
+    {
+        assert( status == SATOKO_UNDEC );
+        Gia_ObjSetFailed( p->pAig, iObj );
+        assert( 0 );
+    }
+    satoko_rollback( p->pSat );
+    return RetValue;
+}
+int Cec2_ManPerformSweeping( Gia_Man_t * p, Cec2_Par_t * pPars )
+{
+    Cec2_Man_t * pMan; 
+    Gia_Obj_t * pObj, * pRepr, * pObjNew; 
+    int i, fDisproved = 1;
+
+    // check if any output trivially fails under all-0 pattern
+    Gia_ManSetPhase( p );
+    if ( pPars->fIsMiter ) 
+    {
+        Gia_ManForEachCo( p, pObj, i )
+            if ( pObj->fPhase )
+            {
+                p->pCexSeq = Cec2_ManDeriveCex( p, i, -1 );
+                return 0;
+            }
+    }
+    // simulate one round and create classes
+    Cec2_ManSimAlloc( p, pPars->nSimWords );
+    Cec2_ManSimulateCis( p );
+    Cec2_ManSimulate( p );
+    if ( pPars->fIsMiter && !Cec2_ManSimulateCos(p) ) // cex detected
+        return 0;
+    Cec2_ManCreateClasses( p );
+    if ( pPars->fVerbose )
+        Gia_ManEquivPrintClasses( p, pPars->fVeryVerbose, 0 );
+
+    // perform additinal simulation
+    for ( i = 0; i < pPars->nSimRounds; i++ )
+    {
+        Cec2_ManSimulateCis( p );
+        Cec2_ManSimulate( p );
+        if ( pPars->fIsMiter && !Cec2_ManSimulateCos(p) ) // cex detected
+            return 0;
+        if ( pPars->fVerbose )
+            Gia_ManEquivPrintClasses( p, pPars->fVeryVerbose, 0 );
+    }
+    // perform sweeping
+    pMan = Cec2_ManCreate( p, pPars );
+    while ( fDisproved )
+    {
+        fDisproved = 0;
+        Cec2_ManSimulateCis( p );
+        Gia_ManForEachAnd( p, pObj, i )
+        {
+            pObj->fMark1 = 0;
+            if ( ~pObj->Value ) // skip swept nodes
+                continue;
+            assert( !Gia_ObjProved(p, i) && !Gia_ObjFailed(p, i) );
+            pObj->fMark1 = Gia_ObjFanin0(pObj)->fMark1 || Gia_ObjFanin1(pObj)->fMark1;
+            if ( pObj->fMark1 ) // skip nodes in the TFO of a disproved one
+                continue;
+            // duplicate the node
+            pObj->Value = Gia_ManHashAnd( pMan->pNew, Gia_ObjFanin0Copy(pObj), Gia_ObjFanin1Copy(pObj) );
+            if ( Vec_IntSize(&pMan->pNew->vCopies) == Abc_Lit2Var(pObj->Value) )
+            {
+                pObjNew = Gia_ManObj( pMan->pNew, Abc_Lit2Var(pObj->Value) );
+                pObjNew->fMark0 = Gia_ObjIsMuxType( pObjNew );
+                Vec_IntPush( &pMan->pNew->vCopies, -1 );
+            }
+            assert( Vec_IntSize(&pMan->pNew->vCopies) == Gia_ManObjNum(pMan->pNew) );
+            pRepr = Gia_ObjReprObj( p, i );
+            if ( pRepr == NULL || pRepr->fMark1 )
+                continue;
+            //if ( Gia_ObjIsConst0(pRepr) )
+            //    continue;
+            if ( Abc_Lit2Var(pObj->Value) == Abc_Lit2Var(pRepr->Value) )
+            {
+                assert( (pObj->Value ^ pRepr->Value) == (pObj->fPhase ^ pRepr->fPhase) );
+                Gia_ObjSetProved( p, i );
+                continue;
+            }
+            if ( Cec2_ManSweepNode(pMan, i) )
+                continue;
+            // mark nodes as disproved
+            pRepr->fMark1 = pObj->fMark1 = 1;
+            fDisproved = 1;
+        }
+        if ( fDisproved )
+        {
+            Cec2_ManSimulate( p );
+            if ( pPars->fIsMiter && !Cec2_ManSimulateCos(p) ) // cex detected
+                break;
+        }
+        if ( pPars->fVerbose )
+            Gia_ManEquivPrintClasses( p, pPars->fVeryVerbose, 0 );
+    }
+    Cec2_ManDestroy( pMan );
+    return p->pCexSeq ? 0 : 1;
+}
+void Cec2_ManSimulateTest( Gia_Man_t * p )
+{
+    abctime clk = Abc_Clock();
+    Cec2_Par_t Pars, * pPars = &Pars;
+    Cec2_SetDefaultParams( pPars );
+    Cec2_ManPerformSweeping( p, pPars );
+    Abc_PrintTime( 1, "SAT sweeping time", Abc_Clock() - clk );
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
+ABC_NAMESPACE_IMPL_END
+
diff --git a/src/proof/cec/module.make b/src/proof/cec/module.make
index 82e0de74..38106e5e 100644
--- a/src/proof/cec/module.make
+++ b/src/proof/cec/module.make
@@ -6,6 +6,7 @@ SRC +=    src/proof/cec/cecCec.c \
     src/proof/cec/cecIso.c \
     src/proof/cec/cecMan.c \
     src/proof/cec/cecPat.c \
+    src/proof/cec/cecSat.c \
     src/proof/cec/cecSeq.c \
     src/proof/cec/cecSolve.c \
     src/proof/cec/cecSplit.c \