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abc/src/sat/bsat/satInter.c

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/**CFile****************************************************************
FileName [satInter.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [SAT sat_solver.]
Synopsis [Interpolation package.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - June 20, 2005.]
Revision [$Id: satInter.c,v 1.4 2005/09/16 22:55:03 casem Exp $]
***********************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <time.h>
#include "satStore.h"
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
// variable assignments
static const lit LIT_UNDEF = 0xffffffff;
// interpolation manager
struct Int_Man_t_
{
// clauses of the problems
Sto_Man_t * pCnf; // the set of CNF clauses for A and B
int pGloVars[16]; // global variables
int nGloVars; // the number of global variables
// various parameters
int fVerbose; // verbosiness flag
int fProofVerif; // verifies the proof
int fProofWrite; // writes the proof file
int nVarsAlloc; // the allocated size of var arrays
int nClosAlloc; // the allocated size of clause arrays
// internal BCP
int nRootSize; // the number of root level assignments
int nTrailSize; // the number of assignments made
lit * pTrail; // chronological order of assignments (size nVars)
lit * pAssigns; // assignments by variable (size nVars)
char * pSeens; // temporary mark (size nVars)
Sto_Cls_t ** pReasons; // reasons for each assignment (size nVars)
Sto_Cls_t ** pWatches; // watched clauses for each literal (size 2*nVars)
// interpolation data
int nVarsAB; // the number of global variables
char * pVarTypes; // variable type (size nVars) [1=A, 0=B, <0=AB]
unsigned * pInters; // storage for interpolants as truth tables (size nClauses)
int nIntersAlloc; // the allocated size of truth table array
int nWords; // the number of words in the truth table
// proof recording
int Counter; // counter of resolved clauses
int * pProofNums; // the proof numbers for each clause (size nClauses)
FILE * pFile; // the file for proof recording
// internal verification
lit * pResLits; // the literals of the resolvent
int nResLits; // the number of literals of the resolvent
int nResLitsAlloc;// the number of literals of the resolvent
// runtime stats
int timeBcp; // the runtime for BCP
int timeTrace; // the runtime of trace construction
int timeTotal; // the total runtime of interpolation
};
// procedure to get hold of the clauses' truth table
static inline unsigned * Int_ManTruthRead( Int_Man_t * p, Sto_Cls_t * pCls ) { return p->pInters + pCls->Id * p->nWords; }
static inline void Int_ManTruthClear( unsigned * p, int nWords ) { int i; for ( i = nWords - 1; i >= 0; i-- ) p[i] = 0; }
static inline void Int_ManTruthFill( unsigned * p, int nWords ) { int i; for ( i = nWords - 1; i >= 0; i-- ) p[i] = ~0; }
static inline void Int_ManTruthCopy( unsigned * p, unsigned * q, int nWords ) { int i; for ( i = nWords - 1; i >= 0; i-- ) p[i] = q[i]; }
static inline void Int_ManTruthAnd( unsigned * p, unsigned * q, int nWords ) { int i; for ( i = nWords - 1; i >= 0; i-- ) p[i] &= q[i]; }
static inline void Int_ManTruthOr( unsigned * p, unsigned * q, int nWords ) { int i; for ( i = nWords - 1; i >= 0; i-- ) p[i] |= q[i]; }
static inline void Int_ManTruthOrNot( unsigned * p, unsigned * q, int nWords ) { int i; for ( i = nWords - 1; i >= 0; i-- ) p[i] |= ~q[i]; }
// reading/writing the proof for a clause
static inline int Int_ManProofGet( Int_Man_t * p, Sto_Cls_t * pCls ) { return p->pProofNums[pCls->Id]; }
static inline void Int_ManProofSet( Int_Man_t * p, Sto_Cls_t * pCls, int n ) { p->pProofNums[pCls->Id] = n; }
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Allocate proof manager.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Int_Man_t * Int_ManAlloc()
{
Int_Man_t * p;
// allocate the manager
p = (Int_Man_t *)malloc( sizeof(Int_Man_t) );
memset( p, 0, sizeof(Int_Man_t) );
// verification
p->nResLitsAlloc = (1<<16);
p->pResLits = malloc( sizeof(lit) * p->nResLitsAlloc );
// parameters
p->fProofWrite = 0;
p->fProofVerif = 1;
return p;
}
/**Function*************************************************************
Synopsis [Allocate proof manager.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int * Int_ManSetGlobalVars( Int_Man_t * p, int nGloVars )
{
p->nGloVars = nGloVars;
return p->pGloVars;
}
/**Function*************************************************************
Synopsis [Count common variables in the clauses of A and B.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Int_ManGlobalVars( Int_Man_t * p )
{
Sto_Cls_t * pClause;
int Var, nVarsAB, v;
// mark the variable encountered in the clauses of A
Sto_ManForEachClauseRoot( p->pCnf, pClause )
{
if ( !pClause->fA )
break;
for ( v = 0; v < (int)pClause->nLits; v++ )
p->pVarTypes[lit_var(pClause->pLits[v])] = 1;
}
if ( p->nGloVars )
{
for ( v = 0; v < p->nGloVars; v++ )
p->pVarTypes[ p->pGloVars[v] ] = - v - 1;
return p->nGloVars;
}
// check variables that appear in clauses of B
nVarsAB = 0;
Sto_ManForEachClauseRoot( p->pCnf, pClause )
{
if ( pClause->fA )
continue;
for ( v = 0; v < (int)pClause->nLits; v++ )
{
Var = lit_var(pClause->pLits[v]);
if ( p->pVarTypes[Var] == 1 ) // var of A
{
// change it into a global variable
nVarsAB++;
p->pVarTypes[Var] = -1;
}
}
}
// order global variables
nVarsAB = 0;
for ( v = 0; v < p->pCnf->nVars; v++ )
if ( p->pVarTypes[v] == -1 )
p->pVarTypes[v] -= nVarsAB++;
//printf( "There are %d global variables.\n", nVarsAB );
return nVarsAB;
}
/**Function*************************************************************
Synopsis [Resize proof manager.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Int_ManResize( Int_Man_t * p )
{
// check if resizing is needed
if ( p->nVarsAlloc < p->pCnf->nVars )
{
// find the new size
if ( p->nVarsAlloc == 0 )
p->nVarsAlloc = 1;
while ( p->nVarsAlloc < p->pCnf->nVars )
p->nVarsAlloc *= 2;
// resize the arrays
p->pTrail = (lit *) realloc( p->pTrail, sizeof(lit) * p->nVarsAlloc );
p->pAssigns = (lit *) realloc( p->pAssigns, sizeof(lit) * p->nVarsAlloc );
p->pSeens = (char *) realloc( p->pSeens, sizeof(char) * p->nVarsAlloc );
p->pVarTypes = (char *) realloc( p->pVarTypes, sizeof(char) * p->nVarsAlloc );
p->pReasons = (Sto_Cls_t **)realloc( p->pReasons, sizeof(Sto_Cls_t *) * p->nVarsAlloc );
p->pWatches = (Sto_Cls_t **)realloc( p->pWatches, sizeof(Sto_Cls_t *) * p->nVarsAlloc*2 );
}
// clean the free space
memset( p->pAssigns , 0xff, sizeof(lit) * p->pCnf->nVars );
memset( p->pSeens , 0, sizeof(char) * p->pCnf->nVars );
memset( p->pVarTypes, 0, sizeof(char) * p->pCnf->nVars );
memset( p->pReasons , 0, sizeof(Sto_Cls_t *) * p->pCnf->nVars );
memset( p->pWatches , 0, sizeof(Sto_Cls_t *) * p->pCnf->nVars*2 );
// compute the number of common variables
p->nVarsAB = Int_ManGlobalVars( p );
// compute the number of words in the truth table
p->nWords = (p->nVarsAB <= 5 ? 1 : (1 << (p->nVarsAB - 5)));
// check if resizing of clauses is needed
if ( p->nClosAlloc < p->pCnf->nClauses )
{
// find the new size
if ( p->nClosAlloc == 0 )
p->nClosAlloc = 1;
while ( p->nClosAlloc < p->pCnf->nClauses )
p->nClosAlloc *= 2;
// resize the arrays
p->pProofNums = (int *) realloc( p->pProofNums, sizeof(int) * p->nClosAlloc );
}
memset( p->pProofNums, 0, sizeof(int) * p->pCnf->nClauses );
// check if resizing of truth tables is needed
if ( p->nIntersAlloc < p->nWords * p->pCnf->nClauses )
{
p->nIntersAlloc = p->nWords * p->pCnf->nClauses;
p->pInters = (unsigned *) realloc( p->pInters, sizeof(unsigned) * p->nIntersAlloc );
}
// memset( p->pInters, 0, sizeof(unsigned) * p->nWords * p->pCnf->nClauses );
}
/**Function*************************************************************
Synopsis [Deallocate proof manager.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Int_ManFree( Int_Man_t * p )
{
/*
printf( "Runtime stats:\n" );
PRT( "BCP ", p->timeBcp );
PRT( "Trace ", p->timeTrace );
PRT( "TOTAL ", p->timeTotal );
*/
free( p->pInters );
free( p->pProofNums );
free( p->pTrail );
free( p->pAssigns );
free( p->pSeens );
free( p->pVarTypes );
free( p->pReasons );
free( p->pWatches );
free( p->pResLits );
free( p );
}
/**Function*************************************************************
Synopsis [Prints the clause.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Int_ManPrintClause( Int_Man_t * p, Sto_Cls_t * pClause )
{
int i;
printf( "Clause ID = %d. Proof = %d. {", pClause->Id, Int_ManProofGet(p, pClause) );
for ( i = 0; i < (int)pClause->nLits; i++ )
printf( " %d", pClause->pLits[i] );
printf( " }\n" );
}
/**Function*************************************************************
Synopsis [Prints the resolvent.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Int_ManPrintResolvent( lit * pResLits, int nResLits )
{
int i;
printf( "Resolvent: {" );
for ( i = 0; i < nResLits; i++ )
printf( " %d", pResLits[i] );
printf( " }\n" );
}
/**Function*************************************************************
Synopsis [Records the proof.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Extra_PrintBinary__( FILE * pFile, unsigned Sign[], int nBits )
{
int Remainder, nWords;
int w, i;
Remainder = (nBits%(sizeof(unsigned)*8));
nWords = (nBits/(sizeof(unsigned)*8)) + (Remainder>0);
for ( w = nWords-1; w >= 0; w-- )
for ( i = ((w == nWords-1 && Remainder)? Remainder-1: 31); i >= 0; i-- )
fprintf( pFile, "%c", '0' + (int)((Sign[w] & (1<<i)) > 0) );
}
/**Function*************************************************************
Synopsis [Prints the interpolant for one clause.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Int_ManPrintInterOne( Int_Man_t * p, Sto_Cls_t * pClause )
{
printf( "Clause %2d : ", pClause->Id );
Extra_PrintBinary__( stdout, Int_ManTruthRead(p, pClause), (1 << p->nVarsAB) );
printf( "\n" );
}
/**Function*************************************************************
Synopsis [Adds one clause to the watcher list.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline void Int_ManWatchClause( Int_Man_t * p, Sto_Cls_t * pClause, lit Lit )
{
assert( lit_check(Lit, p->pCnf->nVars) );
if ( pClause->pLits[0] == Lit )
pClause->pNext0 = p->pWatches[lit_neg(Lit)];
else
{
assert( pClause->pLits[1] == Lit );
pClause->pNext1 = p->pWatches[lit_neg(Lit)];
}
p->pWatches[lit_neg(Lit)] = pClause;
}
/**Function*************************************************************
Synopsis [Records implication.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Int_ManEnqueue( Int_Man_t * p, lit Lit, Sto_Cls_t * pReason )
{
int Var = lit_var(Lit);
if ( p->pAssigns[Var] != LIT_UNDEF )
return p->pAssigns[Var] == Lit;
p->pAssigns[Var] = Lit;
p->pReasons[Var] = pReason;
p->pTrail[p->nTrailSize++] = Lit;
//printf( "assigning var %d value %d\n", Var, !lit_sign(Lit) );
return 1;
}
/**Function*************************************************************
Synopsis [Records implication.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline void Int_ManCancelUntil( Int_Man_t * p, int Level )
{
lit Lit;
int i, Var;
for ( i = p->nTrailSize - 1; i >= Level; i-- )
{
Lit = p->pTrail[i];
Var = lit_var( Lit );
p->pReasons[Var] = NULL;
p->pAssigns[Var] = LIT_UNDEF;
//printf( "cancelling var %d\n", Var );
}
p->nTrailSize = Level;
}
/**Function*************************************************************
Synopsis [Propagate one assignment.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline Sto_Cls_t * Int_ManPropagateOne( Int_Man_t * p, lit Lit )
{
Sto_Cls_t ** ppPrev, * pCur, * pTemp;
lit LitF = lit_neg(Lit);
int i;
// iterate through the literals
ppPrev = p->pWatches + Lit;
for ( pCur = p->pWatches[Lit]; pCur; pCur = *ppPrev )
{
// make sure the false literal is in the second literal of the clause
if ( pCur->pLits[0] == LitF )
{
pCur->pLits[0] = pCur->pLits[1];
pCur->pLits[1] = LitF;
pTemp = pCur->pNext0;
pCur->pNext0 = pCur->pNext1;
pCur->pNext1 = pTemp;
}
assert( pCur->pLits[1] == LitF );
// if the first literal is true, the clause is satisfied
if ( pCur->pLits[0] == p->pAssigns[lit_var(pCur->pLits[0])] )
{
ppPrev = &pCur->pNext1;
continue;
}
// look for a new literal to watch
for ( i = 2; i < (int)pCur->nLits; i++ )
{
// skip the case when the literal is false
if ( lit_neg(pCur->pLits[i]) == p->pAssigns[lit_var(pCur->pLits[i])] )
continue;
// the literal is either true or unassigned - watch it
pCur->pLits[1] = pCur->pLits[i];
pCur->pLits[i] = LitF;
// remove this clause from the watch list of Lit
*ppPrev = pCur->pNext1;
// add this clause to the watch list of pCur->pLits[i] (now it is pCur->pLits[1])
Int_ManWatchClause( p, pCur, pCur->pLits[1] );
break;
}
if ( i < (int)pCur->nLits ) // found new watch
continue;
// clause is unit - enqueue new implication
if ( Int_ManEnqueue(p, pCur->pLits[0], pCur) )
{
ppPrev = &pCur->pNext1;
continue;
}
// conflict detected - return the conflict clause
return pCur;
}
return NULL;
}
/**Function*************************************************************
Synopsis [Propagate the current assignments.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Sto_Cls_t * Int_ManPropagate( Int_Man_t * p, int Start )
{
Sto_Cls_t * pClause;
int i;
int clk = clock();
for ( i = Start; i < p->nTrailSize; i++ )
{
pClause = Int_ManPropagateOne( p, p->pTrail[i] );
if ( pClause )
{
p->timeBcp += clock() - clk;
return pClause;
}
}
p->timeBcp += clock() - clk;
return NULL;
}
/**Function*************************************************************
Synopsis [Writes one root clause into a file.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Int_ManProofWriteOne( Int_Man_t * p, Sto_Cls_t * pClause )
{
Int_ManProofSet( p, pClause, ++p->Counter );
if ( p->fProofWrite )
{
int v;
fprintf( p->pFile, "%d", Int_ManProofGet(p, pClause) );
for ( v = 0; v < (int)pClause->nLits; v++ )
fprintf( p->pFile, " %d", lit_print(pClause->pLits[v]) );
fprintf( p->pFile, " 0 0\n" );
}
}
/**Function*************************************************************
Synopsis [Traces the proof for one clause.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Int_ManProofTraceOne( Int_Man_t * p, Sto_Cls_t * pConflict, Sto_Cls_t * pFinal )
{
Sto_Cls_t * pReason;
int i, v, Var, PrevId;
int fPrint = 0;
int clk = clock();
// collect resolvent literals
if ( p->fProofVerif )
{
assert( (int)pConflict->nLits <= p->nResLitsAlloc );
memcpy( p->pResLits, pConflict->pLits, sizeof(lit) * pConflict->nLits );
p->nResLits = pConflict->nLits;
}
// mark all the variables in the conflict as seen
for ( v = 0; v < (int)pConflict->nLits; v++ )
p->pSeens[lit_var(pConflict->pLits[v])] = 1;
// start the anticedents
// pFinal->pAntis = Vec_PtrAlloc( 32 );
// Vec_PtrPush( pFinal->pAntis, pConflict );
if ( p->pCnf->nClausesA )
Int_ManTruthCopy( Int_ManTruthRead(p, pFinal), Int_ManTruthRead(p, pConflict), p->nWords );
// follow the trail backwards
PrevId = Int_ManProofGet(p, pConflict);
for ( i = p->nTrailSize - 1; i >= 0; i-- )
{
// skip literals that are not involved
Var = lit_var(p->pTrail[i]);
if ( !p->pSeens[Var] )
continue;
p->pSeens[Var] = 0;
// skip literals of the resulting clause
pReason = p->pReasons[Var];
if ( pReason == NULL )
continue;
assert( p->pTrail[i] == pReason->pLits[0] );
// add the variables to seen
for ( v = 1; v < (int)pReason->nLits; v++ )
p->pSeens[lit_var(pReason->pLits[v])] = 1;
// record the reason clause
assert( Int_ManProofGet(p, pReason) > 0 );
p->Counter++;
if ( p->fProofWrite )
fprintf( p->pFile, "%d * %d %d 0\n", p->Counter, PrevId, Int_ManProofGet(p, pReason) );
PrevId = p->Counter;
if ( p->pCnf->nClausesA )
{
if ( p->pVarTypes[Var] == 1 ) // var of A
Int_ManTruthOr( Int_ManTruthRead(p, pFinal), Int_ManTruthRead(p, pReason), p->nWords );
else
Int_ManTruthAnd( Int_ManTruthRead(p, pFinal), Int_ManTruthRead(p, pReason), p->nWords );
}
// resolve the temporary resolvent with the reason clause
if ( p->fProofVerif )
{
int v1, v2;
if ( fPrint )
Int_ManPrintResolvent( p->pResLits, p->nResLits );
// check that the var is present in the resolvent
for ( v1 = 0; v1 < p->nResLits; v1++ )
if ( lit_var(p->pResLits[v1]) == Var )
break;
if ( v1 == p->nResLits )
printf( "Recording clause %d: Cannot find variable %d in the temporary resolvent.\n", pFinal->Id, Var );
if ( p->pResLits[v1] != lit_neg(pReason->pLits[0]) )
printf( "Recording clause %d: The resolved variable %d is in the wrong polarity.\n", pFinal->Id, Var );
// remove this variable from the resolvent
assert( lit_var(p->pResLits[v1]) == Var );
p->nResLits--;
for ( ; v1 < p->nResLits; v1++ )
p->pResLits[v1] = p->pResLits[v1+1];
// add variables of the reason clause
for ( v2 = 1; v2 < (int)pReason->nLits; v2++ )
{
for ( v1 = 0; v1 < p->nResLits; v1++ )
if ( lit_var(p->pResLits[v1]) == lit_var(pReason->pLits[v2]) )
break;
// if it is a new variable, add it to the resolvent
if ( v1 == p->nResLits )
{
if ( p->nResLits == p->nResLitsAlloc )
printf( "Recording clause %d: Ran out of space for intermediate resolvent.\n", pFinal->Id );
p->pResLits[ p->nResLits++ ] = pReason->pLits[v2];
continue;
}
// if the variable is the same, the literal should be the same too
if ( p->pResLits[v1] == pReason->pLits[v2] )
continue;
// the literal is different
printf( "Recording clause %d: Trying to resolve the clause with more than one opposite literal.\n", pFinal->Id );
}
}
// Vec_PtrPush( pFinal->pAntis, pReason );
}
// unmark all seen variables
// for ( i = p->nTrailSize - 1; i >= 0; i-- )
// p->pSeens[lit_var(p->pTrail[i])] = 0;
// check that the literals are unmarked
// for ( i = p->nTrailSize - 1; i >= 0; i-- )
// assert( p->pSeens[lit_var(p->pTrail[i])] == 0 );
// use the resulting clause to check the correctness of resolution
if ( p->fProofVerif )
{
int v1, v2;
if ( fPrint )
Int_ManPrintResolvent( p->pResLits, p->nResLits );
for ( v1 = 0; v1 < p->nResLits; v1++ )
{
for ( v2 = 0; v2 < (int)pFinal->nLits; v2++ )
if ( pFinal->pLits[v2] == p->pResLits[v1] )
break;
if ( v2 < (int)pFinal->nLits )
continue;
break;
}
if ( v1 < p->nResLits )
{
printf( "Recording clause %d: The final resolvent is wrong.\n", pFinal->Id );
Int_ManPrintClause( p, pConflict );
Int_ManPrintResolvent( p->pResLits, p->nResLits );
Int_ManPrintClause( p, pFinal );
}
// if there are literals in the clause that are not in the resolvent
// it means that the derived resolvent is stronger than the clause
// we can replace the clause with the resolvent by removing these literals
if ( p->nResLits != (int)pFinal->nLits )
{
for ( v1 = 0; v1 < (int)pFinal->nLits; v1++ )
{
for ( v2 = 0; v2 < p->nResLits; v2++ )
if ( pFinal->pLits[v1] == p->pResLits[v2] )
break;
if ( v2 < p->nResLits )
continue;
// remove literal v1 from the final clause
pFinal->nLits--;
for ( v2 = v1; v2 < (int)pFinal->nLits; v2++ )
pFinal->pLits[v2] = pFinal->pLits[v2+1];
v1--;
}
assert( p->nResLits == (int)pFinal->nLits );
}
}
p->timeTrace += clock() - clk;
// return the proof pointer
if ( p->pCnf->nClausesA )
{
// Int_ManPrintInterOne( p, pFinal );
}
Int_ManProofSet( p, pFinal, p->Counter );
// make sure the same proof ID is not asssigned to two consecutive clauses
assert( p->pProofNums[pFinal->Id-1] != p->Counter );
return p->Counter;
}
/**Function*************************************************************
Synopsis [Records the proof for one clause.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Int_ManProofRecordOne( Int_Man_t * p, Sto_Cls_t * pClause )
{
Sto_Cls_t * pConflict;
int i;
// empty clause never ends up there
assert( pClause->nLits > 0 );
if ( pClause->nLits == 0 )
printf( "Error: Empty clause is attempted.\n" );
// add assumptions to the trail
assert( !pClause->fRoot );
assert( p->nTrailSize == p->nRootSize );
// if any of the clause literals are already assumed
// it means that the clause is redundant and can be skipped
for ( i = 0; i < (int)pClause->nLits; i++ )
if ( p->pAssigns[lit_var(pClause->pLits[i])] == pClause->pLits[i] )
return 1;
for ( i = 0; i < (int)pClause->nLits; i++ )
if ( !Int_ManEnqueue( p, lit_neg(pClause->pLits[i]), NULL ) )
{
assert( 0 ); // impossible
return 0;
}
// propagate the assumptions
pConflict = Int_ManPropagate( p, p->nRootSize );
if ( pConflict == NULL )
{
assert( 0 ); // cannot prove
return 0;
}
// skip the clause if it is weaker or the same as the conflict clause
if ( pClause->nLits >= pConflict->nLits )
{
// check if every literal of conflict clause can be found in the given clause
int j;
for ( i = 0; i < (int)pConflict->nLits; i++ )
{
for ( j = 0; j < (int)pClause->nLits; j++ )
if ( pConflict->pLits[i] == pClause->pLits[j] )
break;
if ( j == (int)pClause->nLits ) // literal pConflict->pLits[i] is not found
break;
}
if ( i == (int)pConflict->nLits ) // all lits are found
{
// undo to the root level
Int_ManCancelUntil( p, p->nRootSize );
return 1;
}
}
// construct the proof
Int_ManProofTraceOne( p, pConflict, pClause );
// undo to the root level
Int_ManCancelUntil( p, p->nRootSize );
// add large clauses to the watched lists
if ( pClause->nLits > 1 )
{
Int_ManWatchClause( p, pClause, pClause->pLits[0] );
Int_ManWatchClause( p, pClause, pClause->pLits[1] );
return 1;
}
assert( pClause->nLits == 1 );
// if the clause proved is unit, add it and propagate
if ( !Int_ManEnqueue( p, pClause->pLits[0], pClause ) )
{
assert( 0 ); // impossible
return 0;
}
// propagate the assumption
pConflict = Int_ManPropagate( p, p->nRootSize );
if ( pConflict )
{
// construct the proof
Int_ManProofTraceOne( p, pConflict, p->pCnf->pEmpty );
if ( p->fVerbose )
printf( "Found last conflict after adding unit clause number %d!\n", pClause->Id );
return 0;
}
// update the root level
p->nRootSize = p->nTrailSize;
return 1;
}
/**Function*************************************************************
Synopsis [Propagate the root clauses.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Int_ManProcessRoots( Int_Man_t * p )
{
Sto_Cls_t * pClause;
int Counter;
// make sure the root clauses are preceeding the learnt clauses
Counter = 0;
Sto_ManForEachClause( p->pCnf, pClause )
{
assert( (int)pClause->fA == (Counter < (int)p->pCnf->nClausesA) );
assert( (int)pClause->fRoot == (Counter < (int)p->pCnf->nRoots) );
Counter++;
}
assert( p->pCnf->nClauses == Counter );
// make sure the last clause if empty
assert( p->pCnf->pTail->nLits == 0 );
// go through the root unit clauses
p->nTrailSize = 0;
Sto_ManForEachClauseRoot( p->pCnf, pClause )
{
// create watcher lists for the root clauses
if ( pClause->nLits > 1 )
{
Int_ManWatchClause( p, pClause, pClause->pLits[0] );
Int_ManWatchClause( p, pClause, pClause->pLits[1] );
}
// empty clause and large clauses
if ( pClause->nLits != 1 )
continue;
// unit clause
assert( lit_check(pClause->pLits[0], p->pCnf->nVars) );
if ( !Int_ManEnqueue( p, pClause->pLits[0], pClause ) )
{
// detected root level conflict
// printf( "Error in Int_ManProcessRoots(): Detected a root-level conflict too early!\n" );
// assert( 0 );
// detected root level conflict
Int_ManProofTraceOne( p, pClause, p->pCnf->pEmpty );
if ( p->fVerbose )
printf( "Found root level conflict!\n" );
return 0;
}
}
// propagate the root unit clauses
pClause = Int_ManPropagate( p, 0 );
if ( pClause )
{
// detected root level conflict
Int_ManProofTraceOne( p, pClause, p->pCnf->pEmpty );
if ( p->fVerbose )
printf( "Found root level conflict!\n" );
return 0;
}
// set the root level
p->nRootSize = p->nTrailSize;
return 1;
}
/**Function*************************************************************
Synopsis [Records the proof.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Int_ManPrepareInter( Int_Man_t * p )
{
// elementary truth tables
unsigned uTruths[8][8] = {
{ 0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA,0xAAAAAAAA },
{ 0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC,0xCCCCCCCC },
{ 0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0,0xF0F0F0F0 },
{ 0xFF00FF00,0xFF00FF00,0xFF00FF00,0xFF00FF00,0xFF00FF00,0xFF00FF00,0xFF00FF00,0xFF00FF00 },
{ 0xFFFF0000,0xFFFF0000,0xFFFF0000,0xFFFF0000,0xFFFF0000,0xFFFF0000,0xFFFF0000,0xFFFF0000 },
{ 0x00000000,0xFFFFFFFF,0x00000000,0xFFFFFFFF,0x00000000,0xFFFFFFFF,0x00000000,0xFFFFFFFF },
{ 0x00000000,0x00000000,0xFFFFFFFF,0xFFFFFFFF,0x00000000,0x00000000,0xFFFFFFFF,0xFFFFFFFF },
{ 0x00000000,0x00000000,0x00000000,0x00000000,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF }
};
Sto_Cls_t * pClause;
int Var, VarAB, v;
assert( p->nVarsAB <= 8 );
// set interpolants for root clauses
Sto_ManForEachClauseRoot( p->pCnf, pClause )
{
if ( !pClause->fA ) // clause of B
{
Int_ManTruthFill( Int_ManTruthRead(p, pClause), p->nWords );
// Int_ManPrintInterOne( p, pClause );
continue;
}
// clause of A
Int_ManTruthClear( Int_ManTruthRead(p, pClause), p->nWords );
for ( v = 0; v < (int)pClause->nLits; v++ )
{
Var = lit_var(pClause->pLits[v]);
if ( p->pVarTypes[Var] < 0 ) // global var
{
VarAB = -p->pVarTypes[Var]-1;
assert( VarAB >= 0 && VarAB < p->nVarsAB );
if ( lit_sign(pClause->pLits[v]) ) // negative var
Int_ManTruthOrNot( Int_ManTruthRead(p, pClause), uTruths[VarAB], p->nWords );
else
Int_ManTruthOr( Int_ManTruthRead(p, pClause), uTruths[VarAB], p->nWords );
}
}
// Int_ManPrintInterOne( p, pClause );
}
}
/**Function*************************************************************
Synopsis [Computes interpolant for the given CNF.]
Description [Returns the number of common variable found and interpolant.
Returns 0, if something did not work.]
SideEffects []
SeeAlso []
***********************************************************************/
int Int_ManInterpolate( Int_Man_t * p, Sto_Man_t * pCnf, int fVerbose, unsigned ** ppResult )
{
Sto_Cls_t * pClause;
int RetValue = 1;
int clkTotal = clock();
// check that the CNF makes sense
assert( pCnf->nVars > 0 && pCnf->nClauses > 0 );
p->pCnf = pCnf;
p->fVerbose = fVerbose;
*ppResult = NULL;
// adjust the manager
Int_ManResize( p );
// prepare the interpolant computation
Int_ManPrepareInter( p );
// construct proof for each clause
// start the proof
if ( p->fProofWrite )
{
p->pFile = fopen( "proof.cnf_", "w" );
p->Counter = 0;
}
// write the root clauses
Sto_ManForEachClauseRoot( p->pCnf, pClause )
Int_ManProofWriteOne( p, pClause );
// propagate root level assignments
if ( Int_ManProcessRoots( p ) )
{
// if there is no conflict, consider learned clauses
Sto_ManForEachClause( p->pCnf, pClause )
{
if ( pClause->fRoot )
continue;
if ( !Int_ManProofRecordOne( p, pClause ) )
{
RetValue = 0;
break;
}
}
}
// stop the proof
if ( p->fProofWrite )
{
fclose( p->pFile );
p->pFile = NULL;
}
if ( fVerbose )
{
printf( "Vars = %d. Roots = %d. Learned = %d. Resol steps = %d. Ave = %.2f. Mem = %.2f Mb\n",
p->pCnf->nVars, p->pCnf->nRoots, p->pCnf->nClauses-p->pCnf->nRoots, p->Counter,
1.0*(p->Counter-p->pCnf->nRoots)/(p->pCnf->nClauses-p->pCnf->nRoots),
1.0*Sto_ManMemoryReport(p->pCnf)/(1<<20) );
p->timeTotal += clock() - clkTotal;
}
*ppResult = Int_ManTruthRead( p, p->pCnf->pTail );
return p->nVarsAB;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
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