Ejemplo n.º 1
0
//
// Performs the actual cnfization
//
bool Tseitin::cnfize( Enode * formula, map< enodeid_t, Enode * > & cnf_cache )
{
  (void)cnf_cache;
  assert( formula );
  assert( !formula->isAnd( ) );

  Enode * arg_def = egraph.valDupMap1( formula );
  if ( arg_def != NULL )
  {
    vector< Enode * > clause;
    clause.push_back( arg_def );
#ifdef PRODUCE_PROOF
    if ( config.produce_inter > 0 )
      return solver.addSMTClause( clause, egraph.getIPartitions( formula ) );
#endif
    return solver.addSMTClause( clause );
  }

  vector< Enode * > unprocessed_enodes;       // Stack for unprocessed enodes
  unprocessed_enodes.push_back( formula );    // formula needs to be processed
  //
  // Visit the DAG of the formula from the leaves to the root
  //
  while( !unprocessed_enodes.empty( ) )
  {
    Enode * enode = unprocessed_enodes.back( );
    //
    // Skip if the node has already been processed before
    //
    if ( egraph.valDupMap1( enode ) != NULL )
    {
      unprocessed_enodes.pop_back( );
      continue;
    }

    bool unprocessed_children = false;
    Enode * arg_list;
    for ( arg_list = enode->getCdr( ) ;
          arg_list != egraph.enil ;
          arg_list = arg_list->getCdr( ) )
    {
      Enode * arg = arg_list->getCar( );

      assert( arg->isTerm( ) );
      //
      // Push only if it is an unprocessed boolean operator
      //
      if ( enode->isBooleanOperator( )
        && egraph.valDupMap1( arg ) == NULL )
      {
        unprocessed_enodes.push_back( arg );
        unprocessed_children = true;
      }
      //
      // If it is an atom (either boolean or theory) just
      // store it in the cache
      //
      else if ( arg->isAtom( ) )
      {
        egraph.storeDupMap1( arg, arg );
      }
    }
    //
    // SKip if unprocessed_children
    //
    if ( unprocessed_children )
      continue;

    unprocessed_enodes.pop_back( );
    Enode * result = NULL;
    //
    // At this point, every child has been processed
    //
    //
    // Do the actual cnfization, according to the node type
    //
    char def_name[ 32 ];

    if ( enode->isLit( ) )
    {
      result = enode;
    }
    else if ( enode->isNot( ) )
    {
      Enode * arg_def = egraph.valDupMap1( enode->get1st( ) );
      assert( arg_def );
      result = egraph.mkNot( egraph.cons( arg_def ) ); // Toggle the literal
    }
    else
    {
      Enode * arg_def = NULL;
      Enode * new_arg_list = egraph.copyEnodeEtypeListWithCache( enode->getCdr( ) );
      //
      // If the enode is not top-level it needs a definition
      //
      if ( formula != enode )
      {
        sprintf( def_name, CNF_STR, formula->getId( ), enode->getId( ) );
        egraph.newSymbol( def_name, sstore.mkBool( ) );
        arg_def = egraph.mkVar( def_name );
#ifdef PRODUCE_PROOF
        if ( config.produce_inter > 0 )
        {
          // Tag Positive and negative literals
          egraph.tagIFormula( arg_def
                            , egraph.getIPartitions( enode ) );
          egraph.tagIFormula( egraph.mkNot( egraph.cons( arg_def ) )
                            , egraph.getIPartitions( enode ) );
        }
#endif
      }
#ifdef PRODUCE_PROOF
      uint64_t partitions = 0;
      if ( config.produce_inter > 0 )
      {
        partitions = egraph.getIPartitions( enode );
        assert( partitions != 0 );
      }
#endif
      //
      // Handle boolean operators
      //
      if ( enode->isAnd( ) )
        cnfizeAnd( new_arg_list, arg_def
#ifdef PRODUCE_PROOF
        , partitions
#endif
        );
      else if ( enode->isOr( ) )
        cnfizeOr( new_arg_list, arg_def
#ifdef PRODUCE_PROOF
        , partitions
#endif
        );
      else if ( enode->isIff( ) )
        cnfizeIff( new_arg_list, arg_def
#ifdef PRODUCE_PROOF
        , partitions
#endif
        );
      else if ( enode->isXor( ) )
        cnfizeXor( new_arg_list, arg_def
#ifdef PRODUCE_PROOF
        , partitions
#endif
        );
      else
      {
        opensmt_error2( "operator not handled ", enode->getCar( ) );
      }

      if ( arg_def != NULL )
        result = arg_def;
    }

    assert( egraph.valDupMap1( enode ) == NULL );
    egraph.storeDupMap1( enode, result );
  }

  if ( formula->isNot( ) )
  {
    // Retrieve definition of argument
    Enode * arg_def = egraph.valDupMap1( formula->get1st( ) );
    assert( arg_def );
    vector< Enode * > clause;
    clause.push_back( toggleLit( arg_def ) );
#ifdef PRODUCE_PROOF
    if ( config.produce_inter > 0 )
      return solver.addSMTClause( clause, egraph.getIPartitions( formula ) );
#endif
    return solver.addSMTClause( clause );
  }

  return true;
}
Ejemplo n.º 2
0
Enode * Egraph::canonizeDTC( Enode * formula
                           , bool split_eqs )
{
  assert( config.sat_lazy_dtc != 0 );
  assert( config.logic == QF_UFLRA
       || config.logic == QF_UFIDL );

  list< Enode * > dtc_axioms;
  vector< Enode * > unprocessed_enodes;
  initDupMap1( );

  unprocessed_enodes.push_back( formula );
  //
  // Visit the DAG of the formula from the leaves to the root
  //
  while( !unprocessed_enodes.empty( ) )
  {
    Enode * enode = unprocessed_enodes.back( );
    //
    // Skip if the node has already been processed before
    //
    if ( valDupMap1( enode ) != NULL )
    {
      unprocessed_enodes.pop_back( );
      continue;
    }

    bool unprocessed_children = false;
    Enode * arg_list;
    for ( arg_list = enode->getCdr( )
	; arg_list != enil
	; arg_list = arg_list->getCdr( ) )
    {
      Enode * arg = arg_list->getCar( );
      assert( arg->isTerm( ) );
      //
      // Push only if it is unprocessed
      //
      if ( valDupMap1( arg ) == NULL )
      {
	unprocessed_enodes.push_back( arg );
	unprocessed_children = true;
      }
    }
    //
    // SKip if unprocessed_children
    //
    if ( unprocessed_children )
      continue;

    unprocessed_enodes.pop_back( );
    Enode * result = NULL;
    //
    // Replace arithmetic atoms with canonized version
    //
    if (  enode->isTAtom( ) 
      && !enode->isIff( )
      && !enode->isUp( ) )
    {
      // No need to do anything if node is purely UF
      if ( isRootUF( enode ) )
      {
	if ( config.verbosity > 2 )
	  cerr << "# Egraph::Skipping canonization of " << enode << " as it's root is purely UF" << endl;
	result = enode;
      }
      else
      {
	LAExpression a( enode );
	result = a.toEnode( *this );
      
	if ( split_eqs && result->isEq( ) )
	{
#ifdef PRODUCE_PROOF
	  if ( config.produce_inter != 0 )
	    opensmt_error2( "can't compute interpolant for equalities at the moment ", enode );
#endif
	  LAExpression aa( enode );
	  Enode * e = aa.toEnode( *this );
	  Enode * lhs = e->get1st( );
	  Enode * rhs = e->get2nd( );
	  Enode * leq = mkLeq( cons( lhs, cons( rhs ) ) );
	  LAExpression b( leq );
	  leq = b.toEnode( *this );
	  Enode * geq = mkGeq( cons( lhs, cons( rhs ) ) );
	  LAExpression c( geq );
	  geq = c.toEnode( *this );
	  Enode * not_e = mkNot( cons( enode ) );
	  Enode * not_l = mkNot( cons( leq ) );
	  Enode * not_g = mkNot( cons( geq ) );
	  // Add clause ( !x=y v x<=y )
	  Enode * c1 = mkOr( cons( not_e
		           , cons( leq ) ) );
	  // Add clause ( !x=y v x>=y )
	  Enode * c2 = mkOr( cons( not_e
		           , cons( geq ) ) );
	  // Add clause ( x=y v !x>=y v !x<=y )
	  Enode * c3 = mkOr( cons( enode
		           , cons( not_l
		           , cons( not_g ) ) ) );
	  // Add conjunction of clauses
	  Enode * ax = mkAnd( cons( c1
		            , cons( c2
		            , cons( c3 ) ) ) );

	  dtc_axioms.push_back( ax );
	  result = enode;
	}
      }
    }
    //
    // If nothing have been done copy and simplify
    //
    if ( result == NULL )
      result = copyEnodeEtypeTermWithCache( enode );

    assert( valDupMap1( enode ) == NULL );
    storeDupMap1( enode, result );
  }

  Enode * new_formula = valDupMap1( formula );
  assert( new_formula );
  doneDupMap1( );

  if ( !dtc_axioms.empty( ) )
  {
    dtc_axioms.push_back( new_formula );
    new_formula = mkAnd( cons( dtc_axioms ) );
  }

  return new_formula;
}