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/********************* */
/*! \file alpha_equivalence.cpp
** \verbatim
** Top contributors (to current version):
** Andrew Reynolds, Tim King
** This file is part of the CVC4 project.
** Copyright (c) 2009-2017 by the authors listed in the file AUTHORS
** in the top-level source directory) and their institutional affiliations.
** All rights reserved. See the file COPYING in the top-level source
** directory for licensing information.\endverbatim
**
** \brief Alpha equivalence checking
**
**/
#include "theory/quantifiers/alpha_equivalence.h"
#include "theory/quantifiers/term_database.h"
using namespace CVC4;
using namespace std;
using namespace CVC4::theory;
using namespace CVC4::theory::quantifiers;
using namespace CVC4::kind;
struct sortTypeOrder {
TermDb* d_tdb;
bool operator() (TypeNode i, TypeNode j) {
return d_tdb->getIdForType( i )<d_tdb->getIdForType( j );
}
};
Node AlphaEquivalenceNode::registerNode( AlphaEquivalenceNode* aen, QuantifiersEngine* qe, Node q, std::vector< Node >& tt, std::vector< int >& arg_index ) {
std::map< Node, bool > visited;
while( !tt.empty() ){
if( tt.size()==arg_index.size()+1 ){
Node t = tt.back();
Node op;
if( t.hasOperator() ){
if( visited.find( t )==visited.end() ){
visited[t] = true;
op = t.getOperator();
arg_index.push_back( 0 );
}else{
op = t;
arg_index.push_back( -1 );
}
}else{
op = t;
arg_index.push_back( 0 );
}
Trace("aeq-debug") << op << " ";
aen = &(aen->d_children[op][t.getNumChildren()]);
}else{
Node t = tt.back();
int i = arg_index.back();
if( i==-1 || i==(int)t.getNumChildren() ){
tt.pop_back();
arg_index.pop_back();
}else{
tt.push_back( t[i] );
arg_index[arg_index.size()-1]++;
}
}
}
Node lem;
Trace("aeq-debug") << std::endl;
if( aen->d_quant.isNull() ){
aen->d_quant = q;
}else{
if( q.getNumChildren()==2 ){
//lemma ( q <=> d_quant )
Trace("alpha-eq") << "Alpha equivalent : " << std::endl;
Trace("alpha-eq") << " " << q << std::endl;
Trace("alpha-eq") << " " << aen->d_quant << std::endl;
lem = q.eqNode( aen->d_quant );
}else{
//do not reduce annotated quantified formulas based on alpha equivalence
}
}
return lem;
}
Node AlphaEquivalenceTypeNode::registerNode( AlphaEquivalenceTypeNode* aetn,
QuantifiersEngine* qe, Node q, Node t, std::vector< TypeNode >& typs, std::map< TypeNode, int >& typ_count, int index ){
while( index<(int)typs.size() ){
TypeNode curr = typs[index];
Assert( typ_count.find( curr )!=typ_count.end() );
Trace("aeq-debug") << "[" << curr << " " << typ_count[curr] << "] ";
aetn = &(aetn->d_children[curr][typ_count[curr]]);
index = index + 1;
}
std::vector< Node > tt;
std::vector< int > arg_index;
tt.push_back( t );
Trace("aeq-debug") << " : ";
return AlphaEquivalenceNode::registerNode( &(aetn->d_data), qe, q, tt, arg_index );
}
Node AlphaEquivalence::reduceQuantifier( Node q ) {
Assert( q.getKind()==FORALL );
Trace("aeq") << "Alpha equivalence : register " << q << std::endl;
//construct canonical quantified formula
Node t = d_qe->getTermDatabase()->getCanonicalTerm( q[1], true );
Trace("aeq") << " canonical form: " << t << std::endl;
//compute variable type counts
std::map< TypeNode, int > typ_count;
std::vector< TypeNode > typs;
for( unsigned i=0; i<q[0].getNumChildren(); i++ ){
TypeNode tn = q[0][i].getType();
typ_count[tn]++;
if( std::find( typs.begin(), typs.end(), tn )==typs.end() ){
typs.push_back( tn );
}
}
sortTypeOrder sto;
sto.d_tdb = d_qe->getTermDatabase();
std::sort( typs.begin(), typs.end(), sto );
Trace("aeq-debug") << " ";
Node ret = AlphaEquivalenceTypeNode::registerNode( &d_ae_typ_trie, d_qe, q, t, typs, typ_count );
Trace("aeq") << " ...result : " << ret << std::endl;
return ret;
}
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