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/********************* */
/*! \file equality_query.cpp
** \verbatim
** Top contributors (to current version):
** Andrew Reynolds, Mathias Preiner, Morgan Deters
** This file is part of the CVC4 project.
** Copyright (c) 2009-2020 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 Utilities used for querying about equality information
**/
#include "theory/quantifiers/equality_query.h"
#include "options/quantifiers_options.h"
#include "theory/quantifiers/first_order_model.h"
#include "theory/quantifiers/quantifiers_attributes.h"
#include "theory/quantifiers/term_util.h"
using namespace std;
using namespace CVC4::kind;
using namespace CVC4::context;
namespace CVC4 {
namespace theory {
namespace quantifiers {
EqualityQueryQuantifiersEngine::EqualityQueryQuantifiersEngine(
QuantifiersState& qs, FirstOrderModel* m)
: d_qstate(qs),
d_model(m),
d_eqi_counter(qs.getSatContext()),
d_reset_count(0)
{
}
EqualityQueryQuantifiersEngine::~EqualityQueryQuantifiersEngine(){
}
bool EqualityQueryQuantifiersEngine::reset( Theory::Effort e ){
d_int_rep.clear();
d_reset_count++;
return true;
}
Node EqualityQueryQuantifiersEngine::getInternalRepresentative(Node a,
Node q,
int index)
{
Assert(q.isNull() || q.getKind() == FORALL);
Node r = d_qstate.getRepresentative(a);
if( options::finiteModelFind() ){
if( r.isConst() && quantifiers::TermUtil::containsUninterpretedConstant( r ) ){
//map back from values assigned by model, if any
if (d_model != nullptr)
{
Node tr = d_model->getRepSet()->getTermForRepresentative(r);
if (!tr.isNull())
{
r = tr;
r = d_qstate.getRepresentative(r);
}else{
if( r.getType().isSort() ){
Trace("internal-rep-warn") << "No representative for UF constant." << std::endl;
//should never happen : UF constants should never escape model
Assert(false);
}
}
}
}
}
TypeNode v_tn = q.isNull() ? a.getType() : q[0][index].getType();
if (options::quantRepMode() == options::QuantRepMode::EE)
{
int score = getRepScore(r, q, index, v_tn);
if (score >= 0)
{
return r;
}
// if we are not a valid representative, try to select one below
}
std::map<Node, Node>& v_int_rep = d_int_rep[v_tn];
std::map<Node, Node>::const_iterator itir = v_int_rep.find(r);
if (itir != v_int_rep.end())
{
return itir->second;
}
// find best selection for representative
Node r_best;
std::vector<Node> eqc;
d_qstate.getEquivalenceClass(r, eqc);
Trace("internal-rep-select")
<< "Choose representative for equivalence class : " << eqc
<< ", type = " << v_tn << std::endl;
int r_best_score = -1;
for (const Node& n : eqc)
{
int score = getRepScore(n, q, index, v_tn);
if (score != -2)
{
if (r_best.isNull()
|| (score >= 0 && (r_best_score < 0 || score < r_best_score)))
{
r_best = n;
r_best_score = score;
}
}
}
if (r_best.isNull())
{
Trace("internal-rep-warn")
<< "No valid choice for representative in eqc class " << eqc
<< std::endl;
return Node::null();
}
// now, make sure that no other member of the class is an instance
std::unordered_map<TNode, Node, TNodeHashFunction> cache;
r_best = getInstance(r_best, eqc, cache);
// store that this representative was chosen at this point
if (d_rep_score.find(r_best) == d_rep_score.end())
{
d_rep_score[r_best] = d_reset_count;
}
Trace("internal-rep-select")
<< "...Choose " << r_best << " with score " << r_best_score
<< " and type " << r_best.getType() << std::endl;
Assert(r_best.getType().isSubtypeOf(v_tn));
v_int_rep[r] = r_best;
if (Trace.isOn("internal-rep-debug"))
{
if (r_best != a)
{
Trace("internal-rep-debug")
<< "rep( " << a << " ) = " << r << ", " << std::endl;
Trace("internal-rep-debug")
<< "int_rep( " << a << " ) = " << r_best << ", " << std::endl;
}
}
return r_best;
}
//helper functions
Node EqualityQueryQuantifiersEngine::getInstance( Node n, const std::vector< Node >& eqc, std::unordered_map<TNode, Node, TNodeHashFunction>& cache ){
if(cache.find(n) != cache.end()) {
return cache[n];
}
for( size_t i=0; i<n.getNumChildren(); i++ ){
Node nn = getInstance( n[i], eqc, cache );
if( !nn.isNull() ){
return cache[n] = nn;
}
}
if( std::find( eqc.begin(), eqc.end(), n )!=eqc.end() ){
return cache[n] = n;
}else{
return cache[n] = Node::null();
}
}
//-2 : invalid, -1 : undesired, otherwise : smaller the score, the better
int EqualityQueryQuantifiersEngine::getRepScore(Node n,
Node q,
int index,
TypeNode v_tn)
{
if( options::cegqi() && quantifiers::TermUtil::hasInstConstAttr(n) ){ //reject
return -2;
}else if( !n.getType().isSubtypeOf( v_tn ) ){ //reject if incorrect type
return -2;
}else if( options::instMaxLevel()!=-1 ){
//score prefer lowest instantiation level
if( n.hasAttribute(InstLevelAttribute()) ){
return n.getAttribute(InstLevelAttribute());
}else{
return options::instLevelInputOnly() ? -1 : 0;
}
}else{
if (options::quantRepMode() == options::QuantRepMode::FIRST)
{
//score prefers earliest use of this term as a representative
return d_rep_score.find( n )==d_rep_score.end() ? -1 : d_rep_score[n];
}
else
{
Assert(options::quantRepMode() == options::QuantRepMode::DEPTH);
return quantifiers::TermUtil::getTermDepth( n );
}
}
}
} /* CVC4::theory::quantifiers namespace */
} /* CVC4::theory namespace */
} /* CVC4 namespace */
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