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/********************* */
/*! \file ce_guided_instantiation.cpp
** \verbatim
** Original author: Andrew Reynolds
** Major contributors: none
** Minor contributors (to current version): none
** This file is part of the CVC4 project.
** Copyright (c) 2009-2014 New York University and The University of Iowa
** See the file COPYING in the top-level source directory for licensing
** information.\endverbatim
**
** \brief counterexample guided instantiation class
**
**/
#include "theory/quantifiers/ce_guided_instantiation.h"
#include "theory/theory_engine.h"
#include "theory/quantifiers/options.h"
#include "theory/quantifiers/term_database.h"
#include "theory/quantifiers/first_order_model.h"
using namespace CVC4;
using namespace CVC4::kind;
using namespace CVC4::theory;
using namespace CVC4::theory::quantifiers;
using namespace std;
namespace CVC4 {
CegInstantiation::CegConjecture::CegConjecture() {
}
void CegInstantiation::CegConjecture::assign( Node q ) {
Assert( d_quant.isNull() );
Assert( q.getKind()==FORALL );
d_quant = q;
for( unsigned i=0; i<q[0].getNumChildren(); i++ ){
d_candidates.push_back( NodeManager::currentNM()->mkSkolem( "e", q[0][i].getType() ) );
}
}
void CegInstantiation::CegConjecture::initializeGuard( QuantifiersEngine * qe ){
if( d_guard.isNull() ){
d_guard = Rewriter::rewrite( NodeManager::currentNM()->mkSkolem( "G", NodeManager::currentNM()->booleanType() ) );
//specify guard behavior
qe->getValuation().ensureLiteral( d_guard );
qe->getOutputChannel().requirePhase( d_guard, true );
}
}
CegInstantiation::CegInstantiation( QuantifiersEngine * qe, context::Context* c ) : QuantifiersModule( qe ), d_conj_active( c, false ), d_conj_infeasible( c, false ), d_guard_assertions( c ) {
}
bool CegInstantiation::needsCheck( Theory::Effort e ) {
return e>=Theory::EFFORT_LAST_CALL;
}
void CegInstantiation::check( Theory::Effort e, unsigned quant_e ) {
if( quant_e==QuantifiersEngine::QEFFORT_STANDARD ){
Trace("cegqi-engine") << "---Countexample Guided Instantiation Engine---" << std::endl;
Trace("cegqi-debug") << "Current conjecture status : " << d_conj_active << " " << d_conj_infeasible << std::endl;
if( d_conj_active && !d_conj_infeasible ){
checkCegConjecture( &d_conj );
}
Trace("cegqi-engine") << "Finished Countexample Guided Instantiation engine." << std::endl;
}
}
void CegInstantiation::registerQuantifier( Node q ) {
if( d_quantEngine->getOwner( q )==this ){
if( !d_conj.isAssigned() ){
Trace("cegqi") << "Register conjecture : " << q << std::endl;
d_conj.assign( q );
//construct base instantiation
d_conj.d_base_inst = Rewriter::rewrite( d_quantEngine->getInstantiation( q, d_conj.d_candidates ) );
Trace("cegqi") << "Base instantiation is : " << d_conj.d_base_inst << std::endl;
if( getTermDatabase()->isQAttrSygus( q ) ){
Assert( d_conj.d_base_inst.getKind()==NOT );
Assert( d_conj.d_base_inst[0].getKind()==FORALL );
for( unsigned j=0; j<d_conj.d_base_inst[0][0].getNumChildren(); j++ ){
d_conj.d_inner_vars.push_back( d_conj.d_base_inst[0][0][j] );
}
}else if( getTermDatabase()->isQAttrSynthesis( q ) ){
//add immediate lemma
Node lem = NodeManager::currentNM()->mkNode( OR, d_conj.d_guard.negate(), d_conj.d_base_inst );
}
}else{
Assert( d_conj.d_quant==q );
}
}
}
void CegInstantiation::assertNode( Node n ) {
Trace("cegqi-debug") << "Cegqi : Assert : " << n << std::endl;
bool pol = n.getKind()!=NOT;
Node lit = n.getKind()==NOT ? n[0] : n;
if( lit==d_conj.d_guard ){
d_guard_assertions[lit] = pol;
d_conj_infeasible = !pol;
}
if( lit==d_conj.d_quant ){
d_conj_active = true;
}
}
Node CegInstantiation::getNextDecisionRequest() {
d_conj.initializeGuard( d_quantEngine );
bool value;
if( !d_quantEngine->getValuation().hasSatValue( d_conj.d_guard, value ) ) {
if( d_guard_assertions.find( d_conj.d_guard )==d_guard_assertions.end() ){
if( d_conj.d_guard_split.isNull() ){
Node lem = NodeManager::currentNM()->mkNode( OR, d_conj.d_guard.negate(), d_conj.d_guard );
d_quantEngine->getOutputChannel().lemma( lem );
}
Trace("cegqi-debug") << "Decide next on : " << d_conj.d_guard << "..." << std::endl;
return d_conj.d_guard;
}
}
return Node::null();
}
void CegInstantiation::checkCegConjecture( CegConjecture * conj ) {
Node q = conj->d_quant;
Trace("cegqi-engine-debug") << "Synthesis conjecture : " << q << std::endl;
Trace("cegqi-engine-debug") << " * Candidate program/output : ";
for( unsigned i=0; i<conj->d_candidates.size(); i++ ){
Trace("cegqi-engine-debug") << conj->d_candidates[i] << " ";
}
Trace("cegqi-engine-debug") << std::endl;
if( getTermDatabase()->isQAttrSygus( q ) ){
Trace("cegqi-engine-debug") << " * Values are : ";
bool success = true;
std::vector< Node > model_values;
for( unsigned i=0; i<conj->d_candidates.size(); i++ ){
Node v = getModelValue( conj->d_candidates[i] );
model_values.push_back( v );
Trace("cegqi-engine-debug") << v << " ";
if( v.isNull() ){
success = false;
}
}
Trace("cegqi-engine-debug") << std::endl;
if( success ){
//must get a counterexample to the value of the current candidate
Node inst = conj->d_base_inst.substitute( conj->d_candidates.begin(), conj->d_candidates.end(), model_values.begin(), model_values.end() );
inst = Rewriter::rewrite( inst );
//body should be an existential
Assert( inst.getKind()==NOT );
Assert( inst[0].getKind()==FORALL );
//immediately skolemize
Node inst_sk = getTermDatabase()->getSkolemizedBody( inst[0] );
Trace("cegqi-lemma") << "Counterexample lemma : " << inst_sk << std::endl;
d_quantEngine->addLemma( NodeManager::currentNM()->mkNode( OR, q.negate(), inst_sk ) );
//candidate refinement : the next candidate must satisfy the counterexample found for the current model of the candidate
Assert( conj->d_inner_vars.size()==getTermDatabase()->d_skolem_constants[inst[0]].size() );
Node inst_ce_refine = conj->d_base_inst[0][1].substitute( conj->d_inner_vars.begin(), conj->d_inner_vars.end(),
getTermDatabase()->d_skolem_constants[inst[0]].begin(), getTermDatabase()->d_skolem_constants[inst[0]].end() );
Node lem = NodeManager::currentNM()->mkNode( OR, conj->d_guard.negate(), inst_ce_refine.negate() );
Trace("cegqi-lemma") << "Candidate refinement lemma : " << lem << std::endl;
d_quantEngine->addLemma( lem );
}
}else if( getTermDatabase()->isQAttrSynthesis( q ) ){
std::vector< Node > model_terms;
for( unsigned i=0; i<conj->d_candidates.size(); i++ ){
Node t = getModelTerm( conj->d_candidates[i] );
model_terms.push_back( t );
}
d_quantEngine->addInstantiation( q, model_terms, false );
}
}
Node CegInstantiation::getModelValue( Node n ) {
Trace("cegqi-mv") << "getModelValue for : " << n << std::endl;
//return d_quantEngine->getTheoryEngine()->getModelValue( n );
TypeNode tn = n.getType();
if( getEqualityEngine()->hasTerm( n ) ){
Node r = getRepresentative( n );
Node v;
eq::EqClassIterator eqc_i = eq::EqClassIterator( r, getEqualityEngine() );
while( !eqc_i.isFinished() ){
TNode nn = (*eqc_i);
if( nn.isConst() ){
Trace("cegqi-mv") << "..constant : " << nn << std::endl;
return nn;
}else if( nn.getKind()==APPLY_CONSTRUCTOR ){
v = nn;
}
++eqc_i;
}
if( !v.isNull() ){
std::vector< Node > children;
if( v.hasOperator() ){
children.push_back( v.getOperator() );
}
for( unsigned i=0; i<v.getNumChildren(); i++ ){
children.push_back( getModelValue( v[i] ) );
}
Node vv = NodeManager::currentNM()->mkNode( v.getKind(), children );
Trace("cegqi-mv") << "...value : " << vv << std::endl;
return vv;
}
}
Node e = getTermDatabase()->getEnumerateTerm( tn, 0 );
Trace("cegqi-mv") << "...enumerate : " << e << std::endl;
return e;
}
Node CegInstantiation::getModelTerm( Node n ){
return getModelValue( n );
}
}
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