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/********************* */
/*! \file justification_heuristic.h
** \verbatim
** Original author: kshitij
** Major contributors: none
** Minor contributors (to current version): none
** This file is part of the CVC4 prototype.
** Copyright (c) 2012 The Analysis of Computer Systems Group (ACSys)
** Courant Institute of Mathematical Sciences
** New York University
** See the file COPYING in the top-level source directory for licensing
** information.\endverbatim
**
** \brief Justification heuristic for decision making
**
** A ATGP-inspired justification-based decision heuristic. See
** [insert reference] for more details. This code is, or not, based
** on the CVC3 implementation of the same heuristic.
**
** It needs access to the simplified but non-clausal formula.
**/
#ifndef __CVC4__DECISION__JUSTIFICATION_HEURISTIC
#define __CVC4__DECISION__JUSTIFICATION_HEURISTIC
#include "decision_engine.h"
#include "decision_strategy.h"
#include "context/cdhashset.h"
#include "expr/node.h"
#include "prop/sat_solver_types.h"
namespace CVC4 {
namespace decision {
class GiveUpException : public Exception {
public:
GiveUpException() :
Exception("justification hueristic: giving up") {
}
};/* class GiveUpException */
class JustificationHeuristic : public DecisionStrategy {
context::CDHashSet<TNode,TNodeHashFunction> d_justified;
context::CDO<unsigned> d_prvsIndex;
IntStat d_helfulness;
IntStat d_giveup;
TimerStat d_timestat;
public:
JustificationHeuristic(CVC4::DecisionEngine* de, context::Context *c):
DecisionStrategy(de, c),
d_justified(c),
d_prvsIndex(c, 0),
d_helfulness("decision::jh::helpfulness", 0),
d_giveup("decision::jh::giveup", 0),
d_timestat("decision::jh::time") {
StatisticsRegistry::registerStat(&d_helfulness);
StatisticsRegistry::registerStat(&d_giveup);
StatisticsRegistry::registerStat(&d_timestat);
Trace("decision") << "Justification heuristic enabled" << std::endl;
}
~JustificationHeuristic() {
StatisticsRegistry::unregisterStat(&d_helfulness);
StatisticsRegistry::unregisterStat(&d_timestat);
}
prop::SatLiteral getNext(bool &stopSearch) {
Trace("decision") << "JustificationHeuristic::getNext()" << std::endl;
TimerStat::CodeTimer codeTimer(d_timestat);
const vector<Node>& assertions = d_decisionEngine->getAssertions();
for(unsigned i = d_prvsIndex; i < assertions.size(); ++i) {
SatLiteral litDecision;
Trace("decision") << assertions[i] << std::endl;
SatValue desiredVal = SAT_VALUE_UNKNOWN;
if(d_decisionEngine->hasSatLiteral(assertions[i]) ) {
//desiredVal = d_decisionEngine->getSatValue( d_decisionEngine->getSatLiteral(assertions[i]) );
Trace("decision") << "JustificationHeuristic encountered a variable not in SatSolver." << std::endl;
// continue;
// Assert(not lit.isNull());
}
if(desiredVal == SAT_VALUE_UNKNOWN) desiredVal = SAT_VALUE_TRUE;
bool ret;
try {
ret = findSplitterRec(assertions[i], desiredVal, &litDecision);
}catch(GiveUpException &e) {
return prop::undefSatLiteral;
}
if(ret == true) {
Trace("decision") << "Yippee!!" << std::endl;
//d_prvsIndex = i;
++d_helfulness;
return litDecision;
}
}
Trace("decision") << "Nothing to split on " << std::endl;
bool alljustified = true;
for(unsigned i = 0 ; i < assertions.size() && alljustified ; ++i) {
alljustified &= assertions[i].getKind() == kind::NOT ?
checkJustified(assertions[i][0]) : checkJustified(assertions[i]);
if(Debug.isOn("decision")) {
bool x = assertions[i].getKind() == kind::NOT ?
checkJustified(assertions[i][0]) : checkJustified(assertions[i]);
if(x==false)
Debug("decision") << "****** Not justified [i="<<i<<"]: " << assertions[i] << std::endl;
}
}
Assert(alljustified);
stopSearch = alljustified;
d_decisionEngine->setResult(SAT_VALUE_TRUE);
return prop::undefSatLiteral;
}
bool needSimplifiedPreITEAssertions() { return true; }
void notifyAssertionsAvailable() {
Trace("decision") << "JustificationHeuristic::notifyAssertionsAvailable()"
<< " size = " << d_decisionEngine->getAssertions().size()
<< std::endl;
/* clear the justifcation labels -- reconsider if/when to do
this */
//d_justified.clear();
//d_prvsIndex = 0;
}
private:
/* Do all the hardwork. */
bool findSplitterRec(Node node, SatValue value, SatLiteral* litDecision);
/* Helper functions */
void setJustified(TNode);
bool checkJustified(TNode);
/* If literal exists corresponding to the node return
that. Otherwise an UNKNOWN */
SatValue tryGetSatValue(Node n)
{
Debug("decision") << " " << n << " has sat value " << " ";
if(d_decisionEngine->hasSatLiteral(n) ) {
Debug("decision") << d_decisionEngine->getSatValue(d_decisionEngine->getSatLiteral(n)) << std::endl;
return d_decisionEngine->getSatValue(d_decisionEngine->getSatLiteral(n));
} else {
Debug("decision") << "NO SAT LITERAL" << std::endl;
return SAT_VALUE_UNKNOWN;
}
}
};/* class JustificationHeuristic */
}/* namespace decision */
}/* namespace CVC4 */
#endif /* __CVC4__DECISION__JUSTIFICATION_HEURISTIC */
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