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/********************* */
/*! \file abduction_solver.cpp
** \verbatim
** Top contributors (to current version):
** Andrew Reynolds, Morgan Deters, Mathias Preiner
** 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 The solver for abduction queries
**/
#include "smt/abduction_solver.h"
#include "options/smt_options.h"
#include "smt/smt_engine.h"
#include "theory/quantifiers/quantifiers_attributes.h"
#include "theory/quantifiers/sygus/sygus_abduct.h"
#include "theory/quantifiers/sygus/sygus_grammar_cons.h"
#include "theory/smt_engine_subsolver.h"
using namespace CVC4::theory;
namespace CVC4 {
namespace smt {
AbductionSolver::AbductionSolver(SmtEngine* parent) : d_parent(parent) {}
AbductionSolver::~AbductionSolver() {}
bool AbductionSolver::getAbduct(const Node& goal,
const TypeNode& grammarType,
Node& abd)
{
if (!options::produceAbducts())
{
const char* msg = "Cannot get abduct when produce-abducts options is off.";
throw ModalException(msg);
}
Trace("sygus-abduct") << "SmtEngine::getAbduct: goal " << goal << std::endl;
std::vector<Node> axioms = d_parent->getExpandedAssertions();
std::vector<Node> asserts(axioms.begin(), axioms.end());
// must expand definitions
Node conjn = d_parent->expandDefinitions(goal);
// now negate
conjn = conjn.negate();
d_abdConj = conjn;
asserts.push_back(conjn);
std::string name("A");
Node aconj = quantifiers::SygusAbduct::mkAbductionConjecture(
name, asserts, axioms, grammarType);
// should be a quantified conjecture with one function-to-synthesize
Assert(aconj.getKind() == kind::FORALL && aconj[0].getNumChildren() == 1);
// remember the abduct-to-synthesize
d_sssf = aconj[0][0];
Trace("sygus-abduct") << "SmtEngine::getAbduct: made conjecture : " << aconj
<< ", solving for " << d_sssf << std::endl;
// we generate a new smt engine to do the abduction query
initializeSubsolver(d_subsolver);
// get the logic
LogicInfo l = d_subsolver->getLogicInfo().getUnlockedCopy();
// enable everything needed for sygus
l.enableSygus();
d_subsolver->setLogic(l);
// assert the abduction query
d_subsolver->assertFormula(aconj);
return getAbductInternal(abd);
}
bool AbductionSolver::getAbduct(const Node& goal, Node& abd)
{
TypeNode grammarType;
return getAbduct(goal, grammarType, abd);
}
bool AbductionSolver::getAbductInternal(Node& abd)
{
// should have initialized the subsolver by now
Assert(d_subsolver != nullptr);
Trace("sygus-abduct") << " SmtEngine::getAbduct check sat..." << std::endl;
Result r = d_subsolver->checkSat();
Trace("sygus-abduct") << " SmtEngine::getAbduct result: " << r << std::endl;
if (r.asSatisfiabilityResult().isSat() == Result::UNSAT)
{
// get the synthesis solution
std::map<Node, Node> sols;
d_subsolver->getSynthSolutions(sols);
Assert(sols.size() == 1);
std::map<Node, Node>::iterator its = sols.find(d_sssf);
if (its != sols.end())
{
Trace("sygus-abduct")
<< "SmtEngine::getAbduct: solution is " << its->second << std::endl;
abd = its->second;
if (abd.getKind() == kind::LAMBDA)
{
abd = abd[1];
}
// get the grammar type for the abduct
Node agdtbv = d_sssf.getAttribute(SygusSynthFunVarListAttribute());
Assert(!agdtbv.isNull());
Assert(agdtbv.getKind() == kind::BOUND_VAR_LIST);
// convert back to original
// must replace formal arguments of abd with the free variables in the
// input problem that they correspond to.
std::vector<Node> vars;
std::vector<Node> syms;
SygusVarToTermAttribute sta;
for (const Node& bv : agdtbv)
{
vars.push_back(bv);
syms.push_back(bv.hasAttribute(sta) ? bv.getAttribute(sta) : bv);
}
abd = abd.substitute(vars.begin(), vars.end(), syms.begin(), syms.end());
// if check abducts option is set, we check the correctness
if (options::checkAbducts())
{
checkAbduct(abd);
}
return true;
}
Trace("sygus-abduct") << "SmtEngine::getAbduct: could not find solution!"
<< std::endl;
throw RecoverableModalException("Could not find solution for get-abduct.");
}
return false;
}
void AbductionSolver::checkAbduct(Node a)
{
Assert(a.getType().isBoolean());
Trace("check-abduct") << "SmtEngine::checkAbduct: get expanded assertions"
<< std::endl;
std::vector<Node> asserts = d_parent->getExpandedAssertions();
asserts.push_back(a);
// two checks: first, consistent with assertions, second, implies negated goal
// is unsatisfiable.
for (unsigned j = 0; j < 2; j++)
{
Trace("check-abduct") << "SmtEngine::checkAbduct: phase " << j
<< ": make new SMT engine" << std::endl;
// Start new SMT engine to check solution
std::unique_ptr<SmtEngine> abdChecker;
initializeSubsolver(abdChecker);
Trace("check-abduct") << "SmtEngine::checkAbduct: phase " << j
<< ": asserting formulas" << std::endl;
for (const Node& e : asserts)
{
abdChecker->assertFormula(e);
}
Trace("check-abduct") << "SmtEngine::checkAbduct: phase " << j
<< ": check the assertions" << std::endl;
Result r = abdChecker->checkSat();
Trace("check-abduct") << "SmtEngine::checkAbduct: phase " << j
<< ": result is " << r << std::endl;
std::stringstream serr;
bool isError = false;
if (j == 0)
{
if (r.asSatisfiabilityResult().isSat() != Result::SAT)
{
isError = true;
serr << "SmtEngine::checkAbduct(): produced solution cannot be shown "
"to be consisconsistenttent with assertions, result was "
<< r;
}
Trace("check-abduct")
<< "SmtEngine::checkAbduct: goal is " << d_abdConj << std::endl;
// add the goal to the set of assertions
Assert(!d_abdConj.isNull());
asserts.push_back(d_abdConj);
}
else
{
if (r.asSatisfiabilityResult().isSat() != Result::UNSAT)
{
isError = true;
serr << "SmtEngine::checkAbduct(): negated goal cannot be shown "
"unsatisfiable with produced solution, result was "
<< r;
}
}
// did we get an unexpected result?
if (isError)
{
InternalError() << serr.str();
}
}
}
} // namespace smt
} // namespace CVC4
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