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/****************************************************************************** |
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* Top contributors (to current version): |
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* Andrew Reynolds, Morgan Deters, Mathias Preiner |
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* |
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* This file is part of the cvc5 project. |
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* |
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* Copyright (c) 2009-2021 by the authors listed in the file AUTHORS |
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* in the top-level source directory and their institutional affiliations. |
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* All rights reserved. See the file COPYING in the top-level source |
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* directory for licensing information. |
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* **************************************************************************** |
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* |
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* The solver for abduction queries. |
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*/ |
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#include "smt/abduction_solver.h" |
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#include <sstream> |
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#include "base/modal_exception.h" |
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#include "options/smt_options.h" |
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#include "smt/env.h" |
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#include "smt/smt_engine.h" |
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#include "theory/quantifiers/quantifiers_attributes.h" |
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#include "theory/quantifiers/sygus/sygus_abduct.h" |
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#include "theory/quantifiers/sygus/sygus_grammar_cons.h" |
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#include "theory/smt_engine_subsolver.h" |
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#include "theory/trust_substitutions.h" |
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using namespace cvc5::theory; |
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namespace cvc5 { |
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namespace smt { |
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AbductionSolver::AbductionSolver(SmtEngine* parent) : d_parent(parent) {} |
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AbductionSolver::~AbductionSolver() {} |
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bool AbductionSolver::getAbduct(const Node& goal, |
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const TypeNode& grammarType, |
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Node& abd) |
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{ |
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if (!options::produceAbducts()) |
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{ |
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const char* msg = "Cannot get abduct when produce-abducts options is off."; |
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throw ModalException(msg); |
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} |
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Trace("sygus-abduct") << "SmtEngine::getAbduct: goal " << goal << std::endl; |
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std::vector<Node> axioms = d_parent->getExpandedAssertions(); |
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std::vector<Node> asserts(axioms.begin(), axioms.end()); |
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// must expand definitions |
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Node conjn = d_parent->getEnv().getTopLevelSubstitutions().apply(goal); |
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// now negate |
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conjn = conjn.negate(); |
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d_abdConj = conjn; |
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asserts.push_back(conjn); |
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std::string name("A"); |
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Node aconj = quantifiers::SygusAbduct::mkAbductionConjecture( |
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name, asserts, axioms, grammarType); |
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// should be a quantified conjecture with one function-to-synthesize |
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Assert(aconj.getKind() == kind::FORALL && aconj[0].getNumChildren() == 1); |
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// remember the abduct-to-synthesize |
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d_sssf = aconj[0][0]; |
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Trace("sygus-abduct") << "SmtEngine::getAbduct: made conjecture : " << aconj |
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<< ", solving for " << d_sssf << std::endl; |
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// we generate a new smt engine to do the abduction query |
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initializeSubsolver(d_subsolver); |
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// get the logic |
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LogicInfo l = d_subsolver->getLogicInfo().getUnlockedCopy(); |
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// enable everything needed for sygus |
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l.enableSygus(); |
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d_subsolver->setLogic(l); |
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// assert the abduction query |
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d_subsolver->assertFormula(aconj); |
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return getAbductInternal(abd); |
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} |
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bool AbductionSolver::getAbduct(const Node& goal, Node& abd) |
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{ |
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TypeNode grammarType; |
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return getAbduct(goal, grammarType, abd); |
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} |
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bool AbductionSolver::getAbductInternal(Node& abd) |
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{ |
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// should have initialized the subsolver by now |
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Assert(d_subsolver != nullptr); |
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Trace("sygus-abduct") << " SmtEngine::getAbduct check sat..." << std::endl; |
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Result r = d_subsolver->checkSat(); |
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Trace("sygus-abduct") << " SmtEngine::getAbduct result: " << r << std::endl; |
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if (r.asSatisfiabilityResult().isSat() == Result::UNSAT) |
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{ |
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// get the synthesis solution |
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std::map<Node, Node> sols; |
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d_subsolver->getSynthSolutions(sols); |
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Assert(sols.size() == 1); |
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std::map<Node, Node>::iterator its = sols.find(d_sssf); |
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if (its != sols.end()) |
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{ |
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Trace("sygus-abduct") |
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<< "SmtEngine::getAbduct: solution is " << its->second << std::endl; |
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abd = its->second; |
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if (abd.getKind() == kind::LAMBDA) |
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{ |
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abd = abd[1]; |
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} |
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// get the grammar type for the abduct |
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Node agdtbv = d_sssf.getAttribute(SygusSynthFunVarListAttribute()); |
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Assert(!agdtbv.isNull()); |
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Assert(agdtbv.getKind() == kind::BOUND_VAR_LIST); |
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// convert back to original |
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// must replace formal arguments of abd with the free variables in the |
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// input problem that they correspond to. |
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std::vector<Node> vars; |
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std::vector<Node> syms; |
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SygusVarToTermAttribute sta; |
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for (const Node& bv : agdtbv) |
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{ |
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vars.push_back(bv); |
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syms.push_back(bv.hasAttribute(sta) ? bv.getAttribute(sta) : bv); |
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} |
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abd = abd.substitute(vars.begin(), vars.end(), syms.begin(), syms.end()); |
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// if check abducts option is set, we check the correctness |
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if (options::checkAbducts()) |
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{ |
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checkAbduct(abd); |
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} |
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return true; |
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} |
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Trace("sygus-abduct") << "SmtEngine::getAbduct: could not find solution!" |
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<< std::endl; |
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throw RecoverableModalException("Could not find solution for get-abduct."); |
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} |
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return false; |
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} |
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void AbductionSolver::checkAbduct(Node a) |
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{ |
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Assert(a.getType().isBoolean()); |
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Trace("check-abduct") << "SmtEngine::checkAbduct: get expanded assertions" |
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<< std::endl; |
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std::vector<Node> asserts = d_parent->getExpandedAssertions(); |
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asserts.push_back(a); |
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// two checks: first, consistent with assertions, second, implies negated goal |
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// is unsatisfiable. |
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for (unsigned j = 0; j < 2; j++) |
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{ |
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Trace("check-abduct") << "SmtEngine::checkAbduct: phase " << j |
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<< ": make new SMT engine" << std::endl; |
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// Start new SMT engine to check solution |
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std::unique_ptr<SmtEngine> abdChecker; |
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initializeSubsolver(abdChecker); |
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Trace("check-abduct") << "SmtEngine::checkAbduct: phase " << j |
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<< ": asserting formulas" << std::endl; |
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for (const Node& e : asserts) |
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{ |
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abdChecker->assertFormula(e); |
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} |
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Trace("check-abduct") << "SmtEngine::checkAbduct: phase " << j |
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<< ": check the assertions" << std::endl; |
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Result r = abdChecker->checkSat(); |
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Trace("check-abduct") << "SmtEngine::checkAbduct: phase " << j |
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<< ": result is " << r << std::endl; |
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std::stringstream serr; |
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bool isError = false; |
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if (j == 0) |
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{ |
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if (r.asSatisfiabilityResult().isSat() != Result::SAT) |
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{ |
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isError = true; |
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serr << "SmtEngine::checkAbduct(): produced solution cannot be shown " |
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"to be consisconsistenttent with assertions, result was " |
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<< r; |
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} |
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Trace("check-abduct") |
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<< "SmtEngine::checkAbduct: goal is " << d_abdConj << std::endl; |
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// add the goal to the set of assertions |
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Assert(!d_abdConj.isNull()); |
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asserts.push_back(d_abdConj); |
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} |
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else |
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{ |
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if (r.asSatisfiabilityResult().isSat() != Result::UNSAT) |
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{ |
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isError = true; |
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serr << "SmtEngine::checkAbduct(): negated goal cannot be shown " |
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"unsatisfiable with produced solution, result was " |
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<< r; |
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} |
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} |
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// did we get an unexpected result? |
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if (isError) |
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{ |
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InternalError() << serr.str(); |
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} |
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} |
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} |
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} // namespace smt |
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} // namespace cvc5 |