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/****************************************************************************** |
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* Top contributors (to current version): |
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* Andrew Reynolds, Aina Niemetz |
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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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* Implementation of sygus abduction utility, which transforms an arbitrary |
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* input into an abduction problem. |
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*/ |
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#include "theory/quantifiers/sygus/sygus_abduct.h" |
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#include <sstream> |
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#include "expr/dtype.h" |
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#include "expr/node_algorithm.h" |
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#include "expr/skolem_manager.h" |
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#include "expr/sygus_datatype.h" |
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#include "theory/datatypes/sygus_datatype_utils.h" |
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#include "theory/quantifiers/quantifiers_attributes.h" |
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#include "theory/quantifiers/quantifiers_rewriter.h" |
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#include "theory/quantifiers/sygus/sygus_grammar_cons.h" |
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#include "theory/quantifiers/sygus/sygus_utils.h" |
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#include "theory/quantifiers/term_util.h" |
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#include "theory/rewriter.h" |
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using namespace std; |
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using namespace cvc5::kind; |
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namespace cvc5 { |
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namespace theory { |
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namespace quantifiers { |
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SygusAbduct::SygusAbduct() {} |
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Node SygusAbduct::mkAbductionConjecture(const std::string& name, |
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const std::vector<Node>& asserts, |
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const std::vector<Node>& axioms, |
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TypeNode abdGType) |
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{ |
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NodeManager* nm = NodeManager::currentNM(); |
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SkolemManager* sm = nm->getSkolemManager(); |
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std::unordered_set<Node> symset; |
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for (size_t i = 0, size = asserts.size(); i < size; i++) |
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{ |
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expr::getSymbols(asserts[i], symset); |
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} |
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Trace("sygus-abduct-debug") |
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<< "...finish, got " << symset.size() << " symbols." << std::endl; |
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Trace("sygus-abduct-debug") << "Setup symbols..." << std::endl; |
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std::vector<Node> syms; |
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std::vector<Node> vars; |
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std::vector<Node> varlist; |
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std::vector<TypeNode> varlistTypes; |
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for (const Node& s : symset) |
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{ |
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TypeNode tn = s.getType(); |
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if (tn.isConstructor() || tn.isSelector() || tn.isTester()) |
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{ |
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// datatype symbols should be considered interpreted symbols here, not |
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// (higher-order) variables. |
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continue; |
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} |
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// Notice that we allow for non-first class (e.g. function) variables here. |
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// This is applicable to the case where we are doing get-abduct in a logic |
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// with UF. |
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std::stringstream ss; |
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ss << s; |
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Node var = nm->mkBoundVar(tn); |
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syms.push_back(s); |
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vars.push_back(var); |
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Node vlv = nm->mkBoundVar(ss.str(), tn); |
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varlist.push_back(vlv); |
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varlistTypes.push_back(tn); |
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// set that this variable encodes the term s |
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SygusVarToTermAttribute sta; |
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vlv.setAttribute(sta, s); |
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} |
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Trace("sygus-abduct-debug") << "...finish" << std::endl; |
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Trace("sygus-abduct-debug") << "Make abduction predicate..." << std::endl; |
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// make the abduction predicate to synthesize |
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TypeNode abdType = varlistTypes.empty() ? nm->booleanType() |
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: nm->mkPredicateType(varlistTypes); |
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Node abd = nm->mkBoundVar(name.c_str(), abdType); |
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Trace("sygus-abduct-debug") << "...finish" << std::endl; |
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// the sygus variable list |
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Node abvl; |
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// if provided, we will associate the provide sygus datatype type with the |
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// function-to-synthesize. However, we must convert it so that its |
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// free symbols are universally quantified. |
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if (!abdGType.isNull()) |
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{ |
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Assert(abdGType.isDatatype() && abdGType.getDType().isSygus()); |
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Trace("sygus-abduct-debug") << "Process abduction type:" << std::endl; |
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Trace("sygus-abduct-debug") << abdGType.getDType().getName() << std::endl; |
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// substitute the free symbols of the grammar with variables corresponding |
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// to the formal argument list of the new sygus datatype type. |
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TypeNode abdGTypeS = datatypes::utils::substituteAndGeneralizeSygusType( |
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abdGType, syms, varlist); |
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Assert(abdGTypeS.isDatatype() && abdGTypeS.getDType().isSygus()); |
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Trace("sygus-abduct-debug") |
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<< "Make sygus grammar attribute..." << std::endl; |
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Node sym = nm->mkBoundVar("sfproxy_abduct", abdGTypeS); |
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// Set the sygus grammar attribute to indicate that abdGTypeS encodes the |
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// grammar for abd. |
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theory::SygusSynthGrammarAttribute ssg; |
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abd.setAttribute(ssg, sym); |
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Trace("sygus-abduct-debug") << "Finished setting up grammar." << std::endl; |
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// use the bound variable list from the new substituted grammar type |
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const DType& agtsd = abdGTypeS.getDType(); |
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abvl = agtsd.getSygusVarList(); |
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Assert(!abvl.isNull() && abvl.getKind() == BOUND_VAR_LIST); |
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} |
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else if (!varlist.empty()) |
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{ |
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// the bound variable list of the abduct-to-synthesize is determined by |
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// the variable list above |
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abvl = nm->mkNode(BOUND_VAR_LIST, varlist); |
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// We do not set a grammar type for abd (SygusSynthGrammarAttribute). |
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// Its grammar will be constructed internally in the default way |
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} |
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Trace("sygus-abduct-debug") << "Make abduction predicate app..." << std::endl; |
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std::vector<Node> achildren; |
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achildren.push_back(abd); |
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achildren.insert(achildren.end(), vars.begin(), vars.end()); |
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Node abdApp = vars.empty() ? abd : nm->mkNode(APPLY_UF, achildren); |
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Trace("sygus-abduct-debug") << "...finish" << std::endl; |
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Trace("sygus-abduct-debug") << "Set attributes..." << std::endl; |
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// set the sygus bound variable list |
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abd.setAttribute(theory::SygusSynthFunVarListAttribute(), abvl); |
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Trace("sygus-abduct-debug") << "...finish" << std::endl; |
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Trace("sygus-abduct-debug") << "Make conjecture body..." << std::endl; |
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Node input = asserts.size() == 1 ? asserts[0] : nm->mkNode(AND, asserts); |
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input = input.substitute(syms.begin(), syms.end(), vars.begin(), vars.end()); |
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// A(x) => ~input( x ) |
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input = nm->mkNode(OR, abdApp.negate(), input.negate()); |
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Trace("sygus-abduct-debug") << "...finish" << std::endl; |
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Trace("sygus-abduct-debug") << "Make conjecture..." << std::endl; |
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Node res = input.negate(); |
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if (!vars.empty()) |
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{ |
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Node bvl = nm->mkNode(BOUND_VAR_LIST, vars); |
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// exists x. ~( A( x ) => ~input( x ) ) |
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res = nm->mkNode(EXISTS, bvl, res); |
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} |
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// sygus attribute |
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Node aconj = axioms.size() == 0 |
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? nm->mkConst(true) |
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: (axioms.size() == 1 ? axioms[0] : nm->mkNode(AND, axioms)); |
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aconj = aconj.substitute(syms.begin(), syms.end(), vars.begin(), vars.end()); |
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Trace("sygus-abduct") << "---> Assumptions: " << aconj << std::endl; |
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Node sc = nm->mkNode(AND, aconj, abdApp); |
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if (!vars.empty()) |
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{ |
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Node vbvl = nm->mkNode(BOUND_VAR_LIST, vars); |
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sc = nm->mkNode(EXISTS, vbvl, sc); |
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} |
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Node sygusScVar = sm->mkDummySkolem("sygus_sc", nm->booleanType()); |
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sygusScVar.setAttribute(theory::SygusSideConditionAttribute(), sc); |
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Node instAttr = nm->mkNode(INST_ATTRIBUTE, sygusScVar); |
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// build in the side condition |
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// exists x. A( x ) ^ input_axioms( x ) |
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// as an additional annotation on the sygus conjecture. In other words, |
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// the abducts A we procedure must be consistent with our axioms. |
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// forall A. exists x. ~( A( x ) => ~input( x ) ) |
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res = SygusUtils::mkSygusConjecture({abd}, res, {instAttr}); |
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Trace("sygus-abduct-debug") << "...finish" << std::endl; |
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res = theory::Rewriter::rewrite(res); |
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Trace("sygus-abduct") << "Generate: " << res << std::endl; |
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return res; |
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} |
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} // namespace quantifiers |
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} // namespace theory |
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} // namespace cvc5 |