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Diffstat (limited to 'src/theory/quantifiers/equality_infer.cpp')
| -rw-r--r-- | src/theory/quantifiers/equality_infer.cpp | 427 |
1 files changed, 427 insertions, 0 deletions
diff --git a/src/theory/quantifiers/equality_infer.cpp b/src/theory/quantifiers/equality_infer.cpp new file mode 100644 index 000000000..c3064116f --- /dev/null +++ b/src/theory/quantifiers/equality_infer.cpp @@ -0,0 +1,427 @@ +/********************* */ +/*! \file equality_infer.cpp + ** \verbatim + ** Top contributors (to current version): + ** Andrew Reynolds, Tim King + ** This file is part of the CVC4 project. + ** Copyright (c) 2009-2016 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 Method for inferring equalities between arithmetic equivalence classes, + ** inspired by "A generalization of Shostak's method for combining decision procedures" Barrett et al. Figure 1. + ** + **/ + +#include "theory/quantifiers/equality_infer.h" +#include "theory/quantifiers/quant_util.h" +#include "context/context_mm.h" + +using namespace CVC4; +using namespace CVC4::kind; +using namespace CVC4::theory; +using namespace CVC4::theory::quantifiers; +using namespace std; + +namespace CVC4 { + +EqualityInference::EqcInfo::EqcInfo(context::Context* c) : d_rep( c ), d_valid( c, false ), d_solved( c, false ), d_master(c) +//, d_rep_exp(c), d_uselist(c) +{ + +} + +EqualityInference::EqualityInference( context::Context* c, bool trackExp ) : +d_c( c ), d_trackExplain( trackExp ), d_elim_vars( c ), +d_rep_to_eqc( c ), d_rep_exp( c ), d_uselist( c ), d_pending_merges( c ), d_pending_merge_exp( c ){ + d_one = NodeManager::currentNM()->mkConst( Rational( 1 ) ); + d_true = NodeManager::currentNM()->mkConst( true ); +} + +EqualityInference::~EqualityInference(){ + for( std::map< Node, EqcInfo * >::iterator it = d_eqci.begin(); it != d_eqci.end(); ++it ){ + delete it->second; + } +} + +void EqualityInference::addToExplanation( std::vector< Node >& exp, Node e ) { + if( std::find( exp.begin(), exp.end(), e )==exp.end() ){ + Trace("eq-infer-debug2") << "......add to explanation " << e << std::endl; + exp.push_back( e ); + } +} + +void EqualityInference::addToExplanationEqc( std::vector< Node >& exp, Node eqc ) { + NodeListMap::iterator re_i = d_rep_exp.find( eqc ); + if( re_i!=d_rep_exp.end() ){ + for( unsigned i=0; i<(*re_i).second->size(); i++ ){ + addToExplanation( exp, (*(*re_i).second)[i] ); + } + } + //for( unsigned i=0; i<d_eqci[n]->d_rep_exp.size(); i++ ){ + // addToExplanation( exp, d_eqci[n]->d_rep_exp[i] ); + //} +} + +void EqualityInference::addToExplanationEqc( Node eqc, std::vector< Node >& exp_to_add ) { + NodeListMap::iterator re_i = d_rep_exp.find( eqc ); + NodeList* re; + if( re_i != d_rep_exp.end() ){ + re = (*re_i).second; + }else{ + re = new(d_c->getCMM()) NodeList( true, d_c, false, context::ContextMemoryAllocator<TNode>(d_c->getCMM()) ); + d_rep_exp.insertDataFromContextMemory( eqc, re ); + } + for( unsigned i=0; i<exp_to_add.size(); i++ ){ + re->push_back( exp_to_add[i] ); + } + //for( unsigned i=0; i<exp_to_add.size(); i++ ){ + // eqci->d_rep_exp.push_back( exp_to_add[i] ); + //} +} + +Node EqualityInference::getMaster( Node t, EqcInfo * eqc, bool& updated, Node new_m ) { + if( !eqc->d_master.get().isNull() ){ + if( eqc->d_master.get()==t ){ + if( !new_m.isNull() && t!=new_m ){ + eqc->d_master = new_m; + updated = true; + return new_m; + }else{ + return t; + } + }else{ + Assert( d_eqci.find( eqc->d_master.get() )!=d_eqci.end() ); + EqcInfo * eqc_m = d_eqci[eqc->d_master.get()]; + Node m = getMaster( eqc->d_master.get(), eqc_m, updated, new_m ); + eqc->d_master = m; + return m; + } + }else{ + return Node::null(); + } +} + +//update the internal "master" representative of the equivalence class, return true if the merge was non-redundant +bool EqualityInference::updateMaster( Node t1, Node t2, EqcInfo * eqc1, EqcInfo * eqc2 ) { + bool updated = false; + Node m1 = getMaster( t1, eqc1, updated ); + if( m1.isNull() ){ + eqc1->d_master = t2; + if( eqc2->d_master.get().isNull() ){ + eqc2->d_master = t2; + } + return true; + }else{ + updated = false; + Node m2 = getMaster( t2, eqc2, updated, m1); + if( m2.isNull() ){ + eqc2->d_master = m1; + return true; + }else{ + return updated; + } + } +} + +void EqualityInference::eqNotifyNewClass(TNode t) { + if( t.getType().isReal() ){ + Trace("eq-infer") << "Notify equivalence class : " << t << std::endl; + EqcInfo * eqci; + std::map< Node, EqcInfo * >::iterator itec = d_eqci.find( t ); + if( itec==d_eqci.end() ){ + eqci = new EqcInfo( d_c ); + d_eqci[t] = eqci; + }else{ + eqci = itec->second; + } + Assert( !eqci->d_valid.get() ); + if( !eqci->d_solved.get() ){ + //somewhat strange: t may not be in rewritten form + Node r = Rewriter::rewrite( t ); + std::map< Node, Node > msum; + if( QuantArith::getMonomialSum( r, msum ) ){ + Trace("eq-infer-debug2") << "...process monomial sum, size = " << msum.size() << std::endl; + eqci->d_valid = true; + bool changed = false; + std::vector< Node > exp; + std::vector< Node > children; + for( std::map< Node, Node >::iterator it = msum.begin(); it != msum.end(); ++it ) { + Trace("eq-infer-debug2") << "...process child " << it->first << ", " << it->second << std::endl; + if( !it->first.isNull() ){ + Node n = it->first; + BoolMap::const_iterator itv = d_elim_vars.find( n ); + if( itv!=d_elim_vars.end() ){ + changed = true; + Assert( d_eqci.find( n )!=d_eqci.end() ); + Assert( n!=t ); + Assert( d_eqci[n]->d_solved.get() ); + Trace("eq-infer-debug2") << "......its solved form is " << d_eqci[n]->d_rep.get() << std::endl; + if( d_trackExplain ){ + //track the explanation: justified by explanation for each substitution + addToExplanationEqc( exp, n ); + } + n = d_eqci[n]->d_rep; + Assert( !n.isNull() ); + } + if( it->second.isNull() ){ + children.push_back( n ); + }else{ + children.push_back( NodeManager::currentNM()->mkNode( MULT, it->second, n ) ); + } + }else{ + Assert( !it->second.isNull() ); + children.push_back( it->second ); + } + } + Trace("eq-infer-debug2") << "...children size = " << children.size() << std::endl; + bool mvalid = true; + if( changed ){ + r = children.size()==1 ? children[0] : NodeManager::currentNM()->mkNode( PLUS, children ); + Trace("eq-infer-debug2") << "...pre-rewrite : " << r << std::endl; + r = Rewriter::rewrite( r ); + msum.clear(); + if( !QuantArith::getMonomialSum( r, msum ) ){ + mvalid = false; + } + } + Trace("eq-infer") << "...value is " << r << std::endl; + setEqcRep( t, r, exp, eqci ); + if( mvalid ){ + for( std::map< Node, Node >::iterator it = msum.begin(); it != msum.end(); ++it ){ + if( !it->first.isNull() ){ + addToUseList( it->first, t ); + } + } + } + }else{ + eqci->d_valid = false; + } + } + } +} + +void EqualityInference::addToUseList( Node used, Node eqc ) { +#if 1 + NodeListMap::iterator ul_i = d_uselist.find( used ); + NodeList* ul; + if( ul_i != d_uselist.end() ){ + ul = (*ul_i).second; + }else{ + ul = new(d_c->getCMM()) NodeList( true, d_c, false, context::ContextMemoryAllocator<TNode>(d_c->getCMM()) ); + d_uselist.insertDataFromContextMemory( used, ul ); + } + Trace("eq-infer-debug") << " add to use list : " << used << " -> " << eqc << std::endl; + (*ul).push_back( eqc ); +#else + std::map< Node, EqcInfo * >::iterator itu = d_eqci.find( used ); + EqcInfo * eqci_used; + if( itu==d_eqci.end() ){ + eqci_used = new EqcInfo( d_c ); + d_eqci[used] = eqci_used; + }else{ + eqci_used = itu->second; + } + Trace("eq-infer-debug") << " add to use list : " << used << " -> " << eqc << std::endl; + eqci_used->d_uselist.push_back( eqc ); +#endif +} + +void EqualityInference::setEqcRep( Node t, Node r, std::vector< Node >& exp_to_add, EqcInfo * eqci ) { + eqci->d_rep = r; + if( d_trackExplain ){ + addToExplanationEqc( t, exp_to_add ); + } + //if this is an active equivalence class + if( eqci->d_valid.get() ){ + Trace("eq-infer-debug") << "Set eqc rep " << t << " -> " << r << std::endl; + NodeMap::const_iterator itr = d_rep_to_eqc.find( r ); + if( itr==d_rep_to_eqc.end() ){ + d_rep_to_eqc[r] = t; + }else{ + //merge two equivalence classes + Node t2 = (*itr).second; + //check if it is valid + std::map< Node, EqcInfo * >::iterator itc = d_eqci.find( t2 ); + if( itc!=d_eqci.end() && itc->second->d_valid.get() ){ + //if we haven't already determined they should be merged + if( updateMaster( t, t2, eqci, itc->second ) ){ + Trace("eq-infer") << "Infer two equivalence classes are equal : " << t << " " << t2 << std::endl; + Trace("eq-infer") << " since they both normalize to : " << r << std::endl; + d_pending_merges.push_back( t.eqNode( t2 ) ); + if( d_trackExplain ){ + std::vector< Node > exp; + for( unsigned j=0; j<2; j++ ){ + addToExplanationEqc( exp, j==0 ? t : t2 ); + } + Node exp_n = exp.empty() ? d_true : ( exp.size()==1 ? exp[0] : NodeManager::currentNM()->mkNode( AND, exp ) ); + Trace("eq-infer") << " explanation : " << exp_n << std::endl; + d_pending_merge_exp.push_back( exp_n ); + } + } + } + } + } +} + +void EqualityInference::eqNotifyMerge(TNode t1, TNode t2) { + Assert( !t1.isNull() ); + Assert( !t2.isNull() ); + std::map< Node, EqcInfo * >::iterator itv1 = d_eqci.find( t1 ); + if( itv1!=d_eqci.end() ){ + std::map< Node, EqcInfo * >::iterator itv2 = d_eqci.find( t2 ); + if( itv2!=d_eqci.end() ){ + Trace("eq-infer") << "Merge equivalence classes : " << t2 << " into " << t1 << std::endl; + Node tr1 = itv1->second->d_rep; + Node tr2 = itv2->second->d_rep; + itv2->second->d_valid = false; + Trace("eq-infer") << "Representatives : " << tr2 << " into " << tr1 << std::endl; + if( tr1!=tr2 ){ + Node eq = tr1.eqNode( tr2 ); + std::map< Node, Node > msum; + if( QuantArith::getMonomialSumLit( eq, msum ) ){ + Node v_solve; + //solve for variables with no coefficient + if( Trace.isOn("eq-infer-debug2") ){ + Trace("eq-infer-debug2") << "Monomial sum : " << std::endl; + for( std::map< Node, Node >::iterator it = msum.begin(); it != msum.end(); ++it ) { + Trace("eq-infer-debug2") << " " << it->first << " * " << it->second << std::endl; + } + } + for( std::map< Node, Node >::iterator it = msum.begin(); it != msum.end(); ++it ) { + Node n = it->first; + if( !n.isNull() ){ + bool canSolve = false; + if( it->second.isNull() ){ + canSolve = true; + }else{ + //Assert( it->second.isConst() ); + Rational r = it->second.getConst<Rational>(); + canSolve = r.isOne() || r.isNegativeOne(); + } + if( canSolve ){ + v_solve = n; + break; + } + } + } + Trace("eq-infer-debug") << "solve for variable : " << v_solve << std::endl; + if( !v_solve.isNull() ){ + //solve for v_solve + Node veq; + if( QuantArith::isolate( v_solve, msum, veq, kind::EQUAL, true )==1 ){ + Node v_value = veq[1]; + Trace("eq-infer") << "...solved " << v_solve << " == " << v_value << std::endl; + Assert( d_elim_vars.find( v_solve )==d_elim_vars.end() ); + d_elim_vars[v_solve] = true; + //store value in eqc info + EqcInfo * eqci_solved; + std::map< Node, EqcInfo * >::iterator itec = d_eqci.find( v_solve ); + if( itec==d_eqci.end() ){ + eqci_solved = new EqcInfo( d_c ); + d_eqci[v_solve] = eqci_solved; + }else{ + eqci_solved = itec->second; + } + eqci_solved->d_solved = true; + eqci_solved->d_rep = v_value; + //track the explanation + std::vector< Node > exp; + if( d_trackExplain ){ + //explanation is t1 = t2 + their explanations + exp.push_back( t1.eqNode( t2 ) ); + for( unsigned i=0; i<2; i++ ){ + addToExplanationEqc( exp, i==0 ? t1 : t2 ); + } + if( Trace.isOn("eq-infer-debug") ){ + Trace("eq-infer-debug") << " explanation for solving " << v_solve << " is "; + for( unsigned i=0; i<exp.size(); i++ ){ + Trace("eq-infer-debug") << exp[i] << " "; + } + Trace("eq-infer-debug") << std::endl; + } + addToExplanationEqc( v_solve, exp ); + } + + std::vector< Node > new_use; + for( std::map< Node, Node >::iterator itmm = msum.begin(); itmm != msum.end(); ++itmm ){ + Node n = itmm->first; + if( !n.isNull() && n!=v_solve ){ + new_use.push_back( n ); + addToUseList( n, v_solve ); + } + } + + //go through all equivalence classes that may refer to v_solve + std::map< Node, bool > processed; + processed[v_solve] = true; + NodeListMap::iterator ul_i = d_uselist.find( v_solve ); + if( ul_i != d_uselist.end() ){ + NodeList* ul = (*ul_i).second; + Trace("eq-infer-debug") << " use list size = " << ul->size() << std::endl; + for( unsigned j=0; j<ul->size(); j++ ){ + Node r = (*ul)[j]; + //Trace("eq-infer-debug") << " use list size = " << eqci_solved->d_uselist.size() << std::endl; + //for( unsigned j=0; j<eqci_solved->d_uselist.size(); j++ ){ + // Node r = eqci_solved->d_uselist[j]; + if( processed.find( r )==processed.end() ){ + processed[r] = true; + std::map< Node, EqcInfo * >::iterator itt = d_eqci.find( r ); + if( itt!=d_eqci.end() && ( itt->second->d_valid || itt->second->d_solved ) ){ + std::map< Node, Node > msum2; + if( QuantArith::getMonomialSum( itt->second->d_rep.get(), msum2 ) ){ + std::map< Node, Node >::iterator itm = msum2.find( v_solve ); + if( itm!=msum2.end() ){ + //substitute in solved form + std::map< Node, Node >::iterator itm2 = msum2.find( v_value ); + if( itm2 == msum2.end() ){ + msum2[v_value] = itm->second; + }else{ + msum2[v_value] = NodeManager::currentNM()->mkNode( PLUS, itm2->second.isNull() ? d_one : itm2->second, + itm->second.isNull() ? d_one : itm->second ); + } + msum2.erase( itm ); + Node rr = QuantArith::mkNode( msum2 ); + rr = Rewriter::rewrite( rr ); + Trace("eq-infer") << "......update " << itt->first << " => " << rr << std::endl; + setEqcRep( itt->first, rr, exp, itt->second ); + //update use list + for( unsigned i=0; i<new_use.size(); i++ ){ + addToUseList( new_use[i], r ); + } + } + }else{ + itt->second->d_valid = false; + } + } + } + } + } + Trace("eq-infer") << "...finished solved." << std::endl; + } + } + } + } + }else{ + //no information to merge + } + }else{ + //carry information (this might happen for non-linear t1 and linear t2?) + std::map< Node, EqcInfo * >::iterator itv2 = d_eqci.find( t2 ); + if( itv2!=d_eqci.end() ){ + d_eqci[t1] = d_eqci[t2]; + d_eqci[t2] = NULL; + } + } +} + +Node EqualityInference::getPendingMergeExplanation( unsigned i ) { + if( d_trackExplain ){ + return d_pending_merge_exp[i]; + }else{ + return d_pending_merges[i]; + } +} + +} |