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/****************************************************************************** |
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* Top contributors (to current version): |
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* Andrew Reynolds |
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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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* A cache of skolems for theory of sets. |
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*/ |
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#include "cvc5_private.h" |
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#ifndef CVC5__THEORY__SETS__SKOLEM_CACHE_H |
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#define CVC5__THEORY__SETS__SKOLEM_CACHE_H |
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#include <map> |
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#include <unordered_set> |
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#include "expr/node.h" |
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namespace cvc5 { |
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namespace theory { |
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namespace sets { |
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/** |
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* A cache of all set skolems generated by the TheorySets class. This |
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* cache is used to ensure that duplicate skolems are not generated when |
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* possible, and helps identify what skolems were allocated in the current run. |
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*/ |
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class SkolemCache |
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{ |
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public: |
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SkolemCache(); |
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/** Identifiers for skolem types |
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* |
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* The comments below document the properties of each skolem introduced by |
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* inference in the sets solver, where by skolem we mean the fresh |
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* set variable that witnesses each of "exists k". |
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*/ |
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enum SkolemId |
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{ |
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// exists k. k = a |
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SK_PURIFY, |
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// a != b => exists k. ( k in a != k in b ) |
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SK_DISEQUAL, |
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// a in tclosure(b) => exists k1 k2. ( a.1, k1 ) in b ^ ( k2, a.2 ) in b ^ |
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// ( k1 = k2 V ( k1, k2 ) in tclosure(b) ) |
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SK_TCLOSURE_DOWN1, |
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SK_TCLOSURE_DOWN2, |
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// (a,b) in join(A,B) => exists k. (a,k) in A ^ (k,b) in B |
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// This is cached by the nodes corresponding to (a,b) and join(A,B). |
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SK_JOIN, |
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}; |
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/** |
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* Makes a skolem of type tn that is cached based on the key (a,b,id). |
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* Argument c is the variable name of the skolem. |
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*/ |
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Node mkTypedSkolemCached( |
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TypeNode tn, Node a, Node b, SkolemId id, const char* c); |
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/** same as above, cached based on key (a,null,id) */ |
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Node mkTypedSkolemCached(TypeNode tn, Node a, SkolemId id, const char* c); |
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/** Same as above, but without caching. */ |
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Node mkTypedSkolem(TypeNode tn, const char* c); |
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/** Returns true if n is a skolem allocated by this class */ |
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bool isSkolem(Node n) const; |
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private: |
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/** map from node pairs and identifiers to skolems */ |
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std::map<Node, std::map<Node, std::map<SkolemId, Node> > > d_skolemCache; |
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/** the set of all skolems we have generated */ |
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std::unordered_set<Node> d_allSkolems; |
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}; |
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} // namespace sets |
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} // namespace theory |
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} // namespace cvc5 |
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#endif /* CVC5__THEORY__STRINGS__SKOLEM_CACHE_H */ |