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       1                 :            : /******************************************************************************
       2                 :            :  * Top contributors (to current version):
       3                 :            :  *   Andrew Reynolds, Mathias Preiner, Andres Noetzli
       4                 :            :  *
       5                 :            :  * This file is part of the cvc5 project.
       6                 :            :  *
       7                 :            :  * Copyright (c) 2009-2024 by the authors listed in the file AUTHORS
       8                 :            :  * in the top-level source directory and their institutional affiliations.
       9                 :            :  * All rights reserved.  See the file COPYING in the top-level source
      10                 :            :  * directory for licensing information.
      11                 :            :  * ****************************************************************************
      12                 :            :  *
      13                 :            :  * dynamic quantifiers splitting
      14                 :            :  */
      15                 :            : 
      16                 :            : #include "cvc5_private.h"
      17                 :            : 
      18                 :            : #ifndef CVC5__THEORY__QUANT_SPLIT_H
      19                 :            : #define CVC5__THEORY__QUANT_SPLIT_H
      20                 :            : 
      21                 :            : #include "context/cdhashmap.h"
      22                 :            : #include "context/cdo.h"
      23                 :            : #include "smt/env_obj.h"
      24                 :            : #include "theory/quantifiers/quant_module.h"
      25                 :            : 
      26                 :            : namespace cvc5::internal {
      27                 :            : namespace theory {
      28                 :            : 
      29                 :            : class QuantifiersEngine;
      30                 :            : 
      31                 :            : namespace quantifiers {
      32                 :            : 
      33                 :            : /** Quantifiers dynamic splitting
      34                 :            :  *
      35                 :            :  * This module identifies quantified formulas that should be "split", e.g.
      36                 :            :  * based on datatype constructor case splitting.
      37                 :            :  *
      38                 :            :  * An example of a quantified formula that we may split is the following. Let:
      39                 :            :  *   optionPair := mkPair( U, U ) | none
      40                 :            :  * where U is an uninterpreted sort. The quantified formula:
      41                 :            :  *   forall x : optionPair. P( x )
      42                 :            :  * may be "split" via the lemma:
      43                 :            :  *   forall x : optionPair. P( x ) <=>
      44                 :            :  *   ( forall xy : U. P( mkPair( x, y ) ) OR P( none ) )
      45                 :            :  *
      46                 :            :  * Notice that such splitting may lead to exponential behavior, say if we
      47                 :            :  * quantify over 32 variables of type optionPair above gives 2^32 disjuncts.
      48                 :            :  * This class is used to compute this splitting dynamically, by splitting
      49                 :            :  * one variable per quantified formula at a time.
      50                 :            :  */
      51                 :            : class QuantDSplit : public QuantifiersModule {
      52                 :            :   using NodeSet = context::CDHashSet<Node>;
      53                 :            :   using NodeIntMap = context::CDHashMap<Node, int>;
      54                 :            : 
      55                 :            :  public:
      56                 :            :   QuantDSplit(Env& env,
      57                 :            :               QuantifiersState& qs,
      58                 :            :               QuantifiersInferenceManager& qim,
      59                 :            :               QuantifiersRegistry& qr,
      60                 :            :               TermRegistry& tr);
      61                 :            :   /** determine whether this quantified formula will be reduced */
      62                 :            :   void checkOwnership(Node q) override;
      63                 :            :   /* whether this module needs to check this round */
      64                 :            :   bool needsCheck(Theory::Effort e) override;
      65                 :            :   /* Call during quantifier engine's check */
      66                 :            :   void check(Theory::Effort e, QEffort quant_e) override;
      67                 :            :   /** check complete for */
      68                 :            :   bool checkCompleteFor(Node q) override;
      69                 :            :   /** Identify this module (for debugging, dynamic configuration, etc..) */
      70                 :          0 :   std::string identify() const override { return "QuantDSplit"; }
      71                 :            : 
      72                 :            :  private:
      73                 :            :   /** list of relevant quantifiers asserted in the current context */
      74                 :            :   NodeIntMap d_quant_to_reduce;
      75                 :            :   /** whether we have instantiated quantified formulas */
      76                 :            :   NodeSet d_added_split;
      77                 :            : };
      78                 :            : 
      79                 :            : }
      80                 :            : }
      81                 :            : }  // namespace cvc5::internal
      82                 :            : 
      83                 :            : #endif