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       1                 :            : /******************************************************************************
       2                 :            :  * Top contributors (to current version):
       3                 :            :  *   Andrew Reynolds
       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                 :            :  * Implementation of witness elimination node conversion
      14                 :            :  */
      15                 :            : #include "cvc5_private.h"
      16                 :            : 
      17                 :            : #ifndef CVC5__EXPR__ELIM_WITNESS_NODE_CONVERTER_H
      18                 :            : #define CVC5__EXPR__ELIM_WITNESS_NODE_CONVERTER_H
      19                 :            : 
      20                 :            : #include <unordered_set>
      21                 :            : 
      22                 :            : #include "expr/node.h"
      23                 :            : #include "expr/node_converter.h"
      24                 :            : #include "smt/env_obj.h"
      25                 :            : 
      26                 :            : namespace cvc5::internal {
      27                 :            : 
      28                 :            : /**
      29                 :            :  * Node converter to eliminate all terms of kind WITNESS. Each term replaced
      30                 :            :  * in this way is captured by an existential, which can be obtained by
      31                 :            :  * getExistentials.
      32                 :            :  */
      33                 :            : class ElimWitnessNodeConverter : protected EnvObj, public NodeConverter
      34                 :            : {
      35                 :            :  public:
      36                 :            :   /** Eliminate witness terms.*/
      37                 :            :   ElimWitnessNodeConverter(Env& env);
      38                 :        687 :   ~ElimWitnessNodeConverter() {}
      39                 :            :   /**
      40                 :            :    * Convert node n as described above during post-order traversal.
      41                 :            :    */
      42                 :            :   Node postConvert(Node n) override;
      43                 :            :   /**
      44                 :            :    * Get the existentials
      45                 :            :    */
      46                 :            :   const std::vector<Node>& getExistentials() const;
      47                 :            : 
      48                 :            :   /**
      49                 :            :    * Get the normal form of a quantified formula for which we are introducing
      50                 :            :    * a skolem variable based on eliminating a witness term.
      51                 :            :    */
      52                 :            :   virtual Node getNormalFormFor(const Node& q);
      53                 :            : 
      54                 :            :  private:
      55                 :            :   /** The list of existentials introduced by eliminating witness */
      56                 :            :   std::vector<Node> d_exists;
      57                 :            : };
      58                 :            : 
      59                 :            : }  // namespace cvc5::internal
      60                 :            : 
      61                 :            : #endif