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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 module for processing the difficulty of input assumptions
      14                 :            :  * based on proof nodes.
      15                 :            :  */
      16                 :            : 
      17                 :            : #include "cvc5_private.h"
      18                 :            : 
      19                 :            : #ifndef CVC5__SMT__DIFFICULTY_POST_PROCESSOR_H
      20                 :            : #define CVC5__SMT__DIFFICULTY_POST_PROCESSOR_H
      21                 :            : 
      22                 :            : #include <map>
      23                 :            : 
      24                 :            : #include "proof/proof_node_updater.h"
      25                 :            : 
      26                 :            : namespace cvc5::internal {
      27                 :            : namespace smt {
      28                 :            : 
      29                 :            : /**
      30                 :            :  * A postprocess callback that computes difficulty based on the structure
      31                 :            :  * of the proof. In particular, this class assesses what the source of an
      32                 :            :  * assertion was by considering the shape of the proof. For instance, if
      33                 :            :  * assertion A entails x=t, and this was used to derive a substitution
      34                 :            :  * { x -> t } to assertion B, then B is the source of B*{ x -> t }. The
      35                 :            :  * difficulty of this assertion is carried to B and not A. The reason is that
      36                 :            :  * A can be understood as a definition, and is eliminated, whereas B was
      37                 :            :  * persistent if B*{ x -> t } was a prepreprocessed assertion.
      38                 :            :  *
      39                 :            :  * Note that this postprocess callback is intended to be run on the proof
      40                 :            :  * of a single preprocessed assertion C. If C was derived by proof with
      41                 :            :  * free assumptions A_1, ..., A_n, then for each A_i that is a "source" as
      42                 :            :  * described above, we increment the difficulty of A_i by the difficulty value
      43                 :            :  * assigned to C.
      44                 :            :  *
      45                 :            :  * This means that the user of this method should:
      46                 :            :  * (1) assign the current difficulty we are incrementing (setCurrentDifficulty),
      47                 :            :  * (2) process the proof using a proof node updater with this callback.
      48                 :            :  * The final difficulty map is accumulated in d_accMap, which can be accessed
      49                 :            :  * at any time via getDifficultyMap.
      50                 :            :  */
      51                 :            : class DifficultyPostprocessCallback : public ProofNodeUpdaterCallback
      52                 :            : {
      53                 :            :  public:
      54                 :            :   DifficultyPostprocessCallback();
      55                 :        201 :   ~DifficultyPostprocessCallback() {}
      56                 :            :   /**
      57                 :            :    * Set current difficulty of the next proof to process to the (integer)
      58                 :            :    * value stored in Node d. This value will be assigned to all the free
      59                 :            :    * assumptions of the proof we traverse next. This value is stored in
      60                 :            :    * d_currDifficulty.
      61                 :            :    *
      62                 :            :    * @return true if the difficulty value was successfully extracted
      63                 :            :    */
      64                 :            :   bool setCurrentDifficulty(Node d);
      65                 :            :   /**
      66                 :            :    * Should proof pn be updated? This is used to selectively traverse to e.g.
      67                 :            :    * the source of an assertion.
      68                 :            :    */
      69                 :            :   bool shouldUpdate(std::shared_ptr<ProofNode> pn,
      70                 :            :                     const std::vector<Node>& fa,
      71                 :            :                     bool& continueUpdate) override;
      72                 :            :   /** Get the (acculumated) difficulty map for the last processed proof node */
      73                 :            :   void getDifficultyMap(std::map<Node, Node>& dmap) const;
      74                 :            : 
      75                 :            :  private:
      76                 :            :   /**
      77                 :            :    * The current difficulty of the assertion whose proof of preprocessing
      78                 :            :    * we are considering.
      79                 :            :    */
      80                 :            :   uint64_t d_currDifficulty;
      81                 :            :   /** The current accumulated difficulty map */
      82                 :            :   std::map<Node, uint64_t> d_accMap;
      83                 :            : };
      84                 :            : 
      85                 :            : }  // namespace smt
      86                 :            : }  // namespace cvc5::internal
      87                 :            : 
      88                 :            : #endif