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       1                 :            : /******************************************************************************
       2                 :            :  * Top contributors (to current version):
       3                 :            :  *   Andrew Reynolds, Haniel Barbosa
       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                 :            :  * Theory proof step buffer utility.
      14                 :            :  */
      15                 :            : 
      16                 :            : #include "cvc5_private.h"
      17                 :            : 
      18                 :            : #ifndef CVC5__PROOF__THEORY_PROOF_STEP_BUFFER_H
      19                 :            : #define CVC5__PROOF__THEORY_PROOF_STEP_BUFFER_H
      20                 :            : 
      21                 :            : #include <vector>
      22                 :            : 
      23                 :            : #include "expr/node.h"
      24                 :            : #include "proof/proof_step_buffer.h"
      25                 :            : #include "theory/builtin/proof_checker.h"
      26                 :            : 
      27                 :            : namespace cvc5::internal {
      28                 :            : /**
      29                 :            :  * Class used to speculatively try and buffer a set of proof steps before
      30                 :            :  * sending them to a proof object, extended with theory-specfic proof rule
      31                 :            :  * utilities.
      32                 :            :  */
      33                 :            : class TheoryProofStepBuffer : public ProofStepBuffer
      34                 :            : {
      35                 :            :  public:
      36                 :            :   TheoryProofStepBuffer(ProofChecker* pc = nullptr,
      37                 :            :                         bool ensureUnique = false,
      38                 :            :                         bool autoSym = true);
      39                 :    3060030 :   ~TheoryProofStepBuffer() {}
      40                 :            :   //---------------------------- utilities builtin proof rules
      41                 :            :   /**
      42                 :            :    * Apply equality introduction. If this method returns true, it adds proof
      43                 :            :    * step(s) to the buffer that conclude (= src tgt) from premises exp. In
      44                 :            :    * particular, it may attempt to apply the rule MACRO_SR_EQ_INTRO. This
      45                 :            :    * method should be applied when tgt is equivalent to src assuming exp.
      46                 :            :    *
      47                 :            :    * @param useExpected If true, we pass (= src tgt) as expected to tryStep.
      48                 :            :    * When true, this method will always succeed if proof checking is
      49                 :            :    * disabled.
      50                 :            :    */
      51                 :            :   bool applyEqIntro(Node src,
      52                 :            :                     Node tgt,
      53                 :            :                     const std::vector<Node>& exp,
      54                 :            :                     MethodId ids = MethodId::SB_DEFAULT,
      55                 :            :                     MethodId ida = MethodId::SBA_SEQUENTIAL,
      56                 :            :                     MethodId idr = MethodId::RW_REWRITE,
      57                 :            :                     bool useExpected = false);
      58                 :            :   /**
      59                 :            :    * Apply predicate transform. If this method returns true, it adds (at most
      60                 :            :    * one) proof step to the buffer that conclude tgt from premises src, exp. In
      61                 :            :    * particular, it may attempt to apply MACRO_SR_PRED_TRANSFORM. This method
      62                 :            :    * should be applied when src and tgt are equivalent formulas assuming exp.
      63                 :            :    *
      64                 :            :    * @param useExpected If true, we pass tgt as expected to tryStep.
      65                 :            :    * When true, this method will always succeed if proof checking is
      66                 :            :    * disabled.
      67                 :            :    */
      68                 :            :   bool applyPredTransform(Node src,
      69                 :            :                           Node tgt,
      70                 :            :                           const std::vector<Node>& exp,
      71                 :            :                           MethodId ids = MethodId::SB_DEFAULT,
      72                 :            :                           MethodId ida = MethodId::SBA_SEQUENTIAL,
      73                 :            :                           MethodId idr = MethodId::RW_REWRITE,
      74                 :            :                           bool useExpected = false);
      75                 :            :   /**
      76                 :            :    * Apply predicate introduction. If this method returns true, it adds proof
      77                 :            :    * step(s) to the buffer that conclude tgt from premises exp. In particular,
      78                 :            :    * it may attempt to apply the rule MACRO_SR_PRED_INTRO. This method should be
      79                 :            :    * applied when tgt is equivalent to true assuming exp.
      80                 :            :    *
      81                 :            :    * @param useExpected If true, we pass tgt as expected to tryStep.
      82                 :            :    * When true, this method will always succeed if proof checking is
      83                 :            :    * disabled.
      84                 :            :    */
      85                 :            :   bool applyPredIntro(Node tgt,
      86                 :            :                       const std::vector<Node>& exp,
      87                 :            :                       MethodId ids = MethodId::SB_DEFAULT,
      88                 :            :                       MethodId ida = MethodId::SBA_SEQUENTIAL,
      89                 :            :                       MethodId idr = MethodId::RW_REWRITE,
      90                 :            :                       bool useExpected = false);
      91                 :            :   /**
      92                 :            :    * Apply predicate elimination. This method returns the result of applying
      93                 :            :    * the rule MACRO_SR_PRED_ELIM on src, exp. The returned formula is equivalent
      94                 :            :    * to src assuming exp. If the return value is equivalent to src, then no
      95                 :            :    * proof step is added to this buffer, since this step is a no-op in this
      96                 :            :    * case.
      97                 :            :    *
      98                 :            :    * Notice that in contrast to the other rules above, predicate elimination
      99                 :            :    * never fails and proves a formula that is not explicitly given as an
     100                 :            :    * argument tgt. Thus, the return value of this method is Node not bool.
     101                 :            :    */
     102                 :            :   Node applyPredElim(Node src,
     103                 :            :                      const std::vector<Node>& exp,
     104                 :            :                      MethodId ids = MethodId::SB_DEFAULT,
     105                 :            :                      MethodId ida = MethodId::SBA_SEQUENTIAL,
     106                 :            :                      MethodId idr = MethodId::RW_REWRITE);
     107                 :            :   //---------------------------- end utilities builtin proof rules
     108                 :            : 
     109                 :            :   //---------------------------- utility methods for normalizing clauses
     110                 :            :   /**
     111                 :            :    * Normalizes a non-unit clause (an OR node) according to factoring and
     112                 :            :    * reordering, i.e. removes duplicates and reorders literals (according to
     113                 :            :    * node ids). Moreover it eliminates double negations, which can be done also
     114                 :            :    * for unit clauses (a arbitrary Boolean node). All normalization steps are
     115                 :            :    * tracked via proof steps added to this proof step buffer.
     116                 :            :    *
     117                 :            :    * @param n the clause to be normalized
     118                 :            :    * @return the normalized clause node
     119                 :            :    */
     120                 :            :   Node factorReorderElimDoubleNeg(Node n);
     121                 :            : 
     122                 :            :   /**
     123                 :            :    * Eliminates double negation of a literal if it has the form
     124                 :            :    *  (not (not t))
     125                 :            :    * If the elimination happens, a step is added to this proof step buffer.
     126                 :            :    *
     127                 :            :    * @param n the node to have the top-level double negation eliminated
     128                 :            :    * @return the normalized clause node
     129                 :            :    */
     130                 :            :   Node elimDoubleNegLit(Node n);
     131                 :            : };
     132                 :            : 
     133                 :            : }  // namespace cvc5::internal
     134                 :            : 
     135                 :            : #endif /* CVC5__PROOF__THEORY_PROOF_STEP_BUFFER_H */