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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                 :            :  * Oracle engine for SMTO
      14                 :            :  */
      15                 :            : 
      16                 :            : #include "cvc5_private.h"
      17                 :            : 
      18                 :            : #ifndef CVC5__THEORY__QUANTIFIERS__ORACLE_ENGINE_H
      19                 :            : #define CVC5__THEORY__QUANTIFIERS__ORACLE_ENGINE_H
      20                 :            : 
      21                 :            : #include "theory/decision_strategy.h"
      22                 :            : #include "theory/quantifiers/oracle_checker.h"
      23                 :            : #include "theory/quantifiers/quant_module.h"
      24                 :            : 
      25                 :            : namespace cvc5::internal {
      26                 :            : namespace theory {
      27                 :            : namespace quantifiers {
      28                 :            : 
      29                 :            : /**
      30                 :            :  * Oracle engine
      31                 :            :  *
      32                 :            :  * This class manages the list of declared oracle functions and asserted
      33                 :            :  * oracle interfaces.
      34                 :            :  *
      35                 :            :  * For SMT modulo oracles (SMTO) queries, this class is responsible for
      36                 :            :  * invoking oracles, as specified by oracle interface quantifiers (see
      37                 :            :  * OracleInterfaceAttribute), until all oracle functions have consistent
      38                 :            :  * definitions with respect to the current model.
      39                 :            :  *
      40                 :            :  * In detail, an oracle function f has a consistent definition with respect to
      41                 :            :  * the current model M if all invocations f(t) in assertions are such that
      42                 :            :  * we have invoked its associated oracle on t^M and that invocation returned
      43                 :            :  * the value f(t)^M. This module is complete for oracle interface quantifiers
      44                 :            :  * if their associated oracle function has a consistent definition.
      45                 :            :  *
      46                 :            :  * For details, see Polgreen et al VMCAI 2022.
      47                 :            :  */
      48                 :            : class OracleEngine : public QuantifiersModule
      49                 :            : {
      50                 :            :  public:
      51                 :            :   OracleEngine(Env& env,
      52                 :            :                QuantifiersState& qs,
      53                 :            :                QuantifiersInferenceManager& qim,
      54                 :            :                QuantifiersRegistry& qr,
      55                 :            :                TermRegistry& tr);
      56                 :        930 :   ~OracleEngine() {}
      57                 :            :   /** Presolve */
      58                 :            :   void presolve() override;
      59                 :            :   /** Needs check. */
      60                 :            :   bool needsCheck(Theory::Effort e) override;
      61                 :            :   /** Needs model. */
      62                 :            :   QEffort needsModel(Theory::Effort e) override;
      63                 :            :   /** Reset round. */
      64                 :            :   void reset_round(Theory::Effort e) override;
      65                 :            :   /** Register quantified formula q */
      66                 :            :   void registerQuantifier(Node q) override;
      67                 :            :   /** Check.
      68                 :            :    * Adds instantiations for all currently asserted
      69                 :            :    * quantified formulas via calls to process(...)
      70                 :            :    */
      71                 :            :   void check(Theory::Effort e, QEffort quant_e) override;
      72                 :            :   /**
      73                 :            :    * Check was complete for quantified formula q, return true if we can say
      74                 :            :    * "sat" provided that q is currently asserted.
      75                 :            :    */
      76                 :            :   bool checkCompleteFor(Node q) override;
      77                 :            :   /** check ownership */
      78                 :            :   void checkOwnership(Node q) override;
      79                 :            :   /** Identify. */
      80                 :            :   std::string identify() const override;
      81                 :            : 
      82                 :            :   /** Declare oracle fun */
      83                 :            :   void declareOracleFun(Node f);
      84                 :            :   /** Get the list of all declared oracle functions */
      85                 :            :   std::vector<Node> getOracleFuns() const;
      86                 :            : 
      87                 :            :   /** Make an oracle interface quantifier */
      88                 :            :   static Node mkOracleInterface(const std::vector<Node>& inputs,
      89                 :            :                                 const std::vector<Node>& outputs,
      90                 :            :                                 Node assume,
      91                 :            :                                 Node constraint,
      92                 :            :                                 Node oracleNode);
      93                 :            :   /**
      94                 :            :    * Get oracle interface, returns true if q is an oracle interface quantifier
      95                 :            :    * (constructed by the above method). Obtains the arguments for which q is
      96                 :            :    * constructed.
      97                 :            :    */
      98                 :            :   bool getOracleInterface(Node q,
      99                 :            :                           std::vector<Node>& inputs,
     100                 :            :                           std::vector<Node>& outputs,
     101                 :            :                           Node& assume,
     102                 :            :                           Node& constraint,
     103                 :            :                           Node& oracleNode) const;
     104                 :            : 
     105                 :            :  private:
     106                 :            :   /** The oracle functions (user-context dependent) */
     107                 :            :   context::CDList<Node> d_oracleFuns;
     108                 :            :   /** Pointer to the oracle checker */
     109                 :            :   OracleChecker* d_ochecker;
     110                 :            :   /**
     111                 :            :    * In a given instantiation round, did consistency checks pass for all
     112                 :            :    * oracle interface quantified formulas?
     113                 :            :    */
     114                 :            :   bool d_consistencyCheckPassed;
     115                 :            :   /**
     116                 :            :    * A decision strategy that prefers equating arguments of oracles to
     117                 :            :    * values that we have already evaluated the oracle on. For example, if
     118                 :            :    * we have an application (f a) of oracle function f, then if a=5 in one
     119                 :            :    * model, we may generate the lemma (=> (= a 5) (= (f a) 10)), where 10 is
     120                 :            :    * result of calling f on 5. This decision strategy will henceforth decide
     121                 :            :    * (= a 5) -> true. This ensures that we don't invoke f for evaluating (f a)
     122                 :            :    * again until we are sure that (= a 5) cannot be made true.
     123                 :            :    */
     124                 :            :   DecisionStrategyVector d_dstrat;
     125                 :            : };
     126                 :            : 
     127                 :            : }  // namespace quantifiers
     128                 :            : }  // namespace theory
     129                 :            : }  // namespace cvc5::internal
     130                 :            : 
     131                 :            : #endif