/******************************************************************************

 * Top contributors (to current version):

 *   Andrew Reynolds, Gereon Kremer, Tim King

 *

 * This file is part of the cvc5 project.

 *

 * Copyright (c) 2009-2021 by the authors listed in the file AUTHORS

 * in the top-level source directory and their institutional affiliations.

 * All rights reserved.  See the file COPYING in the top-level source

 * directory for licensing information.

 * ****************************************************************************

 *

 * Extensions to the theory of arithmetic incomplete handling of nonlinear

 * multiplication via axiom instantiations.

 */

#ifndef CVC5__THEORY__ARITH__NL__NONLINEAR_EXTENSION_H

#define CVC5__THEORY__ARITH__NL__NONLINEAR_EXTENSION_H

#include <map>

#include <vector>

#include "expr/node.h"

#include "smt/env_obj.h"

#include "theory/arith/nl/cad_solver.h"

#include "theory/arith/nl/ext/ext_state.h"

#include "theory/arith/nl/ext/factoring_check.h"

#include "theory/arith/nl/ext/monomial_bounds_check.h"

#include "theory/arith/nl/ext/monomial_check.h"

#include "theory/arith/nl/ext/proof_checker.h"

#include "theory/arith/nl/ext/split_zero_check.h"

#include "theory/arith/nl/ext/tangent_plane_check.h"

#include "theory/arith/nl/ext_theory_callback.h"

#include "theory/arith/nl/iand_solver.h"

#include "theory/arith/nl/icp/icp_solver.h"

#include "theory/arith/nl/nl_model.h"

#include "theory/arith/nl/pow2_solver.h"

#include "theory/arith/nl/stats.h"

#include "theory/arith/nl/strategy.h"

#include "theory/arith/nl/transcendental/transcendental_solver.h"

#include "theory/ext_theory.h"

#include "theory/theory.h"

#include "util/result.h"

namespace cvc5 {

namespace theory {

namespace eq {

  class EqualityEngine;

}

namespace arith {

class InferenceManager;

class TheoryArith;

namespace nl {

class NlLemma;

/** Non-linear extension class

 *

 * This class implements model-based refinement schemes

 * for non-linear arithmetic, described in:

 *

 * - "Invariant Checking of NRA Transition Systems

 * via Incremental Reduction to LRA with EUF" by

 * Cimatti et al., TACAS 2017.

 *

 * - Section 5 of "Desiging Theory Solvers with

 * Extensions" by Reynolds et al., FroCoS 2017.

 *

 * - "Satisfiability Modulo Transcendental

 * Functions via Incremental Linearization" by Cimatti

 * et al., CADE 2017.

 *

 * It's main functionality is a check(...) method,

 * which is called by TheoryArithPrivate either:

 * (1) at full effort with no conflicts or lemmas emitted, or

 * (2) at last call effort.

 * In this method, this class calls d_im.lemma(...)

 * for valid arithmetic theory lemmas, based on the current set of assertions,

 * where d_im is the inference manager of TheoryArith.

 */

class NonlinearExtension : EnvObj

{

  typedef context::CDHashSet<Node> NodeSet;

 public:

  NonlinearExtension(Env& env, TheoryArith& containing, ArithState& state);

  ~NonlinearExtension();

  /**

   * Does non-context dependent setup for a node connected to a theory.

   */

  void preRegisterTerm(TNode n);

  /** Check at effort level e.

   *

   * This call may result in (possibly multiple) calls to d_im.lemma(...)

   * where d_im is the inference manager of TheoryArith.

   *

   * If e is FULL, then we add lemmas based on context-depedent

   * simplification (see Reynolds et al FroCoS 2017).

   *

   * If e is LAST_CALL, we add lemmas based on model-based refinement

   * (see additionally Cimatti et al., TACAS 2017). The lemmas added at this

   * effort may be computed during a call to interceptModel as described below.

   */

  void check(Theory::Effort e);

  /** intercept model

   *

   * This method is called during TheoryArith::collectModelInfo, which is

   * invoked after the linear arithmetic solver passes a full effort check

   * with no lemmas.

   *

   * The argument arithModel is a map of the form { v1 -> c1, ..., vn -> cn }

   * which represents the linear arithmetic theory solver's contribution to the

   * current candidate model. That is, its collectModelInfo method is requesting

   * that equalities v1 = c1, ..., vn = cn be added to the current model, where

   * v1, ..., vn are arithmetic variables and c1, ..., cn are constants. Notice

   * arithmetic variables may be real-valued terms belonging to other theories,

   * or abstractions of applications of multiplication (kind NONLINEAR_MULT).

   *

   * This method requests that the non-linear solver inspect this model and

   * do any number of the following:

   * (1) Construct lemmas based on a model-based refinement procedure inspired

   * by Cimatti et al., TACAS 2017.,

   * (2) In the case that the nonlinear solver finds that the current

   * constraints are satisfiable, it may "repair" the values in the argument

   * arithModel so that it satisfies certain nonlinear constraints. This may

   * involve e.g. solving for variables in nonlinear equations.

   */

  void interceptModel(std::map<Node, Node>& arithModel,

                      const std::set<Node>& termSet);

  /** Does this class need a call to check(...) at last call effort? */

  /** presolve

   *

   * This function is called during TheoryArith's presolve command.

   * In this function, we send lemmas we accumulated during preprocessing,

   * for instance, definitional lemmas from expandDefinitions are sent out

   * on the output channel of TheoryArith in this function.

   */

  void presolve();

  /** Process side effect se */

  void processSideEffect(const NlLemma& se);

 private:

  /** Model-based refinement

   *

   * This is the main entry point of this class for generating lemmas on the

   * output channel of the theory of arithmetic.

   *

   * It is currently run at last call effort. It applies lemma schemas

   * described in Reynolds et al. FroCoS 2017 that are based on ruling out

   * the current candidate model.

   *

   * This function returns whether we found a satisfying assignment

   * (Result::Sat::SAT), or not (Result::Sat::UNSAT). Note that UNSAT does not

   * necessarily means the whole query is UNSAT, but that the linear model was

   * refuted by a lemma.

   */

  Result::Sat modelBasedRefinement(const std::set<Node>& termSet);

  /** get assertions

   *

   * Let M be the set of assertions known by THEORY_ARITH. This function adds a

   * set of literals M' to assertions such that M' and M are equivalent.

   *

   * Examples of how M' differs with M:

   * (1) M' may not include t < c (in M) if t < c' is in M' for c' < c, where

   * c and c' are constants,

   * (2) M' may contain t = c if both t >= c and t <= c are in M.

   */

  void getAssertions(std::vector<Node>& assertions);

  /** check model

   *

   * Returns the subset of assertions whose concrete values we cannot show are

   * true in the current model. Notice that we typically cannot compute concrete

   * values for assertions involving transcendental functions. Any assertion

   * whose model value cannot be computed is included in the return value of

   * this function.

   */

  std::vector<Node> checkModelEval(const std::vector<Node>& assertions);

  //---------------------------check model

  /** Check model

   *

   * Checks the current model based on solving for equalities, and using error

   * bounds on the Taylor approximation.

   *

   * If this function returns true, then all assertions in the input argument

   * "assertions" are satisfied for all interpretations of variables within

   * their computed bounds (as stored in d_check_model_bounds).

   *

   * For details, see Section 3 of Cimatti et al CADE 2017 under the heading

   * "Detecting Satisfiable Formulas".

   */

  bool checkModel(const std::vector<Node>& assertions);

  //---------------------------end check model

  /** compute relevant assertions */

  void computeRelevantAssertions(const std::vector<Node>& assertions,

                                 std::vector<Node>& keep);

  /** run check strategy

   *

   * Check assertions for consistency in the effort LAST_CALL with a subset of

   * the assertions, false_asserts, that evaluate to false in the current model.

   *

   * xts : the list of (non-reduced) extended terms in the current context.

   *

   * This method adds lemmas to d_im directly.

   */

  void runStrategy(Theory::Effort effort,

                   const std::vector<Node>& assertions,

                   const std::vector<Node>& false_asserts,

                   const std::vector<Node>& xts);

  /** commonly used terms */

  Node d_zero;

  Node d_one;

  Node d_neg_one;

  Node d_true;

  // The theory of arithmetic containing this extension.

  TheoryArith& d_containing;

  /** A reference to the arithmetic state object */

  ArithState& d_astate;

  InferenceManager& d_im;

  /** The statistics class */

  NlStats d_stats;

  // needs last call effort

  bool d_needsLastCall;

  /**

   * The number of times we have the called main check method

   * (modelBasedRefinement). This counter is used for interleaving strategies.

   */

  unsigned d_checkCounter;

  /** The callback for the extended theory below */

  NlExtTheoryCallback d_extTheoryCb;

  /** Extended theory, responsible for context-dependent simplification. */

  ExtTheory d_extTheory;

  /** The non-linear model object

   *

   * This class is responsible for computing model values for arithmetic terms

   * and for establishing when we are able to answer "SAT".

   */

  NlModel d_model;

  /** The transcendental extension object

   *

   * This is the subsolver responsible for running the procedure for

   * transcendental functions.

   */

  transcendental::TranscendentalSolver d_trSlv;

  /** The proof checker for proofs of the nlext. */

  ExtProofRuleChecker d_proofChecker;

  /**

   * Holds common lookup data for the checks implemented in the "nl-ext"

   * solvers (from Cimatti et al., TACAS 2017).

   */

  ExtState d_extState;

  /** Solver for factoring lemmas. */

  FactoringCheck d_factoringSlv;

  /** Solver for lemmas about monomial bounds. */

  MonomialBoundsCheck d_monomialBoundsSlv;

  /** Solver for lemmas about monomials. */

  MonomialCheck d_monomialSlv;

  /** Solver for lemmas that split multiplication at zero. */

  SplitZeroCheck d_splitZeroSlv;

  /** Solver for tangent plane lemmas. */

  TangentPlaneCheck d_tangentPlaneSlv;

  /** The CAD-based solver */

  CadSolver d_cadSlv;

  /** The ICP-based solver */

  icp::ICPSolver d_icpSlv;

  /** The integer and solver

   *

   * This is the subsolver responsible for running the procedure for

   * constraints involving integer and.

   */

  IAndSolver d_iandSlv;

  /** The pow2 solver

   *

   * This is the subsolver responsible for running the procedure for

   * constraints involving powers of 2.

   */

  Pow2Solver d_pow2Slv;

  /** The strategy for the nonlinear extension. */

  Strategy d_strategy;

  /**

   * The approximations computed during collectModelInfo. For details, see

   * NlModel::getModelValueRepair.

   */

  std::map<Node, std::pair<Node, Node>> d_approximations;

  /**

   * The witnesses computed during collectModelInfo. For details, see

   * NlModel::getModelValueRepair.

   */

  std::map<Node, Node> d_witnesses;

}; /* class NonlinearExtension */

}  // namespace nl

}  // namespace arith

}  // namespace theory

}  // namespace cvc5

#endif /* CVC5__THEORY__ARITH__NONLINEAR_EXTENSION_H */