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/******************************************************************************
* Top contributors (to current version):
* Yoni Zohar
*
* 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.
* ****************************************************************************
*
* Solver for pow2 constraints.
*/
#ifndef CVC5__THEORY__ARITH__NL__POW2_SOLVER_H
#define CVC5__THEORY__ARITH__NL__POW2_SOLVER_H
#include <vector>
#include "context/cdhashset.h"
#include "expr/node.h"
#include "smt/env_obj.h"
namespace cvc5 {
namespace theory {
namespace arith {
class ArithState;
class InferenceManager;
namespace nl {
class NlModel;
/** pow2 solver class
*
*/
class Pow2Solver : protected EnvObj
{
using NodeSet = context::CDHashSet<Node>;
public:
Pow2Solver(Env& env, InferenceManager& im, ArithState& state, NlModel& model);
~Pow2Solver();
/** init last call
*
* This is called at the beginning of last call effort check, where
* assertions are the set of assertions belonging to arithmetic,
* false_asserts is the subset of assertions that are false in the current
* model, and xts is the set of extended function terms that are active in
* the current context.
*/
void initLastCall(const std::vector<Node>& assertions,
const std::vector<Node>& false_asserts,
const std::vector<Node>& xts);
//-------------------------------------------- lemma schemas
/** check initial refine
*
* Returns a set of valid theory lemmas, based on simple facts about pow2.
*
* Examples
*
* x>=0 --> x < pow2(x)
*
* This should be a heuristic incomplete check that only introduces a
* small number of new terms in the lemmas it returns.
*/
void checkInitialRefine();
/** check full refine
*
* This should be a complete check that returns at least one lemma to
* rule out the current model.
*/
void checkFullRefine();
/** sort d_pow2 according to their values in the current model */
void sortPow2sBasedOnModel();
//-------------------------------------------- end lemma schemas
private:
// The inference manager that we push conflicts and lemmas to.
InferenceManager& d_im;
/** Reference to the non-linear model object */
NlModel& d_model;
/** commonly used terms */
Node d_false;
Node d_true;
Node d_zero;
Node d_one;
Node d_two;
NodeSet d_initRefine;
/** all pow2 terms
* Cleared at each last call effort check.
* */
std::vector<Node> d_pow2s;
/**
* Value-based refinement lemma for i of the form (pow2 x). Returns:
* x = M(x) /\ x>= 0 ---->
* (pow2 x) = rewrite((pow2 M(x)))
*/
Node valueBasedLemma(Node i);
}; /* class Pow2Solver */
} // namespace nl
} // namespace arith
} // namespace theory
} // namespace cvc5
#endif /* CVC5__THEORY__ARITH__POW2_SOLVER_H */
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