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/****************************************************************************** |
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* Top contributors (to current version): |
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* Gereon Kremer |
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* |
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* This file is part of the cvc5 project. |
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* |
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* Copyright (c) 2009-2021 by the authors listed in the file AUTHORS |
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* in the top-level source directory and their institutional affiliations. |
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* All rights reserved. See the file COPYING in the top-level source |
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* directory for licensing information. |
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* **************************************************************************** |
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* |
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* Represents a contraction candidate for ICP-style propagation. |
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*/ |
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#ifndef CVC5__THEORY__ARITH__ICP__CANDIDATE_H |
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#define CVC5__THEORY__ARITH__ICP__CANDIDATE_H |
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#include "cvc5_private.h" |
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#ifdef CVC5_POLY_IMP |
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#include <poly/polyxx.h> |
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#include "expr/node.h" |
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#include "theory/arith/nl/icp/intersection.h" |
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namespace cvc5 { |
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namespace theory { |
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namespace arith { |
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namespace nl { |
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namespace icp { |
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/** |
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* A contraction candidate for ICP-style propagation with the following |
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* semantics: |
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* |
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* lhs ~rel~ rhsmult*rhs |
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* |
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* where lhs is the variable whose interval we aim to contract, rel is a |
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* relation symbol (other than disequality), rhsmult is a fractional constant |
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* and rhs a polynomial. As poly::Polynomial only holds integer polynomials, |
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* rhsmult is necessary to encode polynomials with rational coefficients. |
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* |
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* Additionally, we store the origin of this constraints (a single theory |
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* constraint) and the variables contained in rhs. |
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* |
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* A candidate is evaluated (or propagated) by evaluating the rhsmult*rhs over |
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* an interval assignment and then updating the interval assignment for lhs with |
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* the result of this evaluation, properly considering the relation. |
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*/ |
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struct Candidate |
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{ |
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/** The target variable */ |
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poly::Variable lhs; |
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/** The relation symbol */ |
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poly::SignCondition rel; |
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/** The (integer) polynomial on the right hand side */ |
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poly::Polynomial rhs; |
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/** The rational multiplier */ |
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poly::Rational rhsmult; |
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/** The origin of this candidate */ |
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Node origin; |
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/** The variable within rhs */ |
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std::vector<Node> rhsVariables; |
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/** |
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* Contract the interval assignment based on this candidate. |
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* Only contract if the new interval is below the given threshold, see |
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* intersect_interval_with(). |
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*/ |
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PropagationResult propagate(poly::IntervalAssignment& ia, |
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std::size_t size_threshold) const; |
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}; |
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/** Print a candidate. */ |
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std::ostream& operator<<(std::ostream& os, const Candidate& c); |
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} // namespace icp |
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} // namespace nl |
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} // namespace arith |
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} // namespace theory |
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} // namespace cvc5 |
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#endif |
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#endif |