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/********************* */
/*! \file intersection.h
** \verbatim
** Top contributors (to current version):
** Gereon Kremer
** This file is part of the CVC4 project.
** Copyright (c) 2009-2020 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.\endverbatim
**
** \brief Implement intersection of intervals for propagation.
**/
#ifndef CVC4__THEORY__ARITH__ICP__INTERSECTION_H
#define CVC4__THEORY__ARITH__ICP__INTERSECTION_H
#include "util/real_algebraic_number.h"
#ifdef CVC4_POLY_IMP
#include <poly/polyxx.h>
namespace CVC4 {
namespace theory {
namespace arith {
namespace nl {
namespace icp {
/**
* Represents the possible results of a single propagation step.
* A propagation tries to refine a current interval with a new interval by
* intersecting them.
*/
enum class PropagationResult
{
/** The propagation did not change the current interval. */
NOT_CHANGED,
/** The propagation contracted the current interval. */
CONTRACTED,
/**
* The propagation contracted the current interval made at least one bound
* finite.
*/
CONTRACTED_STRONGLY,
/**
* The propagation only used the new interval (as it was a subset of the
* current interval).
*/
CONTRACTED_WITHOUT_CURRENT,
/**
* The propagation only used the new interval (as it was a subset of the
* current interval) and made at least one bound finite.
*/
CONTRACTED_STRONGLY_WITHOUT_CURRENT,
/**
* The propagation found a conflict as the two intervals did not intersect.
*/
CONFLICT
};
/**
* Update the current interval by intersection with the new interval and return
* the appropriate result. If the size of any of the bounds, as computed by
* bitsize(), would grow beyond the given threshold, no intersection is
* performed and PropagationResult::NOT_CHANGED is returned.
*/
PropagationResult intersect_interval_with(poly::Interval& cur,
const poly::Interval& res,
std::size_t size_threshold);
} // namespace icp
} // namespace nl
} // namespace arith
} // namespace theory
} // namespace CVC4
#endif
#endif
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