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/********************* */
/*! \file model_blocker.h
** \verbatim
** Top contributors (to current version):
** Andrew Reynolds, Mathias Preiner
** 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 Utility for blocking the current model
**/
#include "cvc4_private.h"
#ifndef __CVC4__THEORY__MODEL_BLOCKER_H
#define __CVC4__THEORY__MODEL_BLOCKER_H
#include <vector>
#include "expr/expr.h"
#include "options/smt_options.h"
#include "theory/theory_model.h"
namespace CVC4 {
/**
* A utility for blocking the current model.
*/
class ModelBlocker
{
public:
/** get model blocker
*
* This returns a disjunction of literals ~L1 V ... V ~Ln with the following
* properties:
* (1) L1 ... Ln hold in the current model (given by argument m),
* (2) if mode is set to "literals", L1 ... Ln are literals that occur in
* assertions and propositionally entail all non-unit top-level assertions.
* (3) if mode is set to "values", L1 ... Ln are literals of the form x=c,
* where c is the value of x in the current model.
* (4) if exprToBlock is not empty, L1 ... Ln are literals of the form t=c,
* where c is the value of t in the current model. If exprToBlock is
* non-empty, then L1 ... Ln are t1=c1 ... tn=cn where exprToBlock is
* { t1 ... tn }; if exprToBlock is empty, then t1 ... tn are the free
* variables of assertions.
*
* We expect exprToBlock to be non-empty only if mode is
* BlockModelsMode::VALUES.
*
* For example, if our input is:
* x > 0 ^ ( y < 0 V z < 0 V w < 0 )
* and m is { x -> 1, y -> 2, z -> -1, w -> -1 }, then this method may
* return ~(z < 0) or ~(w < 0) when set to mode "literals".
*
* Notice that we do not require that L1...Ln entail unit top-level assertions
* since these literals are trivially entailed to be true in all models of
* our input. In other words, we do not return ~(x < 0) V ~(w < 0) since the
* left disjunct is always false.
*/
static Expr getModelBlocker(
const std::vector<Expr>& assertions,
theory::TheoryModel* m,
options::BlockModelsMode mode,
const std::vector<Expr>& exprToBlock = std::vector<Expr>());
}; /* class TheoryModelCoreBuilder */
} // namespace CVC4
#endif /* __CVC4__THEORY__MODEL_BLOCKER_H */
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