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+/*********************                                                        */
+/*! \file model_blocker.h
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Andrew Reynolds
+ ** This file is part of the CVC4 project.
+ ** Copyright (c) 2009-2019 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 BLOCK_MODELS_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,
+      BlockModelsMode mode,
+      const std::vector<Expr>& exprToBlock = std::vector<Expr>());
+}; /* class TheoryModelCoreBuilder */
+
+}  // namespace CVC4
+
+#endif /* __CVC4__THEORY__MODEL_BLOCKER_H */