Support model cores via option --produce-model-cores. (#2407)

This adds support for model cores, fixes #1233.

It includes some minor cleanup and additions to utility functions.

1 files changed, 66 insertions, 0 deletions

diff --git a/src/theory/subs_minimize.h b/src/theory/subs_minimize.h
new file mode 100644
index 000000000..55e57b921
--- /dev/null
+++ b/src/theory/subs_minimize.h
@@ -0,0 +1,66 @@
+/*********************                                                        */
+/*! \file subs_minimize.h
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Andrew Reynolds
+ ** This file is part of the CVC4 project.
+ ** Copyright (c) 2009-2018 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 Substitution minimization.
+ **/
+
+#include "cvc4_private.h"
+
+#ifndef __CVC4__THEORY__SUBS_MINIMIZE_H
+#define __CVC4__THEORY__SUBS_MINIMIZE_H
+
+#include <vector>
+
+#include "expr/node.h"
+
+namespace CVC4 {
+namespace theory {
+
+/** SubstitutionMinimize
+ *
+ * This class is used for finding a minimal substitution under which an
+ * evaluation holds.
+ */
+class SubstitutionMinimize
+{
+ public:
+  SubstitutionMinimize();
+  ~SubstitutionMinimize() {}
+  /** find
+   *
+   * If n { vars -> subs } rewrites to target, this method returns true, and
+   * vars[i1], ..., vars[in] are added to rewVars, such that
+   * n { vars[i_1] -> subs[i_1], ..., vars[i_n] -> subs[i_n] } also rewrites to
+   * target.
+   *
+   * If n { vars -> subs } does not rewrite to target, this method returns
+   * false.
+   */
+  static bool find(Node n,
+                   Node target,
+                   const std::vector<Node>& vars,
+                   const std::vector<Node>& subs,
+                   std::vector<Node>& reqVars);
+
+ private:
+  /** is singular arg
+   *
+   * Returns true if
+   *   <k>( ... t_{arg-1}, n, t_{arg+1}...) = c
+   * always holds for some constant c.
+   */
+  static bool isSingularArg(Node n, Kind k, unsigned arg);
+};
+
+}  // namespace theory
+}  // namespace CVC4
+
+#endif /* __CVC4__THEORY__SUBS_MINIMIZE_H */