Non-implied mode for model cores (#2653)

1 files changed, 40 insertions, 6 deletions

diff --git a/src/theory/subs_minimize.h b/src/theory/subs_minimize.h
index 55e57b921..bf6ccffae 100644
--- a/src/theory/subs_minimize.h
+++ b/src/theory/subs_minimize.h
@@ -36,21 +36,55 @@ class 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 t { vars -> subs } rewrites to target, this method returns true, and
+   * vars[i_1], ..., vars[i_n] are added to reqVars, such that i_1, ..., i_n are
+   * distinct, and t { vars[i_1] -> subs[i_1], ..., vars[i_n] -> subs[i_n] }
+   * rewrites to target.
    *
-   * If n { vars -> subs } does not rewrite to target, this method returns
+   * If t { vars -> subs } does not rewrite to target, this method returns
    * false.
    */
-  static bool find(Node n,
+  static bool find(Node t,
                    Node target,
                    const std::vector<Node>& vars,
                    const std::vector<Node>& subs,
                    std::vector<Node>& reqVars);
+  /** find with implied
+   *
+   * This method should be called on a formula t.
+   *
+   * If t { vars -> subs } rewrites to true, this method returns true,
+   * vars[i_1], ..., vars[i_n] are added to reqVars, and
+   * vars[i_{n+1}], ..., vars[i_{n+m}] are added to impliedVars such that
+   * i_1...i_{n+m} are distinct, i_{n+1} < ... < i_{n+m}, and:
+   *
+   * (1) t { vars[i_1]->subs[i_1], ..., vars[i_{n+k}]->subs[i_{n+k}] } implies
+   * vars[i_{n+k+1}] = subs[i_{n+k+1}] for k = 0, ..., m-1.
+   *
+   * (2) t { vars[i_1] -> subs[i_1], ..., vars[i_{n+m}] -> subs[i_{n+m}] }
+   * rewrites to true.
+   *
+   * For example, given (x>0 ^ x = y ^ y = z){ x -> 1, y -> 1, z -> 1, w -> 0 },
+   * this method may add { x } to reqVars, and { y, z } to impliedVars.
+   *
+   * Notice that the order of variables in vars matters. By the semantics above,
+   * variables that appear earlier in the variable list vars are more likely
+   * to appear in reqVars, whereas those later in the vars are more likely to
+   * appear in impliedVars.
+   */
+  static bool findWithImplied(Node t,
+                              const std::vector<Node>& vars,
+                              const std::vector<Node>& subs,
+                              std::vector<Node>& reqVars,
+                              std::vector<Node>& impliedVars);
 
  private:
+  /** Common helper function for the above functions. */
+  static bool findInternal(Node t,
+                           Node target,
+                           const std::vector<Node>& vars,
+                           const std::vector<Node>& subs,
+                           std::vector<Node>& reqVars);
   /** is singular arg
    *
    * Returns true if