perf improvements, mus

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/sat/sat_mus.h

@@ -0,0 +1,44 @@
+/*++
+Copyright (c) 2014 Microsoft Corporation
+
+Module Name:
+
+    mus.h
+
+Abstract:
+   
+    Faster MUS extraction based on Belov et.al. HYB (Algorithm 3, 4)
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2014-20-7
+
+Notes:
+
+--*/
+#ifndef _SAT_MUS_H_
+#define _SAT_MUS_H_
+
+namespace sat {
+    class mus {
+        literal_vector m_core;
+        literal_vector m_assumptions;
+        literal_vector m_mus;
+        literal_vector m_toswap;        
+        solver& s;
+    public:
+        mus(solver& s);
+        ~mus();        
+        lbool operator()();
+    private:
+        void rmr();
+        bool has_single_unsat(literal& assumption_lit);
+        void find_swappable(literal lit);
+        void reset();
+        void set_core();
+        lbool eval(literal l) const;
+    };
+
+};
+
+#endif