move mus to solver

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

src/solver/mus.h

@@ -0,0 +1,54 @@
+/*++
+Copyright (c) 2014 Microsoft Corporation
+
+Module Name:
+
+    mus.h
+
+Abstract:
+   
+    Basic MUS extraction
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2014-20-7
+
+Notes:
+
+--*/
+#ifndef MUS_H_
+#define MUS_H_
+
+class mus {
+    struct imp;
+    imp * m_imp;
+ public:
+    mus(solver& s);
+    ~mus();
+    /**
+       Add soft constraint.
+       
+       Assume that the solver context enforces that 
+       cls is equivalent to a disjunction of args.
+       Assume also that cls is a literal.           
+    */
+    unsigned add_soft(expr* cls);
+    
+    lbool get_mus(unsigned_vector& mus);
+    
+    void reset();
+    
+    /**
+       Instrument MUS extraction to also provide the minimal
+       penalty model, if any is found.
+       The minimal penalty model has the least weight for the 
+       supplied soft constraints.
+    */
+    void set_soft(unsigned sz, expr* const* soft, rational const* weights);
+
+    rational get_best_model(model_ref& mdl);
+    
+};
+
+
+#endif