added pareto utility

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

src/opt/opt_pareto.h

@@ -0,0 +1,109 @@
+/*++
+Copyright (c) 2014 Microsoft Corporation
+
+Module Name:
+
+    opt_pareto.h
+
+Abstract:
+
+    Pareto front utilities
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2014-4-24
+
+Notes:
+
+   
+--*/
+#ifndef _OPT_PARETO_H_
+#define _OPT_PARETO_H_
+
+#include "solver.h"
+#include "model.h"
+
+namespace opt {
+   
+    class pareto_callback {
+    public:
+        virtual void yield(model_ref& model) = 0;
+        virtual unsigned num_objectives() = 0;
+        virtual expr_ref mk_gt(unsigned i, model_ref& model) = 0;
+        virtual expr_ref mk_ge(unsigned i, model_ref& model) = 0;
+        virtual expr_ref mk_le(unsigned i, model_ref& model) = 0;
+    };
+    class pareto_base {
+    protected:
+        ast_manager&     m;
+        pareto_callback& cb;
+        volatile bool    m_cancel;
+        ref<solver>      m_solver;
+        params_ref       m_params;
+    public:
+        pareto_base(
+            ast_manager & m, 
+            pareto_callback& cb, 
+            solver* s, 
+            params_ref & p):
+            m(m),
+            cb(cb),            
+            m_cancel(false),
+            m_solver(s),
+            m_params(p) {
+        }
+        virtual ~pareto_base() {}
+        virtual void updt_params(params_ref & p) {
+            m_solver->updt_params(p);
+            m_params.copy(p);
+        }
+        virtual void collect_param_descrs(param_descrs & r) {
+            m_solver->collect_param_descrs(r);
+        }
+        virtual void collect_statistics(statistics & st) const {
+            m_solver->collect_statistics(st);
+        }
+        virtual void set_cancel(bool f) {
+            m_solver->set_cancel(f);
+            m_cancel = f;
+        }
+        virtual void display(std::ostream & out) const {
+            m_solver->display(out);
+        }
+        virtual lbool operator()() = 0;
+
+    protected:
+
+        void mk_dominates(model_ref& model);
+
+        void mk_not_dominated_by(model_ref& model);            
+    };
+    class gia_pareto : public pareto_base {
+    public:
+        gia_pareto(ast_manager & m, 
+                   pareto_callback& cb, 
+                   solver* s, 
+                   params_ref & p):
+            pareto_base(m, cb, s, p) {            
+        }
+        virtual ~gia_pareto() {}
+
+        virtual lbool operator()();
+    };
+
+    // opportunistic improvement algorithm.
+    class oia_pareto : public pareto_base {
+    public:
+        oia_pareto(ast_manager & m, 
+                   pareto_callback& cb, 
+                   solver* s, 
+                   params_ref & p):
+            pareto_base(m, cb, s, p) {            
+        }
+        virtual ~oia_pareto() {}
+
+        virtual lbool operator()();
+    };
+}
+
+#endif