diff --git a/src/opt/fu_malik.cpp b/src/opt/fu_malik.cpp
index d6e435be9..fe4cdb1f7 100644
--- a/src/opt/fu_malik.cpp
+++ b/src/opt/fu_malik.cpp
@@ -35,19 +35,20 @@ Notes:
 */
 namespace opt {
 
-    class fu_malik {
+    struct fu_malik::imp {
         ast_manager& m;
         solver& s;
         expr_ref_vector m_soft;
         expr_ref_vector m_aux;
+        expr_ref_vector m_assignment;
 
-    public:
 
-        fu_malik(ast_manager& m, solver& s, expr_ref_vector const& soft):
+        imp(ast_manager& m, solver& s, expr_ref_vector const& soft):
             m(m),
             s(s),
             m_soft(soft),
-            m_aux(m)
+            m_aux(m),
+            m_assignment(m)
         {
             for (unsigned i = 0; i < m_soft.size(); ++i) {
                 m_aux.push_back(m.mk_fresh_const("p", m.mk_bool_sort()));
@@ -106,8 +107,6 @@ namespace opt {
             return l_false;
         }
 
-    private:
-
         void assert_at_most_one(expr_ref_vector const& block_vars) {
             expr_ref has_one(m), has_zero(m), at_most_one(m);
             mk_at_most_one(block_vars.size(), block_vars.c_ptr(), has_one, has_zero);
@@ -131,46 +130,71 @@ namespace opt {
             }
         }
 
-    };
-
-    // TBD: bug when cancel flag is set, fu_malik returns is_sat == l_true instead of l_undef
-    
-    lbool fu_malik_maxsat(solver& s, expr_ref_vector& soft_constraints) {
-        ast_manager& m = soft_constraints.get_manager();
-        lbool is_sat = s.check_sat(0,0);
-        if (!soft_constraints.empty() && is_sat == l_true) {
-            s.push();
-
-            fu_malik fm(m, s, soft_constraints);
-            lbool is_sat = l_true;
-            do {
-                is_sat = fm.step();
-            }
-            while (is_sat == l_false);
-            
-            if (is_sat == l_true) {
-                // Get a list of satisfying soft_constraints
-                model_ref model;
-                s.get_model(model);
+        // TBD: bug when cancel flag is set, fu_malik returns is_sat == l_true instead of l_undef
+        lbool operator()() {
+            lbool is_sat = s.check_sat(0,0);
+            if (!m_soft.empty() && is_sat == l_true) {
+                opt_solver::scoped_push _sp(s);
                 
-                expr_ref_vector result(m);
-                for (unsigned i = 0; i < soft_constraints.size(); ++i) {
-                    expr_ref val(m);
-                    VERIFY(model->eval(soft_constraints[i].get(), val));
-                    if (!m.is_false(val)) {
-                        result.push_back(soft_constraints[i].get());
+                lbool is_sat = l_true;
+                do {
+                    is_sat = step();
+                }
+                while (is_sat == l_false);
+                
+                if (is_sat == l_true) {
+                    // Get a list of satisfying m_soft
+                    model_ref model;
+                    s.get_model(model);
+
+                    m_assignment.reset();                    
+                    for (unsigned i = 0; i < m_soft.size(); ++i) {
+                        expr_ref val(m);
+                        VERIFY(model->eval(m_soft[i].get(), val));
+                        if (m.is_true(val)) {
+                            m_assignment.push_back(m_soft[i].get());
+                        }
                     }
                 }
-                soft_constraints.reset();
-                soft_constraints.append(result);
             }
-            s.pop(1);
+            // We are done and soft_constraints has 
+            // been updated with the max-sat assignment.            
+            return is_sat;            
         }
-        // We are done and soft_constraints has 
-        // been updated with the max-sat assignment.
 
-        return is_sat;
+    };
+
+    fu_malik::fu_malik(ast_manager& m, solver& s, expr_ref_vector& soft_constraints) {
+        m_imp = alloc(imp, m, s, soft_constraints);
     }
+    fu_malik::~fu_malik() {
+        dealloc(m_imp);
+    }
+    
+    lbool fu_malik::operator()() {
+        return (*m_imp)();
+    }
+    rational fu_malik::get_lower() const {
+        NOT_IMPLEMENTED_YET();
+        return rational(0);
+    }
+    rational fu_malik::get_upper() const {
+        NOT_IMPLEMENTED_YET();
+        return rational(m_imp->m_soft.size());
+    }
+    rational fu_malik::get_value() const {
+        NOT_IMPLEMENTED_YET();
+        return rational(m_imp->m_assignment.size());
+    }
+    expr_ref_vector fu_malik::get_assignment() const {
+        return m_imp->m_assignment;
+    }
+    void fu_malik::set_cancel(bool f) {
+        // no-op
+    }
+
+
+
 };
 
 
diff --git a/src/opt/fu_malik.h b/src/opt/fu_malik.h
index 6bfe37f63..48be07316 100644
--- a/src/opt/fu_malik.h
+++ b/src/opt/fu_malik.h
@@ -20,6 +20,7 @@ Notes:
 #define _OPT_FU_MALIK_H_
 
 #include "solver.h"
+#include "maxsmt.h"
 
 namespace opt {
     /**
@@ -27,8 +28,21 @@ namespace opt {
        Returns a maximal satisfying subset of soft_constraints
        that are still consistent with the solver state.
     */
+
+    class fu_malik : public maxsmt_solver {
+        struct imp;
+        imp* m_imp;
+    public:
+        fu_malik(ast_manager& m, solver& s, expr_ref_vector& soft_constraints);
+        virtual ~fu_malik();
+        virtual lbool operator()();
+        virtual rational get_lower() const;
+        virtual rational get_upper() const;
+        virtual rational get_value() const;
+        virtual expr_ref_vector get_assignment() const;
+        virtual void set_cancel(bool f);
+    };
     
-    lbool fu_malik_maxsat(solver& s, expr_ref_vector& soft_constraints);
 };
 
 #endif
diff --git a/src/opt/weighted_maxsat.cpp b/src/opt/weighted_maxsat.cpp
index b74bb1ab8..0434e3afb 100644
--- a/src/opt/weighted_maxsat.cpp
+++ b/src/opt/weighted_maxsat.cpp
@@ -151,11 +151,9 @@ namespace smt {
 
         virtual final_check_status final_check_eh() {
             if (block(true)) {
-                return FC_CONTINUE;
-            }
-            else {
                 return FC_DONE;
             }
+            return FC_CONTINUE;
         }
 
         virtual bool use_diseqs() const { 
@@ -203,6 +201,9 @@ namespace smt {
         };
 
         bool block(bool is_final) {
+            if (m_vars.empty()) {
+                return true;
+            }
             ast_manager& m = get_manager();
             context& ctx = get_context();
             literal_vector lits;
@@ -218,6 +219,11 @@ namespace smt {
                 lits.push_back(~literal(m_min_cost_bv));
             }
             IF_VERBOSE(2, verbose_stream() << "block: " << m_costs.size() << " " << lits.size() << " " << m_min_cost << "\n";);
+            IF_VERBOSE(2, for (unsigned i = 0; i < lits.size(); ++i) {
+                    verbose_stream() << lits[i] << " ";
+                }
+                verbose_stream() << "\n";
+                );
 
             ctx.mk_th_axiom(get_id(), lits.size(), lits.c_ptr());
             if (is_final && m_cost < m_min_cost) {
@@ -225,7 +231,7 @@ namespace smt {
                 m_cost_save.reset();
                 m_cost_save.append(m_costs);
             }
-            return !lits.empty();
+            return false;
         }                
     };
 
@@ -259,42 +265,101 @@ namespace opt {
         return result;
     }
 
+
+    struct wmaxsmt::imp {
+        ast_manager&     m;
+        opt_solver&      s;
+        expr_ref_vector  m_soft;
+        expr_ref_vector  m_assignment;
+        rational         m_lower;
+        rational         m_upper;
+        rational         m_value;
+        vector<rational> m_weights;
+
+        imp(ast_manager& m, opt_solver& s, expr_ref_vector& soft_constraints, vector<rational> const& weights):
+            m(m), s(s), m_soft(soft_constraints), m_assignment(m), m_weights(weights)
+        {}
+        ~imp() {}
+
+        smt::theory_weighted_maxsat& ensure_theory() {
+            smt::context& ctx = s.get_context();                        
+            smt::theory_id th_id = m.get_family_id("weighted_maxsat");
+            smt::theory* th = ctx.get_theory(th_id);               
+            smt::theory_weighted_maxsat* wth;
+            if (th) {
+                wth = dynamic_cast<smt::theory_weighted_maxsat*>(th);
+                wth->reset();
+            }
+            else {
+                wth = alloc(smt::theory_weighted_maxsat, m);
+                ctx.register_plugin(wth);
+            }
+            return *wth;
+        }
+
     /**
        Takes solver with hard constraints added.
        Returns a maximal satisfying subset of weighted soft_constraints
        that are still consistent with the solver state.
     */
-    
-    lbool weighted_maxsat(opt_solver& s, expr_ref_vector& soft_constraints, vector<rational> const& weights) {
-        ast_manager& m = soft_constraints.get_manager();
-        smt::context& ctx = s.get_context();                        
-        smt::theory_id th_id = m.get_family_id("weighted_maxsat");
-        smt::theory* th = ctx.get_theory(th_id);               
-        smt::theory_weighted_maxsat* wth;
-        if (th) {
-            wth = dynamic_cast<smt::theory_weighted_maxsat*>(th);
-            wth->reset();
-        }
-        else {
-            wth = alloc(smt::theory_weighted_maxsat, m);
-            ctx.register_plugin(wth);
-        }
         
-        opt_solver::scoped_push _s(s);
-        for (unsigned i = 0; i < soft_constraints.size(); ++i) {
-            wth->assert_weighted(soft_constraints[i].get(), weights[i]);
-        }
-#if 0
-        lbool result = s.check_sat_core(0,0);
+        lbool operator()() {
+            smt::theory_weighted_maxsat& wth = ensure_theory();
+            lbool result;
+            {
+                opt_solver::scoped_push _s(s);
+                for (unsigned i = 0; i < m_soft.size(); ++i) {
+                    wth.assert_weighted(m_soft[i].get(), m_weights[i]);
+                }
+#if 1
+                result = s.check_sat_core(0,0);
 #else
-        lbool result = iterative_weighted_maxsat(s, *wth);
+                result = iterative_weighted_maxsat(s, *wth);
 #endif
+                
+                wth.get_assignment(m_assignment);
+                if (!m_assignment.empty() && result == l_false) {
+                    result = l_true;
+                }
+            }
+            wth.reset();
+            return result;            
+        }        
+    };
 
-        wth->get_assignment(soft_constraints);
-        if (!soft_constraints.empty() && result == l_false) {
-            result = l_true;
-        }
-        return result;
+    wmaxsmt::wmaxsmt(ast_manager& m, opt_solver& s, expr_ref_vector& soft_constraints, vector<rational> const& weights) {
+        m_imp = alloc(imp, m, s, soft_constraints, weights);
     }
+
+    wmaxsmt::~wmaxsmt() {
+        dealloc(m_imp);
+    }
+    
+    lbool wmaxsmt::operator()() {
+        return (*m_imp)();
+    }
+    rational wmaxsmt::get_lower() const {
+        NOT_IMPLEMENTED_YET();
+        return m_imp->m_lower;
+    }
+    rational wmaxsmt::get_upper() const {
+        NOT_IMPLEMENTED_YET();
+        return m_imp->m_upper;
+    }
+    rational wmaxsmt::get_value() const {
+        NOT_IMPLEMENTED_YET();
+        return m_imp->m_value;
+    }
+    expr_ref_vector wmaxsmt::get_assignment() const {
+        return m_imp->m_assignment;
+    }
+    void wmaxsmt::set_cancel(bool f) {
+        // no-op
+    }
+
+
+
+    
+
 };
 
diff --git a/src/opt/weighted_maxsat.h b/src/opt/weighted_maxsat.h
index 120609a8c..3e1cd8529 100644
--- a/src/opt/weighted_maxsat.h
+++ b/src/opt/weighted_maxsat.h
@@ -19,6 +19,7 @@ Notes:
 #define _OPT_WEIGHTED_MAX_SAT_H_
 
 #include "opt_solver.h"
+#include "maxsmt.h"
 
 namespace opt {
     /**
@@ -26,8 +27,19 @@ namespace opt {
        Returns a maximal satisfying subset of weighted soft_constraints
        that are still consistent with the solver state.
     */
-    
-    lbool weighted_maxsat(opt_solver& s, expr_ref_vector& soft_constraints, vector<rational> const& weights);
+    class wmaxsmt : public maxsmt_solver {
+        struct imp;
+        imp* m_imp;
+    public:
+        wmaxsmt(ast_manager& m, opt_solver& s, expr_ref_vector& soft_constraints, vector<rational> const& weights);
+        ~wmaxsmt();
+        virtual lbool operator()();
+        virtual rational get_lower() const;
+        virtual rational get_upper() const;
+        virtual rational get_value() const;
+        virtual expr_ref_vector get_assignment() const;
+        virtual void set_cancel(bool f);
+    };
 };
 
 #endif