diff --git a/src/opt/opt_context.cpp b/src/opt/opt_context.cpp
index b11078b3f..ac6e7f084 100644
--- a/src/opt/opt_context.cpp
+++ b/src/opt/opt_context.cpp
@@ -16,7 +16,6 @@ Notes:
 
 --*/
 
-
 #include "opt_context.h"
 #include "fu_malik.h"
 #include "weighted_maxsat.h"
@@ -62,7 +61,7 @@ namespace opt {
         }
 
         if (!m_objectives.empty()) {
-            vector<optional<rational> > values;
+            vector<inf_eps_rational<rational> > values;
             for (unsigned i = 0; i < fmls_copy.size(); ++i) {
                 s->assert_expr(fmls_copy[i].get());
             }
@@ -75,11 +74,7 @@ namespace opt {
             }
 
             for (unsigned i = 0; i < values.size(); ++i) {
-                if (values[i]) {
-                    std::cout << "objective function: " << mk_pp(m_objectives[i].get(), m) << " -> " << *values[i] << "\n";
-                } else {
-                    std::cout << "objective function: " << mk_pp(m_objectives[i].get(), m) << " -> unbounded\n";
-                }
+                std::cout << "objective function: " << mk_pp(m_objectives[i].get(), m) << " -> " << values[i].to_string() << "\n";                
             }
         }     
 
diff --git a/src/opt/opt_context.h b/src/opt/opt_context.h
index 0555cdd83..9e7658625 100644
--- a/src/opt/opt_context.h
+++ b/src/opt/opt_context.h
@@ -66,7 +66,6 @@ namespace opt {
 
     };
 
-
 }
 
 #endif
diff --git a/src/opt/opt_solver.cpp b/src/opt/opt_solver.cpp
index 311d90275..c2a01f92f 100644
--- a/src/opt/opt_solver.cpp
+++ b/src/opt/opt_solver.cpp
@@ -7,7 +7,6 @@ namespace opt {
 
     opt_solver::opt_solver(ast_manager & m, params_ref const & p, symbol const & l):
         solver_na2as(m),
-        m_manager(m),
         m_params(p),
         m_context(m, m_params),
         m_objective_enabled(false) {
@@ -15,7 +14,7 @@ namespace opt {
         if (m_logic != symbol::null)
             m_context.set_logic(m_logic);
     }
-        
+    
     opt_solver::~opt_solver() {
     }
 
@@ -64,14 +63,14 @@ namespace opt {
 
     
     lbool opt_solver::check_sat_core(unsigned num_assumptions, expr * const * assumptions) {
-        TRACE("opt_solver_na2as", tout << "smt_opt_solver::check_sat_core: " << num_assumptions << "\n";);
+        TRACE("opt_solver_na2as", tout << "opt_opt_solver::check_sat_core: " << num_assumptions << "\n";);
         lbool r = m_context.check(num_assumptions, assumptions);
         if (r == l_true && m_objective_enabled) {
-            bool is_bounded = get_optimizer().max(m_objective_var);
+            bool is_bounded = get_optimizer().maximize(m_objective_var);
             if (is_bounded) {
                 m_objective_value = get_optimizer().get_objective_value(m_objective_var);
             } else {
-                optional<rational> r;
+                inf_eps_rational<rational> r(rational(1), rational(0));
                 m_objective_value = r;
             }
         }
@@ -132,7 +131,7 @@ namespace opt {
         m_objective_enabled = enable;
     }
 
-    optional<rational> opt_solver::get_objective_value() {
+    inf_eps_rational<rational> opt_solver::get_objective_value() {
         return m_objective_value;
     }
 
diff --git a/src/opt/opt_solver.h b/src/opt/opt_solver.h
index 0c8147f03..3904a3646 100644
--- a/src/opt/opt_solver.h
+++ b/src/opt/opt_solver.h
@@ -20,6 +20,7 @@ Notes:
 #ifndef _OPT_SOLVER_H_
 #define _OPT_SOLVER_H_
 
+#include"inf_eps_rational.h"
 #include"ast.h"
 #include"params.h"
 #include"solver_na2as.h"
@@ -37,8 +38,7 @@ namespace opt {
         symbol              m_logic;
         bool                m_objective_enabled;
         smt::theory_var     m_objective_var;
-        ast_manager&        m_manager;
-        optional<rational>  m_objective_value;
+        inf_eps_rational<rational>  m_objective_value;
     public:
         opt_solver(ast_manager & m, params_ref const & p, symbol const & l);
         virtual ~opt_solver();
@@ -64,7 +64,7 @@ namespace opt {
         void set_objective(app* term);
         void toggle_objective(bool enable);
         
-        optional<rational> get_objective_value();
+        inf_eps_rational<rational> get_objective_value();
     private:
         smt::theory_opt& get_optimizer();
     };
diff --git a/src/opt/optimize_objectives.cpp b/src/opt/optimize_objectives.cpp
index 81d71e507..8dc942c32 100644
--- a/src/opt/optimize_objectives.cpp
+++ b/src/opt/optimize_objectives.cpp
@@ -31,7 +31,7 @@ namespace opt {
     */
     lbool mathsat_style_opt(opt_solver& s, 
                           expr_ref_vector& objectives, svector<bool> const& is_max,
-                          vector<optional<rational> >& values) {
+                          vector<inf_eps_rational<rational> >& values) {
         enable_trace("maximize");        
         // First check_sat call for initialize theories
         lbool is_sat = s.check_sat(0, 0);
@@ -39,38 +39,47 @@ namespace opt {
             return l_false;
         }
 
+        s.push();
+
         // Assume there is only one objective function
         ast_manager& m = objectives.get_manager();
         arith_util autil(m);
-        app* objective = is_max[0] ? (app*) objectives[0].get() : autil.mk_uminus(objectives[0].get());
+        app* objective = m.mk_fresh_const("objective", autil.mk_real());
+        if (is_max[0]) {
+	        s.assert_expr(autil.mk_eq(objective, objectives[0].get()));
+        } else {
+	        s.assert_expr(autil.mk_eq(objective, autil.mk_uminus(objectives[0].get())));
+        };
         s.set_objective(objective);
         s.toggle_objective(true);
         is_sat = s.check_sat(0, 0);        
         
         while (is_sat != l_false) {
-            // Extract values for objectives.
-            optional<rational> rat;
-            rat = s.get_objective_value();
+            // Extract values for objectives
+            inf_eps_rational<rational> val;
+			val = is_max[0] ? s.get_objective_value() : -s.get_objective_value();
 
-            // Unbounded objective
-            if (!rat) {
+            // Check whether objective is unbounded
+            if (!val.is_rational()) {
                 values.reset();
-                values.push_back(rat);
-                return l_true;
+                values.push_back(val);
+                break;
             }
             
-            // If values have initial data, they will be dropped.
+            // If values have initial data, they will be dropped
             values.reset();
-            values.push_back(rat);
+            values.push_back(val);
             
-            // Assert there must be something better.            
+            // Assert there must be something better            
             expr_ref_vector assumptions(m);
             expr* bound = m.mk_fresh_const("bound", m.mk_bool_sort());
             assumptions.push_back(bound);
-            expr* r = autil.mk_numeral(*rat, false);
+            expr* r = autil.mk_numeral(val.get_rational(), false);
             s.assert_expr(m.mk_eq(bound, is_max[0] ? autil.mk_gt(objectives[0].get(), r) : autil.mk_lt(objectives[0].get(), r)));
             is_sat = s.check_sat(1, assumptions.c_ptr());            
-        }              
+        }      
+
+        s.pop(1);
                 
         return l_true;
     }
@@ -82,7 +91,7 @@ namespace opt {
     
     lbool optimize_objectives(opt_solver& s, 
                           expr_ref_vector& objectives, svector<bool> const& is_max,
-                          vector<optional<rational> >& values) {
+                          vector<inf_eps_rational<rational> >& values) {
         return mathsat_style_opt(s, objectives, is_max, values);
     }
 }
diff --git a/src/opt/optimize_objectives.h b/src/opt/optimize_objectives.h
index f14cb37db..aa02a992e 100644
--- a/src/opt/optimize_objectives.h
+++ b/src/opt/optimize_objectives.h
@@ -29,7 +29,7 @@ namespace opt {
     
     lbool optimize_objectives(opt_solver& s, 
                           expr_ref_vector& objectives, svector<bool> const& is_max,
-                          vector<optional<rational> >& values);
+                          vector<inf_eps_rational<rational> >& values);
 };
 
 #endif
diff --git a/src/smt/theory_arith.h b/src/smt/theory_arith.h
index 0f5f33756..99b7e34f3 100644
--- a/src/smt/theory_arith.h
+++ b/src/smt/theory_arith.h
@@ -992,9 +992,9 @@ namespace smt {
         // Optimization
         //
         // -----------------------------------
-        virtual bool max(theory_var v) { return max_min(v, true); }
+        virtual bool maximize(theory_var v) { return max_min(v, true); }
         virtual theory_var add_objective(app* term);
-        virtual optional<rational> get_objective_value(theory_var v);
+        virtual inf_eps_rational<rational> get_objective_value(theory_var v);
         inf_rational m_objective;
 
         // -----------------------------------
diff --git a/src/smt/theory_arith_aux.h b/src/smt/theory_arith_aux.h
index 87624acb6..da56f8b0f 100644
--- a/src/smt/theory_arith_aux.h
+++ b/src/smt/theory_arith_aux.h
@@ -19,6 +19,7 @@ Revision History:
 #ifndef _THEORY_ARITH_AUX_H_
 #define _THEORY_ARITH_AUX_H_
 
+#include"inf_eps_rational.h"
 #include"theory_arith.h"
 
 namespace smt {
@@ -960,12 +961,10 @@ namespace smt {
     }
 
     template<typename Ext>
-    optional<rational> theory_arith<Ext>::get_objective_value(theory_var v) { 
-        optional<rational> rat;        
-        if (m_objective.is_rational()) {
-            rat = m_objective.get_rational();            
-        };
-        return rat; 
+    inf_eps_rational<rational> theory_arith<Ext>::get_objective_value(theory_var v) { 
+        inf_eps_rational<rational> val;        
+        val = m_objective.get_rational();
+        return val; 
     }
 
     /**
diff --git a/src/smt/theory_opt.h b/src/smt/theory_opt.h
index 4f742f73b..4a558a09c 100644
--- a/src/smt/theory_opt.h
+++ b/src/smt/theory_opt.h
@@ -18,15 +18,21 @@ Notes:
 
 --*/
 
+#include "inf_eps_rational.h"
+
 #ifndef _THEORY_OPT_H_
 #define _THEORY_OPT_H_
 
 namespace smt {
     class theory_opt {
     public:
-        virtual bool max(theory_var v) { UNREACHABLE(); return false; };
+        virtual bool maximize(theory_var v) { UNREACHABLE(); return false; };
         virtual theory_var add_objective(app* term) { UNREACHABLE(); return null_theory_var; }
-        virtual optional<rational> get_objective_value(theory_var v) { UNREACHABLE(); optional<rational> r; return r;}
+		virtual inf_eps_rational<rational> get_objective_value(theory_var v) { 
+            UNREACHABLE(); 
+            inf_eps_rational<rational> r(rational(1), rational(0)); 
+            return r; 
+		}
     };
 }