diff --git a/src/opt/opt_context.cpp b/src/opt/opt_context.cpp
index cd40944b2..d1b7a489e 100644
--- a/src/opt/opt_context.cpp
+++ b/src/opt/opt_context.cpp
@@ -273,7 +273,8 @@ namespace opt {
         display_benchmark();
         IF_VERBOSE(1, verbose_stream() << "(optimize:check-sat)\n";);
         lbool is_sat = s.check_sat(0,0);
-        TRACE("opt", tout << "initial search result: " << is_sat << "\n";);
+        TRACE("opt", tout << "initial search result: " << is_sat << "\n";
+              s.display(tout););
         if (is_sat != l_false) {
             s.get_model(m_model);
             s.get_labels(m_labels);
@@ -1037,6 +1038,10 @@ namespace opt {
             TRACE("opt", tout << "Purifying " << term << "\n";);
             term = purify(fm, term);
         }
+        else if (m.is_ite(term)) {
+            TRACE("opt", tout << "Purifying " << term << "\n";);
+            term = purify(fm, term);
+        }
         if (fm) {
             m_model_converter = concat(m_model_converter.get(), fm.get());
         }
diff --git a/src/opt/opt_solver.cpp b/src/opt/opt_solver.cpp
index 8ae4e467f..bc6462a18 100644
--- a/src/opt/opt_solver.cpp
+++ b/src/opt/opt_solver.cpp
@@ -358,6 +358,7 @@ namespace opt {
         }
         smt::theory_opt& opt = get_optimizer();
         smt::theory_var v = m_objective_vars[var];
+        TRACE("opt", tout << "v" << var << " " << val << "\n";);
 
         if (typeid(smt::theory_inf_arith) == typeid(opt)) {
             smt::theory_inf_arith& th = dynamic_cast<smt::theory_inf_arith&>(opt); 
@@ -387,8 +388,32 @@ namespace opt {
             smt::theory_rdl& th = dynamic_cast<smt::theory_rdl&>(opt);
             return th.mk_ge(m_fm, v, val);
         }
+        
+        if (typeid(smt::theory_dense_i) == typeid(opt) &&
+            val.get_infinitesimal().is_zero()) {
+            smt::theory_dense_i& th = dynamic_cast<smt::theory_dense_i&>(opt);
+            return th.mk_ge(m_fm, v, val);
+        }
 
-        // difference logic?
+        if (typeid(smt::theory_dense_mi) == typeid(opt) &&
+            val.get_infinitesimal().is_zero()) {
+            smt::theory_dense_mi& th = dynamic_cast<smt::theory_dense_mi&>(opt);
+            return th.mk_ge(m_fm, v, val);
+        }
+
+        if (typeid(smt::theory_dense_si) == typeid(opt) &&
+            val.get_infinitesimal().is_zero()) {
+            smt::theory_dense_si& th = dynamic_cast<smt::theory_dense_si&>(opt);
+            return th.mk_ge(m_fm, v, val);
+        }
+
+        if (typeid(smt::theory_dense_smi) == typeid(opt) &&
+            val.get_infinitesimal().is_zero()) {
+            smt::theory_dense_smi& th = dynamic_cast<smt::theory_dense_smi&>(opt);
+            return th.mk_ge(m_fm, v, val);
+        }
+        
+        IF_VERBOSE(0, verbose_stream() << "WARNING: unhandled theory " << typeid(opt).name() << "\n";);
         return expr_ref(m.mk_true(), m);
     } 
 
diff --git a/src/smt/theory_dense_diff_logic_def.h b/src/smt/theory_dense_diff_logic_def.h
index 628eeea83..addb5d92b 100644
--- a/src/smt/theory_dense_diff_logic_def.h
+++ b/src/smt/theory_dense_diff_logic_def.h
@@ -868,7 +868,8 @@ namespace smt {
                 e = ctx.get_enode(to_app(n));                
             }
             else {
-                e = ctx.mk_enode(to_app(n), false, false, true);
+                ctx.internalize(n, false);
+                e = ctx.get_enode(n);
             }            
             v = e->get_th_var(get_id());
             if (v == null_theory_var) {
@@ -1008,7 +1009,8 @@ namespace smt {
             inf_eps result(rational(0), r);
             blocker = mk_gt(v, result);
             IF_VERBOSE(10, verbose_stream() << blocker << "\n";);
-            return result;
+            r += m_objective_consts[v];
+            return inf_eps(rational(0), r);
         }
         default:
             TRACE("opt", tout << "unbounded\n"; );        
@@ -1019,6 +1021,7 @@ namespace smt {
 
     template<typename Ext>
     theory_var theory_dense_diff_logic<Ext>::add_objective(app* term) {
+        TRACE("opt", tout << mk_pp(term, get_manager()) << "\n";);
         objective_term objective;
         theory_var result = m_objectives.size();
         rational q(1), r(0);
@@ -1053,6 +1056,7 @@ namespace smt {
         ast_manager& m = get_manager();
         objective_term const& t = m_objectives[v];
         expr_ref e(m), f(m), f2(m);
+        TRACE("opt", tout << "mk_ineq " << v << " " << val << "\n";);
         if (t.size() == 1 && t[0].second.is_one()) {
             f = get_enode(t[0].first)->get_owner();
         }