diff --git a/src/api/api_solver.cpp b/src/api/api_solver.cpp
index b9b3d8166..e57050e82 100644
--- a/src/api/api_solver.cpp
+++ b/src/api/api_solver.cpp
@@ -149,7 +149,7 @@ extern "C" {
             to_param_ref(p).validate(r);
             to_solver_ref(s)->updt_params(to_param_ref(p));
         }
-        to_solver(s)->m_params = to_param_ref(p);
+        to_solver(s)->m_params.append(to_param_ref(p));
         Z3_CATCH;
     }
     
diff --git a/src/opt/inc_sat_solver.cpp b/src/opt/inc_sat_solver.cpp
index 1c450bbef..1a3fc7ff5 100644
--- a/src/opt/inc_sat_solver.cpp
+++ b/src/opt/inc_sat_solver.cpp
@@ -81,8 +81,8 @@ public:
         simp2_p.set_bool("hoist_mul", false); // required by som
         m_preprocess = 
             and_then(mk_card2bv_tactic(m, m_params),
-                     mk_simplify_tactic(m),
-                     mk_propagate_values_tactic(m),
+                     //mk_simplify_tactic(m),
+                     //mk_propagate_values_tactic(m),
                      using_params(mk_simplify_tactic(m), simp2_p),
                      mk_max_bv_sharing_tactic(m),
                      mk_bit_blaster_tactic(m), 
diff --git a/src/opt/maxres.cpp b/src/opt/maxres.cpp
index d0694222a..209601c78 100644
--- a/src/opt/maxres.cpp
+++ b/src/opt/maxres.cpp
@@ -88,6 +88,7 @@ private:
     rational         m_max_upper;
     bool             m_found_feasible_optimum;
     bool             m_hill_climb;             // prefer large weight soft clauses for cores
+    unsigned         m_last_index;             // last index used during hill-climbing
     bool             m_add_upper_bound_block;  // restrict upper bound with constraint
     unsigned         m_max_num_cores;          // max number of cores per round.
     unsigned         m_max_core_size;          // max core size per round.
@@ -110,6 +111,7 @@ public:
         m_st(st),
         m_found_feasible_optimum(false),
         m_hill_climb(true),
+        m_last_index(0),
         m_add_upper_bound_block(false),
         m_max_num_cores(UINT_MAX),
         m_max_core_size(3),
@@ -352,16 +354,21 @@ public:
             /**
                Give preference to cores that have large minmal values.
             */
-            sort_assumptions(asms);            
-            unsigned index = 0;
-            unsigned last_index = 0;
+            sort_assumptions(asms);  
+            
+            m_last_index = std::min(m_last_index, asms.size()-1);
+            m_last_index = 0;
+            unsigned index = m_last_index>0?m_last_index-1:0;
+            m_last_index = 0;
+            bool first = index > 0;
+            SASSERT(index < asms.size() || asms.empty());
             while (index < asms.size() && is_sat == l_true) {
-                while (asms.size() > 20*(index - last_index) && index < asms.size()) {
+                while (!first && asms.size() > 20*(index - m_last_index) && index < asms.size()) {
                     index = next_index(asms, index);
-                    //break;
                 }
-                IF_VERBOSE(3, verbose_stream() << "weight: " << get_weight(asms[0].get()) << " " << get_weight(asms[index-1].get()) << "\n";);
-                last_index = index;
+                first = false;
+                IF_VERBOSE(3, verbose_stream() << "weight: " << get_weight(asms[0].get()) << " " << get_weight(asms[index-1].get()) << " num soft: " << index << "\n";);
+                m_last_index = index;
                 is_sat = s().check_sat(index, asms.c_ptr());
             }            
         }
@@ -880,6 +887,7 @@ public:
         }
         m_max_upper = m_upper;
         m_found_feasible_optimum = false;
+        m_last_index = 0;
         add_upper_bound_block();
     }
 
diff --git a/src/opt/opt_context.cpp b/src/opt/opt_context.cpp
index e61289f02..d41277df9 100644
--- a/src/opt/opt_context.cpp
+++ b/src/opt/opt_context.cpp
@@ -123,6 +123,7 @@ namespace opt {
         m_objective_refs(m),
         m_enable_sat(false),
         m_enable_sls(false),
+        m_is_clausal(false),
         m_pp_neat(false)
     {
         params_ref p;
@@ -553,6 +554,10 @@ namespace opt {
     }
 
     void context::simplify_fmls(expr_ref_vector& fmls) {
+        if (m_is_clausal) {
+            return;
+        }
+
         goal_ref g(alloc(goal, m, true, false));
         for (unsigned i = 0; i < fmls.size(); ++i) {
             g->assert_expr(fmls[i].get());
diff --git a/src/opt/opt_context.h b/src/opt/opt_context.h
index 0a342e058..5618efe7b 100644
--- a/src/opt/opt_context.h
+++ b/src/opt/opt_context.h
@@ -126,6 +126,7 @@ namespace opt {
         tactic_ref                   m_simplify;
         bool                         m_enable_sat;
         bool                         m_enable_sls;
+        bool                         m_is_clausal;
         bool                         m_pp_neat;
         symbol                       m_maxsat_engine;
         symbol                       m_logic;
@@ -155,6 +156,7 @@ namespace opt {
         virtual void display_assignment(std::ostream& out);
         virtual bool is_pareto() { return m_pareto.get() != 0; }
         virtual void set_logic(symbol const& s) { m_logic = s; }
+        void set_clausal(bool f) { m_is_clausal = f; }
 
         void display(std::ostream& out);
         static void collect_param_descrs(param_descrs & r);
diff --git a/src/opt/opt_solver.cpp b/src/opt/opt_solver.cpp
index 8b23a4e8a..d1136a636 100644
--- a/src/opt/opt_solver.cpp
+++ b/src/opt/opt_solver.cpp
@@ -161,17 +161,9 @@ namespace opt {
 
     void opt_solver::maximize_objectives(expr_ref_vector& blockers) {
         expr_ref blocker(m);
-        vector<inf_eps> values;
-        for (unsigned i = 0; i < m_objective_vars.size(); ++i) {
-            values.push_back(current_objective_value(i));
-        }
         for (unsigned i = 0; i < m_objective_vars.size(); ++i) {
             maximize_objective(i, blocker);
             blockers.push_back(blocker);
-            if (values[i] > m_objective_values[i]) {
-                std::cout << "local optimization produced a worse result\n";
-                exit(0);
-            }
         }
     }
 
diff --git a/src/sat/sat_mus.cpp b/src/sat/sat_mus.cpp
index c66f8ef6f..65d776d84 100644
--- a/src/sat/sat_mus.cpp
+++ b/src/sat/sat_mus.cpp
@@ -90,15 +90,17 @@ namespace sat {
                 break;
             }
             unsigned num_literals = core.size() + mus.size();
+            if (num_literals <= 2) {
+                // IF_VERBOSE(0, verbose_stream() << "num literals: " << core << " " << mus << "\n";);
+                break;
+            }
 
             literal lit = core.back();
             core.pop_back();
             lbool is_sat;
             {
                 scoped_append _sa(mus, core);
-                if (true || core_miss < 2) {
-                    mus.push_back(~lit); // TBD: measure
-                }
+                mus.push_back(~lit); 
                 is_sat = s.check(mus.size(), mus.c_ptr());
                 TRACE("sat", tout << "mus: " << mus << "\n";);
             }
@@ -146,7 +148,7 @@ namespace sat {
         }
         TRACE("sat", tout << "new core: " << mus << "\n";);
         set_core();
-        IF_VERBOSE(2, verbose_stream() << "(sat.mus.new " << core << ")\n";);
+        IF_VERBOSE(2, verbose_stream() << "(sat.mus.new " << s.m_core << ")\n";);
         return l_true;
     }
     
diff --git a/src/shell/opt_frontend.cpp b/src/shell/opt_frontend.cpp
index 6f8143ff1..616fc1962 100644
--- a/src/shell/opt_frontend.cpp
+++ b/src/shell/opt_frontend.cpp
@@ -118,7 +118,9 @@ class wcnf {
 
 public:
     
-    wcnf(opt::context& opt, stream_buffer& in): opt(opt), m(opt.get_manager()), in(in) {}
+    wcnf(opt::context& opt, stream_buffer& in): opt(opt), m(opt.get_manager()), in(in) {
+        opt.set_clausal(true);
+    }
     
     void parse() {
         int num_vars = 0, num_clauses = 0, max_weight = 0;
diff --git a/src/tactic/core/propagate_values_tactic.cpp b/src/tactic/core/propagate_values_tactic.cpp
index 5873efd61..39df3b174 100644
--- a/src/tactic/core/propagate_values_tactic.cpp
+++ b/src/tactic/core/propagate_values_tactic.cpp
@@ -135,6 +135,7 @@ class propagate_values_tactic : public tactic {
 
             TRACE("shallow_context_simplifier_bug", tout << mk_ismt2_pp(curr, m()) << "\n---->\n" << mk_ismt2_pp(new_curr, m()) << "\n";);
             push_result(new_curr, new_pr);
+            
             if (new_curr != curr)
                 m_modified = true;
         }
@@ -160,6 +161,9 @@ class propagate_values_tactic : public tactic {
             if (m_goal->inconsistent())
                 goto end;
 
+            if (m_max_rounds == 0)
+                goto end;
+
             m_subst = alloc(expr_substitution, m(), g->unsat_core_enabled(), g->proofs_enabled());
             m_r.set_substitution(m_subst.get());
             m_occs(*m_goal);
diff --git a/src/util/gparams.cpp b/src/util/gparams.cpp
index 04acf1ad9..197f65c10 100644
--- a/src/util/gparams.cpp
+++ b/src/util/gparams.cpp
@@ -230,6 +230,7 @@ public:
         }
     }
 
+
     void set(param_descrs const & d, symbol const & param_name, char const * value, symbol const & mod_name) {
         param_kind k = d.get_kind(param_name);
         params_ref & ps = get_params(mod_name);