diff --git a/src/muz/pdr/pdr_context.cpp b/src/muz/pdr/pdr_context.cpp
index 37d80e2d6..1d3232deb 100644
--- a/src/muz/pdr/pdr_context.cpp
+++ b/src/muz/pdr/pdr_context.cpp
@@ -149,30 +149,27 @@ namespace pdr {
     }
 
     datalog::rule const& pred_transformer::find_rule(model_core const& model) const {
-        obj_map<expr, datalog::rule const*>::iterator it = m_tag2rule.begin(), end = m_tag2rule.end();
         TRACE("pdr_verbose",
               datalog::rule_manager& rm = ctx.get_context().get_rule_manager();
-              for (; it != end; ++it) {
-                  expr* pred = it->m_key;
+              for (auto const& kv : m_tag2rule) {
+                  expr* pred = kv.m_key;
                   tout << mk_pp(pred, m) << ":\n";
-                  if (it->m_value) rm.display_smt2(*it->m_value, tout) << "\n";
+                  if (kv.m_value) rm.display_smt2(*kv.m_value, tout) << "\n";
               }
         );
 
-        it = m_tag2rule.begin();
         if (m_tag2rule.size() == 1) {
-            return *it->m_value;
+            return *m_tag2rule.begin()->m_value;
         }
 
         expr_ref vl(m);
-        for (; it != end; ++it) {
-            expr* pred = it->m_key;
+        for (auto const& kv : m_tag2rule) {
+            expr* pred = kv.m_key;
             if (model.eval(to_app(pred)->get_decl(), vl) && m.is_true(vl)) {
-                return *it->m_value;
+                return *kv.m_value;
             }
         }
-        UNREACHABLE();
-        return *((datalog::rule*)0);
+        throw default_exception("could not find rule");
     }
 
     void pred_transformer::find_predecessors(datalog::rule const& r, ptr_vector<func_decl>& preds) const {
@@ -201,7 +198,7 @@ namespace pdr {
 
     void pred_transformer::simplify_formulas(tactic& tac, expr_ref_vector& v) {
         goal_ref g(alloc(goal, m, false, false, false));
-        for (unsigned j = 0; j < v.size(); ++j) g->assert_expr(v[j].get());
+        for (expr* e : v) g->assert_expr(e);
         model_converter_ref mc;
         proof_converter_ref pc;
         expr_dependency_ref core(m);
@@ -216,9 +213,8 @@ namespace pdr {
     void pred_transformer::simplify_formulas() {
         tactic_ref us = mk_unit_subsumption_tactic(m);
         simplify_formulas(*us, m_invariants);
-        for (unsigned i = 0; i < m_levels.size(); ++i) {
-            simplify_formulas(*us, m_levels[i]);
-        }
+        for (auto & fmls : m_levels) 
+            simplify_formulas(*us, fmls);
     }
 
     expr_ref pred_transformer::get_formulas(unsigned level, bool add_axioms) {
diff --git a/src/smt/smt_conflict_resolution.cpp b/src/smt/smt_conflict_resolution.cpp
index 80168df18..6188c8b1a 100644
--- a/src/smt/smt_conflict_resolution.cpp
+++ b/src/smt/smt_conflict_resolution.cpp
@@ -257,10 +257,8 @@ namespace smt {
         literal_vector & antecedents = m_tmp_literal_vector;
         antecedents.reset();
         justification2literals(js, antecedents);
-        literal_vector::iterator it  = antecedents.begin();
-        literal_vector::iterator end = antecedents.end();
-        for(; it != end; ++it)
-            r = std::max(r, m_ctx.get_assign_level(*it));
+        for (literal lit : antecedents) 
+            r = std::max(r, m_ctx.get_assign_level(lit));
         return r;
     }
 
@@ -335,6 +333,7 @@ namespace smt {
             }
 
             if (lvl == m_conflict_lvl) {
+                TRACE("conflict", m_ctx.display_literal(tout << "marking:", antecedent) << "\n";);
                 num_marks++;
             }
             else {
@@ -486,6 +485,20 @@ namespace smt {
     }
 
     bool conflict_resolution::resolve(b_justification conflict, literal not_l) {
+
+#if 0
+        // for debugging #1233
+        if (not_l == to_literal(22267)) {
+            std::cout << not_l << "\n";
+            enable_trace("conflict");
+            enable_trace("conflict_verbose");
+            TRACE("conflict", 
+                  unsigned idx = 0;
+                  for (literal lit : m_assigned_literals) {
+                      m_ctx.display_literal(tout << (idx++) << ":", lit); tout << "\n";
+                  });
+        }
+#endif
         b_justification js;
         literal consequent;
 
@@ -514,7 +527,7 @@ namespace smt {
                 get_manager().trace_stream() << "\n";
             }
 
-            TRACE("conflict", tout << "processing consequent: "; m_ctx.display_literal_verbose(tout, consequent); tout << "\n";
+            TRACE("conflict", tout << "processing consequent: " << idx << " "; m_ctx.display_literal_verbose(tout, consequent); tout << "\n";
                   tout << "num_marks: " << num_marks << ", js kind: " << js.get_kind() << " level: " << m_ctx.get_assign_level(consequent) << "\n";
                   );
             SASSERT(js != null_b_justification);
@@ -566,8 +579,10 @@ namespace smt {
                 if (m_ctx.is_marked(l.var()))
                     break;
                 CTRACE("conflict", m_ctx.get_assign_level(l) != m_conflict_lvl && m_ctx.get_assign_level(l) != m_ctx.get_base_level(),
-                       tout << "assign_level(l): " << m_ctx.get_assign_level(l) << ", conflict_lvl: " << m_conflict_lvl << ", l: "; m_ctx.display_literal_verbose(tout, l);
-                       tout << "\n";);
+                       tout << "assign_level(l): " << m_ctx.get_assign_level(l) << ", conflict_lvl: ";
+                       tout << m_conflict_lvl << ", l: "; m_ctx.display_literal_verbose(tout, l);
+                       tout << "\n";
+                       tout << "num marks: " << num_marks << "\n";);
                 SASSERT(m_ctx.get_assign_level(l) == m_conflict_lvl ||
                         // it may also be an (out-of-order) asserted literal
                         m_ctx.get_assign_level(l) == m_ctx.get_base_level());
@@ -606,10 +621,8 @@ namespace smt {
     */
     level_approx_set conflict_resolution::get_lemma_approx_level_set() {
         level_approx_set result;
-        literal_vector::const_iterator it  = m_lemma.begin();
-        literal_vector::const_iterator end = m_lemma.end();
-        for(; it != end; ++it)
-            result.insert(m_ctx.get_assign_level(*it));
+        for (literal l : m_lemma) 
+            result.insert(m_ctx.get_assign_level(l));
         return result;
     }
 
@@ -660,10 +673,8 @@ namespace smt {
         // The method unmark_justifications must be invoked to reset these caches.
         // Remark: The method reset_unmark_and_justifications invokes unmark_justifications.
         justification2literals_core(js, antecedents);
-        literal_vector::iterator it  = antecedents.begin();
-        literal_vector::iterator end = antecedents.end();
-        for(; it != end; ++it)
-            if (!process_antecedent_for_minimization(*it))
+        for (literal l : antecedents) 
+            if (!process_antecedent_for_minimization(l))
                 return false;
         return true;
     }
@@ -1063,10 +1074,8 @@ namespace smt {
         m_eq2proof.reset();
         m_lit2proof.reset();
         m_js2proof.reset();
-        literal_vector::iterator it  = m_lemma.begin();
-        literal_vector::iterator end = m_lemma.end();
-        for (; it != end;  ++it)
-            m_ctx.set_mark((*it).var());
+        for (literal lit : m_lemma)
+            m_ctx.set_mark(lit.var());
     }
 
     bool conflict_resolution::visit_b_justification(literal l, b_justification js) {
@@ -1246,12 +1255,9 @@ namespace smt {
         SASSERT(conflict.get_kind() != b_justification::BIN_CLAUSE);
         SASSERT(conflict.get_kind() != b_justification::AXIOM);
         SASSERT(not_l == null_literal || conflict.get_kind() == b_justification::JUSTIFICATION);
-        TRACE("mk_conflict_proof", tout << "lemma literals: ";
-              literal_vector::iterator it  = m_lemma.begin();
-              literal_vector::iterator end = m_lemma.end();
-              for (; it != end; ++it) {
-                  m_ctx.display_literal(tout, *it);
-                  tout << " ";
+        TRACE("mk_conflict_proof", tout << "lemma literals:";
+              for (literal lit : m_lemma) {
+                  m_ctx.display_literal(tout << " ", lit);
               }
               tout << "\n";);
         init_mk_proof();
@@ -1328,12 +1334,10 @@ namespace smt {
             pr = m_manager.mk_unit_resolution(2, prs);
         }
         expr_ref_buffer lits(m_manager);
-        literal_vector::iterator it  = m_lemma.begin();
-        literal_vector::iterator end = m_lemma.end();
-        for (; it != end; ++it) {
-            m_ctx.unset_mark((*it).var());
+        for (literal lit : m_lemma) {
+            m_ctx.unset_mark(lit.var());
             expr_ref l_expr(m_manager);
-            m_ctx.literal2expr(*it, l_expr);
+            m_ctx.literal2expr(lit, l_expr);
             lits.push_back(l_expr);
         }
         expr * fact = 0;
@@ -1369,10 +1373,8 @@ namespace smt {
         literal_vector & antecedents = m_tmp_literal_vector;
         antecedents.reset();
         justification2literals_core(js, antecedents);
-        literal_vector::iterator it  = antecedents.begin();
-        literal_vector::iterator end = antecedents.end();
-        for(; it != end; ++it)
-            process_antecedent_for_unsat_core(*it);
+        for (literal lit : antecedents) 
+            process_antecedent_for_unsat_core(lit);
     }
 
     void conflict_resolution::mk_unsat_core(b_justification conflict, literal not_l) {
diff --git a/src/smt/smt_context.cpp b/src/smt/smt_context.cpp
index 2e65fddc9..30979fc4b 100644
--- a/src/smt/smt_context.cpp
+++ b/src/smt/smt_context.cpp
@@ -1615,11 +1615,9 @@ namespace smt {
        \brief Return set of assigned literals as expressions.
     */
     void context::get_assignments(expr_ref_vector& assignments) {
-        literal_vector::const_iterator it  = m_assigned_literals.begin();
-        literal_vector::const_iterator end = m_assigned_literals.end();
-        for (; it != end; ++it) {
+        for (literal lit : m_assigned_literals) {
             expr_ref e(m_manager);
-            literal2expr(*it, e);
+            literal2expr(lit, e);
             assignments.push_back(e);
         }
     }
@@ -1694,10 +1692,8 @@ namespace smt {
     }
 
     bool context::propagate_theories() {
-        ptr_vector<theory>::iterator it  = m_theory_set.begin();
-        ptr_vector<theory>::iterator end = m_theory_set.end();
-        for (; it != end; ++it) {
-            (*it)->propagate();
+        for (theory * t : m_theory_set) {
+            t->propagate();
             if (inconsistent())
                 return false;
         }
@@ -1733,10 +1729,8 @@ namespace smt {
     }
 
     bool context::can_theories_propagate() const {
-        ptr_vector<theory>::const_iterator it  = m_theory_set.begin();
-        ptr_vector<theory>::const_iterator end = m_theory_set.end();
-        for (; it != end; ++it) {
-            if ((*it)->can_propagate()) {
+        for (theory* t : m_theory_set) {
+            if (t->can_propagate()) {
                 return true;
             }
         }
@@ -1821,7 +1815,7 @@ namespace smt {
     }
 
     void context::rescale_bool_var_activity() {
-        TRACE("case_split", tout << "rescale\n";);
+        TRACE("case_split", tout << "rescale\n";);        
         svector<double>::iterator it  = m_activity.begin();
         svector<double>::iterator end = m_activity.end();
         for (; it != end; ++it)
@@ -1968,10 +1962,8 @@ namespace smt {
         m_case_split_queue->push_scope();
         m_asserted_formulas.push_scope();
 
-        ptr_vector<theory>::iterator it  = m_theory_set.begin();
-        ptr_vector<theory>::iterator end = m_theory_set.end();
-        for (; it != end; ++it)
-            (*it)->push_scope_eh();
+        for (theory* t : m_theory_set) 
+            t->push_scope_eh();
         CASSERT("context", check_invariant());
     }
 
@@ -2146,10 +2138,7 @@ namespace smt {
             }
             for (unsigned i = new_scope_lvl; i <= lim; i++) {
                 clause_vector & v = m_clauses_to_reinit[i];
-                clause_vector::iterator it  = v.begin();
-                clause_vector::iterator end = v.end();
-                for (; it != end; ++it) {
-                    clause * cls        = *it;
+                for (clause* cls : v) {
                     cache_generation(cls, new_scope_lvl);
                 }
             }
@@ -2246,10 +2235,7 @@ namespace smt {
         }
         for (unsigned i = m_scope_lvl+1; i <= lim; i++) {
             clause_vector & v = m_clauses_to_reinit[i];
-            clause_vector::iterator it  = v.begin();
-            clause_vector::iterator end = v.end();
-            for (; it != end; ++it) {
-                clause * cls        = *it;
+            for (clause* cls : v) {
                 if (cls->deleted()) {
                     cls->release_atoms(m_manager);
                     cls->m_reinit              = false;
@@ -2922,10 +2908,8 @@ namespace smt {
         TRACE("flush", tout << "m_scope_lvl: " << m_scope_lvl << "\n";);
         m_relevancy_propagator = 0;
         m_model_generator->reset();
-        ptr_vector<theory>::iterator it  = m_theory_set.begin();
-        ptr_vector<theory>::iterator end = m_theory_set.end();
-        for (; it != end; ++it)
-            (*it)->flush_eh();
+        for (theory* t : m_theory_set) 
+            t->flush_eh();
         undo_trail_stack(0);
         m_qmanager = 0;
         del_clauses(m_aux_clauses, 0);
@@ -3183,10 +3167,8 @@ namespace smt {
     }
 
     void context::reset_assumptions() {
-        literal_vector::iterator it  = m_assumptions.begin();
-        literal_vector::iterator end = m_assumptions.end();
-        for (; it != end; ++it)
-            get_bdata(it->var()).m_assumption = false;
+        for (literal lit : m_assumptions) 
+            get_bdata(lit.var()).m_assumption = false;
         m_assumptions.reset();
     }
 
diff --git a/src/smt/smt_context.h b/src/smt/smt_context.h
index c6cca2c43..d55e36f44 100644
--- a/src/smt/smt_context.h
+++ b/src/smt/smt_context.h
@@ -1235,24 +1235,24 @@ namespace smt {
 
         void display_asserted_formulas(std::ostream & out) const;
 
-        void display_literal(std::ostream & out, literal l) const;
+        std::ostream& display_literal(std::ostream & out, literal l) const;
 
         void display_detailed_literal(std::ostream & out, literal l) const { l.display(out, m_manager, m_bool_var2expr.c_ptr()); }
 
         void display_literal_info(std::ostream & out, literal l) const;
 
-        void display_literals(std::ostream & out, unsigned num_lits, literal const * lits) const;
+        std::ostream& display_literals(std::ostream & out, unsigned num_lits, literal const * lits) const;
 
-        void display_literals(std::ostream & out, literal_vector const& lits) const {
-            display_literals(out, lits.size(), lits.c_ptr());
+        std::ostream& display_literals(std::ostream & out, literal_vector const& lits) const {
+            return display_literals(out, lits.size(), lits.c_ptr());
         }
 
-        void display_literal_verbose(std::ostream & out, literal lit) const;
+        std::ostream& display_literal_verbose(std::ostream & out, literal lit) const;
 
-        void display_literals_verbose(std::ostream & out, unsigned num_lits, literal const * lits) const;
-
-        void display_literals_verbose(std::ostream & out, literal_vector const& lits) const {
-            display_literals_verbose(out, lits.size(), lits.c_ptr());
+        std::ostream& display_literals_verbose(std::ostream & out, unsigned num_lits, literal const * lits) const;
+        
+        std::ostream& display_literals_verbose(std::ostream & out, literal_vector const& lits) const {
+            return display_literals_verbose(out, lits.size(), lits.c_ptr());
         }
 
         void display_watch_list(std::ostream & out, literal l) const;
diff --git a/src/smt/smt_context_pp.cpp b/src/smt/smt_context_pp.cpp
index 6d66368ff..f2fb1084b 100644
--- a/src/smt/smt_context_pp.cpp
+++ b/src/smt/smt_context_pp.cpp
@@ -71,11 +71,9 @@ namespace smt {
         case NUM_CONFLICTS: r = "max-conflicts-reached"; break;
         case THEORY: {
             r = "(incomplete (theory";
-            ptr_vector<theory>::const_iterator it  = m_incomplete_theories.begin();
-            ptr_vector<theory>::const_iterator end = m_incomplete_theories.end();
-            for (; it != end; ++it) {
+            for (theory* t : m_incomplete_theories) {
                 r += " ";
-                r += (*it)->get_name();
+                r += t->get_name();
             }
             r += "))";
             break;
@@ -91,20 +89,20 @@ namespace smt {
         m_asserted_formulas.display_ll(out, get_pp_visited());
     }
 
-    void context::display_literal(std::ostream & out, literal l) const {
-        l.display_compact(out, m_bool_var2expr.c_ptr());
+    std::ostream& context::display_literal(std::ostream & out, literal l) const {
+        l.display_compact(out, m_bool_var2expr.c_ptr()); return out;
     }
 
-    void context::display_literals(std::ostream & out, unsigned num_lits, literal const * lits) const {
-        display_compact(out, num_lits, lits, m_bool_var2expr.c_ptr());
+    std::ostream& context::display_literals(std::ostream & out, unsigned num_lits, literal const * lits) const {
+        display_compact(out, num_lits, lits, m_bool_var2expr.c_ptr()); return out;
     }
 
-    void context::display_literal_verbose(std::ostream & out, literal lit) const {
-        display_literals_verbose(out, 1, &lit);
+    std::ostream& context::display_literal_verbose(std::ostream & out, literal lit) const {
+        return display_literals_verbose(out, 1, &lit);
     }
 
-    void context::display_literals_verbose(std::ostream & out, unsigned num_lits, literal const * lits) const {
-        display_verbose(out, m_manager, num_lits, lits, m_bool_var2expr.c_ptr(), "\n");
+    std::ostream& context::display_literals_verbose(std::ostream & out, unsigned num_lits, literal const * lits) const {
+        display_verbose(out, m_manager, num_lits, lits, m_bool_var2expr.c_ptr(), "\n"); return out;
     }
 
     void context::display_literal_info(std::ostream & out, literal l) const {
@@ -136,10 +134,8 @@ namespace smt {
     }
 
     void context::display_enode_defs(std::ostream & out) const {
-        ptr_vector<enode>::const_iterator it  = m_enodes.begin();
-        ptr_vector<enode>::const_iterator end = m_enodes.end();
-        for (; it != end; ++it) {
-            expr * n = (*it)->get_owner();
+        for (enode * x : m_enodes) {
+            expr * n = x->get_owner();
             ast_def_ll_pp(out, m_manager, n, get_pp_visited(), true, false);
         }
     }
@@ -169,10 +165,8 @@ namespace smt {
     }
 
     void context::display_clauses(std::ostream & out, ptr_vector<clause> const & v) const {
-        ptr_vector<clause>::const_iterator it  = v.begin();
-        ptr_vector<clause>::const_iterator end = v.end();
-        for (; it != end; ++it) {
-            display_clause(out, *it);
+        for (clause* cp : v) {
+            display_clause(out, cp);
             out << "\n";
         }
     }
@@ -207,12 +201,10 @@ namespace smt {
     void context::display_assignment(std::ostream & out) const {
         if (!m_assigned_literals.empty()) {
             out << "current assignment:\n";
-            literal_vector::const_iterator it  = m_assigned_literals.begin();
-            literal_vector::const_iterator end = m_assigned_literals.end();
-            for (; it != end; ++it) {
-                display_literal(out, *it);
+            for (literal lit : m_assigned_literals) {
+                display_literal(out, lit);
                 out << ": ";
-                display_verbose(out, m_manager, 1, &*it, m_bool_var2expr.c_ptr());
+                display_verbose(out, m_manager, 1, &lit, m_bool_var2expr.c_ptr());
                 out << "\n";
             }
         }
@@ -223,11 +215,9 @@ namespace smt {
         pp.set_benchmark_name("lemma");
         pp.set_status("unknown");
         pp.set_logic(logic);
-        literal_vector::const_iterator it  = m_assigned_literals.begin();
-        literal_vector::const_iterator end = m_assigned_literals.end();
-        for (; it != end; ++it) {
+        for (literal lit : m_assigned_literals) {
             expr_ref n(m_manager);
-            literal2expr(*it, n);
+            literal2expr(lit, n);
             pp.add_assumption(n);
         }
         pp.display_smt2(out, m_manager.mk_true());
@@ -235,11 +225,9 @@ namespace smt {
 
     void context::display_eqc(std::ostream & out) const {
         bool first = true;
-        ptr_vector<enode>::const_iterator it  = m_enodes.begin();
-        ptr_vector<enode>::const_iterator end = m_enodes.end();
-        for (; it != end; ++it) {
-            expr * n = (*it)->get_owner();
-            expr * r = (*it)->get_root()->get_owner();
+        for (enode * x : m_enodes) {
+            expr * n = x->get_owner();
+            expr * r = x->get_root()->get_owner();
             if (n != r) {
                 if (first) {
                     out << "equivalence classes:\n";
@@ -610,7 +598,7 @@ namespace smt {
             break;
         }
         case b_justification::JUSTIFICATION: {
-            out << "justification ";
+            out << "justification " << j.get_justification()->get_from_theory() << ": ";
             literal_vector lits;
             const_cast<conflict_resolution&>(*m_conflict_resolution).justification2literals(j.get_justification(), lits);
             display_literals(out, lits.size(), lits.c_ptr());
diff --git a/src/solver/solver_pool.cpp b/src/solver/solver_pool.cpp
index c6c85ec29..c8899e365 100644
--- a/src/solver/solver_pool.cpp
+++ b/src/solver/solver_pool.cpp
@@ -143,7 +143,6 @@ public:
             }
             out << ")\n";            
             m_base->display(out, num_assumptions, assumptions);
-            bool first = true;
             out << "(check-sat";
             for (unsigned i = 0; i < num_assumptions; ++i) {
                 out << " " << mk_pp(assumptions[i], m);