diff --git a/README.md b/README.md
index 8ebf6a078..447034a84 100644
--- a/README.md
+++ b/README.md
@@ -189,3 +189,6 @@ python -c 'import z3; print(z3.get_version_string())'
 
 See [``examples/python``](examples/python) for examples.
 
+### ``Web Assembly``
+
+[WebAssembly](https://github.com/cpitclaudel/z3.wasm) bindings are provided by Clément Pit-Claudel.
diff --git a/scripts/update_api.py b/scripts/update_api.py
index 8a7b33efd..78fad45be 100755
--- a/scripts/update_api.py
+++ b/scripts/update_api.py
@@ -1657,7 +1657,7 @@ else:
   if hasattr(builtins, "Z3_LIB_DIRS"):
     _all_dirs = builtins.Z3_LIB_DIRS
 
-for v in ('Z3_LIBRARY_PATH', 'PATH'):
+for v in ('Z3_LIBRARY_PATH', 'PATH', 'PYTHONPATH'):
   if v in os.environ:
     lp = os.environ[v];
     lds = lp.split(';') if sys.platform in ('win32') else lp.split(':')
diff --git a/src/api/api_context.cpp b/src/api/api_context.cpp
index c8b365f22..5993e9fdd 100644
--- a/src/api/api_context.cpp
+++ b/src/api/api_context.cpp
@@ -78,7 +78,6 @@ namespace api {
         m_bv_util(m()),
         m_datalog_util(m()),
         m_fpa_util(m()),
-        m_dtutil(m()),
         m_sutil(m()),
         m_last_result(m()),
         m_ast_trail(m()),
diff --git a/src/api/api_context.h b/src/api/api_context.h
index 185eb9e0f..72a0e4bbb 100644
--- a/src/api/api_context.h
+++ b/src/api/api_context.h
@@ -61,7 +61,6 @@ namespace api {
         bv_util                    m_bv_util;
         datalog::dl_decl_util      m_datalog_util;
         fpa_util                   m_fpa_util;
-        datatype_util              m_dtutil;
         seq_util                   m_sutil;
 
         // Support for old solver API
@@ -122,12 +121,12 @@ namespace api {
         bool produce_unsat_cores() const { return m_params.m_unsat_core; }
         bool use_auto_config() const { return m_params.m_auto_config; }
         unsigned get_timeout() const { return m_params.m_timeout; }
-        unsigned get_rlimit() const { return m_params.m_rlimit; }
+        unsigned get_rlimit() const { return m_params.rlimit(); }
         arith_util & autil() { return m_arith_util; }
         bv_util & bvutil() { return m_bv_util; }
         datalog::dl_decl_util & datalog_util() { return m_datalog_util; }
         fpa_util & fpautil() { return m_fpa_util; }
-        datatype_util& dtutil() { return m_dtutil; }
+        datatype_util& dtutil() { return m_dt_plugin->u(); }
         seq_util& sutil() { return m_sutil; }
         family_id get_basic_fid() const { return m_basic_fid; }
         family_id get_array_fid() const { return m_array_fid; }
diff --git a/src/ast/ast.cpp b/src/ast/ast.cpp
index 7e143e1a3..12ca136c5 100644
--- a/src/ast/ast.cpp
+++ b/src/ast/ast.cpp
@@ -2254,7 +2254,12 @@ var * ast_manager::mk_var(unsigned idx, sort * s) {
     unsigned sz     = var::get_obj_size();
     void * mem      = allocate_node(sz);
     var * new_node  = new (mem) var(idx, s);
-    return register_node(new_node);
+    var * r         = register_node(new_node);
+
+    if (m_trace_stream && r == new_node) {
+        *m_trace_stream << "[mk-var] #" << r->get_id() << "\n";
+    }
+    return r;
 }
 
 app * ast_manager::mk_label(bool pos, unsigned num_names, symbol const * names, expr * n) {
diff --git a/src/ast/datatype_decl_plugin.cpp b/src/ast/datatype_decl_plugin.cpp
index f685c70d5..d3704a84a 100644
--- a/src/ast/datatype_decl_plugin.cpp
+++ b/src/ast/datatype_decl_plugin.cpp
@@ -390,6 +390,7 @@ namespace datatype {
                 TRACE("datatype", tout << "declaring " << datatypes[i]->name() << "\n";);
                 if (m_defs.find(datatypes[i]->name(), d)) {
                     TRACE("datatype", tout << "delete previous version for " << datatypes[i]->name() << "\n";);
+                    u().reset();
                     dealloc(d);
                 }
                 m_defs.insert(datatypes[i]->name(), datatypes[i]);
diff --git a/src/ast/datatype_decl_plugin.h b/src/ast/datatype_decl_plugin.h
index f32e9990d..88b50af82 100644
--- a/src/ast/datatype_decl_plugin.h
+++ b/src/ast/datatype_decl_plugin.h
@@ -239,7 +239,6 @@ namespace datatype {
             map<symbol, def*, symbol_hash_proc, symbol_eq_proc> m_defs; 
             svector<symbol>          m_def_block;
             unsigned                 m_class_id;
-            util & u() const;
 
             void inherit(decl_plugin* other_p, ast_translation& tr) override;
 
@@ -279,6 +278,8 @@ namespace datatype {
             def const& get_def(sort* s) const { return *(m_defs[datatype_name(s)]); }
             def& get_def(symbol const& s) { return *(m_defs[s]); }
             bool is_declared(sort* s) const { return m_defs.contains(datatype_name(s)); }
+            util & u() const;
+
         private:
             bool is_value_visit(expr * arg, ptr_buffer<app> & todo) const;
         
diff --git a/src/ast/fpa/fpa2bv_converter.cpp b/src/ast/fpa/fpa2bv_converter.cpp
index d23794e54..b079fc2ca 100644
--- a/src/ast/fpa/fpa2bv_converter.cpp
+++ b/src/ast/fpa/fpa2bv_converter.cpp
@@ -3252,7 +3252,9 @@ void fpa2bv_converter::mk_to_bv(func_decl * f, unsigned num, expr * const * args
     expr_ref ul(m), in_range(m);
     if (!is_signed) {
         ul = m_bv_util.mk_zero_extend(3, m_bv_util.mk_bv_neg(m_bv_util.mk_numeral(1, bv_sz)));
-        in_range = m.mk_and(m.mk_not(x_is_neg), m.mk_not(ovfl),
+        in_range = m.mk_and(m.mk_or(m.mk_not(x_is_neg),
+                                    m.mk_eq(pre_rounded, m_bv_util.mk_numeral(0, bv_sz+3))),
+                            m.mk_not(ovfl),
                             m_bv_util.mk_ule(pre_rounded, ul));
     }
     else {
diff --git a/src/ast/pattern/expr_pattern_match.cpp b/src/ast/pattern/expr_pattern_match.cpp
index d688c840c..c441fb4ce 100644
--- a/src/ast/pattern/expr_pattern_match.cpp
+++ b/src/ast/pattern/expr_pattern_match.cpp
@@ -387,7 +387,7 @@ expr_pattern_match::initialize(char const * spec_string) {
     m_instrs.push_back(instr(BACKTRACK));
 
     std::istringstream is(spec_string);
-    cmd_context      ctx(true, &m_manager);
+    cmd_context      ctx(true, &m_manager);	
     bool ps = ctx.print_success_enabled();
     ctx.set_print_success(false);
     VERIFY(parse_smt2_commands(ctx, is));
diff --git a/src/ast/rewriter/seq_rewriter.cpp b/src/ast/rewriter/seq_rewriter.cpp
index 186abda48..3ead59833 100644
--- a/src/ast/rewriter/seq_rewriter.cpp
+++ b/src/ast/rewriter/seq_rewriter.cpp
@@ -367,6 +367,9 @@ br_status seq_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * con
         SASSERT(num_args == 2);
         return mk_re_concat(args[0], args[1], result);
     case OP_RE_UNION:
+        if (num_args == 1) {
+            result = args[0]; return BR_DONE;
+        }
         SASSERT(num_args == 2);
         return mk_re_union(args[0], args[1], result);
     case OP_RE_RANGE:
@@ -853,7 +856,7 @@ br_status seq_rewriter::mk_seq_replace(expr* a, expr* b, expr* c, expr_ref& resu
         return BR_DONE;
     }
     if (m_util.str.is_string(b, s2) && s2.length() == 0) {
-        result = m_util.str.mk_concat(a, c);
+        result = m_util.str.mk_concat(c, a);
         return BR_REWRITE1;
     }
     if (m_util.str.is_string(a, s1) && s1.length() == 0) {
diff --git a/src/ast/seq_decl_plugin.cpp b/src/ast/seq_decl_plugin.cpp
index b592b719a..cd8571a95 100644
--- a/src/ast/seq_decl_plugin.cpp
+++ b/src/ast/seq_decl_plugin.cpp
@@ -177,7 +177,7 @@ zstring zstring::replace(zstring const& src, zstring const& dst) const {
         return zstring(*this);
     }
     if (src.length() == 0) {
-        return zstring(*this);
+        return dst + zstring(*this);
     }
     bool found = false;
     for (unsigned i = 0; i < length(); ++i) {
@@ -256,6 +256,7 @@ bool zstring::contains(zstring const& other) const {
 
 int zstring::indexof(zstring const& other, int offset) const {
     SASSERT(offset >= 0);
+    if (static_cast<unsigned>(offset) <= length() && other.length() == 0) return offset;
     if (static_cast<unsigned>(offset) == length()) return -1;
     if (other.length() + offset > length()) return -1;
     unsigned last = length() - other.length();
diff --git a/src/cmd_context/basic_cmds.cpp b/src/cmd_context/basic_cmds.cpp
index 0c9c5360c..4e8806d62 100644
--- a/src/cmd_context/basic_cmds.cpp
+++ b/src/cmd_context/basic_cmds.cpp
@@ -503,7 +503,7 @@ public:
             ctx.set_random_seed(to_unsigned(val));
         }
         else if (m_option == m_reproducible_resource_limit) {
-            ctx.params().m_rlimit = to_unsigned(val);
+            ctx.params().set_rlimit(to_unsigned(val));
         }
         else if (m_option == m_verbosity) {
             set_verbosity_level(to_unsigned(val));
diff --git a/src/cmd_context/cmd_context.cpp b/src/cmd_context/cmd_context.cpp
index aabe43110..9f93e1b93 100644
--- a/src/cmd_context/cmd_context.cpp
+++ b/src/cmd_context/cmd_context.cpp
@@ -718,8 +718,8 @@ void cmd_context::init_manager_core(bool new_manager) {
     }
     m_dt_eh = alloc(dt_eh, *this);
     m_pmanager->set_new_datatype_eh(m_dt_eh.get());
-    if (!has_logic()) {
-        TRACE("cmd_context", tout << "init manager\n";);
+    if (!has_logic() && new_manager) {
+        TRACE("cmd_context", tout << "init manager " << m_logic << "\n";);
         // add list type only if the logic is not specified.
         // it prevents clashes with builtin types.
         insert(pm().mk_plist_decl());
@@ -757,6 +757,7 @@ void cmd_context::init_external_manager() {
 }
 
 bool cmd_context::set_logic(symbol const & s) {
+    TRACE("cmd_context", tout << s << "\n";);
     if (has_logic())
         throw cmd_exception("the logic has already been set");
     if (has_manager() && m_main_ctx)
@@ -1240,7 +1241,7 @@ void cmd_context::insert_aux_pdecl(pdecl * p) {
     m_aux_pdecls.push_back(p);
 }
 
-void cmd_context::reset(bool finalize) {
+void cmd_context::reset(bool finalize) {    
     m_processing_pareto = false;
     m_logic = symbol::null;
     m_check_sat_result = nullptr;
@@ -1327,7 +1328,8 @@ void cmd_context::push() {
     s.m_macros_stack_lim       = m_macros_stack.size();
     s.m_aux_pdecls_lim         = m_aux_pdecls.size();
     s.m_assertions_lim         = m_assertions.size();
-    if (m_solver)
+    m().limit().push(m_params.rlimit());
+    if (m_solver) 
         m_solver->push();
     if (m_opt)
         m_opt->push();
@@ -1350,9 +1352,10 @@ void cmd_context::restore_func_decls(unsigned old_sz) {
 }
 
 void cmd_context::restore_psort_inst(unsigned old_sz) {
-    for (unsigned i = old_sz; i < m_psort_inst_stack.size(); ++i) {
+    for (unsigned i = m_psort_inst_stack.size(); i-- > old_sz; ) {
         pdecl * s = m_psort_inst_stack[i];
-        s->reset_cache(*m_pmanager);
+        s->reset_cache(pm());
+        pm().dec_ref(s);
     }
     m_psort_inst_stack.resize(old_sz);
 }
@@ -1441,6 +1444,9 @@ void cmd_context::pop(unsigned n) {
     restore_assertions(s.m_assertions_lim);
     restore_psort_inst(s.m_psort_inst_stack_lim);
     m_scopes.shrink(new_lvl);
+    while (n--) {
+        m().limit().pop();
+    }
 
 }
 
@@ -1451,7 +1457,7 @@ void cmd_context::check_sat(unsigned num_assumptions, expr * const * assumptions
     TRACE("before_check_sat", dump_assertions(tout););
     init_manager();
     unsigned timeout = m_params.m_timeout;
-    unsigned rlimit  = m_params.m_rlimit;
+    unsigned rlimit  = m_params.rlimit();
     scoped_watch sw(*this);
     lbool r;
     bool was_opt = false;
@@ -1528,7 +1534,7 @@ void cmd_context::check_sat(unsigned num_assumptions, expr * const * assumptions
 
 void cmd_context::get_consequences(expr_ref_vector const& assumptions, expr_ref_vector const& vars, expr_ref_vector & conseq) {
     unsigned timeout = m_params.m_timeout;
-    unsigned rlimit  = m_params.m_rlimit;
+    unsigned rlimit  = m_params.rlimit();
     lbool r;
     m_check_sat_result = m_solver.get(); // solver itself stores the result.
     m_solver->set_progress_callback(this);
@@ -2024,8 +2030,8 @@ void cmd_context::dt_eh::operator()(sort * dt, pdecl* pd) {
         }
     }
     if (m_owner.m_scopes.size() > 0) {
+        m_owner.pm().inc_ref(pd);
         m_owner.m_psort_inst_stack.push_back(pd);
-
     }
 }
 
diff --git a/src/cmd_context/context_params.h b/src/cmd_context/context_params.h
index df62057fe..3d2947b7a 100644
--- a/src/cmd_context/context_params.h
+++ b/src/cmd_context/context_params.h
@@ -27,6 +27,8 @@ class context_params {
     void set_bool(bool & opt, char const * param, char const * value);
     void set_uint(unsigned & opt, char const * param, char const * value);
 
+    unsigned    m_rlimit;
+
 public:
     bool        m_auto_config;
     bool        m_proof;
@@ -42,10 +44,11 @@ public:
     bool        m_unsat_core;
     bool        m_smtlib2_compliant; // it must be here because it enable/disable the use of coercions in the ast_manager.
     unsigned    m_timeout;
-    unsigned    m_rlimit;
 
+    unsigned rlimit() const { return m_rlimit; }
     context_params();
     void set(char const * param, char const * value);
+    void set_rlimit(unsigned lim) { m_rlimit = lim; }
     void updt_params();
     void updt_params(params_ref const & p);
     static void collect_param_descrs(param_descrs & d);
diff --git a/src/cmd_context/tactic_cmds.cpp b/src/cmd_context/tactic_cmds.cpp
index 32a92ea59..78187ebe1 100644
--- a/src/cmd_context/tactic_cmds.cpp
+++ b/src/cmd_context/tactic_cmds.cpp
@@ -205,7 +205,7 @@ public:
         tref->set_logic(ctx.get_logic());
         ast_manager & m = ctx.m();
         unsigned timeout   = p.get_uint("timeout", ctx.params().m_timeout);
-        unsigned rlimit  =   p.get_uint("rlimit", ctx.params().m_rlimit);
+        unsigned rlimit  =   p.get_uint("rlimit", ctx.params().rlimit());
         labels_vec labels;
         goal_ref g = alloc(goal, m, ctx.produce_proofs(), ctx.produce_models(), ctx.produce_unsat_cores());
         assert_exprs_from(ctx, *g);
@@ -321,7 +321,7 @@ public:
             assert_exprs_from(ctx, *g);
 
             unsigned timeout   = p.get_uint("timeout", ctx.params().m_timeout);
-            unsigned rlimit  =   p.get_uint("rlimit", ctx.params().m_rlimit);
+            unsigned rlimit  =   p.get_uint("rlimit", ctx.params().rlimit());
 
             goal_ref_buffer     result_goals;
             model_converter_ref mc;
diff --git a/src/muz/base/dl_util.cpp b/src/muz/base/dl_util.cpp
index e8a1c5139..87cfac04c 100644
--- a/src/muz/base/dl_util.cpp
+++ b/src/muz/base/dl_util.cpp
@@ -31,6 +31,10 @@ Revision History:
 #include "muz/base/dl_rule.h"
 #include "muz/base/dl_util.h"
 #include "util/stopwatch.h"
+#ifndef __STDC_FORMAT_MACROS
+#define __STDC_FORMAT_MACROS
+#endif
+#include <inttypes.h>
 
 namespace datalog {
 
@@ -623,9 +627,9 @@ namespace datalog {
 
     bool string_to_uint64(const char * s, uint64_t & res) {
 #if _WINDOWS
-        int converted = sscanf_s(s, "%I64u", &res);
+        int converted = sscanf_s(s, "%" SCNu64, &res);
 #else
-        int converted = sscanf(s, "%I64u", &res);
+        int converted = sscanf(s, "%" SCNu64, &res);
 #endif
         if(converted==0) {
             return false;
diff --git a/src/opt/opt_context.cpp b/src/opt/opt_context.cpp
index 1950a199d..69177e290 100644
--- a/src/opt/opt_context.cpp
+++ b/src/opt/opt_context.cpp
@@ -265,6 +265,9 @@ namespace opt {
         normalize();
         internalize();
         update_solver();
+        if (contains_quantifiers()) {
+            warning_msg("optimization with quantified constraints is not supported");
+        }
 #if 0
         if (is_qsat_opt()) {
             return run_qsat_opt();
@@ -368,7 +371,6 @@ namespace opt {
         if (result == l_true && committed) m_optsmt.commit_assignment(index);
         if (result == l_true && m_optsmt.is_unbounded(index, is_max) && contains_quantifiers()) {
             throw default_exception("unbounded objectives on quantified constraints is not supported");
-            result = l_undef;
         }
         return result;
     }
diff --git a/src/opt/opt_context.h b/src/opt/opt_context.h
index 6af106ef3..e97fabbe4 100644
--- a/src/opt/opt_context.h
+++ b/src/opt/opt_context.h
@@ -283,13 +283,13 @@ namespace opt {
         struct is_propositional_fn;
         bool is_propositional(expr* e);
 
-        void    init_solver();
-        void    update_solver();
-        void    setup_arith_solver();
-        void    add_maxsmt(symbol const& id, unsigned index);
-        void    set_simplify(tactic *simplify);
-        void    set_pareto(pareto_base* p);        
-        void    clear_state();
+        void init_solver();
+        void update_solver();
+        void setup_arith_solver();
+        void add_maxsmt(symbol const& id, unsigned index);
+        void set_simplify(tactic *simplify);
+        void set_pareto(pareto_base* p);        
+        void clear_state();
 
         bool is_numeral(expr* e, rational& n) const;
 
diff --git a/src/opt/wmax.cpp b/src/opt/wmax.cpp
index 52b87e536..513c68d6e 100644
--- a/src/opt/wmax.cpp
+++ b/src/opt/wmax.cpp
@@ -84,6 +84,9 @@ namespace opt {
                 if (m.canceled()) {
                     is_sat = l_undef;
                 }
+                if (is_sat == l_undef) {
+                    break;
+                }
                 if (is_sat == l_false) {
                     TRACE("opt", tout << "Unsat\n";);
                     break;
@@ -97,9 +100,6 @@ namespace opt {
                     //DEBUG_CODE(verify_cores(cores););
                     s().assert_expr(fml);
                 }
-                else {
-                    //DEBUG_CODE(verify_cores(cores););
-                }
                 update_cores(wth(), cores);
                 wth().init_min_cost(m_upper - m_lower);
                 trace_bounds("wmax");
diff --git a/src/parsers/util/pattern_validation.cpp b/src/parsers/util/pattern_validation.cpp
index 0d076aadd..df1f6cd00 100644
--- a/src/parsers/util/pattern_validation.cpp
+++ b/src/parsers/util/pattern_validation.cpp
@@ -48,7 +48,7 @@ struct pattern_validation_functor {
 
     bool is_forbidden(func_decl const * decl) {
         family_id fid = decl->get_family_id();
-        if (fid == m_bfid && decl->get_decl_kind() != OP_TRUE && decl->get_decl_kind() != OP_FALSE)
+        if (fid == m_bfid && decl->get_decl_kind() != OP_EQ && decl->get_decl_kind() != OP_TRUE && decl->get_decl_kind() != OP_FALSE)
             return true;
         if (fid == m_lfid)
             return true;
diff --git a/src/smt/theory_datatype.cpp b/src/smt/theory_datatype.cpp
index 9ff81fa08..049555297 100644
--- a/src/smt/theory_datatype.cpp
+++ b/src/smt/theory_datatype.cpp
@@ -461,7 +461,7 @@ namespace smt {
         TRACE("datatype", tout << "occurs_check_explain " << mk_bounded_pp(app->get_owner(), get_manager()) << " <-> " << mk_bounded_pp(root->get_owner(), get_manager()) << "\n";);
         enode* app_parent = nullptr;
 
-        // first: explain that root=v, given that app=cstor(…,v,…)
+        // first: explain that root=v, given that app=cstor(...,v,...)
         for (enode * arg : enode::args(oc_get_cstor(app))) {
             // found an argument which is equal to root
             if (arg->get_root() == root->get_root()) {
diff --git a/src/smt/theory_seq.cpp b/src/smt/theory_seq.cpp
index 94841603d..95f804863 100644
--- a/src/smt/theory_seq.cpp
+++ b/src/smt/theory_seq.cpp
@@ -134,8 +134,7 @@ void theory_seq::solution_map::pop_scope(unsigned num_scopes) {
     if (num_scopes == 0) return;
     m_cache.reset();
     unsigned start = m_limit[m_limit.size() - num_scopes];
-    for (unsigned i = m_updates.size(); i > start; ) {
-        --i;
+    for (unsigned i = m_updates.size(); i-- > start; ) {
         if (m_updates[i] == INS) {
             m_map.remove(m_lhs[i].get());
         }
@@ -436,8 +435,8 @@ bool theory_seq::is_unit_eq(expr_ref_vector const& ls, expr_ref_vector const& rs
     if (ls.empty() || !is_var(ls[0])) {
         return false;
     }
-    for (unsigned i = 0; i < rs.size(); ++i) {
-        if (!m_util.str.is_unit(rs[i])) {
+    for (expr* r : rs) {
+        if (!m_util.str.is_unit(r)) {
             return false;
         }
     }
@@ -482,8 +481,7 @@ void theory_seq::branch_unit_variable(dependency* dep, expr* X, expr_ref_vector
 
 bool theory_seq::branch_variable_mb() {
     bool change = false;
-    for (unsigned i = 0; i < m_eqs.size(); ++i) {
-        eq const& e = m_eqs[i];
+    for (eq const& e : m_eqs) {
         vector<rational> len1, len2;
         if (!is_complex(e)) {
             continue;
@@ -1473,7 +1471,7 @@ bool theory_seq::add_solution(expr* l, expr* r, dependency* deps)  {
     if (l == r) {
         return false;
     }
-    TRACE("seq", tout << mk_pp(l, m) << " ==> " << mk_pp(r, m) << "\n";);
+    TRACE("seq", tout << mk_pp(l, m) << " ==> " << mk_pp(r, m) << "\n"; display_deps(tout, deps););
     m_new_solution = true;
     m_rep.update(l, r, deps);
     enode* n1 = ensure_enode(l);
@@ -1513,7 +1511,9 @@ bool theory_seq::solve_eq(expr_ref_vector const& l, expr_ref_vector const& r, de
     change = canonize(r, rs, dep2) || change;
     deps = m_dm.mk_join(dep2, deps);
     TRACE("seq", tout << l << " = " << r << " ==> ";
-          tout << ls << " = " << rs << "\n";);
+          tout << ls << " = " << rs << "\n";
+          display_deps(tout, deps);
+          );
     if (!ctx.inconsistent() && simplify_eq(ls, rs, deps)) {
         return true;
     }
@@ -2224,63 +2224,7 @@ void theory_seq::internalize_eq_eh(app * atom, bool_var v) {
 }
 
 bool theory_seq::internalize_atom(app* a, bool) {
-#if 1
     return internalize_term(a);
-#else
-    if (is_skolem(m_eq, a)) {
-        return internalize_term(a);
-    }
-    context & ctx   = get_context();
-    bool_var bv = ctx.mk_bool_var(a);
-    ctx.set_var_theory(bv, get_id());
-    ctx.mark_as_relevant(bv);
-
-    expr* e1, *e2;
-    if (m_util.str.is_in_re(a, e1, e2)) {        
-        return internalize_term(to_app(e1)) && internalize_re(e2);
-    }
-    if (m_util.str.is_contains(a, e1, e2) ||
-        m_util.str.is_prefix(a, e1, e2) ||
-        m_util.str.is_suffix(a, e1, e2)) {
-        return internalize_term(to_app(e1)) && internalize_term(to_app(e2));        
-    }
-    if (is_accept(a) || is_reject(a) || is_step(a) || is_skolem(symbol("seq.is_digit"), a)) {
-        return true;
-    }
-    UNREACHABLE();
-    return internalize_term(a);
-#endif
-}
-
-bool theory_seq::internalize_re(expr* e) {
-    expr* e1, *e2;
-    unsigned lc, uc;
-    if (m_util.re.is_to_re(e, e1)) {
-        return internalize_term(to_app(e1));
-    }
-    if (m_util.re.is_star(e, e1) ||
-        m_util.re.is_plus(e, e1) ||
-        m_util.re.is_opt(e, e1) ||
-        m_util.re.is_loop(e, e1, lc) ||
-        m_util.re.is_loop(e, e1, lc, uc) ||
-        m_util.re.is_complement(e, e1)) {
-        return internalize_re(e1);
-    }
-    if (m_util.re.is_union(e, e1, e2) ||
-        m_util.re.is_intersection(e, e1, e2) ||
-        m_util.re.is_concat(e, e1, e2)) {
-        return internalize_re(e1) && internalize_re(e2);
-    }
-    if (m_util.re.is_full_seq(e) ||
-        m_util.re.is_full_char(e) ||
-        m_util.re.is_empty(e)) {
-        return true;
-    }
-    if (m_util.re.is_range(e, e1, e2)) {
-        return internalize_term(to_app(e1)) && internalize_term(to_app(e2));
-    }
-    UNREACHABLE();
-    return internalize_term(to_app(e));
 }
 
 bool theory_seq::internalize_term(app* term) {
@@ -2344,8 +2288,8 @@ void theory_seq::add_int_string(expr* e) {
 
 bool theory_seq::check_int_string() {
     bool change = false;
-    for (unsigned i = 0; i < m_int_string.size(); ++i) {
-        expr* e = m_int_string[i].get(), *n;
+    for (expr * e : m_int_string) {
+        expr* n = nullptr;
         if (m_util.str.is_itos(e) && add_itos_val_axiom(e)) {
             change = true;
         }
@@ -2358,9 +2302,21 @@ bool theory_seq::check_int_string() {
 
 void theory_seq::add_stoi_axiom(expr* e) {
     TRACE("seq", tout << mk_pp(e, m) << "\n";);
-    SASSERT(m_util.str.is_stoi(e));
-    literal l = mk_simplified_literal(m_autil.mk_ge(e, arith_util(m).mk_int(-1)));
+    expr* s = nullptr;
+    VERIFY (m_util.str.is_stoi(e, s));
+
+    // stoi(s) >= -1
+    literal l = mk_simplified_literal(m_autil.mk_ge(e, m_autil.mk_int(-1)));
     add_axiom(l);    
+    
+    // stoi(s) >= 0 <=> s in (0-9)+
+    expr_ref num_re(m);
+    num_re = m_util.re.mk_range(m_util.str.mk_string(symbol("0")), m_util.str.mk_string(symbol("9")));
+    num_re = m_util.re.mk_plus(num_re);
+    app_ref in_re(m_util.re.mk_in_re(s, num_re), m);
+    literal ge0 = mk_simplified_literal(m_autil.mk_ge(e, m_autil.mk_int(0)));
+    add_axiom(~ge0, mk_literal(in_re));
+    add_axiom(ge0, ~mk_literal(in_re));
 }
 
 bool theory_seq::add_stoi_val_axiom(expr* e) {
@@ -2404,8 +2360,9 @@ bool theory_seq::add_stoi_val_axiom(expr* e) {
             lits.push_back(~is_digit(ith_char));
             nums.push_back(digit2int(ith_char));
         }        
-        for (unsigned i = sz, c = 1; i-- > 0; c *= 10) {
-            coeff = m_autil.mk_int(c);
+        rational c(1);
+        for (unsigned i = sz; i-- > 0; c *= rational(10)) {
+            coeff = m_autil.mk_numeral(c, true);
             nums[i] = m_autil.mk_mul(coeff, nums[i].get());
         }
         num = m_autil.mk_add(nums.size(), nums.c_ptr());
@@ -2674,7 +2631,12 @@ void theory_seq::init_model(expr_ref_vector const& es) {
     }
 }
 
+void theory_seq::finalize_model(model_generator& mg) {
+    m_rep.pop_scope(1);
+}
+
 void theory_seq::init_model(model_generator & mg) {
+    m_rep.push_scope();
     m_factory = alloc(seq_factory, get_manager(), get_family_id(), mg.get_model());
     mg.register_factory(m_factory);
     for (ne const& n : m_nqs) {
@@ -3428,8 +3390,8 @@ void theory_seq::add_itos_length_axiom(expr* len) {
 
 void theory_seq::propagate_in_re(expr* n, bool is_true) {
     TRACE("seq", tout << mk_pp(n, m) << " <- " << (is_true?"true":"false") << "\n";);
-    expr* e1 = nullptr, *e2 = nullptr;
-    VERIFY(m_util.str.is_in_re(n, e1, e2));
+    expr* s = nullptr, *re = nullptr;
+    VERIFY(m_util.str.is_in_re(n, s, re));
 
     expr_ref tmp(n, m);
     m_rewrite(tmp);
@@ -3450,21 +3412,21 @@ void theory_seq::propagate_in_re(expr* n, bool is_true) {
         return;
     }
 
-    expr_ref e3(e2, m);
+    expr_ref e3(re, m);
     context& ctx = get_context();
     literal lit = ctx.get_literal(n);
     if (!is_true) {
-        e3 = m_util.re.mk_complement(e2);
+        e3 = m_util.re.mk_complement(re);
         lit.neg();
     }
     eautomaton* a = get_automaton(e3);
     if (!a) return;
 
 
-    expr_ref len(m_util.str.mk_length(e1), m);
+    expr_ref len(m_util.str.mk_length(s), m);
     for (unsigned i = 0; i < a->num_states(); ++i) {
-        literal acc = mk_accept(e1, len, e3, i);
-        literal rej = mk_reject(e1, len, e3, i);
+        literal acc = mk_accept(s, len, e3, i);
+        literal rej = mk_reject(s, len, e3, i);
         add_axiom(a->is_final_state(i)?acc:~acc);
         add_axiom(a->is_final_state(i)?~rej:rej);
     }
@@ -3475,8 +3437,8 @@ void theory_seq::propagate_in_re(expr* n, bool is_true) {
     literal_vector lits;
     lits.push_back(~lit);
     
-    for (unsigned i = 0; i < states.size(); ++i) {
-        lits.push_back(mk_accept(e1, zero, e3, states[i]));
+    for (unsigned st : states) {
+        lits.push_back(mk_accept(s, zero, e3, st));
     }
     if (lits.size() == 2) {
         propagate_lit(nullptr, 1, &lit, lits[1]);
@@ -3527,8 +3489,8 @@ static bool get_arith_value(context& ctx, theory_id afid, expr* e, expr_ref& v)
 bool theory_seq::get_num_value(expr* e, rational& val) const {
     context& ctx = get_context();
     expr_ref _val(m);
-	if (!ctx.e_internalized(e))
-		return false;
+    if (!ctx.e_internalized(e))
+        return false;
     enode* next = ctx.get_enode(e), *n = next;
     do { 
         if (get_arith_value(ctx, m_autil.get_family_id(), next->get_owner(), _val) && m_autil.is_numeral(_val, val) && val.is_int()) {
@@ -3925,8 +3887,8 @@ theory_seq::dependency* theory_seq::mk_join(dependency* deps, literal lit) {
 }
 
 theory_seq::dependency* theory_seq::mk_join(dependency* deps, literal_vector const& lits) {
-    for (unsigned i = 0; i < lits.size(); ++i) {
-        deps = mk_join(deps, lits[i]);
+    for (literal l : lits) {
+        deps = mk_join(deps, l);
     } 
     return deps;
 }
@@ -4131,53 +4093,15 @@ void theory_seq::new_diseq_eh(theory_var v1, theory_var v2) {
     TRACE("seq", tout << "new disequality " << get_context().get_scope_level() << ": " << eq << "\n";);
     m_rewrite(eq);
     if (!m.is_false(eq)) {
-
         literal lit = mk_eq(e1, e2, false);
 
-
         if (m_util.str.is_empty(e2)) {
             std::swap(e1, e2);
         }
 
-        if (false && m_util.str.is_empty(e1)) {
-            expr_ref head(m), tail(m), conc(m);
-            mk_decompose(e2, head, tail);
-            conc = mk_concat(head, tail);
-            propagate_eq(~lit, e2, conc, true);
-        }
-#if 0
-
-        // (e1 = "" & e2 = xdz) or (e2 = "" & e1 = xcy) or (e1 = xcy & e2 = xdz & c != d) or (e1 = x & e2 = xdz) or (e2 = x & e1 = xcy)
-        // e1 = "" or e1 = xcy or e1 = x
-        // e2 = "" or e2 = xdz or e2 = x
-        // e1 = xcy or e2 = xdz
-        // c != d
-
-        sort* char_sort = 0;
-        expr_ref emp(m);
-        VERIFY(m_util.is_seq(m.get_sort(e1), char_sort));
-        emp = m_util.str.mk_empty(m.get_sort(e1));
-
-        expr_ref x = mk_skolem(symbol("seq.ne.x"), e1, e2);
-        expr_ref y = mk_skolem(symbol("seq.ne.y"), e1, e2);
-        expr_ref z = mk_skolem(symbol("seq.ne.z"), e1, e2);
-        expr_ref c = mk_skolem(symbol("seq.ne.c"), e1, e2, 0, char_sort);
-        expr_ref d = mk_skolem(symbol("seq.ne.d"), e1, e2, 0, char_sort);
-        literal e1_is_emp = mk_seq_eq(e1, emp);
-        literal e2_is_emp = mk_seq_eq(e2, emp);
-        literal e1_is_xcy = mk_seq_eq(e1, mk_concat(x, m_util.str.mk_unit(c), y));
-        literal e2_is_xdz = mk_seq_eq(e2, mk_concat(x, m_util.str.mk_unit(d), z));
-        add_axiom(lit, e1_is_emp, e1_is_xcy, mk_seq_eq(e1, x));
-        add_axiom(lit, e2_is_emp, e2_is_xdz, mk_seq_eq(e2, x));
-        add_axiom(lit, e1_is_xcy, e2_is_xdz);
-        add_axiom(lit, ~mk_eq(c, d, false));
-#else
-        else {
-            dependency* dep = m_dm.mk_leaf(assumption(~lit));
-            m_nqs.push_back(ne(e1, e2, dep));
-            solve_nqs(m_nqs.size() - 1);
-        }
-#endif
+        dependency* dep = m_dm.mk_leaf(assumption(~lit));
+        m_nqs.push_back(ne(e1, e2, dep));
+        solve_nqs(m_nqs.size() - 1);        
     }
 }
 
@@ -4508,8 +4432,7 @@ bool theory_seq::add_reject2reject(expr* rej, bool& change) {
     ensure_nth(~len_le_idx, s, idx);
     literal_vector eqs;
     bool has_undef = false;
-    for (unsigned i = 0; i < mvs.size(); ++i) {
-        eautomaton::move const& mv = mvs[i];
+    for (eautomaton::move const& mv : mvs) {
         literal eq = mk_literal(mv.t()->accept(nth));
         switch (ctx.get_assignment(eq)) {
         case l_false:
diff --git a/src/smt/theory_seq.h b/src/smt/theory_seq.h
index 21aedd7e3..b6b553dec 100644
--- a/src/smt/theory_seq.h
+++ b/src/smt/theory_seq.h
@@ -64,14 +64,14 @@ namespace smt {
         // + a cache for normalization.
         class solution_map {
             enum map_update { INS, DEL };
-            ast_manager&                      m;
+            ast_manager&           m;
             dependency_manager&    m_dm;
-            eqdep_map_t                       m_map;            
-            eval_cache                        m_cache;
-            expr_ref_vector                   m_lhs, m_rhs;
+            eqdep_map_t            m_map;            
+            eval_cache             m_cache;
+            expr_ref_vector        m_lhs, m_rhs;
             ptr_vector<dependency> m_deps;
-            svector<map_update>               m_updates;
-            unsigned_vector                   m_limit;
+            svector<map_update>    m_updates;
+            unsigned_vector        m_limit;
 
             void add_trail(map_update op, expr* l, expr* r, dependency* d);
         public:
@@ -362,6 +362,7 @@ namespace smt {
         void collect_statistics(::statistics & st) const override;
         model_value_proc * mk_value(enode * n, model_generator & mg) override;
         void init_model(model_generator & mg) override;
+        void finalize_model(model_generator & mg) override;
         void init_search_eh() override;
 
         void init_model(expr_ref_vector const& es);
@@ -389,7 +390,6 @@ namespace smt {
                            vector<rational> const& ll, vector<rational> const& rl);
         bool set_empty(expr* x);
         bool is_complex(eq const& e);
-        bool internalize_re(expr* e);
 
         bool check_extensionality();
         bool check_contains();
diff --git a/src/smt/theory_str.cpp b/src/smt/theory_str.cpp
index 0f9d42b3d..126594b06 100644
--- a/src/smt/theory_str.cpp
+++ b/src/smt/theory_str.cpp
@@ -8096,7 +8096,7 @@ namespace smt {
             rational nn1Len, nn2Len;
             bool nn1Len_exists = get_len_value(lhs, nn1Len);
             bool nn2Len_exists = get_len_value(rhs, nn2Len);
-            expr * emptyStr = mk_string("");
+            expr_ref emptyStr(mk_string(""), m);
 
             if (nn1Len_exists && nn1Len.is_zero()) {
                 if (!in_same_eqc(lhs, emptyStr) && rhs != emptyStr) {
diff --git a/src/solver/smt_logics.cpp b/src/solver/smt_logics.cpp
index 874f1cfcc..7ed2b0445 100644
--- a/src/solver/smt_logics.cpp
+++ b/src/solver/smt_logics.cpp
@@ -22,14 +22,14 @@ Revision History:
 
 
 bool smt_logics::supported_logic(symbol const & s) {
-    return logic_has_uf(s) || logic_is_all(s) || logic_has_fd(s) || 
+    return logic_has_uf(s) || logic_is_all(s) || logic_has_fd(s) ||
         logic_has_arith(s) || logic_has_bv(s) ||
         logic_has_array(s) || logic_has_seq(s) || logic_has_str(s) ||
         logic_has_horn(s) || logic_has_fpa(s);
 }
 
 bool smt_logics::logic_has_reals_only(symbol const& s) {
-    return 
+    return
         s == "QF_RDL" ||
         s == "QF_LRA" ||
         s == "UFLRA" ||
@@ -84,8 +84,9 @@ bool smt_logics::logic_has_arith(symbol const & s) {
         s == "QF_BVFP" ||
         s == "QF_S" ||
         s == "ALL" ||
-        s == "QF_FD" || 
-        s == "HORN";
+        s == "QF_FD" ||
+        s == "HORN" ||
+        s == "QF_FPLRA";
 }
 
 bool smt_logics::logic_has_bv(symbol const & s) {
@@ -137,7 +138,7 @@ bool smt_logics::logic_has_str(symbol const & s) {
 }
 
 bool smt_logics::logic_has_fpa(symbol const & s) {
-    return s == "QF_FP" || s == "QF_FPBV" || s == "QF_BVFP" || s == "ALL";
+    return s == "QF_FP" || s == "QF_FPBV" || s == "QF_BVFP" || s == "QF_FPLRA"  || s == "ALL";
 }
 
 bool smt_logics::logic_has_uf(symbol const & s) {
diff --git a/src/tactic/fpa/CMakeLists.txt b/src/tactic/fpa/CMakeLists.txt
index a54212235..c647df7fc 100644
--- a/src/tactic/fpa/CMakeLists.txt
+++ b/src/tactic/fpa/CMakeLists.txt
@@ -3,6 +3,7 @@ z3_add_component(fpa_tactics
     fpa2bv_model_converter.cpp
     fpa2bv_tactic.cpp
     qffp_tactic.cpp
+    qffplra_tactic.cpp
   COMPONENT_DEPENDENCIES
     arith_tactics
     bv_tactics
@@ -14,4 +15,5 @@ z3_add_component(fpa_tactics
   TACTIC_HEADERS
     fpa2bv_tactic.h
     qffp_tactic.h
+    qffplra_tactic.h
 )
diff --git a/src/tactic/fpa/qffplra_tactic.cpp b/src/tactic/fpa/qffplra_tactic.cpp
new file mode 100644
index 000000000..947a41111
--- /dev/null
+++ b/src/tactic/fpa/qffplra_tactic.cpp
@@ -0,0 +1,72 @@
+/*++
+Copyright (c) 2012 Microsoft Corporation
+
+Module Name:
+
+    qffpalra_tactic.cpp
+
+Abstract:
+
+    Tactic for QF_FPLRA benchmarks.
+
+Author:
+
+    Christoph (cwinter) 2018-04-24
+
+Notes:
+
+--*/
+#include "tactic/tactical.h"
+#include "tactic/fpa/qffp_tactic.h"
+#include "tactic/fpa/qffplra_tactic.h"
+
+tactic * mk_qffplra_tactic(ast_manager & m, params_ref const & p) {
+    tactic * st = mk_qffp_tactic(m, p);
+    st->updt_params(p);
+    return st;
+}
+
+struct is_non_qffplra_predicate {
+    struct found {};
+    ast_manager & m;
+    bv_util       bu;
+    fpa_util      fu;
+    arith_util    au;
+
+    is_non_qffplra_predicate(ast_manager & _m) : m(_m), bu(m), fu(m), au(m) {}
+
+    void operator()(var *) { throw found(); }
+
+    void operator()(quantifier *) { throw found(); }
+
+    void operator()(app * n) {
+        sort * s = get_sort(n);
+        if (!m.is_bool(s) && !fu.is_float(s) && !fu.is_rm(s) && !bu.is_bv_sort(s) && !au.is_real(s))
+            throw found();
+        family_id fid = n->get_family_id();
+        if (fid == m.get_basic_family_id() ||
+            fid == fu.get_family_id() ||
+            fid == bu.get_family_id() ||
+            fid == au.get_family_id())
+            return;
+        if (is_uninterp_const(n))
+            return;
+        if (au.is_real(s))
+            return;
+
+        throw found();
+    }
+};
+
+class is_qffplra_probe : public probe {
+public:
+    result operator()(goal const & g) override {
+        return !test<is_non_qffplra_predicate>(g);
+    }
+
+    ~is_qffplra_probe() override {}
+};
+
+probe * mk_is_qffplra_probe() {
+    return alloc(is_qffplra_probe);
+}
diff --git a/src/tactic/fpa/qffplra_tactic.h b/src/tactic/fpa/qffplra_tactic.h
new file mode 100644
index 000000000..b5a741ac3
--- /dev/null
+++ b/src/tactic/fpa/qffplra_tactic.h
@@ -0,0 +1,38 @@
+#pragma once
+/*++
+Copyright (c) 2012 Microsoft Corporation
+
+Module Name:
+
+    qffplra_tactic.h
+
+Abstract:
+
+    Tactic for QF_FPLRA benchmarks.
+
+Author:
+
+    Christoph (cwinter) 2018-04-24
+
+Notes:
+
+
+--*/
+#ifndef QFFPLRA_TACTIC_H_
+#define QFFPLRA_TACTIC_H_
+
+#include "util/params.h"
+class ast_manager;
+class tactic;
+
+tactic * mk_qffplra_tactic(ast_manager & m, params_ref const & p = params_ref());
+/*
+ADD_TACTIC("qffplra", "(try to) solve goal using the tactic for QF_FPLRA.", "mk_qffplra_tactic(m, p)")
+*/
+
+probe * mk_is_qffplra_probe();
+/*
+ADD_PROBE("is-qffplra", "true if the goal is in QF_FPLRA.", "mk_is_qffplra_probe()")
+*/
+
+#endif
diff --git a/src/tactic/portfolio/default_tactic.cpp b/src/tactic/portfolio/default_tactic.cpp
index 09052869b..5cf06ca86 100644
--- a/src/tactic/portfolio/default_tactic.cpp
+++ b/src/tactic/portfolio/default_tactic.cpp
@@ -28,24 +28,26 @@ Notes:
 #include "tactic/arith/probe_arith.h"
 #include "tactic/smtlogics/quant_tactics.h"
 #include "tactic/fpa/qffp_tactic.h"
+#include "tactic/fpa/qffplra_tactic.h"
 #include "tactic/smtlogics/qfaufbv_tactic.h"
 #include "tactic/smtlogics/qfauflia_tactic.h"
 #include "tactic/smtlogics/qfufnra_tactic.h"
 
 tactic * mk_default_tactic(ast_manager & m, params_ref const & p) {
     tactic * st = using_params(and_then(mk_simplify_tactic(m),
-                                        cond(mk_is_qfbv_probe(),  mk_qfbv_tactic(m),
-                                        cond(mk_is_qfaufbv_probe(), mk_qfaufbv_tactic(m),                                        
+                                        cond(mk_is_qfbv_probe(), mk_qfbv_tactic(m),
+                                        cond(mk_is_qfaufbv_probe(), mk_qfaufbv_tactic(m),
                                         cond(mk_is_qflia_probe(), mk_qflia_tactic(m),
                                         cond(mk_is_qfauflia_probe(), mk_qfauflia_tactic(m),
                                         cond(mk_is_qflra_probe(), mk_qflra_tactic(m),
                                         cond(mk_is_qfnra_probe(), mk_qfnra_tactic(m),
                                         cond(mk_is_qfnia_probe(), mk_qfnia_tactic(m),
-                                        cond(mk_is_lira_probe(),  mk_lira_tactic(m, p),
-                                        cond(mk_is_nra_probe(),   mk_nra_tactic(m),
+                                        cond(mk_is_lira_probe(), mk_lira_tactic(m, p),
+                                        cond(mk_is_nra_probe(), mk_nra_tactic(m),
                                         cond(mk_is_qffp_probe(), mk_qffp_tactic(m, p),
+                                        cond(mk_is_qffplra_probe(), mk_qffplra_tactic(m, p),
                                         //cond(mk_is_qfufnra_probe(), mk_qfufnra_tactic(m, p),
-                                             mk_smt_tactic()))))))))))),
+                                             mk_smt_tactic())))))))))))),
                                p);
     return st;
 }
diff --git a/src/util/scoped_timer.cpp b/src/util/scoped_timer.cpp
index a2a0cc269..56d40c47a 100644
--- a/src/util/scoped_timer.cpp
+++ b/src/util/scoped_timer.cpp
@@ -208,14 +208,22 @@ struct scoped_timer::imp {
         pthread_cond_signal(&m_condition_var);
         pthread_mutex_unlock(&m_mutex);
 
-        if (pthread_join(m_thread_id, nullptr) != 0)
-            throw default_exception("failed to join thread");
-        if (pthread_mutex_destroy(&m_mutex) != 0)
-            throw default_exception("failed to destroy pthread mutex");
-        if (pthread_cond_destroy(&m_condition_var) != 0)
-            throw default_exception("failed to destroy pthread condition variable");
-        if (pthread_attr_destroy(&m_attributes) != 0)
-            throw default_exception("failed to destroy pthread attributes object");
+        if (pthread_join(m_thread_id, nullptr) != 0) {
+            warning_msg("failed to join thread");
+            return;
+        }
+        if (pthread_mutex_destroy(&m_mutex) != 0) {
+            warning_msg("failed to destroy pthread mutex");
+            return;
+        }
+        if (pthread_cond_destroy(&m_condition_var) != 0) {
+            warning_msg("failed to destroy pthread condition variable");
+            return;
+        }
+        if (pthread_attr_destroy(&m_attributes) != 0) {
+            warning_msg("failed to destroy pthread attributes object");
+            return;
+        }
 #elif defined(_LINUX_) || defined(_FREEBSD_) || defined(_NETBSD_)
         // Linux & FreeBSD & NetBSD
         bool init = false;