diff --git a/src/api/api_parsers.cpp b/src/api/api_parsers.cpp
index 2d5c3d0c4..b6d18096f 100644
--- a/src/api/api_parsers.cpp
+++ b/src/api/api_parsers.cpp
@@ -23,6 +23,7 @@ Revision History:
 #include"cmd_context.h"
 #include"smt2parser.h"
 #include"smtparser.h"
+#include"solver_na2as.h"
 
 extern "C" {
 
@@ -251,20 +252,19 @@ extern "C" {
     // ---------------
     // Support for SMTLIB2
 
-    class z3_context_solver : public solver {
+    class z3_context_solver : public solver_na2as {
         api::context & m_ctx;
         smt::kernel & ctx() const { return m_ctx.get_smt_kernel(); }
     public:
         virtual ~z3_context_solver() {}
         z3_context_solver(api::context& c) : m_ctx(c) {}
-        virtual void init(ast_manager & m, symbol const & logic) {}
+        virtual void init_core(ast_manager & m, symbol const & logic) {}
         virtual void collect_statistics(statistics & st) const {}
-        virtual void reset() { ctx().reset(); }
+        virtual void reset_core() { ctx().reset(); }
         virtual void assert_expr(expr * t) { ctx().assert_expr(t); }
-        virtual void push() { ctx().push(); }
-        virtual void pop(unsigned n) { ctx().pop(n); }
-        virtual unsigned get_scope_level() const { return ctx().get_scope_level(); }
-        virtual lbool check_sat(unsigned num_assumptions, expr * const * assumptions) {
+        virtual void push_core() { ctx().push(); }
+        virtual void pop_core(unsigned n) { ctx().pop(n); }
+        virtual lbool check_sat_core(unsigned num_assumptions, expr * const * assumptions) {
             return ctx().check(num_assumptions, assumptions);
         }
         virtual void get_unsat_core(ptr_vector<expr> & r) {
diff --git a/src/api/api_solver.cpp b/src/api/api_solver.cpp
index 8aecc0a3a..6d1becb4d 100644
--- a/src/api/api_solver.cpp
+++ b/src/api/api_solver.cpp
@@ -33,14 +33,29 @@ Revision History:
 
 extern "C" {
 
+    static void init_solver_core(Z3_context c, Z3_solver _s) {
+        ast_manager & m = mk_c(c)->m();
+        Z3_solver_ref * s = to_solver(_s);
+        s->m_solver->set_produce_proofs(m.proofs_enabled());
+        s->m_solver->set_produce_unsat_cores(s->m_params.get_bool(":unsat-core", false));
+        s->m_solver->set_produce_models(s->m_params.get_bool(":model", true));
+        s->m_solver->set_front_end_params(mk_c(c)->fparams());
+        s->m_solver->updt_params(s->m_params);
+        s->m_solver->init(m, s->m_logic);
+        s->m_initialized = true;
+    }
+
+    static void init_solver(Z3_context c, Z3_solver s) {
+        if (!to_solver(s)->m_initialized)
+            init_solver_core(c, s);
+    }
+
     Z3_solver Z3_API Z3_mk_simple_solver(Z3_context c) {
         Z3_TRY;
         LOG_Z3_mk_simple_solver(c);
         RESET_ERROR_CODE();
         Z3_solver_ref * s = alloc(Z3_solver_ref);
         s->m_solver       = mk_smt_solver();
-        s->m_solver->set_front_end_params(mk_c(c)->fparams());
-        s->m_solver->init(mk_c(c)->m(), symbol::null);
         mk_c(c)->save_object(s);
         Z3_solver r = of_solver(s);
         RETURN_Z3(r);
@@ -53,8 +68,6 @@ extern "C" {
         RESET_ERROR_CODE();
         Z3_solver_ref * s = alloc(Z3_solver_ref);
         s->m_solver       = mk_smt_strategic_solver();
-        s->m_solver->set_front_end_params(mk_c(c)->fparams());
-        s->m_solver->init(mk_c(c)->m(), symbol::null);
         mk_c(c)->save_object(s);
         Z3_solver r = of_solver(s);
         RETURN_Z3(r);
@@ -65,10 +78,8 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_mk_solver_for_logic(c, logic);
         RESET_ERROR_CODE();
-        Z3_solver_ref * s = alloc(Z3_solver_ref);
+        Z3_solver_ref * s = alloc(Z3_solver_ref, to_symbol(logic));
         s->m_solver       = mk_smt_strategic_solver(true /* force solver to use tactics even when auto_config is disabled */);
-        s->m_solver->set_front_end_params(mk_c(c)->fparams());
-        s->m_solver->init(mk_c(c)->m(), to_symbol(logic));
         mk_c(c)->save_object(s);
         Z3_solver r = of_solver(s);
         RETURN_Z3(r);
@@ -81,8 +92,6 @@ extern "C" {
         RESET_ERROR_CODE();
         Z3_solver_ref * s = alloc(Z3_solver_ref);
         s->m_solver       = alloc(tactic2solver, to_tactic_ref(t));
-        s->m_solver->set_front_end_params(mk_c(c)->fparams());
-        s->m_solver->init(mk_c(c)->m(), symbol::null);
         mk_c(c)->save_object(s);
         Z3_solver r = of_solver(s);
         RETURN_Z3(r);
@@ -117,7 +126,13 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_set_params(c, s, p);
         RESET_ERROR_CODE();
-        to_solver_ref(s)->updt_params(to_param_ref(p));
+        if (to_solver(s)->m_initialized) {
+            bool old_model = to_solver(s)->m_params.get_bool(":model", true);
+            bool new_model = to_param_ref(p).get_bool(":model", true);
+            if (old_model != new_model)
+                to_solver_ref(s)->set_produce_models(new_model);
+            to_solver_ref(s)->updt_params(to_param_ref(p));
+        }
         to_solver(s)->m_params = to_param_ref(p);
         Z3_CATCH;
     }
@@ -142,6 +157,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_push(c, s);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         to_solver_ref(s)->push();
         Z3_CATCH;
     }
@@ -150,6 +166,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_pop(c, s, n);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         if (n > to_solver_ref(s)->get_scope_level()) {
             SET_ERROR_CODE(Z3_IOB);
             return;
@@ -164,7 +181,7 @@ extern "C" {
         LOG_Z3_solver_reset(c, s);
         RESET_ERROR_CODE();
         to_solver_ref(s)->reset();
-        to_solver_ref(s)->init(mk_c(c)->m(), symbol::null);
+        to_solver(s)->m_initialized = false;
         Z3_CATCH;
     }
     
@@ -172,6 +189,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_get_num_scopes(c, s);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         return to_solver_ref(s)->get_scope_level();
         Z3_CATCH_RETURN(0);
     }
@@ -180,7 +198,8 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_assert(c, s, a);
         RESET_ERROR_CODE();
-        CHECK_FORMULA(a,);        
+        init_solver(c, s);
+        CHECK_FORMULA(a,);
         to_solver_ref(s)->assert_expr(to_expr(a));
         Z3_CATCH;
     }
@@ -189,6 +208,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_get_assertions(c, s);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         Z3_ast_vector_ref * v = alloc(Z3_ast_vector_ref, mk_c(c)->m());
         mk_c(c)->save_object(v);
         unsigned sz = to_solver_ref(s)->get_num_assertions();
@@ -207,9 +227,6 @@ extern "C" {
             }
         }
         expr * const * _assumptions = to_exprs(assumptions);
-        to_solver_ref(s)->set_produce_models(to_solver(s)->m_params.get_bool(":model", true));
-        to_solver_ref(s)->set_produce_proofs(mk_c(c)->m().proofs_enabled());
-        to_solver_ref(s)->set_produce_unsat_cores(num_assumptions > 0);
         unsigned timeout     = to_solver(s)->m_params.get_uint(":timeout", UINT_MAX);
         bool     use_ctrl_c  = to_solver(s)->m_params.get_bool(":ctrl-c", false);
         cancel_eh<solver> eh(*to_solver_ref(s));
@@ -233,6 +250,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_check(c, s);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         return _solver_check(c, s, 0, 0);
         Z3_CATCH_RETURN(Z3_L_UNDEF);
     }
@@ -241,6 +259,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_check_assumptions(c, s, num_assumptions, assumptions);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         return _solver_check(c, s, num_assumptions, assumptions);
         Z3_CATCH_RETURN(Z3_L_UNDEF);
     }
@@ -249,6 +268,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_get_model(c, s);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         model_ref _m;
         to_solver_ref(s)->get_model(_m);
         if (!_m) {
@@ -266,6 +286,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_get_proof(c, s);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         proof * p = to_solver_ref(s)->get_proof();
         if (!p) {
             SET_ERROR_CODE(Z3_INVALID_USAGE);
@@ -280,6 +301,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_get_unsat_core(c, s);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         ptr_vector<expr> core;
         to_solver_ref(s)->get_unsat_core(core);
         Z3_ast_vector_ref * v = alloc(Z3_ast_vector_ref, mk_c(c)->m());
@@ -295,6 +317,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_get_reason_unknown(c, s);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         return mk_c(c)->mk_external_string(to_solver_ref(s)->reason_unknown());
         Z3_CATCH_RETURN("");
     }
@@ -303,6 +326,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_get_statistics(c, s);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         Z3_stats_ref * st = alloc(Z3_stats_ref);
         to_solver_ref(s)->collect_statistics(st->m_stats);
         mk_c(c)->save_object(st);
@@ -315,6 +339,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_solver_to_string(c, s);
         RESET_ERROR_CODE();
+        init_solver(c, s);
         std::ostringstream buffer;
         to_solver_ref(s)->display(buffer);
         return mk_c(c)->mk_external_string(buffer.str());
diff --git a/src/api/api_solver.h b/src/api/api_solver.h
index a39475bac..1569ef0da 100644
--- a/src/api/api_solver.h
+++ b/src/api/api_solver.h
@@ -24,7 +24,10 @@ Revision History:
 struct Z3_solver_ref : public api::object {
     solver *   m_solver;
     params_ref m_params;
-    Z3_solver_ref():m_solver(0) {}
+    bool       m_initialized;
+    symbol     m_logic;
+    Z3_solver_ref():m_solver(0), m_initialized(false), m_logic(symbol::null) {}
+    Z3_solver_ref(symbol const & logic):m_solver(0), m_initialized(false), m_logic(logic) {}
     virtual ~Z3_solver_ref() { dealloc(m_solver); }
 };
 
diff --git a/src/cmd_context/basic_cmds.cpp b/src/cmd_context/basic_cmds.cpp
index c6fa7718c..4c24b5ae6 100644
--- a/src/cmd_context/basic_cmds.cpp
+++ b/src/cmd_context/basic_cmds.cpp
@@ -359,14 +359,14 @@ class set_option_cmd : public set_get_option_cmd {
         }
         else if (m_option == m_produce_proofs) {
             check_not_initialized(ctx, m_produce_proofs);
-            ctx.params().m_proof_mode = to_bool(value) ? PGM_FINE : PGM_DISABLED;
+            ctx.set_produce_proofs(to_bool(value));
         }
         else if (m_option == m_produce_unsat_cores) {
             check_not_initialized(ctx, m_produce_unsat_cores);
             ctx.set_produce_unsat_cores(to_bool(value));
         }
         else if (m_option == m_produce_models) {
-            ctx.params().m_model = to_bool(value);
+            ctx.set_produce_models(to_bool(value));
         }
         else if (m_option == m_produce_assignments) {
             ctx.set_produce_assignments(to_bool(value));
diff --git a/src/cmd_context/cmd_context.cpp b/src/cmd_context/cmd_context.cpp
index c56066827..2d0d349d7 100644
--- a/src/cmd_context/cmd_context.cpp
+++ b/src/cmd_context/cmd_context.cpp
@@ -348,6 +348,24 @@ cmd_context::~cmd_context() {
     }
 }
 
+void cmd_context::set_produce_models(bool f) {
+    params().m_model = f;
+    if (m_solver)
+        m_solver->set_produce_models(f);
+}
+
+void cmd_context::set_produce_unsat_cores(bool f) {
+    // can only be set before initialization
+    SASSERT(!has_manager());
+    m_produce_unsat_cores = f;
+}
+
+void cmd_context::set_produce_proofs(bool f) {
+    // can only be set before initialization
+    SASSERT(!has_manager());
+    params().m_proof_mode = f ? PGM_FINE : PGM_DISABLED;
+}
+
 bool cmd_context::is_smtlib2_compliant() const { 
     return params().m_smtlib2_compliant; 
 }
@@ -540,8 +558,12 @@ void cmd_context::init_manager_core(bool new_manager) {
         // it prevents clashes with builtin types.
         insert(pm().mk_plist_decl());
     }
-    if (m_solver)
+    if (m_solver) {
+        m_solver->set_produce_unsat_cores(m_produce_unsat_cores);
+        m_solver->set_produce_models(params().m_model);
+        m_solver->set_produce_proofs(params().m_proof_mode == PGM_FINE);
         m_solver->init(m(), m_logic);
+    }
     m_check_logic.set_logic(m(), m_logic);
 }
 
@@ -1076,7 +1098,6 @@ void cmd_context::reset(bool finalize) {
     reset_macros();
     reset_func_decls();
     restore_assertions(0);
-    restore_assumptions(0);
     if (m_solver)
         m_solver->reset();
     m_pp_env = 0;
@@ -1108,6 +1129,8 @@ void cmd_context::assert_expr(expr * t) {
     m_check_sat_result = 0;
     m().inc_ref(t);
     m_assertions.push_back(t);
+    if (m_produce_unsat_cores)
+        m_assertion_names.push_back(0);
     if (m_solver)
         m_solver->assert_expr(t);
 }
@@ -1119,11 +1142,14 @@ void cmd_context::assert_expr(symbol const & name, expr * t) {
         assert_expr(t);
         return;
     }
-    app * proxy  = m().mk_const(name, m().mk_bool_sort());
-    expr * new_t = m().mk_implies(proxy, t);
-    m().inc_ref(proxy);
-    m_assumptions.push_back(proxy);
-    assert_expr(new_t);
+    m_check_sat_result = 0;
+    m().inc_ref(t);
+    m_assertions.push_back(t);
+    expr * ans  = m().mk_const(name, m().mk_bool_sort());
+    m().inc_ref(ans);
+    m_assertion_names.push_back(ans);
+    if (m_solver)
+        m_solver->assert_expr(t, ans);
 }
 
 void cmd_context::push() {
@@ -1137,7 +1163,6 @@ 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();
-    s.m_assumptions_lim        = m_assumptions.size();
     if (m_solver) 
         m_solver->push();
 }
@@ -1200,29 +1225,25 @@ void cmd_context::restore_aux_pdecls(unsigned old_sz) {
     m_aux_pdecls.shrink(old_sz);
 }
 
+static void restore(ast_manager & m, ptr_vector<expr> & c, unsigned old_sz) {
+    ptr_vector<expr>::iterator it  = c.begin() + old_sz;
+    ptr_vector<expr>::iterator end = c.end();
+    for (; it != end; ++it) {
+        m.dec_ref(*it);
+    }
+    c.shrink(old_sz);
+}
+
 void cmd_context::restore_assertions(unsigned old_sz) {
     SASSERT(old_sz <= m_assertions.size());
     SASSERT(!m_interactive_mode || m_assertions.size() == m_assertion_strings.size());
-    ptr_vector<expr>::iterator it  = m_assertions.begin() + old_sz;
-    ptr_vector<expr>::iterator end = m_assertions.end();
-    for (; it != end; ++it) {
-        m().dec_ref(*it);
-    }
-    m_assertions.shrink(old_sz);
+    restore(m(), m_assertions, old_sz);
+    if (m_produce_unsat_cores)
+        restore(m(), m_assertion_names, old_sz);
     if (m_interactive_mode)
         m_assertion_strings.shrink(old_sz);
 }
 
-void cmd_context::restore_assumptions(unsigned old_sz) {
-    SASSERT(old_sz <= m_assumptions.size());
-    ptr_vector<expr>::iterator it  = m_assumptions.begin() + old_sz;
-    ptr_vector<expr>::iterator end = m_assumptions.end();
-    for (; it != end; ++it) {
-        m().dec_ref(*it);
-    }
-    m_assumptions.shrink(old_sz);
-}
-
 void cmd_context::pop(unsigned n) {
     m_check_sat_result = 0;
     if (n == 0)
@@ -1240,7 +1261,6 @@ void cmd_context::pop(unsigned n) {
     restore_macros(s.m_macros_stack_lim);
     restore_aux_pdecls(s.m_aux_pdecls_lim);
     restore_assertions(s.m_assertions_lim);
-    restore_assumptions(s.m_assumptions_lim);
     m_scopes.shrink(new_lvl);
 }
 
@@ -1260,17 +1280,12 @@ void cmd_context::check_sat(unsigned num_assumptions, expr * const * assumptions
         m_check_sat_result = m_solver.get(); // solver itself stores the result.
         m_solver->set_front_end_params(params());
         m_solver->set_progress_callback(this);
-        m_solver->set_produce_proofs(produce_proofs());
-        m_solver->set_produce_models(produce_models());
-        m_solver->set_produce_unsat_cores(produce_unsat_cores());
         scoped_watch sw(*this);
         cancel_eh<solver> eh(*m_solver);
         scoped_ctrl_c ctrlc(eh);
-        unsigned old_sz = m_assumptions.size();
-        m_assumptions.append(num_assumptions, assumptions);
         lbool r;
         try {
-            r = m_solver->check_sat(m_assumptions.size(), m_assumptions.c_ptr());
+            r = m_solver->check_sat(num_assumptions, assumptions);
         }
         catch (z3_error & ex) {
             throw ex;
@@ -1278,7 +1293,6 @@ void cmd_context::check_sat(unsigned num_assumptions, expr * const * assumptions
         catch (z3_exception & ex) {
             throw cmd_exception(ex.msg());
         }
-        m_assumptions.shrink(old_sz);
         m_solver->set_status(r);
         display_sat_result(r);
         validate_check_sat_result(r);
@@ -1410,6 +1424,9 @@ void cmd_context::set_solver(solver * s) {
     m_solver = s;
     m_solver->set_front_end_params(params());
     if (has_manager() && s != 0) {
+        m_solver->set_produce_unsat_cores(m_produce_unsat_cores);
+        m_solver->set_produce_models(params().m_model);
+        m_solver->set_produce_proofs(params().m_proof_mode == PGM_FINE);
         m_solver->init(m(), m_logic);
         // assert formulas and create scopes in the new solver.
         unsigned lim = 0;
diff --git a/src/cmd_context/cmd_context.h b/src/cmd_context/cmd_context.h
index 9296f0735..34a3375d7 100644
--- a/src/cmd_context/cmd_context.h
+++ b/src/cmd_context/cmd_context.h
@@ -175,16 +175,15 @@ protected:
     ptr_vector<pdecl>            m_aux_pdecls;
     ptr_vector<expr>             m_assertions;
     vector<std::string>          m_assertion_strings;
-    ptr_vector<expr>             m_assumptions; // for unsat-core extraction
+    ptr_vector<expr>             m_assertion_names; // named assertions are represented using boolean variables.
 
     struct scope {
         unsigned m_func_decls_stack_lim;
         unsigned m_psort_decls_stack_lim;
         unsigned m_macros_stack_lim;
         unsigned m_aux_pdecls_lim;
-        // only m_assertions_lim and m_assumptions_lim are relevant when m_global_decls = true
+        // only m_assertions_lim is relevant when m_global_decls = true
         unsigned m_assertions_lim;
-        unsigned m_assumptions_lim;
     };
 
     svector<scope>               m_scopes;
@@ -225,7 +224,6 @@ protected:
     void restore_macros(unsigned old_sz);
     void restore_aux_pdecls(unsigned old_sz);
     void restore_assertions(unsigned old_sz);
-    void restore_assumptions(unsigned old_sz);
 
     void erase_func_decl_core(symbol const & s, func_decl * f);
     void erase_psort_decl_core(symbol const & s);
@@ -272,7 +270,9 @@ public:
     bool produce_models() const;
     bool produce_proofs() const;
     bool produce_unsat_cores() const { return m_produce_unsat_cores; }
-    void set_produce_unsat_cores(bool flag) { m_produce_unsat_cores = flag; }
+    void set_produce_models(bool flag);
+    void set_produce_unsat_cores(bool flag);
+    void set_produce_proofs(bool flag);
     bool produce_assignments() const { return m_produce_assignments; }
     void set_produce_assignments(bool flag) { m_produce_assignments = flag; }
     void set_status(status st) { m_status = st; }
@@ -369,8 +369,8 @@ public:
     ptr_vector<expr>::const_iterator begin_assertions() const { return m_assertions.begin(); }
     ptr_vector<expr>::const_iterator end_assertions() const { return m_assertions.end(); }
 
-    ptr_vector<expr>::const_iterator begin_assumptions() const { return m_assumptions.begin(); }
-    ptr_vector<expr>::const_iterator end_assumptions() const { return m_assumptions.end(); }
+    ptr_vector<expr>::const_iterator begin_assertion_names() const { return m_assertion_names.begin(); }
+    ptr_vector<expr>::const_iterator end_assertion_names() const { return m_assertion_names.end(); }
 
     /**
        \brief Hack: consume assertions if there are no scopes.
@@ -380,7 +380,6 @@ public:
         if (num_scopes() > 0)
             return false;
         restore_assertions(0);
-        restore_assumptions(0);
         return true;
     }
 
diff --git a/src/cmd_context/cmd_context_to_goal.cpp b/src/cmd_context/cmd_context_to_goal.cpp
index 21f8445d5..26cb2766b 100644
--- a/src/cmd_context/cmd_context_to_goal.cpp
+++ b/src/cmd_context/cmd_context_to_goal.cpp
@@ -27,20 +27,22 @@ void assert_exprs_from(cmd_context const & ctx, goal & t) {
         throw cmd_exception("Frontend does not support simultaneous generation of proofs and unsat cores");
     ast_manager & m = t.m();
     bool proofs_enabled = t.proofs_enabled();
-    ptr_vector<expr>::const_iterator it  = ctx.begin_assertions();
-    ptr_vector<expr>::const_iterator end = ctx.end_assertions();
-    for (; it != end; ++it) {
-        t.assert_expr(*it, proofs_enabled ? m.mk_asserted(*it) : 0, 0);
-    }
     if (ctx.produce_unsat_cores()) {
-        SASSERT(!ctx.produce_proofs());
-        it  = ctx.begin_assumptions();
-        end = ctx.end_assumptions();
-        for (; it != end; ++it) {
-            t.assert_expr(*it, 0, m.mk_leaf(*it));
+        ptr_vector<expr>::const_iterator it   = ctx.begin_assertions();
+        ptr_vector<expr>::const_iterator end  = ctx.end_assertions();
+        ptr_vector<expr>::const_iterator it2  = ctx.begin_assertion_names();
+        ptr_vector<expr>::const_iterator end2 = ctx.end_assertion_names();
+        SASSERT(end - it == end2 - it2);
+        for (; it != end; ++it, ++it2) {
+            t.assert_expr(*it, proofs_enabled ? m.mk_asserted(*it) : 0, m.mk_leaf(*it2));
         }
     }
     else {
-        SASSERT(ctx.begin_assumptions() == ctx.end_assumptions());
+        ptr_vector<expr>::const_iterator it  = ctx.begin_assertions();
+        ptr_vector<expr>::const_iterator end = ctx.end_assertions();
+        for (; it != end; ++it) {
+            t.assert_expr(*it, proofs_enabled ? m.mk_asserted(*it) : 0, 0);
+        }
+        SASSERT(ctx.begin_assertion_names() == ctx.end_assertion_names());
     }
 }
diff --git a/src/cmd_context/strategic_solver_cmd.cpp b/src/cmd_context/strategic_solver_cmd.cpp
deleted file mode 100644
index 3bb820e0d..000000000
--- a/src/cmd_context/strategic_solver_cmd.cpp
+++ /dev/null
@@ -1,34 +0,0 @@
-/*++
-Copyright (c) 2012 Microsoft Corporation
-
-Module Name:
-
-    strategic_solver_cmd.h
-
-Abstract:
-
-    Specialization of the strategic solver that
-    used cmd_context to access the assertion set.
-
-Author:
-
-    Leonardo (leonardo) 2012-11-01
-
-Notes:
-
---*/
-#include"strategic_solver_cmd.h"
-#include"cmd_context.h"
-
-strategic_solver_cmd::strategic_solver_cmd(cmd_context & ctx):
-    m_ctx(ctx) {
-}
-
-unsigned strategic_solver_cmd::get_num_assertions() const {
-    return static_cast<unsigned>(m_ctx.end_assertions() - m_ctx.begin_assertions());
-}
-
-expr * strategic_solver_cmd::get_assertion(unsigned idx) const {
-    SASSERT(idx < get_num_assertions());
-    return m_ctx.begin_assertions()[idx];
-}
diff --git a/src/cmd_context/strategic_solver_cmd.h b/src/cmd_context/strategic_solver_cmd.h
deleted file mode 100644
index 014d2dee6..000000000
--- a/src/cmd_context/strategic_solver_cmd.h
+++ /dev/null
@@ -1,40 +0,0 @@
-/*++
-Copyright (c) 2012 Microsoft Corporation
-
-Module Name:
-
-    strategic_solver_cmd.h
-
-Abstract:
-
-    Specialization of the strategic solver that
-    used cmd_context to access the assertion set.
-
-Author:
-
-    Leonardo (leonardo) 2012-11-01
-
-Notes:
-
---*/
-#ifndef _STRATEGIC_SOLVER_CMD_H_
-#define _STRATEGIC_SOLVER_CMD_H_
-
-#include"strategic_solver.h"
-
-class cmd_context;
-
-/**
-   Specialization for the SMT 2.0 command language frontend.
-
-   The strategic solver does not have to maintain a copy of the assertion set in the cmd_context.
-*/
-class strategic_solver_cmd : public strategic_solver_core {
-    cmd_context &        m_ctx;
-public:
-    strategic_solver_cmd(cmd_context & ctx);
-    virtual unsigned get_num_assertions() const;
-    virtual expr * get_assertion(unsigned idx) const;
-};
-
-#endif 
diff --git a/src/parsers/smt/smtlib_solver.cpp b/src/parsers/smt/smtlib_solver.cpp
index 77c2455dc..dd54de350 100644
--- a/src/parsers/smt/smtlib_solver.cpp
+++ b/src/parsers/smt/smtlib_solver.cpp
@@ -83,7 +83,7 @@ namespace smtlib {
             benchmark.add_formula(m_ast_manager.mk_true());
         }
         m_ctx = alloc(cmd_context, &m_params, true, &m_ast_manager, benchmark.get_logic());
-        m_ctx->set_solver(mk_smt_strategic_solver(*m_ctx));
+        m_ctx->set_solver(mk_smt_strategic_solver(false));
         theory::expr_iterator fit  = benchmark.begin_formulas();
         theory::expr_iterator fend = benchmark.end_formulas();
         for (; fit != fend; ++fit)
diff --git a/src/shell/smtlib_frontend.cpp b/src/shell/smtlib_frontend.cpp
index 6711158fd..08b070183 100644
--- a/src/shell/smtlib_frontend.cpp
+++ b/src/shell/smtlib_frontend.cpp
@@ -106,7 +106,7 @@ unsigned read_smtlib2_commands(char const* file_name, front_end_params& front_en
         ctx.set_solver(s);
     }
     else {
-        solver * s = mk_smt_strategic_solver(ctx);
+        solver * s = mk_smt_strategic_solver(false);
         ctx.set_solver(s);
     }
     install_dl_cmds(ctx);
diff --git a/src/smt/ni_solver.cpp b/src/smt/ni_solver.cpp
deleted file mode 100644
index cd0cd503a..000000000
--- a/src/smt/ni_solver.cpp
+++ /dev/null
@@ -1,236 +0,0 @@
-/*++
-Copyright (c) 2011 Microsoft Corporation
-
-Module Name:
-
-    ni_solver.cpp
-
-Abstract:
-    Wrappers for smt::kernel that are non-incremental & (quasi-incremental).
-
-Author:
-
-    Leonardo (leonardo) 2011-03-30
-
-Notes:
-
---*/
-#include"ni_solver.h"
-#include"smt_kernel.h"
-#include"cmd_context.h"
-
-class ni_smt_solver : public solver {
-protected:
-    cmd_context &       m_cmd_ctx;
-    smt::kernel *       m_context;
-    progress_callback * m_callback;
-public:
-    ni_smt_solver(cmd_context & ctx):m_cmd_ctx(ctx), m_context(0), m_callback(0) {}
-
-    virtual ~ni_smt_solver() {
-        if (m_context != 0)
-            dealloc(m_context);
-    }
-
-    virtual void init(ast_manager & m, symbol const & logic) {
-        // do nothing
-    }
-
-    virtual void collect_statistics(statistics & st) const {
-        if (m_context == 0) {
-            return;
-        }
-        else {
-            m_context->collect_statistics(st);
-        }
-    }
-
-    virtual void reset() {
-        if (m_context != 0) {
-            #pragma omp critical (ni_solver) 
-            {
-                dealloc(m_context);
-                m_context = 0;
-            }
-        }
-    }
-
-    virtual void assert_expr(expr * t) {
-        // do nothing
-    }
-
-    virtual void push() {
-        // do nothing
-    }
-
-    virtual void pop(unsigned n) {
-        // do nothing
-    }
-
-    virtual unsigned get_scope_level() const {
-        return m_cmd_ctx.num_scopes();
-    }
-
-    void assert_exprs() {
-        ptr_vector<expr>::const_iterator it  = m_cmd_ctx.begin_assertions();
-        ptr_vector<expr>::const_iterator end = m_cmd_ctx.end_assertions();
-        for (; it != end; ++it) {
-            m_context->assert_expr(*it);
-        }
-    }
-
-    void init_solver() {
-        reset();
-        #pragma omp critical (ni_solver)
-        {
-            m_context = alloc(smt::kernel, m_cmd_ctx.m(), m_cmd_ctx.params());
-        }
-        if (m_cmd_ctx.has_logic())
-            m_context->set_logic(m_cmd_ctx.get_logic());
-        if (m_callback)
-            m_context->set_progress_callback(m_callback);
-        assert_exprs();
-    }
-
-    virtual lbool check_sat(unsigned num_assumptions, expr * const * assumptions) {
-        // erase current solver, and create a new one.
-        init_solver();
-
-        if (num_assumptions == 0) {
-            return m_context->setup_and_check();
-        }
-        else {
-            return m_context->check(num_assumptions, assumptions); 
-        }
-    }
-
-    virtual void get_unsat_core(ptr_vector<expr> & r) {
-        SASSERT(m_context);
-        unsigned sz = m_context->get_unsat_core_size();
-        for (unsigned i = 0; i < sz; i++)
-            r.push_back(m_context->get_unsat_core_expr(i));
-    }
-
-    virtual void get_model(model_ref & m) {
-        SASSERT(m_context);
-        m_context->get_model(m);
-    }
-
-    virtual proof * get_proof() {
-        SASSERT(m_context);
-        return m_context->get_proof();
-    }
-
-    virtual std::string reason_unknown() const {
-        SASSERT(m_context);
-        return m_context->last_failure_as_string();
-    }
-
-    virtual void get_labels(svector<symbol> & r) {
-        SASSERT(m_context);
-        buffer<symbol> tmp;
-        m_context->get_relevant_labels(0, tmp);
-        r.append(tmp.size(), tmp.c_ptr());
-    }
-
-    virtual void set_cancel(bool f) {
-        #pragma omp critical (ni_solver)
-        {
-            if (m_context)
-                m_context->set_cancel(f);
-        }
-    }
-
-    virtual void set_progress_callback(progress_callback * callback) {
-        m_callback = callback;
-        if (m_context)
-            m_context->set_progress_callback(callback);
-    }
-
-
-    virtual void collect_param_descrs(param_descrs & r) {
-        smt::kernel::collect_param_descrs(r);
-    }
-
-};
-
-solver * mk_non_incremental_smt_solver(cmd_context & ctx) {
-    return alloc(ni_smt_solver, ctx);
-}
-
-class qi_smt_solver : public ni_smt_solver {
-    bool            m_inc_mode;   
-public:
-    qi_smt_solver(cmd_context & ctx):ni_smt_solver(ctx), m_inc_mode(false) {}
-    
-    virtual ~qi_smt_solver() {}
-
-    virtual void init(ast_manager & m, symbol const & logic) {
-        if (m_inc_mode) {
-            init_solver();
-            m_inc_mode = true;
-        }
-    }
-
-    virtual void reset() {
-        ni_smt_solver::reset();
-        m_inc_mode = false;
-    }
-
-    void switch_to_inc() {
-        if (!m_inc_mode) {
-            init_solver();
-            m_inc_mode = true;
-        }
-        SASSERT(m_inc_mode);
-    }
-
-    virtual void assert_expr(expr * t) {
-        if (m_context != 0 && !m_inc_mode) {
-            // solver was already created to solve a check_sat query...
-            switch_to_inc();
-        }
-        if (m_inc_mode) {
-            SASSERT(m_context);
-            m_context->assert_expr(t);
-        }
-    }
-
-    virtual void push() {
-        switch_to_inc();
-        SASSERT(m_context);
-        m_context->push();
-        SASSERT(m_inc_mode);
-    }
-
-    virtual void pop(unsigned n) {
-        switch_to_inc();
-        SASSERT(m_context);
-        m_context->pop(n);
-        SASSERT(m_inc_mode);
-    }
-
-    virtual unsigned get_scope_level() const {
-        if (!m_inc_mode)
-            return 0;
-        else
-            return m_context->get_scope_level();
-    }
-
-
-    virtual lbool check_sat(unsigned num_assumptions, expr * const * assumptions) {
-        if (!m_inc_mode) {
-            lbool r = ni_smt_solver::check_sat(num_assumptions, assumptions);
-            SASSERT(!m_inc_mode);
-            return r;
-        }
-        else {
-            return m_context->check(num_assumptions, assumptions); 
-        }
-    }
-};
-
-
-solver * mk_quasi_incremental_smt_solver(cmd_context & ctx) {
-    return alloc(qi_smt_solver, ctx);
-}
diff --git a/src/smt/ni_solver.h b/src/smt/ni_solver.h
deleted file mode 100644
index c78707319..000000000
--- a/src/smt/ni_solver.h
+++ /dev/null
@@ -1,30 +0,0 @@
-/*++
-Copyright (c) 2011 Microsoft Corporation
-
-Module Name:
-
-    ni_solver.h
-
-Abstract:
-    Wrappers for smt::context that are non-incremental & (quasi-incremental).
-
-Author:
-
-    Leonardo (leonardo) 2011-03-30
-
-Notes:
-
---*/
-#ifndef _NI_SOLVER_H_
-#define _NI_SOLVER_H_
-
-#include"solver.h"
-class cmd_context;
-
-// Creates a solver that restarts from scratch for every call to check_sat
-solver * mk_non_incremental_smt_solver(cmd_context & ctx);
-
-// Creates a solver that restarts from scratch for the first call to check_sat, and then moves to incremental behavior.
-solver * mk_quasi_incremental_smt_solver(cmd_context & ctx);
-
-#endif
diff --git a/src/smt/smt_solver.cpp b/src/smt/smt_solver.cpp
index 516a6321e..888e1b34c 100644
--- a/src/smt/smt_solver.cpp
+++ b/src/smt/smt_solver.cpp
@@ -16,18 +16,19 @@ Author:
 Notes:
 
 --*/
-#include"solver.h"
+#include"solver_na2as.h"
 #include"smt_kernel.h"
 #include"reg_decl_plugins.h"
 #include"front_end_params.h"
 
 namespace smt {
 
-    class solver : public ::solver {
-        front_end_params * m_params;
-        smt::kernel *     m_context;
+    class solver : public solver_na2as {
+        front_end_params *  m_params;
+        smt::kernel *       m_context;
+        progress_callback * m_callback;
     public:
-        solver():m_params(0), m_context(0) {}
+        solver():m_params(0), m_context(0), m_callback(0) {}
 
         virtual ~solver() {
             if (m_context != 0)
@@ -57,12 +58,14 @@ namespace smt {
             }
         }
 
-        virtual void init(ast_manager & m, symbol const & logic) {
+        virtual void init_core(ast_manager & m, symbol const & logic) {
             SASSERT(m_params);
             reset();
 #pragma omp critical (solver)
             {
                 m_context = alloc(smt::kernel, m, *m_params);
+                if (m_callback)
+                    m_context->set_progress_callback(m_callback);
             }
             if (logic != symbol::null)
                 m_context->set_logic(logic);
@@ -77,7 +80,7 @@ namespace smt {
             }
         }
 
-        virtual void reset() {
+        virtual void reset_core() {
             if (m_context != 0) {
 #pragma omp critical (solver)
                 {
@@ -92,25 +95,19 @@ namespace smt {
             m_context->assert_expr(t);
         }
 
-        virtual void push() {
+        virtual void push_core() {
             SASSERT(m_context);
             m_context->push();
         }
 
-        virtual void pop(unsigned n) {
+        virtual void pop_core(unsigned n) {
             SASSERT(m_context);
             m_context->pop(n);
         }
 
-        virtual unsigned get_scope_level() const {
-            if (m_context)
-                return m_context->get_scope_level();
-            else
-                return 0;
-        }
-
-        virtual lbool check_sat(unsigned num_assumptions, expr * const * assumptions) {
+        virtual lbool check_sat_core(unsigned num_assumptions, expr * const * assumptions) {
             SASSERT(m_context);
+            TRACE("solver_na2as", tout << "smt_solver::check_sat_core: " << num_assumptions << "\n";);
             return m_context->check(num_assumptions, assumptions);
         }
 
@@ -152,8 +149,9 @@ namespace smt {
         }
 
         virtual void set_progress_callback(progress_callback * callback) {
-            SASSERT(m_context);
-            m_context->set_progress_callback(callback);
+            m_callback = callback;
+            if (m_context)
+                m_context->set_progress_callback(callback);
         }
 
         virtual unsigned get_num_assertions() const {
diff --git a/src/solver/solver.h b/src/solver/solver.h
index 1cbc681c0..6f9887c1a 100644
--- a/src/solver/solver.h
+++ b/src/solver/solver.h
@@ -64,19 +64,20 @@ public:
     /**
        \brief Enable/Disable proof production for this solver object.
     
-       It is invoked after init(m, logic).
+       It is invoked before init(m, logic).
     */
     virtual void set_produce_proofs(bool f) {}
     /**
        \brief Enable/Disable model generation for this solver object.
 
-       It is invoked after init(m, logic).
+       It is invoked before init(m, logic). 
+       The user may optionally invoke it after init(m, logic).
     */
     virtual void set_produce_models(bool f) {}
     /**
        \brief Enable/Disable unsat core generation for this solver object.
 
-       It is invoked after init(m, logic).
+       It is invoked before init(m, logic).
     */
     virtual void set_produce_unsat_cores(bool f) {}
     
@@ -95,6 +96,13 @@ public:
     */
     virtual void assert_expr(expr * t) = 0;
 
+    /**
+       \brief Add a new formula \c t to the assertion stack, and "tag" it with \c a.
+       The propositional varialbe \c a is used to track the use of \c t in a proof
+       of unsatisfiability.
+    */
+    virtual void assert_expr(expr * t, expr * a) = 0;
+
     /**
        \brief Create a backtracking point.
     */
diff --git a/src/solver/solver_na2as.cpp b/src/solver/solver_na2as.cpp
new file mode 100644
index 000000000..f6d7414a5
--- /dev/null
+++ b/src/solver/solver_na2as.cpp
@@ -0,0 +1,101 @@
+/*++
+Copyright (c) 2012 Microsoft Corporation
+
+Module Name:
+
+    solver_na2as.cpp
+
+Abstract:
+
+    Solver that implements "named" assertions using assumptions (aka answer literals).
+    That is, a named assertion assert_expr(t, a) is mapped into
+          a implies t
+    and 'a' is used as an extra assumption for check_sat.
+
+Author:
+
+    Leonardo (leonardo) 2012-11-02
+
+Notes:
+
+--*/
+#include"solver_na2as.h"
+#include"ast_smt2_pp.h"
+
+solver_na2as::solver_na2as() {
+    m_manager = 0;
+}
+
+solver_na2as::~solver_na2as() {
+    restore_assumptions(0);
+}
+
+void solver_na2as::assert_expr(expr * t, expr * a) {
+    SASSERT(m_manager != 0);
+    SASSERT(is_uninterp_const(a));
+    SASSERT(m_manager->is_bool(a));
+    TRACE("solver_na2as", tout << "asserting\n" << mk_ismt2_pp(t, *m_manager) << "\n" << mk_ismt2_pp(a, *m_manager) << "\n";);
+    m_manager->inc_ref(a);
+    m_assumptions.push_back(a);
+    expr_ref new_t(*m_manager);
+    new_t = m_manager->mk_implies(a, t);
+    assert_expr(new_t);
+}
+    
+void solver_na2as::init(ast_manager & m, symbol const & logic) {
+    SASSERT(m_assumptions.empty());
+    m_manager = &m;
+    init_core(m, logic);
+}
+
+struct append_assumptions {
+    ptr_vector<expr> & m_assumptions;
+    unsigned           m_old_sz;
+    append_assumptions(ptr_vector<expr> & _m_assumptions, 
+                       unsigned num_assumptions, 
+                       expr * const * assumptions):
+        m_assumptions(_m_assumptions) {
+        m_old_sz = m_assumptions.size();
+        m_assumptions.append(num_assumptions, assumptions);
+    }
+
+    ~append_assumptions() {
+        m_assumptions.shrink(m_old_sz);
+    }
+};
+
+lbool solver_na2as::check_sat(unsigned num_assumptions, expr * const * assumptions) {
+    append_assumptions app(m_assumptions, num_assumptions, assumptions);
+    return check_sat_core(m_assumptions.size(), m_assumptions.c_ptr());
+}
+
+void solver_na2as::push() {
+    m_scopes.push_back(m_assumptions.size());
+    push_core();
+}
+
+void solver_na2as::pop(unsigned n) {
+    pop_core(n);
+    unsigned lvl = m_scopes.size();
+    SASSERT(n <= lvl);
+    unsigned new_lvl = lvl - n;
+    restore_assumptions(m_scopes[new_lvl]);
+    m_scopes.shrink(new_lvl);
+}
+
+void solver_na2as::restore_assumptions(unsigned old_sz) {
+    SASSERT(old_sz == 0 || m_manager != 0);
+    for (unsigned i = old_sz; i < m_assumptions.size(); i++) {
+        m_manager->dec_ref(m_assumptions[i]);
+    }
+    m_assumptions.shrink(old_sz);
+}
+
+unsigned solver_na2as::get_scope_level() const {
+    return m_scopes.size();
+}
+
+void solver_na2as::reset() {
+    reset_core();
+    restore_assumptions(0);
+}
diff --git a/src/solver/solver_na2as.h b/src/solver/solver_na2as.h
new file mode 100644
index 000000000..eb12479fc
--- /dev/null
+++ b/src/solver/solver_na2as.h
@@ -0,0 +1,55 @@
+/*++
+Copyright (c) 2012 Microsoft Corporation
+
+Module Name:
+
+    solver_na2as.h
+
+Abstract:
+
+    Solver that implements "named" assertions using assumptions (aka answer literals).
+    That is, a named assertion assert_expr(t, a) is mapped into
+          a implies t
+    and 'a' is used as an extra assumption for check_sat.
+
+Author:
+
+    Leonardo (leonardo) 2012-11-02
+
+Notes:
+
+--*/
+#ifndef _SOLVER_NA2AS_H_
+#define _SOLVER_NA2AS_H_
+
+#include"solver.h"
+
+class solver_na2as : public solver {
+    ast_manager *      m_manager;
+    ptr_vector<expr>   m_assumptions;
+    unsigned_vector    m_scopes;
+    void restore_assumptions(unsigned old_sz);
+public:
+    solver_na2as();
+    virtual ~solver_na2as();
+
+    virtual void assert_expr(expr * t, expr * a);
+    virtual void assert_expr(expr * t) = 0;
+    
+    // Subclasses of solver_na2as should redefine the following *_core methods instead of these ones.
+    virtual void init(ast_manager & m, symbol const & logic);
+    virtual lbool check_sat(unsigned num_assumptions, expr * const * assumptions);
+    virtual void push();
+    virtual void pop(unsigned n);
+    virtual unsigned get_scope_level() const;
+    virtual void reset();
+protected:
+    virtual void init_core(ast_manager & m, symbol const & logic) = 0;
+    virtual lbool check_sat_core(unsigned num_assumptions, expr * const * assumptions) = 0;
+    virtual void push_core() = 0;
+    virtual void pop_core(unsigned n) = 0;
+    virtual void reset_core() = 0;
+};
+
+
+#endif
diff --git a/src/solver/strategic_solver.cpp b/src/solver/strategic_solver.cpp
index a32aec2b1..616ec5342 100644
--- a/src/solver/strategic_solver.cpp
+++ b/src/solver/strategic_solver.cpp
@@ -25,7 +25,13 @@ Notes:
 // minimum verbosity level for portfolio verbose messages
 #define PS_VB_LVL 15
 
-strategic_solver_core::strategic_solver_core():
+    
+strategic_solver::ctx::ctx(ast_manager & m):
+    m_assertions(m), 
+    m_assertion_names(m) {
+    }    
+
+strategic_solver::strategic_solver():
     m_manager(0),
     m_fparams(0),
     m_force_tactic(false),
@@ -37,6 +43,7 @@ strategic_solver_core::strategic_solver_core():
     m_default_fct(0),
     m_curr_tactic(0),
     m_proof(0),
+    m_core(0),
     m_callback(0) {
     m_use_inc_solver_results = false;
     DEBUG_CODE(m_num_scopes = 0;);
@@ -45,7 +52,7 @@ strategic_solver_core::strategic_solver_core():
     m_produce_unsat_cores = false;
 }
 
-strategic_solver_core::~strategic_solver_core() {
+strategic_solver::~strategic_solver() {
     SASSERT(!m_curr_tactic);
     dictionary<tactic_factory*>::iterator it  = m_logic2fct.begin();
     dictionary<tactic_factory*>::iterator end = m_logic2fct.end();
@@ -54,9 +61,11 @@ strategic_solver_core::~strategic_solver_core() {
     }
     if (m_proof)
         m().dec_ref(m_proof);
+    if (m_core)
+        m().dec_ref(m_core);
 }
 
-bool strategic_solver_core::has_quantifiers() const {
+bool strategic_solver::has_quantifiers() const {
     unsigned sz = get_num_assertions();
     for (unsigned i = 0; i < sz; i++) {
         if (::has_quantifiers(get_assertion(i)))
@@ -68,7 +77,7 @@ bool strategic_solver_core::has_quantifiers() const {
 /**
    \brief Return true if a tactic should be used when the incremental solver returns unknown.
 */
-bool strategic_solver_core::use_tactic_when_undef() const {
+bool strategic_solver::use_tactic_when_undef() const {
     switch (m_inc_unknown_behavior) {
     case IUB_RETURN_UNDEF: return false;
     case IUB_USE_TACTIC_IF_QF: return !has_quantifiers();
@@ -79,7 +88,7 @@ bool strategic_solver_core::use_tactic_when_undef() const {
     }
 }
 
-void strategic_solver_core::set_inc_solver(solver * s) {
+void strategic_solver::set_inc_solver(solver * s) {
     SASSERT(m_inc_solver == 0);
     SASSERT(m_num_scopes == 0);
     m_inc_solver = s;
@@ -87,7 +96,7 @@ void strategic_solver_core::set_inc_solver(solver * s) {
         m_inc_solver->set_progress_callback(m_callback);
 }
 
-void strategic_solver_core::updt_params(params_ref const & p) {
+void strategic_solver::updt_params(params_ref const & p) {
     if (m_inc_solver)
         m_inc_solver->updt_params(p);
     if (m_fparams)
@@ -95,7 +104,7 @@ void strategic_solver_core::updt_params(params_ref const & p) {
 }
 
 
-void strategic_solver_core::collect_param_descrs(param_descrs & r) {
+void strategic_solver::collect_param_descrs(param_descrs & r) {
     if (m_inc_solver)
         m_inc_solver->collect_param_descrs(r);
 }
@@ -105,7 +114,7 @@ void strategic_solver_core::collect_param_descrs(param_descrs & r) {
    timeout == UINT_MAX means infinite
    After the timeout a strategy is used.
 */
-void strategic_solver_core::set_inc_solver_timeout(unsigned timeout) {
+void strategic_solver::set_inc_solver_timeout(unsigned timeout) {
     m_inc_solver_timeout = timeout;
 }
 
@@ -113,14 +122,14 @@ void strategic_solver_core::set_inc_solver_timeout(unsigned timeout) {
    \brief Set the default tactic factory.
    It is used if there is no tactic for a given logic.
 */
-void strategic_solver_core::set_default_tactic(tactic_factory * fct) {
+void strategic_solver::set_default_tactic(tactic_factory * fct) {
     m_default_fct = fct;
 }
 
 /**
    \brief Set a tactic factory for a given logic.
 */
-void strategic_solver_core::set_tactic_for(symbol const & logic, tactic_factory * fct) {
+void strategic_solver::set_tactic_for(symbol const & logic, tactic_factory * fct) {
     tactic_factory * old_fct;
     if (m_logic2fct.find(logic, old_fct)) {
         dealloc(old_fct);
@@ -128,31 +137,77 @@ void strategic_solver_core::set_tactic_for(symbol const & logic, tactic_factory
     m_logic2fct.insert(logic, fct);
 }
 
-void strategic_solver_core::init(ast_manager & m, symbol const & logic) {
+void strategic_solver::init(ast_manager & m, symbol const & logic) {
     m_manager = &m;
     m_logic   = logic;
     if (m_inc_mode) {
         SASSERT(m_inc_solver);
         m_inc_solver->init(m, logic);
     }
+    m_ctx = alloc(ctx, m);
+    TRACE("strategic_solver", tout << "strategic_solver was initialized.\n";);
+}
+
+unsigned strategic_solver::get_num_assertions() const {
+    if (m_ctx == 0)
+        return 0;
+    return m_ctx->m_assertions.size();
+}
+
+expr * strategic_solver::get_assertion(unsigned idx) const {
+    SASSERT(m_ctx);
+    return m_ctx->m_assertions.get(idx);
+}
+
+expr * strategic_solver::get_assertion_name(unsigned idx) const {
+    SASSERT(m_ctx);
+    SASSERT(m_produce_unsat_cores);
+    return m_ctx->m_assertion_names.get(idx);
+}
+
+void strategic_solver::set_produce_proofs(bool f) { 
+    m_produce_proofs = f; 
+    // do not need to propagate to inc_solver since flag cannot be changed after initialization
+}
+
+void strategic_solver::set_produce_models(bool f) { 
+    m_produce_models = f; 
+    if (m_inc_solver) 
+        m_inc_solver->set_produce_models(f);
+}
+
+void strategic_solver::set_produce_unsat_cores(bool f) { 
+    m_produce_unsat_cores = f; 
+    // do not need to propagate to inc_solver since flag cannot be changed after initialization
 }
 
 // delayed inc solver initialization
-void strategic_solver_core::init_inc_solver() {
+void strategic_solver::init_inc_solver() {
     if (m_inc_mode) 
         return; // solver was already initialized
     if (!m_inc_solver)
         return; // inc solver was not installed
     m_inc_mode = true;
+    m_inc_solver->set_produce_proofs(m_produce_proofs);
+    m_inc_solver->set_produce_models(m_produce_models);
+    m_inc_solver->set_produce_unsat_cores(m_produce_unsat_cores);
     m_inc_solver->set_front_end_params(*m_fparams);
     m_inc_solver->init(m(), m_logic);
     unsigned sz = get_num_assertions();
-    for (unsigned i = 0; i < sz; i++) {
-        m_inc_solver->assert_expr(get_assertion(i));
+    if (m_produce_unsat_cores) {
+        SASSERT(m_ctx->m_assertions.size() == m_ctx->m_assertion_names.size());
+        for (unsigned i = 0; i < sz; i++) {
+            m_inc_solver->assert_expr(get_assertion(i), get_assertion_name(i));
+        }
+    }
+    else {
+        for (unsigned i = 0; i < sz; i++) {
+            m_inc_solver->assert_expr(get_assertion(i));
+        }
     }
 }
 
-void strategic_solver_core::collect_statistics(statistics & st) const {
+void strategic_solver::collect_statistics(statistics & st) const {
     if (m_use_inc_solver_results) {
         SASSERT(m_inc_solver);
         m_inc_solver->collect_statistics(st);
@@ -165,7 +220,8 @@ void strategic_solver_core::collect_statistics(statistics & st) const {
     }
 }
 
-void strategic_solver_core::reset() {
+void strategic_solver::reset() {
+    m_ctx      = 0;
     m_logic    = symbol::null;
     m_inc_mode = false;
     m_check_sat_executed = false;
@@ -176,18 +232,22 @@ void strategic_solver_core::reset() {
     reset_results();
 }
 
-void strategic_solver_core::reset_results() {
+void strategic_solver::reset_results() {
     m_use_inc_solver_results = false;
     m_model = 0;
     if (m_proof) {
         m().dec_ref(m_proof);
         m_proof = 0;
     }
+    if (m_core) {
+        m().dec_ref(m_core);
+        m_core = 0;
+    }
     m_reason_unknown.clear();
     m_stats.reset();
 }
 
-void strategic_solver_core::assert_expr(expr * t) {
+void strategic_solver::assert_expr(expr * t) {
     if (m_check_sat_executed && !m_inc_mode) {
         // a check sat was already executed --> switch to incremental mode
         init_inc_solver();
@@ -197,16 +257,37 @@ void strategic_solver_core::assert_expr(expr * t) {
         SASSERT(m_inc_solver);
         m_inc_solver->assert_expr(t);
     }
+    SASSERT(m_ctx);
+    m_ctx->m_assertions.push_back(t);
+    if (m_produce_unsat_cores)
+        m_ctx->m_assertion_names.push_back(0);
 }
 
-void strategic_solver_core::push() {
+void strategic_solver::assert_expr(expr * t, expr * a) {
+    if (m_check_sat_executed && !m_inc_mode) {
+        // a check sat was already executed --> switch to incremental mode
+        init_inc_solver();
+        SASSERT(m_inc_solver == 0 || m_inc_mode);
+    }
+    if (m_inc_mode) {
+        SASSERT(m_inc_solver);
+        m_inc_solver->assert_expr(t, a);
+    }
+    SASSERT(m_ctx);
+    m_ctx->m_assertions.push_back(t);
+    if (m_produce_unsat_cores)
+        m_ctx->m_assertion_names.push_back(a);
+}
+
+void strategic_solver::push() {
     DEBUG_CODE(m_num_scopes++;);
     init_inc_solver();
     if (m_inc_solver)
         m_inc_solver->push();
+    m_ctx->m_scopes.push_back(m_ctx->m_assertions.size());
 }
 
-void strategic_solver_core::pop(unsigned n) {
+void strategic_solver::pop(unsigned n) {
     DEBUG_CODE({
             SASSERT(n <= m_num_scopes);
             m_num_scopes -= n;
@@ -214,13 +295,20 @@ void strategic_solver_core::pop(unsigned n) {
     init_inc_solver();
     if (m_inc_solver)
         m_inc_solver->pop(n);
+
+    SASSERT(m_ctx);
+    unsigned new_lvl = m_ctx->m_scopes.size() - n;
+    unsigned old_sz  = m_ctx->m_scopes[new_lvl];
+    m_ctx->m_assertions.shrink(old_sz);
+    if (m_produce_unsat_cores)
+        m_ctx->m_assertion_names.shrink(old_sz);
+    m_ctx->m_scopes.shrink(new_lvl);
 }
 
-unsigned strategic_solver_core::get_scope_level() const {
-    if (m_inc_solver)
-        return m_inc_solver->get_scope_level();
-    else
+unsigned strategic_solver::get_scope_level() const {
+    if (m_ctx == 0)
         return 0;
+    return m_ctx->m_assertions.size();
 }
 
 struct aux_timeout_eh : public event_handler {
@@ -233,10 +321,10 @@ struct aux_timeout_eh : public event_handler {
     }
 };
 
-struct strategic_solver_core::mk_tactic {
-    strategic_solver_core *  m_solver;
+struct strategic_solver::mk_tactic {
+    strategic_solver *  m_solver;
 
-    mk_tactic(strategic_solver_core * s, tactic_factory * f):m_solver(s) {
+    mk_tactic(strategic_solver * s, tactic_factory * f):m_solver(s) {
         ast_manager & m = s->m();
         params_ref p;
         front_end_params2params(*s->m_fparams, p);
@@ -259,14 +347,14 @@ struct strategic_solver_core::mk_tactic {
     }
 };
 
-tactic_factory * strategic_solver_core::get_tactic_factory() const {
+tactic_factory * strategic_solver::get_tactic_factory() const {
     tactic_factory * f = 0;
     if (m_logic2fct.find(m_logic, f))
         return f;
     return m_default_fct.get();
 }
 
-lbool strategic_solver_core::check_sat_with_assumptions(unsigned num_assumptions, expr * const * assumptions) {
+lbool strategic_solver::check_sat_with_assumptions(unsigned num_assumptions, expr * const * assumptions) {
     if (!m_inc_solver) {
         IF_VERBOSE(PS_VB_LVL, verbose_stream() << "incremental solver was not installed, returning unknown...\n";);
         m_use_inc_solver_results = false;
@@ -275,10 +363,16 @@ lbool strategic_solver_core::check_sat_with_assumptions(unsigned num_assumptions
     }
     init_inc_solver();
     m_use_inc_solver_results = true;
+    TRACE("strategic_solver", tout << "invoking inc_solver with " << num_assumptions << " assumptions\n";);
     return m_inc_solver->check_sat(num_assumptions, assumptions);
 }
 
-lbool strategic_solver_core::check_sat(unsigned num_assumptions, expr * const * assumptions) {
+lbool strategic_solver::check_sat(unsigned num_assumptions, expr * const * assumptions) {
+    TRACE("strategic_solver", tout << "assumptions at strategic_solver:\n";
+          for (unsigned i = 0; i < num_assumptions; i++) {
+              tout << mk_ismt2_pp(assumptions[i], m()) << "\n";
+          }
+          tout << "m_produce_unsat_cores: " << m_produce_unsat_cores << ", m_inc_mode: " << m_inc_mode << "\n";);
     reset_results();
     m_check_sat_executed = true;
     if (num_assumptions > 0 || // assumptions were provided
@@ -333,10 +427,18 @@ lbool strategic_solver_core::check_sat(unsigned num_assumptions, expr * const *
 
     goal_ref g = alloc(goal, m(), m_produce_proofs, m_produce_models, m_produce_unsat_cores);
     unsigned sz = get_num_assertions();
-    for (unsigned i = 0; i < sz; i++) {
-        g->assert_expr(get_assertion(i));
+    if (m_produce_unsat_cores) {
+        SASSERT(m_ctx->m_assertions.size() == m_ctx->m_assertion_names.size());
+        for (unsigned i = 0; i < sz; i++)
+            g->assert_expr(get_assertion(i), get_assertion_name(i));
+    }
+    else {
+        for (unsigned i = 0; i < sz; i++)
+            g->assert_expr(get_assertion(i));
     }
     expr_dependency_ref core(m());
+
+    TRACE("strategic_solver", tout << "using goal...\n"; g->display_with_dependencies(tout););
     
     mk_tactic tct_maker(this, factory);
     SASSERT(m_curr_tactic);
@@ -348,10 +450,14 @@ lbool strategic_solver_core::check_sat(unsigned num_assumptions, expr * const *
         m_proof = pr; 
         m().inc_ref(m_proof);
     }
+    if (core) {
+        m_core = core;
+        m().inc_ref(m_core);
+    }
     return r;
 }
 
-void strategic_solver_core::set_cancel(bool f) {
+void strategic_solver::set_cancel(bool f) {
     if (m_inc_solver)
         m_inc_solver->set_cancel(f);
     #pragma omp critical (strategic_solver)
@@ -361,14 +467,18 @@ void strategic_solver_core::set_cancel(bool f) {
     }
 }
 
-void strategic_solver_core::get_unsat_core(ptr_vector<expr> & r) {
+void strategic_solver::get_unsat_core(ptr_vector<expr> & r) {
+    TRACE("strategic_solver", tout << "get_unsat_core, m_use_inc_solver_results: " << m_use_inc_solver_results << "\n";);
     if (m_use_inc_solver_results) {
         SASSERT(m_inc_solver);
         m_inc_solver->get_unsat_core(r); 
     }
+    else {
+        m().linearize(m_core, r);
+    }
 }
 
-void strategic_solver_core::get_model(model_ref & m) {
+void strategic_solver::get_model(model_ref & m) {
     if (m_use_inc_solver_results) {
         SASSERT(m_inc_solver);
         m_inc_solver->get_model(m);
@@ -378,7 +488,7 @@ void strategic_solver_core::get_model(model_ref & m) {
     }
 }
 
-proof * strategic_solver_core::get_proof() {
+proof * strategic_solver::get_proof() {
     if (m_use_inc_solver_results) {
         SASSERT(m_inc_solver);
         return m_inc_solver->get_proof();
@@ -388,7 +498,7 @@ proof * strategic_solver_core::get_proof() {
     }
 }
 
-std::string strategic_solver_core::reason_unknown() const {
+std::string strategic_solver::reason_unknown() const {
     if (m_use_inc_solver_results) {
         SASSERT(m_inc_solver);
         return m_inc_solver->reason_unknown();
@@ -396,20 +506,20 @@ std::string strategic_solver_core::reason_unknown() const {
     return m_reason_unknown;
 }
 
-void strategic_solver_core::get_labels(svector<symbol> & r) {
+void strategic_solver::get_labels(svector<symbol> & r) {
     if (m_use_inc_solver_results) {
         SASSERT(m_inc_solver);
         m_inc_solver->get_labels(r);
     }
 }
 
-void strategic_solver_core::set_progress_callback(progress_callback * callback) { 
+void strategic_solver::set_progress_callback(progress_callback * callback) { 
     m_callback = callback; 
     if (m_inc_solver)
         m_inc_solver->set_progress_callback(callback);
 }
 
-void strategic_solver_core::display(std::ostream & out) const {
+void strategic_solver::display(std::ostream & out) const {
     if (m_manager) {
         unsigned num = get_num_assertions();
         out << "(solver";
@@ -424,50 +534,7 @@ void strategic_solver_core::display(std::ostream & out) const {
 }
 
 
-strategic_solver::ctx::ctx(ast_manager & m):m_assertions(m) {
-}
-
-void strategic_solver::init(ast_manager & m, symbol const & logic) {
-    strategic_solver_core::init(m, logic);
-    m_ctx = alloc(ctx, m);
-}
-
-unsigned strategic_solver::get_num_assertions() const {
-    if (m_ctx == 0)
-        return 0;
-    return m_ctx->m_assertions.size();
-}
-
-expr * strategic_solver::get_assertion(unsigned idx) const {
-    SASSERT(m_ctx);
-    return m_ctx->m_assertions.get(idx);
-}
-
-void strategic_solver::assert_expr(expr * t) {
-    SASSERT(m_ctx);
-    strategic_solver_core::assert_expr(t);
-    m_ctx->m_assertions.push_back(t);
-}
-
-void strategic_solver::push() {
-    SASSERT(m_ctx);
-    strategic_solver_core::push();
-    m_ctx->m_scopes.push_back(m_ctx->m_assertions.size());
-}
-
-void strategic_solver::pop(unsigned n) {
-    SASSERT(m_ctx);
-    unsigned new_lvl = m_ctx->m_scopes.size() - n;
-    unsigned old_sz  = m_ctx->m_scopes[new_lvl];
-    m_ctx->m_assertions.shrink(old_sz);
-    m_ctx->m_scopes.shrink(new_lvl);
-    strategic_solver_core::pop(n);
-}
-
-void strategic_solver::reset() {
-    m_ctx = 0;
-    strategic_solver_core::reset();
-}
+
 
 
 
diff --git a/src/solver/strategic_solver.h b/src/solver/strategic_solver.h
index 4d4a47388..e903e9bd0 100644
--- a/src/solver/strategic_solver.h
+++ b/src/solver/strategic_solver.h
@@ -46,7 +46,7 @@ struct front_end_params;
    It goes back to non_incremental mode when:
        - reset is invoked.
 */
-class strategic_solver_core : public solver {
+class strategic_solver : public solver {
 public:
     // Behavior when the incremental solver returns unknown.
     enum inc_unknown_behavior {
@@ -73,9 +73,18 @@ private:
     bool                 m_use_inc_solver_results;
     model_ref            m_model;
     proof *              m_proof;
+    expr_dependency *    m_core;
     std::string          m_reason_unknown;
     statistics           m_stats;
 
+    struct ctx {
+        expr_ref_vector         m_assertions;
+        expr_ref_vector         m_assertion_names;
+        unsigned_vector         m_scopes;
+        ctx(ast_manager & m);
+    };
+    scoped_ptr<ctx>             m_ctx;
+
 #ifdef Z3DEBUG
     unsigned             m_num_scopes;
 #endif
@@ -97,8 +106,8 @@ private:
     bool use_tactic_when_undef() const;
 
 public:
-    strategic_solver_core();
-    ~strategic_solver_core();
+    strategic_solver();
+    ~strategic_solver();
 
     ast_manager & m() const { SASSERT(m_manager); return *m_manager; }
 
@@ -114,19 +123,21 @@ public:
     virtual void updt_params(params_ref const & p);
     virtual void collect_param_descrs(param_descrs & r);
 
-    virtual void set_produce_proofs(bool f) { m_produce_proofs = f; }
-    virtual void set_produce_models(bool f) { m_produce_models = f; }
-    virtual void set_produce_unsat_cores(bool f) { m_produce_unsat_cores = f; }
+    virtual void set_produce_proofs(bool f);
+    virtual void set_produce_models(bool f);
+    virtual void set_produce_unsat_cores(bool f);
+
+    unsigned get_num_assertions() const;
+    expr * get_assertion(unsigned idx) const;
+    expr * get_assertion_name(unsigned idx) const;
 
-    virtual unsigned get_num_assertions() const = 0;
-    virtual expr * get_assertion(unsigned idx) const = 0;
-    
     virtual void display(std::ostream & out) const;
     
     virtual void init(ast_manager & m, symbol const & logic);
     virtual void collect_statistics(statistics & st) const;
     virtual void reset();
     virtual void assert_expr(expr * t);
+    virtual void assert_expr(expr * t, expr * a);
     virtual void push();
     virtual void pop(unsigned n);
     virtual unsigned get_scope_level() const;
@@ -140,30 +151,4 @@ public:
     virtual void set_progress_callback(progress_callback * callback);
 };
 
-/**
-   \brief Default implementation of strategic_solver_core
-*/
-class strategic_solver : public strategic_solver_core {
-    struct ctx {
-        expr_ref_vector              m_assertions;
-        unsigned_vector              m_scopes;
-        ctx(ast_manager & m);
-    };
-    scoped_ptr<ctx>            m_ctx;
-public:
-    strategic_solver() {}
-
-    virtual void init(ast_manager & m, symbol const & logic);
-
-    virtual void assert_expr(expr * t);
-    virtual void push();
-    virtual void pop(unsigned n);
-    virtual void reset();
-
-    virtual unsigned get_num_assertions() const;
-    virtual expr * get_assertion(unsigned idx) const;
-};
-
-
-
 #endif
diff --git a/src/solver/tactic2solver.cpp b/src/solver/tactic2solver.cpp
index 0747c7c9d..63308bd27 100644
--- a/src/solver/tactic2solver.cpp
+++ b/src/solver/tactic2solver.cpp
@@ -31,7 +31,7 @@ tactic2solver_core::ctx::ctx(ast_manager & m, symbol const & logic):
 tactic2solver_core::~tactic2solver_core() {
 }
 
-void tactic2solver_core::init(ast_manager & m, symbol const & logic) {
+void tactic2solver_core::init_core(ast_manager & m, symbol const & logic) {
     m_ctx = alloc(ctx, m, logic);
 }
 
@@ -62,7 +62,7 @@ void tactic2solver_core::collect_param_descrs(param_descrs & r) {
     }
 }
 
-void tactic2solver_core::reset() {
+void tactic2solver_core::reset_core() {
     SASSERT(m_ctx);
     m_ctx->m_assertions.reset();
     m_ctx->m_scopes.reset();
@@ -75,13 +75,13 @@ void tactic2solver_core::assert_expr(expr * t) {
     m_ctx->m_result = 0;
 }
 
-void tactic2solver_core::push() {
+void tactic2solver_core::push_core() {
     SASSERT(m_ctx);
     m_ctx->m_scopes.push_back(m_ctx->m_assertions.size());
     m_ctx->m_result = 0;
 }
 
-void tactic2solver_core::pop(unsigned n) {
+void tactic2solver_core::pop_core(unsigned n) {
     SASSERT(m_ctx);
     unsigned new_lvl = m_ctx->m_scopes.size() - n;
     unsigned old_sz  = m_ctx->m_scopes[new_lvl];
@@ -90,12 +90,7 @@ void tactic2solver_core::pop(unsigned n) {
     m_ctx->m_result = 0;
 }
 
-unsigned tactic2solver_core::get_scope_level() const {
-    SASSERT(m_ctx);
-    return m_ctx->m_scopes.size();
-}
-
-lbool tactic2solver_core::check_sat(unsigned num_assumptions, expr * const * assumptions) {
+lbool tactic2solver_core::check_sat_core(unsigned num_assumptions, expr * const * assumptions) {
     SASSERT(m_ctx);
     ast_manager & m = m_ctx->m();
     params_ref p = m_params;
diff --git a/src/solver/tactic2solver.h b/src/solver/tactic2solver.h
index fe92f3a7d..8cf3551b4 100644
--- a/src/solver/tactic2solver.h
+++ b/src/solver/tactic2solver.h
@@ -22,7 +22,7 @@ Notes:
 #ifndef _TACTIC2SOLVER_H_
 #define _TACTIC2SOLVER_H_
 
-#include"solver.h"
+#include"solver_na2as.h"
 #include"tactic.h"
 
 /**
@@ -32,7 +32,7 @@ Notes:
    option for applications trying to solve many easy queries that a
    similar to each other.
 */
-class tactic2solver_core : public solver {
+class tactic2solver_core : public solver_na2as {
     struct ctx {
         symbol                       m_logic;
         expr_ref_vector              m_assertions;
@@ -63,13 +63,13 @@ public:
     virtual void set_produce_models(bool f) { m_produce_models = f; }
     virtual void set_produce_unsat_cores(bool f) { m_produce_unsat_cores = f; }
 
-    virtual void init(ast_manager & m, symbol const & logic);
-    virtual void reset();
     virtual void assert_expr(expr * t);
-    virtual void push();
-    virtual void pop(unsigned n);
-    virtual unsigned get_scope_level() const;
-    virtual lbool check_sat(unsigned num_assumptions, expr * const * assumptions);
+
+    virtual void init_core(ast_manager & m, symbol const & logic);
+    virtual void reset_core();
+    virtual void push_core();
+    virtual void pop_core(unsigned n);
+    virtual lbool check_sat_core(unsigned num_assumptions, expr * const * assumptions);
 
     virtual void set_cancel(bool f);
 
diff --git a/src/tactic/core/propagate_values_tactic.cpp b/src/tactic/core/propagate_values_tactic.cpp
index 52637b1c3..9ab597dfa 100644
--- a/src/tactic/core/propagate_values_tactic.cpp
+++ b/src/tactic/core/propagate_values_tactic.cpp
@@ -209,6 +209,7 @@ class propagate_values_tactic : public tactic {
             result.push_back(m_goal);
             SASSERT(m_goal->is_well_sorted());
             TRACE("propagate_values", m_goal->display(tout););
+            TRACE("propagate_values_core", m_goal->display_with_dependencies(tout););
             m_goal = 0;
         }
     };
diff --git a/src/tactic/goal.cpp b/src/tactic/goal.cpp
index ad259f843..c6dad42b2 100644
--- a/src/tactic/goal.cpp
+++ b/src/tactic/goal.cpp
@@ -233,6 +233,10 @@ void goal::assert_expr(expr * f, proof * pr, expr_dependency * d) {
         quick_process(false, f, d);
 }
 
+void goal::assert_expr(expr * f, expr_dependency * d) {
+    assert_expr(f, proofs_enabled() ? m().mk_asserted(f) : 0, d);
+}
+
 void goal::get_formulas(ptr_vector<expr> & result) {
     unsigned sz = size();
     for (unsigned i = 0; i < sz; i++) {
diff --git a/src/tactic/goal.h b/src/tactic/goal.h
index 2b7162b85..294987699 100644
--- a/src/tactic/goal.h
+++ b/src/tactic/goal.h
@@ -105,9 +105,9 @@ public:
     void copy_from(goal const & src) { src.copy_to(*this); }
     
     void assert_expr(expr * f, proof * pr, expr_dependency * d);
-    void assert_expr(expr * f) {
-        assert_expr(f, proofs_enabled() ? m().mk_asserted(f) : 0, 0);
-    }
+    void assert_expr(expr * f, expr_dependency * d);
+    void assert_expr(expr * f, expr * d) { assert_expr(f, m().mk_leaf(d)); }
+    void assert_expr(expr * f) { assert_expr(f, static_cast<expr_dependency*>(0)); }
     
     unsigned size() const { return m().size(m_forms); }
 
diff --git a/src/tactic/portfolio/smt_strategic_solver.cpp b/src/tactic/portfolio/smt_strategic_solver.cpp
index 00c0afaa5..50d972a0d 100644
--- a/src/tactic/portfolio/smt_strategic_solver.cpp
+++ b/src/tactic/portfolio/smt_strategic_solver.cpp
@@ -18,8 +18,7 @@ Notes:
 
 --*/
 #include"cmd_context.h"
-#include"ni_solver.h"
-#include"strategic_solver_cmd.h"
+#include"strategic_solver.h"
 #include"qfbv_tactic.h"
 #include"qflia_tactic.h"
 #include"qfnia_tactic.h"
@@ -56,7 +55,7 @@ MK_SIMPLE_TACTIC_FACTORY(qfnra_fct, mk_qfnra_tactic(m, p));
 MK_SIMPLE_TACTIC_FACTORY(qffpa_fct, mk_qffpa_tactic(m, p));
 MK_SIMPLE_TACTIC_FACTORY(ufbv_fct, mk_ufbv_tactic(m, p));
 
-static void init(strategic_solver_core * s) {
+static void init(strategic_solver * s) {
     s->set_default_tactic(alloc(default_fct));
     s->set_tactic_for(symbol("QF_UF"),     alloc(qfuf_fct));
     s->set_tactic_for(symbol("QF_BV"),     alloc(qfbv_fct));
@@ -80,13 +79,6 @@ static void init(strategic_solver_core * s) {
     s->set_tactic_for(symbol("QF_FPA"),    alloc(qffpa_fct));
 }
 
-solver * mk_smt_strategic_solver(cmd_context & ctx) {
-    strategic_solver_cmd * s = alloc(strategic_solver_cmd, ctx);
-    s->set_inc_solver(mk_quasi_incremental_smt_solver(ctx));
-    init(s);
-    return s;
-}
-
 solver * mk_smt_strategic_solver(bool force_tactic) {
     strategic_solver * s = alloc(strategic_solver);
     s->force_tactic(force_tactic);
diff --git a/src/tactic/portfolio/smt_strategic_solver.h b/src/tactic/portfolio/smt_strategic_solver.h
index f3cc2e0e0..060721e09 100644
--- a/src/tactic/portfolio/smt_strategic_solver.h
+++ b/src/tactic/portfolio/smt_strategic_solver.h
@@ -20,9 +20,7 @@ Notes:
 #ifndef _SMT_STRATEGIC_SOLVER_H_
 #define _SMT_STRATEGIC_SOLVER_H_
 
-class cmd_context;
-// Create a strategic solver for the SMT 2.0 frontend.
-solver * mk_smt_strategic_solver(cmd_context & ctx);
+class solver;
 // Create a strategic solver for the Z3 API
 solver * mk_smt_strategic_solver(bool force_tactic=false);