From 3de8c193eaac44c8b5c6ce4e04af6efe19bb00de Mon Sep 17 00:00:00 2001
From: Nikolaj Bjorner <nbjorner@microsoft.com>
Date: Mon, 30 Oct 2017 16:11:51 -0500
Subject: [PATCH] implementing model updates

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
---
 src/ackermannization/ackr_model_converter.cpp |  5 ++
 .../lackr_model_converter_lazy.cpp            |  5 ++
 src/api/python/z3/z3.py                       | 15 ----
 src/ast/ast.cpp                               |  4 +
 src/ast/ast.h                                 |  2 +
 src/ast/ast_pp_util.cpp                       |  6 +-
 src/ast/ast_pp_util.h                         |  6 +-
 src/ast/ast_printer.cpp                       |  2 +-
 src/ast/ast_smt2_pp.cpp                       | 73 +++++++++++++---
 src/ast/ast_smt2_pp.h                         |  5 +-
 src/ast/ast_translation.h                     |  1 +
 src/cmd_context/cmd_context.cpp               | 15 +++-
 src/cmd_context/cmd_context.h                 | 20 +++--
 src/cmd_context/tactic_cmds.cpp               |  3 +-
 src/muz/base/dl_util.cpp                      | 15 ++--
 src/muz/spacer/spacer_itp_solver.h            |  2 +-
 src/muz/spacer/spacer_virtual_solver.h        |  2 +-
 src/muz/transforms/dl_mk_bit_blast.cpp        |  2 +
 src/muz/transforms/dl_mk_karr_invariants.cpp  |  2 +
 .../dl_mk_quantifier_abstraction.cpp          |  8 +-
 src/muz/transforms/dl_mk_scale.cpp            |  3 +
 src/muz/transforms/dl_mk_slice.cpp            |  4 +
 src/opt/opt_context.cpp                       |  2 +-
 src/opt/opt_context.h                         |  2 +-
 src/opt/opt_solver.cpp                        |  2 +-
 src/opt/opt_solver.h                          |  2 +-
 src/parsers/smt2/smt2parser.cpp               | 37 +++++++-
 src/sat/sat_model_converter.cpp               | 86 +++++++++----------
 src/sat/sat_model_converter.h                 | 11 ++-
 src/sat/sat_simplifier.cpp                    | 16 ++--
 src/sat/sat_solver/inc_sat_solver.cpp         | 15 +++-
 src/sat/tactic/goal2sat.cpp                   | 36 +++++---
 src/smt/smt_solver.cpp                        |  4 +-
 src/solver/check_sat_result.cpp               |  2 +-
 src/solver/check_sat_result.h                 | 12 ++-
 src/solver/combined_solver.cpp                |  2 +-
 src/solver/solver.cpp                         |  6 ++
 src/solver/solver.h                           | 21 ++---
 src/solver/solver2tactic.cpp                  | 11 +--
 src/solver/tactic2solver.cpp                  | 13 +--
 src/tactic/CMakeLists.txt                     |  1 +
 src/tactic/arith/degree_shift_tactic.cpp      | 66 ++++++--------
 src/tactic/arith/elim01_tactic.cpp            |  5 ++
 src/tactic/arith/eq2bv_tactic.cpp             | 12 ++-
 src/tactic/bv/dt2bv_tactic.cpp                | 27 ++----
 src/tactic/converter.h                        | 36 +++-----
 src/tactic/core/elim_uncnstr_tactic.cpp       |  6 +-
 src/tactic/core/pb_preprocess_tactic.cpp      | 14 ++-
 src/tactic/core/split_clause_tactic.cpp       |  2 +
 src/tactic/equiv_proof_converter.h            |  1 +
 src/tactic/extension_model_converter.cpp      | 25 +++---
 src/tactic/extension_model_converter.h        |  5 +-
 src/tactic/filter_model_converter.cpp         |  6 +-
 src/tactic/filter_model_converter.h           |  2 +-
 src/tactic/horn_subsume_model_converter.h     |  1 +
 src/tactic/model_converter.cpp                | 54 ++++++++++--
 src/tactic/model_converter.h                  | 14 ++-
 .../portfolio/bounded_int2bv_solver.cpp       |  2 +-
 src/tactic/portfolio/enum2bv_solver.cpp       |  2 +-
 src/tactic/portfolio/pb2bv_solver.cpp         |  2 +-
 src/tactic/replace_proof_converter.h          |  2 +
 src/tactic/tactic.cpp                         |  9 +-
 src/tactic/tactic.h                           |  2 +-
 63 files changed, 482 insertions(+), 294 deletions(-)

diff --git a/src/ackermannization/ackr_model_converter.cpp b/src/ackermannization/ackr_model_converter.cpp
index a7c021913..3cd86d2f1 100644
--- a/src/ackermannization/ackr_model_converter.cpp
+++ b/src/ackermannization/ackr_model_converter.cpp
@@ -62,6 +62,10 @@ public:
         }
     }
 
+    virtual void display(std::ostream & out) {
+        out << "(ackr-model-converter)\n";
+    }
+
 protected:
     ast_manager &             m;
     const ackr_info_ref       info;
@@ -144,6 +148,7 @@ void ackr_model_converter::add_entry(model_evaluator & evaluator,
     else {
         TRACE("ackr_model", tout << "entry already present\n";);
     }
+
 }
 
 model_converter * mk_ackr_model_converter(ast_manager & m, const ackr_info_ref& info) {
diff --git a/src/ackermannization/lackr_model_converter_lazy.cpp b/src/ackermannization/lackr_model_converter_lazy.cpp
index 2a7adb839..ffb4cae9d 100644
--- a/src/ackermannization/lackr_model_converter_lazy.cpp
+++ b/src/ackermannization/lackr_model_converter_lazy.cpp
@@ -48,6 +48,11 @@ public:
     virtual model_converter * translate(ast_translation & translator) {
         NOT_IMPLEMENTED_YET();
     }
+
+    virtual void display(std::ostream & out) {
+        out << "(lackr-model-converter)\n";
+    }
+
 protected:
     ast_manager&                       m;
     const lackr_model_constructor_ref  model_constructor;
diff --git a/src/api/python/z3/z3.py b/src/api/python/z3/z3.py
index ab6249ff6..b47873398 100644
--- a/src/api/python/z3/z3.py
+++ b/src/api/python/z3/z3.py
@@ -6279,21 +6279,6 @@ class Solver(Z3PPObject):
         consequences = [ consequences[i] for i in range(sz) ]
         return CheckSatResult(r), consequences
     
-    def lemmas(self):
-        """Extract auxiliary lemmas produced by solver"""
-        return AstVector(Z3_solver_get_lemmas(self.ctx.ref(), self.solver), self.ctx)
-        
-    def lookahead(self, candidates = None):
-        """Get lookahead literal"""
-        if candidates is None:
-            candidates = AstVector(None, self.ctx)
-        elif not isinstance(candidates, AstVector):
-            _cs = AstVector(None, self.ctx)
-            for c in candidates:
-                _asms.push(c)
-            candidates = _cs
-        return _to_expr_ref(Z3_solver_lookahead(self.ctx.ref(), self.solver, candidates), self.ctx)        
-
     def cube(self):
         """Get set of cubes"""
         rounds = 0
diff --git a/src/ast/ast.cpp b/src/ast/ast.cpp
index 232e7b6d0..c8de22899 100644
--- a/src/ast/ast.cpp
+++ b/src/ast/ast.cpp
@@ -1356,6 +1356,10 @@ ast_manager::ast_manager(ast_manager const & src, bool disable_proofs):
     copy_families_plugins(src);
 }
 
+void ast_manager::update_fresh_id(ast_manager const& m) {
+    m_fresh_id = std::max(m_fresh_id, m.m_fresh_id);
+}
+
 void ast_manager::init() {
     m_int_real_coercions = true;
     m_debug_ref_count = false;
diff --git a/src/ast/ast.h b/src/ast/ast.h
index 4eb43d30b..d1466e569 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -1435,6 +1435,8 @@ public:
 
     void show_id_gen();
 
+    void update_fresh_id(ast_manager const& other);
+
 protected:
     reslimit                  m_limit;
     small_object_allocator    m_alloc;
diff --git a/src/ast/ast_pp_util.cpp b/src/ast/ast_pp_util.cpp
index 455addf73..bbd1d0f41 100644
--- a/src/ast/ast_pp_util.cpp
+++ b/src/ast/ast_pp_util.cpp
@@ -36,7 +36,6 @@ void ast_pp_util::collect(expr_ref_vector const& es) {
 }
 
 void ast_pp_util::display_decls(std::ostream& out) {
-    smt2_pp_environment_dbg env(m);
     ast_smt_pp pp(m);
     unsigned n = coll.get_num_sorts();
     for (unsigned i = 0; i < n; ++i) {
@@ -46,7 +45,7 @@ void ast_pp_util::display_decls(std::ostream& out) {
     for (unsigned i = 0; i < n; ++i) {
         func_decl* f = coll.get_func_decls()[i];
         if (f->get_family_id() == null_family_id) {
-            ast_smt2_pp(out, f, env);
+            ast_smt2_pp(out, f, m_env);
             out << "\n";
         }
     }
@@ -54,10 +53,9 @@ void ast_pp_util::display_decls(std::ostream& out) {
 
 void ast_pp_util::display_asserts(std::ostream& out, expr_ref_vector const& fmls, bool neat) {
     if (neat) {
-        smt2_pp_environment_dbg env(m);
         for (expr* f : fmls) {
             out << "(assert ";
-            ast_smt2_pp(out, f, env);
+            ast_smt2_pp(out, f, m_env);
             out << ")\n";
         }
     }
diff --git a/src/ast/ast_pp_util.h b/src/ast/ast_pp_util.h
index 964a862a2..ead31a475 100644
--- a/src/ast/ast_pp_util.h
+++ b/src/ast/ast_pp_util.h
@@ -20,14 +20,16 @@ Revision History:
 #define AST_PP_UTIL_H_
 
 #include "ast/decl_collector.h"
+#include "ast/ast_smt2_pp.h"
 
 class ast_pp_util {
     ast_manager&        m;
+    smt2_pp_environment_dbg m_env;
  public:        
 
     decl_collector      coll;
 
-    ast_pp_util(ast_manager& m): m(m), coll(m, false) {}
+    ast_pp_util(ast_manager& m): m(m), m_env(m), coll(m, false) {}
 
     void collect(expr* e);
 
@@ -38,6 +40,8 @@ class ast_pp_util {
     void display_decls(std::ostream& out);
 
     void display_asserts(std::ostream& out, expr_ref_vector const& fmls, bool neat = true);
+
+    smt2_pp_environment& env() { return m_env; }
 };
 
 #endif /* AST_PP_UTIL_H_ */
diff --git a/src/ast/ast_printer.cpp b/src/ast/ast_printer.cpp
index b5cf60ee9..9e19e4bfe 100644
--- a/src/ast/ast_printer.cpp
+++ b/src/ast/ast_printer.cpp
@@ -34,7 +34,7 @@ public:
         out << f->get_name();
     }
     virtual void pp(sort * s, format_ns::format_ref & r) const { mk_smt2_format(s, env(), params_ref(), r); }
-    virtual void pp(func_decl * f, format_ns::format_ref & r) const { mk_smt2_format(f, env(), params_ref(), r); }
+    virtual void pp(func_decl * f, format_ns::format_ref & r) const { mk_smt2_format(f, env(), params_ref(), r, "declare-fun"); }
     virtual void pp(expr * n, format_ns::format_ref & r) const { 
         sbuffer<symbol> buf;
         mk_smt2_format(n, env(), params_ref(), 0, 0, r, buf); 
diff --git a/src/ast/ast_smt2_pp.cpp b/src/ast/ast_smt2_pp.cpp
index e093dc2ff..db66d9097 100644
--- a/src/ast/ast_smt2_pp.cpp
+++ b/src/ast/ast_smt2_pp.cpp
@@ -876,8 +876,21 @@ class smt2_printer {
         }
     }
 
+    void register_var_names(unsigned n) {
+        unsigned idx = 1;
+        for (unsigned i = 0; i < n; i++) {
+            symbol name = next_name("x", idx);            
+            SASSERT(!m_var_names_set.contains(name));
+            m_var_names.push_back(name);
+            m_var_names_set.insert(name);
+        }
+    }
+
     void unregister_var_names(quantifier * q) {
-        unsigned num_decls = q->get_num_decls();
+        unregister_var_names(q->get_num_decls());
+    }
+
+    void unregister_var_names(unsigned num_decls) {
         for (unsigned i = 0; i < num_decls; i++) {
             symbol s = m_var_names.back();
             m_var_names.pop_back();
@@ -885,25 +898,28 @@ class smt2_printer {
         }
     }
 
-    format * pp_var_decls(quantifier * q) {
+    format * pp_var_args(unsigned num_decls, sort* const* srts) {
         ptr_buffer<format> buf;
-        unsigned num_decls = q->get_num_decls();
         SASSERT(num_decls <= m_var_names.size());
         symbol * it = m_var_names.end() - num_decls;
         for (unsigned i = 0; i < num_decls; i++, it++) {
-            format * fs[1] = { m_env.pp_sort(q->get_decl_sort(i)) };
+            format * fs[1] = { m_env.pp_sort(srts[i]) };
             std::string var_name;
             if (is_smt2_quoted_symbol (*it)) {
                 var_name = mk_smt2_quoted_symbol (*it);
             }
             else {
-              var_name = it->str ();\
+                var_name = it->str ();          
             }
             buf.push_back(mk_seq1<format**,f2f>(m(), fs, fs+1, f2f(), var_name.c_str ()));
         }
         return mk_seq5(m(), buf.begin(), buf.end(), f2f());
     }
 
+    format * pp_var_decls(quantifier * q) {
+        return pp_var_args(q->get_num_decls(), q->get_decl_sorts());
+    }
+
     void process_quantifier(quantifier * q, frame & fr) {
         if (fr.m_idx == 0) {
             begin_scope();
@@ -1098,7 +1114,7 @@ public:
         r = m_env.pp_sort(s);
     }
 
-    void operator()(func_decl * f, format_ref & r) {
+    void operator()(func_decl * f, format_ref & r, char const* cmd) {
         unsigned arity = f->get_arity();
         unsigned len;
         format * fname = m_env.pp_fdecl_name(f, len);
@@ -1110,9 +1126,27 @@ public:
         }
         args[1] = mk_seq5<format**, f2f>(m(), buf.begin(), buf.end(), f2f());
         args[2] = m_env.pp_sort(f->get_range());
-        r = mk_seq1<format**, f2f>(m(), args, args+3, f2f(), "declare-fun");
+        r = mk_seq1<format**, f2f>(m(), args, args+3, f2f(), cmd); 
     }
 
+
+    void operator()(func_decl * f, expr * e, format_ref & r, char const* cmd) {
+        unsigned arity = f->get_arity();
+        unsigned len;
+        format * fname = m_env.pp_fdecl_name(f, len);
+        register_var_names(f->get_arity());        
+        format * args[4];
+        args[0] = fname;
+        args[1] = pp_var_args(f->get_arity(), f->get_domain());
+        args[2] = m_env.pp_sort(f->get_range());
+        process(e, r);
+        args[3] = r;
+        r = mk_seq1<format**, f2f>(m(), args, args+4, f2f(), cmd); 
+        unregister_var_names(f->get_arity());
+    }
+
+
+
 };
 
 void mk_smt2_format(expr * n, smt2_pp_environment & env, params_ref const & p,
@@ -1127,9 +1161,14 @@ void mk_smt2_format(sort * s, smt2_pp_environment & env, params_ref const & p, f
     pr(s, r);
 }
 
-void mk_smt2_format(func_decl * f, smt2_pp_environment & env, params_ref const & p, format_ref & r) {
+void mk_smt2_format(func_decl * f, smt2_pp_environment & env, params_ref const & p, format_ref & r, char const* cmd) {
     smt2_printer pr(env, p);
-    pr(f, r);
+    pr(f, r, cmd);
+}
+
+void mk_smt2_format(func_decl * f, expr * e, smt2_pp_environment & env, params_ref const & p, format_ref & r, char const* cmd) {
+    smt2_printer pr(env, p);
+    pr(f, e, r, cmd);
 }
 
 void mk_smt2_format(unsigned sz, expr * const* es, smt2_pp_environment & env, params_ref const & p,
@@ -1170,17 +1209,29 @@ std::ostream & ast_smt2_pp(std::ostream & out, sort * s, smt2_pp_environment & e
     return out;
 }
 
-std::ostream & ast_smt2_pp(std::ostream & out, func_decl * f, smt2_pp_environment & env, params_ref const & p, unsigned indent) {
+std::ostream & ast_smt2_pp(std::ostream & out, func_decl * f, smt2_pp_environment & env, params_ref const & p, unsigned indent, char const* cmd) {
     ast_manager & m = env.get_manager();
     format_ref r(fm(m));
     sbuffer<symbol> var_names;
-    mk_smt2_format(f, env, p, r);
+    mk_smt2_format(f, env, p, r, cmd);
     if (indent > 0)
         r = mk_indent(m, indent, r.get());
     pp(out, r.get(), m, p);
     return out;
 }
 
+std::ostream & ast_smt2_pp(std::ostream & out, func_decl * f, expr* e, smt2_pp_environment & env, params_ref const & p, unsigned indent, char const* cmd) {
+    ast_manager & m = env.get_manager();
+    format_ref r(fm(m));
+    sbuffer<symbol> var_names;
+    mk_smt2_format(f, e, env, p, r, cmd);
+    if (indent > 0)
+        r = mk_indent(m, indent, r.get());
+    pp(out, r.get(), m, p);
+    return out;
+}
+
+
 std::ostream & ast_smt2_pp(std::ostream & out, unsigned sz, expr * const* es, smt2_pp_environment & env, params_ref const & p, unsigned indent,
                             unsigned num_vars, char const * var_prefix) {
     ast_manager & m = env.get_manager();
diff --git a/src/ast/ast_smt2_pp.h b/src/ast/ast_smt2_pp.h
index 7a0267960..8a4b3d80a 100644
--- a/src/ast/ast_smt2_pp.h
+++ b/src/ast/ast_smt2_pp.h
@@ -97,12 +97,13 @@ void mk_smt2_format(expr * n, smt2_pp_environment & env, params_ref const & p,
                     unsigned num_vars, char const * var_prefix,
                     format_ns::format_ref & r, sbuffer<symbol> & var_names);
 void mk_smt2_format(sort * s, smt2_pp_environment & env, params_ref const & p, format_ns::format_ref & r);
-void mk_smt2_format(func_decl * f, smt2_pp_environment & env, params_ref const & p, format_ns::format_ref & r);
+void mk_smt2_format(func_decl * f, smt2_pp_environment & env, params_ref const & p, format_ns::format_ref & r, char const* cmd);
 
 std::ostream & ast_smt2_pp(std::ostream & out, expr * n, smt2_pp_environment & env, params_ref const & p = params_ref(), unsigned indent = 0, 
                            unsigned num_vars = 0, char const * var_prefix = 0);
 std::ostream & ast_smt2_pp(std::ostream & out, sort * s, smt2_pp_environment & env, params_ref const & p = params_ref(), unsigned indent = 0);
-std::ostream & ast_smt2_pp(std::ostream & out, func_decl * f, smt2_pp_environment & env, params_ref const & p = params_ref(), unsigned indent = 0);
+std::ostream & ast_smt2_pp(std::ostream & out, func_decl * f, smt2_pp_environment & env, params_ref const & p = params_ref(), unsigned indent = 0, char const* cmd = "declare-fun");
+std::ostream & ast_smt2_pp(std::ostream & out, func_decl * f, expr* e, smt2_pp_environment & env, params_ref const & p = params_ref(), unsigned indent = 0, char const* cmd = "define-fun");
 
 /**
    \brief Internal wrapper (for debugging purposes only)
diff --git a/src/ast/ast_translation.h b/src/ast/ast_translation.h
index b278791d7..886aaf417 100644
--- a/src/ast/ast_translation.h
+++ b/src/ast/ast_translation.h
@@ -52,6 +52,7 @@ public:
     ast_translation(ast_manager & from, ast_manager & to, bool copy_plugins = true) : m_from_manager(from), m_to_manager(to) {
         if (copy_plugins)
             m_to_manager.copy_families_plugins(m_from_manager);
+        m_to_manager.update_fresh_id(m_from_manager);
     }
 
     ~ast_translation();
diff --git a/src/cmd_context/cmd_context.cpp b/src/cmd_context/cmd_context.cpp
index ce6c4a65a..97c53d423 100644
--- a/src/cmd_context/cmd_context.cpp
+++ b/src/cmd_context/cmd_context.cpp
@@ -43,6 +43,7 @@ Notes:
 #include "model/model_v2_pp.h"
 #include "model/model_params.hpp"
 #include "tactic/tactic_exception.h"
+#include "tactic/generic_model_converter.h"
 #include "solver/smt_logics.h"
 #include "cmd_context/basic_cmds.h"
 #include "cmd_context/interpolant_cmds.h"
@@ -864,6 +865,17 @@ void cmd_context::insert(symbol const & s, object_ref * r) {
     m_object_refs.insert(s, r);
 }
 
+void cmd_context::model_add(symbol const & s, unsigned arity, sort *const* domain, expr * t) {
+    if (!m_mc0) m_mc0 = alloc(generic_model_converter, m());
+    func_decl_ref fn(m().mk_func_decl(s, arity, domain, m().get_sort(t)), m());
+    m_mc0->add(fn, t);
+}
+
+void cmd_context::model_del(func_decl* f) {
+    if (!m_mc0) m_mc0 = alloc(generic_model_converter, m());
+    m_mc0->hide(f);
+}
+
 void cmd_context::insert_rec_fun(func_decl* f, expr_ref_vector const& binding, svector<symbol> const& ids, expr* e) {
     expr_ref eq(m());
     app_ref lhs(m());
@@ -1573,6 +1585,7 @@ void cmd_context::display_dimacs() {
 
 void cmd_context::display_model(model_ref& mdl) {
     if (mdl) {
+        if (m_mc0) (*m_mc0)(mdl);
         model_params p;
         if (p.v1() || p.v2()) {
             std::ostringstream buffer;
@@ -1895,7 +1908,7 @@ void cmd_context::pp(expr * n, format_ns::format_ref & r) const {
 }
 
 void cmd_context::pp(func_decl * f, format_ns::format_ref & r) const {
-    mk_smt2_format(f, get_pp_env(), params_ref(), r);
+    mk_smt2_format(f, get_pp_env(), params_ref(), r, "declare-fun");
 }
 
 void cmd_context::display(std::ostream & out, sort * s, unsigned indent) const {
diff --git a/src/cmd_context/cmd_context.h b/src/cmd_context/cmd_context.h
index b60f590a9..48dd17cb0 100644
--- a/src/cmd_context/cmd_context.h
+++ b/src/cmd_context/cmd_context.h
@@ -23,20 +23,21 @@ Notes:
 
 #include<sstream>
 #include<vector>
-#include "ast/ast.h"
-#include "ast/ast_printer.h"
-#include "cmd_context/pdecl.h"
-#include "util/dictionary.h"
-#include "solver/solver.h"
-#include "ast/datatype_decl_plugin.h"
 #include "util/stopwatch.h"
 #include "util/cmd_context_types.h"
 #include "util/event_handler.h"
 #include "util/sexpr.h"
+#include "util/dictionary.h"
+#include "util/scoped_ptr_vector.h"
+#include "ast/ast.h"
+#include "ast/ast_printer.h"
+#include "ast/datatype_decl_plugin.h"
+#include "tactic/generic_model_converter.h"
+#include "solver/solver.h"
+#include "solver/progress_callback.h"
+#include "cmd_context/pdecl.h"
 #include "cmd_context/tactic_manager.h"
 #include "cmd_context/check_logic.h"
-#include "solver/progress_callback.h"
-#include "util/scoped_ptr_vector.h"
 #include "cmd_context/context_params.h"
 
 
@@ -303,6 +304,7 @@ protected:
     void erase_macro(symbol const& s);
     bool macros_find(symbol const& s, unsigned n, expr*const* args, expr*& t) const;
 
+    ref<generic_model_converter> m_mc0;
 
 public:
     cmd_context(bool main_ctx = true, ast_manager * m = 0, symbol const & l = symbol::null);
@@ -381,6 +383,8 @@ public:
     void insert_user_tactic(symbol const & s, sexpr * d);
     void insert_aux_pdecl(pdecl * p);
     void insert_rec_fun(func_decl* f, expr_ref_vector const& binding, svector<symbol> const& ids, expr* e);
+    void model_add(symbol const & s, unsigned arity, sort *const* domain, expr * t);
+    void model_del(func_decl* f);
     func_decl * find_func_decl(symbol const & s) const;
     func_decl * find_func_decl(symbol const & s, unsigned num_indices, unsigned const * indices,
                                unsigned arity, sort * const * domain, sort * range) const;
diff --git a/src/cmd_context/tactic_cmds.cpp b/src/cmd_context/tactic_cmds.cpp
index cbc90c62c..20a2b1c11 100644
--- a/src/cmd_context/tactic_cmds.cpp
+++ b/src/cmd_context/tactic_cmds.cpp
@@ -211,6 +211,7 @@ public:
         assert_exprs_from(ctx, *g);
         TRACE("check_sat_using", g->display(tout););
         model_ref           md;
+        model_converter_ref mc;
         proof_ref           pr(m);
         expr_dependency_ref core(m);
         std::string reason_unknown;
@@ -226,7 +227,7 @@ public:
                 cmd_context::scoped_watch sw(ctx);
                 lbool r = l_undef;
                 try {
-                    r = check_sat(t, g, md, result->labels, pr, core, reason_unknown);                    
+                    r = check_sat(t, g, md, mc, result->labels, pr, core, reason_unknown);                    
                     ctx.display_sat_result(r);
                     result->set_status(r);
                     if (r == l_undef) {
diff --git a/src/muz/base/dl_util.cpp b/src/muz/base/dl_util.cpp
index f0439a55c..463b78c4a 100644
--- a/src/muz/base/dl_util.cpp
+++ b/src/muz/base/dl_util.cpp
@@ -384,6 +384,7 @@ namespace datalog {
             return alloc(skip_model_converter);
         }
 
+        virtual void display(std::ostream & out) { }
     };
 
     model_converter* mk_skip_model_converter() { return alloc(skip_model_converter); }
@@ -398,6 +399,7 @@ namespace datalog {
             return alloc(skip_proof_converter);
         }
 
+        virtual void display(std::ostream & out) { out << "(skip-proof-converter)\n"; }
     };
 
     proof_converter* mk_skip_proof_converter() { return alloc(skip_proof_converter); }
@@ -508,10 +510,9 @@ namespace datalog {
     }
 
     void collect_and_transform(const unsigned_vector & src, const unsigned_vector & translation, 
-            unsigned_vector & res) {
-        unsigned n = src.size();
-        for(unsigned i=0; i<n; i++) {
-            unsigned translated = translation[src[i]];
+                               unsigned_vector & res) {
+        for (unsigned s : src) {
+            unsigned translated = translation[s];
             if(translated!=UINT_MAX) {
                 res.push_back(translated);
             }
@@ -520,10 +521,8 @@ namespace datalog {
 
 
     void transform_set(const unsigned_vector & map, const idx_set & src, idx_set & result) {
-        idx_set::iterator it = src.begin();
-        idx_set::iterator end = src.end();
-        for(; it!=end; ++it) {
-            result.insert(map[*it]);
+        for (unsigned s : src) {
+            result.insert(map[s]);
         }
     }
 
diff --git a/src/muz/spacer/spacer_itp_solver.h b/src/muz/spacer/spacer_itp_solver.h
index ec878af00..450e2f197 100644
--- a/src/muz/spacer/spacer_itp_solver.h
+++ b/src/muz/spacer/spacer_itp_solver.h
@@ -146,7 +146,7 @@ public:
     virtual void collect_statistics(statistics &st) const ;
     virtual void reset_statistics();
     virtual void get_unsat_core(ptr_vector<expr> &r);
-    virtual void get_model(model_ref &m) {m_solver.get_model(m);}
+    virtual void get_model_core(model_ref &m) {m_solver.get_model(m);}
     virtual proof *get_proof() {return m_solver.get_proof();}
     virtual std::string reason_unknown() const
     {return m_solver.reason_unknown();}
diff --git a/src/muz/spacer/spacer_virtual_solver.h b/src/muz/spacer/spacer_virtual_solver.h
index fafaf2020..613f85169 100644
--- a/src/muz/spacer/spacer_virtual_solver.h
+++ b/src/muz/spacer/spacer_virtual_solver.h
@@ -80,7 +80,7 @@ public:
     virtual void get_unsat_core(ptr_vector<expr> &r);
     virtual void assert_expr(expr *e);
     virtual void collect_statistics(statistics &st) const {}
-    virtual void get_model(model_ref &m) {m_context.get_model(m);}
+    virtual void get_model_core(model_ref &m) {m_context.get_model(m);}
     virtual proof* get_proof();
     virtual std::string reason_unknown() const
     {return m_context.last_failure_as_string();}
diff --git a/src/muz/transforms/dl_mk_bit_blast.cpp b/src/muz/transforms/dl_mk_bit_blast.cpp
index 3c8045e34..924b12eda 100644
--- a/src/muz/transforms/dl_mk_bit_blast.cpp
+++ b/src/muz/transforms/dl_mk_bit_blast.cpp
@@ -63,6 +63,8 @@ namespace datalog {
             return alloc(bit_blast_model_converter, m);
         }
 
+        virtual void display(std::ostream& out) { out << "(bit-blast-model-converter)\n"; }
+
         virtual void operator()(model_ref & model) {
             for (unsigned i = 0; i < m_new_funcs.size(); ++i) {
                 func_decl* p = m_new_funcs[i].get();
diff --git a/src/muz/transforms/dl_mk_karr_invariants.cpp b/src/muz/transforms/dl_mk_karr_invariants.cpp
index 48219eeb9..678c673a8 100644
--- a/src/muz/transforms/dl_mk_karr_invariants.cpp
+++ b/src/muz/transforms/dl_mk_karr_invariants.cpp
@@ -150,6 +150,8 @@ namespace datalog {
             return mc;
         }
 
+        virtual void display(std::ostream& out) { out << "(add-invariant-model-converter)\n"; }
+
     private:
         void mk_body(matrix const& M, expr_ref& body) {
             expr_ref_vector conj(m);
diff --git a/src/muz/transforms/dl_mk_quantifier_abstraction.cpp b/src/muz/transforms/dl_mk_quantifier_abstraction.cpp
index b171aaa7c..888e1ebb5 100644
--- a/src/muz/transforms/dl_mk_quantifier_abstraction.cpp
+++ b/src/muz/transforms/dl_mk_quantifier_abstraction.cpp
@@ -53,6 +53,8 @@ namespace datalog {
             return alloc(qa_model_converter, m);
         }
 
+        virtual void display(std::ostream& out) { display_add(out, m); }
+
         void insert(func_decl* old_p, func_decl* new_p, expr_ref_vector& sub, sort_ref_vector& sorts, svector<bool> const& bound) {
             m_old_funcs.push_back(old_p);
             m_new_funcs.push_back(new_p);
@@ -81,7 +83,11 @@ namespace datalog {
                     SASSERT(body);                    
                 }
                 else {
-                    body = m.mk_false();  
+                    expr_ref_vector args(m);
+                    for (unsigned i = 0; i < p->get_arity(); ++i) {
+                        args.push_back(m.mk_var(i, p->get_domain(i)));
+                    }
+                    body = m.mk_app(p, args.size(), args.c_ptr());
                 }
                 // Create quantifier wrapper around body.
 
diff --git a/src/muz/transforms/dl_mk_scale.cpp b/src/muz/transforms/dl_mk_scale.cpp
index 5bc10b957..5eeaaaeca 100644
--- a/src/muz/transforms/dl_mk_scale.cpp
+++ b/src/muz/transforms/dl_mk_scale.cpp
@@ -99,6 +99,9 @@ namespace datalog {
             UNREACHABLE();
             return 0;
         }
+
+        virtual void display(std::ostream& out) { out << "(scale-model-converter)\n"; }
+
     };
 
 
diff --git a/src/muz/transforms/dl_mk_slice.cpp b/src/muz/transforms/dl_mk_slice.cpp
index c094e5520..8b38335e0 100644
--- a/src/muz/transforms/dl_mk_slice.cpp
+++ b/src/muz/transforms/dl_mk_slice.cpp
@@ -283,6 +283,8 @@ namespace datalog {
             // this would require implementing translation for the dl_context.
             return 0;
         }
+
+        virtual void display(std::ostream& out) { out << "(slice-proof-converter)\n"; }
     };
 
     class mk_slice::slice_model_converter : public model_converter {
@@ -396,6 +398,8 @@ namespace datalog {
             return 0;
         }
 
+        virtual void display(std::ostream& out) { out << "(slice-model-converter)\n"; }
+
     };
    
     mk_slice::mk_slice(context & ctx):
diff --git a/src/opt/opt_context.cpp b/src/opt/opt_context.cpp
index 29470ba18..9c861eb49 100644
--- a/src/opt/opt_context.cpp
+++ b/src/opt/opt_context.cpp
@@ -331,7 +331,7 @@ namespace opt {
         }
     }
 
-    void context::get_model(model_ref& mdl) {
+    void context::get_model_core(model_ref& mdl) {
         mdl = m_model;
         fix_model(mdl);
     }
diff --git a/src/opt/opt_context.h b/src/opt/opt_context.h
index ad40db074..4fec5d452 100644
--- a/src/opt/opt_context.h
+++ b/src/opt/opt_context.h
@@ -184,7 +184,7 @@ namespace opt {
         virtual void set_hard_constraints(ptr_vector<expr> & hard);
         virtual lbool optimize();
         virtual void set_model(model_ref& _m) { m_model = _m; }
-        virtual void get_model(model_ref& _m);
+        virtual void get_model_core(model_ref& _m);
         virtual void get_box_model(model_ref& _m, unsigned index);
         virtual void fix_model(model_ref& _m);
         virtual void collect_statistics(statistics& stats) const;
diff --git a/src/opt/opt_solver.cpp b/src/opt/opt_solver.cpp
index 69b62083f..78ae2bbbb 100644
--- a/src/opt/opt_solver.cpp
+++ b/src/opt/opt_solver.cpp
@@ -296,7 +296,7 @@ namespace opt {
         }
     }
 
-    void opt_solver::get_model(model_ref & m) {
+    void opt_solver::get_model_core(model_ref & m) {
         m_context.get_model(m);
     }
     
diff --git a/src/opt/opt_solver.h b/src/opt/opt_solver.h
index 46b52e387..1f0a518b2 100644
--- a/src/opt/opt_solver.h
+++ b/src/opt/opt_solver.h
@@ -97,7 +97,7 @@ namespace opt {
         virtual void pop_core(unsigned n);
         virtual lbool check_sat_core(unsigned num_assumptions, expr * const * assumptions);        
         virtual void get_unsat_core(ptr_vector<expr> & r);
-        virtual void get_model(model_ref & _m);        
+        virtual void get_model_core(model_ref & _m);        
         virtual proof * get_proof();
         virtual std::string reason_unknown() const;
         virtual void set_reason_unknown(char const* msg);
diff --git a/src/parsers/smt2/smt2parser.cpp b/src/parsers/smt2/smt2parser.cpp
index b8ad7e610..446059227 100644
--- a/src/parsers/smt2/smt2parser.cpp
+++ b/src/parsers/smt2/smt2parser.cpp
@@ -96,6 +96,8 @@ namespace smt2 {
         symbol               m_check_sat;
         symbol               m_define_fun;
         symbol               m_define_const;
+        symbol               m_model_add;
+        symbol               m_model_del;
         symbol               m_declare_fun;
         symbol               m_declare_const;
         symbol               m_define_sort;
@@ -2179,9 +2181,9 @@ namespace smt2 {
             next();
         }
 
-        void parse_define_fun() {
+        void parse_define(bool is_fun) {
             SASSERT(curr_is_identifier());
-            SASSERT(curr_id() == m_define_fun);
+            SASSERT(curr_id() == (is_fun ? m_define_fun : m_model_add));
             SASSERT(m_num_bindings == 0);
             next();
             check_identifier("invalid function/constant definition, symbol expected");
@@ -2195,7 +2197,10 @@ namespace smt2 {
             parse_expr();
             if (m().get_sort(expr_stack().back()) != sort_stack().back())
                 throw parser_exception("invalid function/constant definition, sort mismatch");
-            m_ctx.insert(id, num_vars, sort_stack().c_ptr() + sort_spos, expr_stack().back());
+            if (is_fun) 
+                m_ctx.insert(id, num_vars, sort_stack().c_ptr() + sort_spos, expr_stack().back());
+            else 
+                m_ctx.model_add(id, num_vars, sort_stack().c_ptr() + sort_spos, expr_stack().back());
             check_rparen("invalid function/constant definition, ')' expected");
             // restore stacks & env
             symbol_stack().shrink(sym_spos);
@@ -2208,6 +2213,22 @@ namespace smt2 {
             next();
         }
 
+        void parse_define_fun() {
+            parse_define(true);
+        }
+
+        void parse_model_add() {
+            parse_define(false);
+        }
+
+        void parse_model_del() {
+            func_decl* f = parse_func_decl_ref();
+            check_rparen("invalid model-del, ')' expected");
+            m_ctx.model_del(f);
+            m_ctx.print_success();
+            next();
+        }
+
         void parse_define_fun_rec() {
             // ( define-fun-rec hfun_defi )
             SASSERT(curr_is_identifier());
@@ -2910,6 +2931,14 @@ namespace smt2 {
                 parse_define_funs_rec();
                 return;
             }
+            if (s == m_model_add) {
+                parse_model_add();
+                return;
+            }
+            if (s == m_model_del) {
+                parse_model_del();
+                return;
+            }
             parse_ext_cmd(line, pos);
         }
 
@@ -2941,6 +2970,8 @@ namespace smt2 {
             m_check_sat("check-sat"),
             m_define_fun("define-fun"),
             m_define_const("define-const"),
+            m_model_add("model-add"),
+            m_model_del("model-del"),
             m_declare_fun("declare-fun"),
             m_declare_const("declare-const"),
             m_define_sort("define-sort"),
diff --git a/src/sat/sat_model_converter.cpp b/src/sat/sat_model_converter.cpp
index 2cc9ceffc..7339f966d 100644
--- a/src/sat/sat_model_converter.cpp
+++ b/src/sat/sat_model_converter.cpp
@@ -295,51 +295,6 @@ namespace sat {
         return out;
     }
 
-    void model_converter::validate_is_blocked(entry const& e, clause const& c) {
-        if (c.is_blocked() || c.is_learned()) return;
-        unsigned index = 0;
-        literal lit = null_literal;
-        bool_var v = e.var();
-        for (literal l : c) {
-            if (l.var() == v) {
-                lit = l;
-                break;
-            }
-        }
-        if (lit == null_literal) return;
-
-        bool sat = false;
-        for (literal l : e.m_clauses) {
-            if (l == null_literal) {
-                if (!sat) {
-                    display(std::cout << "clause is not blocked\n", e) << "\n";
-                    std::cout << c << "\n";
-                }
-                sat = false;
-                elim_stack* st = e.m_elim_stack[index];
-                if (st) {
-                    elim_stackv const& stack = st->stack();
-                    unsigned sz = stack.size();
-                    for (unsigned i = sz; i-- > 0; ) {
-                        // verify ...
-                    }
-
-                }
-                ++index;
-                continue;
-            }
-            if (sat) {
-                continue;
-            }
-            if (l.var() == v) {
-                sat = l == lit;
-            }
-            else {
-                sat = c.contains(~l);
-            }
-        }
-    }
-
     void model_converter::copy(model_converter const & src) {
         reset();
         m_entries.append(src.m_entries);
@@ -362,4 +317,45 @@ namespace sat {
         return result;
     }
 
+    void model_converter::expand(vector<literal_vector>& update_stack) {
+        literal_vector clause;
+        for (entry const& e : m_entries) {
+            clause.reset();
+            unsigned index = 0;
+            bool var_sign = false;
+            for (literal l : e.m_clauses) {
+                if (l == null_literal) {
+                    elim_stack* st = e.m_elim_stack[index];                    
+                    if (st) {
+                        // clause sizes increase
+                        elim_stackv const& stack = st->stack();
+                        unsigned sz = stack.size();
+                        for (unsigned i = 0; i < sz; ++i) {
+                            unsigned csz = stack[i].first;
+                            literal lit = stack[i].second;
+                            BOOL found = false;
+                            unsigned j = 0;
+                            for (j = 0; j < csz; ++j) {
+                                if (clause[j] == lit) {
+                                    std::swap(clause[j], clause[0]);
+                                    found = true;
+                                    break;
+                                }
+                            }
+                            SASSERT(found);
+                            update_stack.push_back(literal_vector(csz, clause.c_ptr()));
+                        }
+                    }
+                    update_stack.push_back(clause);
+                    clause.reset();
+                    continue;
+                }
+                clause.push_back(l);
+                if (l.var() == e.var()) {
+                    std::swap(clause[0], clause.back());
+                }
+            }
+        }
+    }
+
 };
diff --git a/src/sat/sat_model_converter.h b/src/sat/sat_model_converter.h
index cdd8c60ed..a6f1f0bbe 100644
--- a/src/sat/sat_model_converter.h
+++ b/src/sat/sat_model_converter.h
@@ -84,8 +84,6 @@ namespace sat {
 
         std::ostream& display(std::ostream & out, entry const& entry) const;
 
-        void validate_is_blocked(entry const& e, clause const& c);
-
     public:
         model_converter();
         ~model_converter();
@@ -109,6 +107,15 @@ namespace sat {
         void copy(model_converter const & src);
         void collect_vars(bool_var_set & s) const;
         unsigned max_var(unsigned min) const;
+        /*
+         * \brief expand entries to a list of clauses, such that
+         *  the first literal in each clause is the literal whose
+         *  truth value is updated as follows:
+         *  
+         *     lit0 := lit0 or (~lit1 & ~lit2 & ... & ~lit_k)
+         *  
+         */
+        void expand(vector<literal_vector>& update_stack);
     };
 
 };
diff --git a/src/sat/sat_simplifier.cpp b/src/sat/sat_simplifier.cpp
index 820000b4c..e2e035dfb 100644
--- a/src/sat/sat_simplifier.cpp
+++ b/src/sat/sat_simplifier.cpp
@@ -1318,7 +1318,7 @@ namespace sat {
 
         void prepare_block_clause(clause& c, literal l, model_converter::entry*& new_entry, model_converter::kind k) {
             TRACE("blocked_clause", tout << "new blocked clause: " << c << "\n";);
-            if (new_entry == 0)
+            if (new_entry == 0 && !s.m_retain_blocked_clauses)
                 new_entry = &(mc.mk(k, l.var()));
             m_to_remove.push_back(&c);
             for (literal lit : c) {
@@ -1330,17 +1330,19 @@ namespace sat {
 
         void block_clause(clause& c, literal l, model_converter::entry *& new_entry) {
             prepare_block_clause(c, l, new_entry, model_converter::BLOCK_LIT);
-            mc.insert(*new_entry, c);
+            if (!s.m_retain_blocked_clauses) 
+                mc.insert(*new_entry, c);
         }
 
         void block_covered_clause(clause& c, literal l, model_converter::kind k) {
             model_converter::entry * new_entry = 0;
             prepare_block_clause(c, l, new_entry, k);
-            mc.insert(*new_entry, m_covered_clause, m_elim_stack);
+            if (!s.m_retain_blocked_clauses) 
+                mc.insert(*new_entry, m_covered_clause, m_elim_stack);
         }
         
         void prepare_block_binary(watch_list::iterator it, literal l1, literal blocked, model_converter::entry*& new_entry, model_converter::kind k) {
-            if (new_entry == 0) 
+            if (new_entry == 0 && !s.m_retain_blocked_clauses) 
                 new_entry = &(mc.mk(k, blocked.var()));
             literal l2 = it->get_literal();
             TRACE("blocked_clause", tout << "new blocked clause: " << l2 << " " << l1 << "\n";);
@@ -1356,13 +1358,15 @@ namespace sat {
         
         void block_binary(watch_list::iterator it, literal l, model_converter::entry *& new_entry) {
             prepare_block_binary(it, l, l, new_entry, model_converter::BLOCK_LIT);
-            mc.insert(*new_entry, l, it->get_literal());
+            if (!s.m_retain_blocked_clauses) 
+                mc.insert(*new_entry, l, it->get_literal());
         }
 
         void block_covered_binary(watch_list::iterator it, literal l, literal blocked, model_converter::kind k) {
             model_converter::entry * new_entry = 0;
             prepare_block_binary(it, l, blocked, new_entry, k);
-            mc.insert(*new_entry, m_covered_clause, m_elim_stack);
+            if (!s.m_retain_blocked_clauses) 
+                mc.insert(*new_entry, m_covered_clause, m_elim_stack);
         }
 
         void bca() {
diff --git a/src/sat/sat_solver/inc_sat_solver.cpp b/src/sat/sat_solver/inc_sat_solver.cpp
index 44dc414af..218646de3 100644
--- a/src/sat/sat_solver/inc_sat_solver.cpp
+++ b/src/sat/sat_solver/inc_sat_solver.cpp
@@ -114,6 +114,7 @@ public:
         if (m_mc0.get()) result->m_mc0 = m_mc0->translate(tr);
         result->m_internalized = m_internalized;
         result->m_internalized_converted = m_internalized_converted;
+        if (mc0()) result->set_model_converter(mc0()->translate(tr));
         return result;
     }
 
@@ -299,7 +300,7 @@ public:
         r.reset();
         r.append(m_core.size(), m_core.c_ptr());
     }
-    virtual void get_model(model_ref & mdl) {
+    virtual void get_model_core(model_ref & mdl) {
         if (!m_model.get()) {
             extract_model();
         }
@@ -442,6 +443,18 @@ public:
         return m_asmsf[idx];
     }
 
+    virtual model_converter_ref get_model_converter() const {
+        if (m_internalized && m_internalized_converted) {
+            NOT_IMPLEMENTED_YET();
+            model_converter_ref mc = concat(m_mc0.get(), mk_bit_blaster_model_converter(m, m_bb_rewriter->const2bits()));
+            mc = concat(solver::get_model_converter().get(), mc.get());
+            return mc;
+        }
+        else {
+            return solver::get_model_converter();
+        }
+    }
+
     void convert_internalized() {
         if (!m_internalized) return;
         sat2goal s2g;
diff --git a/src/sat/tactic/goal2sat.cpp b/src/sat/tactic/goal2sat.cpp
index 1270b67c2..8daeb7ec0 100644
--- a/src/sat/tactic/goal2sat.cpp
+++ b/src/sat/tactic/goal2sat.cpp
@@ -968,21 +968,31 @@ struct sat2goal::imp {
             return res;
         }
         
-        void display(std::ostream & out) {
-            out << "(sat-model-converter\n";
-            m_mc.display(out);
-            sat::bool_var_set vars;
-            m_mc.collect_vars(vars);
-            out << "(atoms";
-            unsigned sz = m_var2expr.size();
-            for (unsigned i = 0; i < sz; i++) {
-                if (vars.contains(i)) {
-                    out << "\n (" << i << "\n  " << mk_ismt2_pp(m_var2expr.get(i), m(), 2) << ")";
-                }
+        expr_ref lit2expr(sat::literal l) {
+            expr_ref result(m_var2expr.get(l.var()), m());
+            if (l.sign()) {
+                result = m().mk_not(result);
+            }
+            return result;
+        }
+
+        void display(std::ostream & out) {
+            vector<sat::literal_vector> updates;
+            m_mc.expand(updates);
+            for (sat::literal_vector const& clause : updates) {
+                expr_ref_vector tail(m());
+                sat::literal lit0 = clause[0];
+                for (unsigned i = 1; i < clause.size(); ++i) {
+                    tail.push_back(lit2expr(~clause[i]));
+                }
+                expr_ref def(m().mk_or(lit2expr(lit0), mk_and(tail)), m());
+                if (lit0.sign()) {
+                    lit0.neg();
+                    def = m().mk_not(def);
+                }
+                display_add(out, m(), to_app(lit2expr(lit0))->get_decl(), def);
             }
-            out << ")\n";
             m_fmc->display(out);
-            out << ")\n";
         }
     };
 
diff --git a/src/smt/smt_solver.cpp b/src/smt/smt_solver.cpp
index 9f411b0e6..b7a686a71 100644
--- a/src/smt/smt_solver.cpp
+++ b/src/smt/smt_solver.cpp
@@ -70,6 +70,8 @@ namespace smt {
                 result->m_name2assertion.insert(translator(kv.m_key),
                                                 translator(kv.m_value));
 
+            if (mc0()) 
+                result->set_model_converter(mc0()->translate(translator));
             return result;
         }
 
@@ -186,7 +188,7 @@ namespace smt {
                 add_nonlocal_pattern_literals_to_core(r);
         }
 
-        virtual void get_model(model_ref & m) {
+        virtual void get_model_core(model_ref & m) {
             m_context.get_model(m);
         }
 
diff --git a/src/solver/check_sat_result.cpp b/src/solver/check_sat_result.cpp
index f1bedfc08..1308c52de 100644
--- a/src/solver/check_sat_result.cpp
+++ b/src/solver/check_sat_result.cpp
@@ -53,7 +53,7 @@ void simple_check_sat_result::get_unsat_core(ptr_vector<expr> & r) {
         r.append(m_core.size(), m_core.c_ptr()); 
 }
  
-void simple_check_sat_result::get_model(model_ref & m) { 
+void simple_check_sat_result::get_model_core(model_ref & m) { 
     if (m_status != l_false) 
         m = m_model; 
     else 
diff --git a/src/solver/check_sat_result.h b/src/solver/check_sat_result.h
index 38720a5e9..572c4d88d 100644
--- a/src/solver/check_sat_result.h
+++ b/src/solver/check_sat_result.h
@@ -23,6 +23,7 @@ Notes:
 #include "util/lbool.h"
 #include "util/statistics.h"
 #include "util/event_handler.h"
+#include "tactic/model_converter.h"
 
 /**
    \brief Abstract interface for the result of a (check-sat) like command.
@@ -40,6 +41,7 @@ class check_sat_result {
 protected:
     unsigned    m_ref_count;
     lbool       m_status; 
+    model_converter_ref m_mc0;
 public:
     check_sat_result():m_ref_count(0), m_status(l_undef) {}
     virtual ~check_sat_result() {}
@@ -54,7 +56,13 @@ public:
         get_unsat_core(core);
         r.append(core.size(), core.c_ptr());
     }
-    virtual void get_model(model_ref & m) = 0;
+    void set_model_converter(model_converter* mc) { m_mc0 = mc; }
+    model_converter* mc0() { return m_mc0.get(); }
+    virtual void get_model_core(model_ref & m) = 0;
+    void get_model(model_ref & m) {
+        get_model_core(m);
+        if (m && mc0()) (*mc0())(m);
+    }
     virtual proof * get_proof() = 0;
     virtual std::string reason_unknown() const = 0;
     virtual void set_reason_unknown(char const* msg) = 0;
@@ -80,7 +88,7 @@ struct simple_check_sat_result : public check_sat_result {
     virtual ast_manager& get_manager() const { return m_proof.get_manager(); }
     virtual void collect_statistics(statistics & st) const;
     virtual void get_unsat_core(ptr_vector<expr> & r);
-    virtual void get_model(model_ref & m);
+    virtual void get_model_core(model_ref & m);
     virtual proof * get_proof();
     virtual std::string reason_unknown() const;
     virtual void get_labels(svector<symbol> & r);
diff --git a/src/solver/combined_solver.cpp b/src/solver/combined_solver.cpp
index 9a685d5b3..6888dd406 100644
--- a/src/solver/combined_solver.cpp
+++ b/src/solver/combined_solver.cpp
@@ -307,7 +307,7 @@ public:
             m_solver2->get_unsat_core(r);
     }
 
-    virtual void get_model(model_ref & m) {
+    virtual void get_model_core(model_ref & m) {
         if (m_use_solver1_results)
             m_solver1->get_model(m);
         else
diff --git a/src/solver/solver.cpp b/src/solver/solver.cpp
index 0f5a72831..122bb2933 100644
--- a/src/solver/solver.cpp
+++ b/src/solver/solver.cpp
@@ -22,6 +22,7 @@ Notes:
 #include "ast/ast_pp.h"
 #include "ast/ast_pp_util.h"
 #include "util/common_msgs.h"
+#include "tactic/model_converter.h"
 
 
 unsigned solver::get_num_assertions() const {
@@ -41,6 +42,11 @@ std::ostream& solver::display(std::ostream & out) const {
     visitor.collect(fmls);
     visitor.display_decls(out);
     visitor.display_asserts(out, fmls, true);
+    model_converter_ref mc = get_model_converter();
+    if (mc.get()) {
+        mc->set_pp_env(&visitor.env());
+        mc->display(out);
+    }
     return out;
 }
 
diff --git a/src/solver/solver.h b/src/solver/solver.h
index 6171f111f..0f64c943d 100644
--- a/src/solver/solver.h
+++ b/src/solver/solver.h
@@ -24,6 +24,7 @@ Notes:
 #include "util/params.h"
 
 class solver;
+class model_converter;
 
 class solver_factory {
 public:
@@ -184,25 +185,17 @@ public:
 
     virtual expr_ref cube() = 0;
 
-#if 0
-    /**
-       \brief extract a lookahead candidates for branching.
-    */
-
-    virtual expr_ref lookahead(expr_ref_vector const& assumptions, expr_ref_vector const& candidates) = 0;
-
-
-    /**
-       \brief extract learned lemmas.
-    */
-    virtual void get_lemmas(expr_ref_vector& lemmas) {}
-#endif
-
     /**
        \brief Display the content of this solver.
     */
     virtual std::ostream& display(std::ostream & out) const;
 
+    /**
+       \brief expose model converter when solver produces partially reduced set of assertions.
+     */
+
+    virtual model_converter_ref get_model_converter() const { return m_mc0; }
+
     class scoped_push {
         solver& s;
         bool    m_nopop;
diff --git a/src/solver/solver2tactic.cpp b/src/solver/solver2tactic.cpp
index 4f7b750f8..eea3aa9c5 100644
--- a/src/solver/solver2tactic.cpp
+++ b/src/solver/solver2tactic.cpp
@@ -122,6 +122,7 @@ public:
                 local_solver->get_model(mdl);
                 mc = model2model_converter(mdl.get());
                 mc = concat(fmc.get(), mc.get());
+                mc = concat(local_solver->mc0(), mc.get());
             }
             in->reset();
             result.push_back(in.get());
@@ -150,14 +151,8 @@ public:
             if (m.canceled()) {
                 throw tactic_exception(Z3_CANCELED_MSG);
             }
-            if (in->models_enabled()) {
-                model_ref mdl;
-                local_solver->get_model(mdl);
-                if (mdl) {
-                    mc = model2model_converter(mdl.get());
-                    mc = concat(fmc.get(), mc.get());
-                }
-            }
+            mc = local_solver->get_model_converter();                
+            mc = concat(fmc.get(), mc.get());            
             in->reset();
             unsigned sz = local_solver->get_num_assertions();
             for (unsigned i = 0; i < sz; ++i) {
diff --git a/src/solver/tactic2solver.cpp b/src/solver/tactic2solver.cpp
index 0286197fa..1dd48fb9c 100644
--- a/src/solver/tactic2solver.cpp
+++ b/src/solver/tactic2solver.cpp
@@ -36,6 +36,7 @@ class tactic2solver : public solver_na2as {
     unsigned_vector              m_scopes;
     ref<simple_check_sat_result> m_result;
     tactic_ref                   m_tactic;
+    ref<model_converter>         m_mc;
     symbol                       m_logic;
     params_ref                   m_params;
     bool                         m_produce_models;
@@ -64,7 +65,7 @@ public:
 
     virtual void collect_statistics(statistics & st) const;
     virtual void get_unsat_core(ptr_vector<expr> & r);
-    virtual void get_model(model_ref & m);
+    virtual void get_model_core(model_ref & m);
     virtual proof * get_proof();
     virtual std::string reason_unknown() const;
     virtual void set_reason_unknown(char const* msg);
@@ -82,6 +83,8 @@ public:
         return expr_ref(m.mk_true(), m);
     }
 
+    virtual model_converter* get_model_converter() { return m_mc.get(); }
+
 };
 
 ast_manager& tactic2solver::get_manager() const { return m_assertions.get_manager(); }
@@ -153,12 +156,12 @@ lbool tactic2solver::check_sat_core(unsigned num_assumptions, expr * const * ass
     }
 
     model_ref           md;
-    proof_ref           pr(m);
+    proof_ref           pr(m);    
     expr_dependency_ref core(m);
     std::string         reason_unknown = "unknown";
     labels_vec labels;
     try {
-        switch (::check_sat(*m_tactic, g, md, labels, pr, core, reason_unknown)) {
+        switch (::check_sat(*m_tactic, g, md, m_mc, labels, pr, core, reason_unknown)) {
         case l_true: 
             m_result->set_status(l_true);
             break;
@@ -226,9 +229,9 @@ void tactic2solver::get_unsat_core(ptr_vector<expr> & r) {
     }
 }
 
-void tactic2solver::get_model(model_ref & m) {
+void tactic2solver::get_model_core(model_ref & m) {
     if (m_result.get())
-        m_result->get_model(m);
+        m_result->get_model_core(m);
 }
 
 proof * tactic2solver::get_proof() {
diff --git a/src/tactic/CMakeLists.txt b/src/tactic/CMakeLists.txt
index e7cfdb644..74379b30f 100644
--- a/src/tactic/CMakeLists.txt
+++ b/src/tactic/CMakeLists.txt
@@ -3,6 +3,7 @@ z3_add_component(tactic
     equiv_proof_converter.cpp
     extension_model_converter.cpp
     filter_model_converter.cpp
+    generic_model_converter.cpp
     goal.cpp
     goal_num_occurs.cpp
     goal_shared_occs.cpp
diff --git a/src/tactic/arith/degree_shift_tactic.cpp b/src/tactic/arith/degree_shift_tactic.cpp
index 6344c4c51..80b7a416c 100644
--- a/src/tactic/arith/degree_shift_tactic.cpp
+++ b/src/tactic/arith/degree_shift_tactic.cpp
@@ -21,7 +21,7 @@ Revision History:
 --*/
 #include "tactic/tactical.h"
 #include "tactic/filter_model_converter.h"
-#include "tactic/extension_model_converter.h"
+#include "tactic/generic_model_converter.h"
 #include "util/cooperate.h"
 #include "ast/arith_decl_plugin.h"
 #include "tactic/core/simplify_tactic.h"
@@ -127,9 +127,7 @@ class degree_shift_tactic : public tactic {
 
         void visit_args(expr * t, expr_fast_mark1 & visited) {
             if (is_app(t)) {
-                unsigned num_args = to_app(t)->get_num_args();
-                for (unsigned i = 0; i < num_args; i++) {
-                    expr * arg = to_app(t)->get_arg(i);
+                for (expr * arg : *to_app(t)) {
                     save_degree(arg, m_one);
                     visit(arg, visited);
                 }
@@ -166,11 +164,9 @@ class degree_shift_tactic : public tactic {
 
         void display_candidates(std::ostream & out) {
             out << "candidates:\n";
-            obj_map<app, rational>::iterator it  = m_var2degree.begin();
-            obj_map<app, rational>::iterator end = m_var2degree.end();
-            for (; it != end; ++it) {
-                if (!it->m_value.is_one()) {
-                    out << "POWER: " << it->m_value << "\n" << mk_ismt2_pp(it->m_key, m) << "\n";
+            for (auto const& kv : m_var2degree) {
+                if (!kv.m_value.is_one()) {
+                    out << "POWER: " << kv.m_value << "\n" << mk_ismt2_pp(kv.m_key, m) << "\n";
                 }
             }
         }
@@ -189,48 +185,42 @@ class degree_shift_tactic : public tactic {
         void discard_non_candidates() {
             m_pinned.reset();
             ptr_vector<app> to_delete;
-            obj_map<app, rational>::iterator it  = m_var2degree.begin();
-            obj_map<app, rational>::iterator end = m_var2degree.end();
-            for (; it != end; ++it) {
-                if (it->m_value.is_one())
-                    to_delete.push_back(it->m_key);
+            for (auto const& kv : m_var2degree) {
+                if (kv.m_value.is_one())
+                    to_delete.push_back(kv.m_key);
                 else
-                    m_pinned.push_back(it->m_key); // make sure it is not deleted during simplifications
+                    m_pinned.push_back(kv.m_key); // make sure it is not deleted during simplifications
             }
-            ptr_vector<app>::iterator it2  = to_delete.begin();
-            ptr_vector<app>::iterator end2 = to_delete.end();
-            for (; it2 != end2; ++it2) 
-                m_var2degree.erase(*it2);
+            for (app* a : to_delete) 
+                m_var2degree.erase(a);
         }
 
         void prepare_substitution(model_converter_ref & mc) {
             SASSERT(!m_var2degree.empty());
             filter_model_converter * fmc = 0;
-            extension_model_converter * xmc = 0;
+            generic_model_converter * xmc = 0;
             if (m_produce_models) {
                 fmc = alloc(filter_model_converter, m);
-                xmc = alloc(extension_model_converter, m);
+                xmc = alloc(generic_model_converter, m);
                 mc = concat(fmc, xmc);
             }
-            obj_map<app, rational>::iterator it  = m_var2degree.begin();
-            obj_map<app, rational>::iterator end = m_var2degree.end();
-            for (; it != end; ++it) {
-                SASSERT(it->m_value.is_int());
-                SASSERT(it->m_value >= rational(2));
-                app * fresh = m.mk_fresh_const(0, it->m_key->get_decl()->get_range());
+            for (auto const& kv : m_var2degree) {
+                SASSERT(kv.m_value.is_int());
+                SASSERT(kv.m_value >= rational(2));
+                app * fresh = m.mk_fresh_const(0, kv.m_key->get_decl()->get_range());
                 m_pinned.push_back(fresh);
-                m_var2var.insert(it->m_key, fresh);
+                m_var2var.insert(kv.m_key, fresh);
                 if (m_produce_models) {
                     fmc->insert(fresh->get_decl());
-                    xmc->insert(it->m_key->get_decl(), mk_power(fresh, rational(1)/it->m_value));
+                    xmc->add(kv.m_key->get_decl(), mk_power(fresh, rational(1)/kv.m_value));
                 }
                 if (m_produce_proofs) {
-                    expr * s  = mk_power(it->m_key, it->m_value);
+                    expr * s  = mk_power(kv.m_key, kv.m_value);
                     expr * eq = m.mk_eq(fresh, s);
                     proof * pr1 = m.mk_def_intro(eq);
                     proof * result_pr = m.mk_apply_def(fresh, s, pr1);
                     m_pinned.push_back(result_pr);
-                    m_var2pr.insert(it->m_key, result_pr);
+                    m_var2pr.insert(kv.m_key, result_pr);
                 }
             }
         }
@@ -267,17 +257,15 @@ class degree_shift_tactic : public tactic {
                 }
 
                 // add >= 0 constraints for variables with even degree
-                obj_map<app, rational>::iterator it  = m_var2degree.begin();
-                obj_map<app, rational>::iterator end = m_var2degree.end();
-                for (; it != end; ++it) {
-                    SASSERT(it->m_value.is_int());
-                    SASSERT(it->m_value >= rational(2));
-                    if (it->m_value.is_even()) {
-                        app * new_var  = m_var2var.find(it->m_key);
+                for (auto const& kv : m_var2degree) {
+                    SASSERT(kv.m_value.is_int());
+                    SASSERT(kv.m_value >= rational(2));
+                    if (kv.m_value.is_even()) {
+                        app * new_var  = m_var2var.find(kv.m_key);
                         app * new_c    = m_autil.mk_ge(new_var, m_autil.mk_numeral(rational(0), false));
                         proof * new_pr = 0;
                         if (m_produce_proofs) {
-                            proof * pr = m_var2pr.find(it->m_key);
+                            proof * pr = m_var2pr.find(kv.m_key);
                             new_pr     = m.mk_th_lemma(m_autil.get_family_id(), new_c, 1, &pr);
                         }
                         g->assert_expr(new_c, new_pr, 0);
diff --git a/src/tactic/arith/elim01_tactic.cpp b/src/tactic/arith/elim01_tactic.cpp
index b6fd5eee7..68534c60b 100644
--- a/src/tactic/arith/elim01_tactic.cpp
+++ b/src/tactic/arith/elim01_tactic.cpp
@@ -113,6 +113,11 @@ public:
         }
         return mc;
     }
+
+    virtual void display(std::ostream & out) {
+        out << "(elim01-model-converter)\n";
+    }
+
 };
 
 
diff --git a/src/tactic/arith/eq2bv_tactic.cpp b/src/tactic/arith/eq2bv_tactic.cpp
index 255665b56..492b12fcf 100644
--- a/src/tactic/arith/eq2bv_tactic.cpp
+++ b/src/tactic/arith/eq2bv_tactic.cpp
@@ -107,12 +107,18 @@ class eq2bv_tactic : public tactic {
         
         virtual model_converter* translate(ast_translation & translator) {
             bvmc* v = alloc(bvmc);
-            obj_map<func_decl, func_decl*>::iterator it = m_map.begin(), end = m_map.end();
-            for (; it != end; ++it) {
-                v->m_map.insert(translator(it->m_key), translator(it->m_value));
+            for (auto const& kv : m_map) {
+                v->m_map.insert(translator(kv.m_key), translator(kv.m_value));
             }
             return v;
         }
+
+        virtual void display(std::ostream & out) {
+            for (auto const& kv : m_map) {
+                out << "(model-set " << kv.m_key->get_name() << " " << kv.m_value->get_name() << ")\n";
+            }
+        }
+
     };
 
 public:
diff --git a/src/tactic/bv/dt2bv_tactic.cpp b/src/tactic/bv/dt2bv_tactic.cpp
index fe59480e7..2b1aa0fdd 100644
--- a/src/tactic/bv/dt2bv_tactic.cpp
+++ b/src/tactic/bv/dt2bv_tactic.cpp
@@ -131,10 +131,8 @@ public:
         for (unsigned i = 0; i < size; ++i) {
             quick_for_each_expr(proc, visited, g->form(i));
         }
-        obj_hashtable<sort>::iterator it = m_non_fd_sorts.begin(), end = m_non_fd_sorts.end();
-        for (; it != end; ++it) {
-            m_fd_sorts.remove(*it);
-        }
+        for (sort* s : m_non_fd_sorts) 
+            m_fd_sorts.remove(s);
         if (!m_fd_sorts.empty()) {
             ref<extension_model_converter> ext = alloc(extension_model_converter, m);
             ref<filter_model_converter> filter = alloc(filter_model_converter, m);
@@ -152,21 +150,12 @@ public:
             }
             expr_ref_vector bounds(m);
             rw.flush_side_constraints(bounds);
-            for (unsigned i = 0; i < bounds.size(); ++i) {
-                g->assert_expr(bounds[i].get());
-            }
-            {
-                obj_map<func_decl, func_decl*>::iterator it = rw.enum2bv().begin(), end = rw.enum2bv().end();
-                for (; it != end; ++it) {
-                    filter->insert(it->m_value);
-                }
-            }
-            {
-                obj_map<func_decl, expr*>::iterator it = rw.enum2def().begin(), end = rw.enum2def().end();
-                for (; it != end; ++it) {
-                    ext->insert(it->m_key, it->m_value);
-                }
-            }
+            for (expr* b : bounds) 
+                g->assert_expr(b);
+            for (auto const& kv : rw.enum2bv()) 
+                filter->insert(kv.m_value);
+            for (auto const& kv : rw.enum2def()) 
+                ext->insert(kv.m_key, kv.m_value);
             
             mc = concat(filter.get(), ext.get());
             report_tactic_progress(":fd-num-translated", rw.num_translated());
diff --git a/src/tactic/converter.h b/src/tactic/converter.h
index 9de8218c3..84df02c94 100644
--- a/src/tactic/converter.h
+++ b/src/tactic/converter.h
@@ -38,8 +38,7 @@ public:
 
     virtual void cancel() {}
     
-    // for debugging purposes
-    virtual void display(std::ostream & out) {}
+    virtual void display(std::ostream & out) = 0;
 };
 
 template<typename T>
@@ -68,10 +67,8 @@ public:
     virtual char const * get_name() const = 0;
     
     virtual void display(std::ostream & out) {
-        out << "(" << get_name() << "\n";
         m_c1->display(out);
         m_c2->display(out);
-        out << ")\n";
     }
 };
 
@@ -86,10 +83,9 @@ protected:
     T * translate_core(ast_translation & translator) {
         T * t1 = m_c1 ? m_c1->translate(translator) : 0;
         ptr_buffer<T> t2s;
-        unsigned num = m_c2s.size();
-        for (unsigned i = 0; i < num; i++)
-            t2s.push_back(m_c2s[i] ? m_c2s[i]->translate(translator) : 0);
-        return alloc(T2, t1, num, t2s.c_ptr(), m_szs.c_ptr());
+        for (T* c : m_c2s)
+            t2s.push_back(c ? c->translate(translator) : 0);
+        return alloc(T2, t1, m_c2s.size(), t2s.c_ptr(), m_szs.c_ptr());
     }
 
 public:
@@ -105,36 +101,24 @@ public:
     }
 
     virtual ~concat_star_converter() {
-        unsigned sz = m_c2s.size();
-        for (unsigned i = 0; i < sz; i++) {
-            T * c2 = m_c2s[i];
-            if (c2)
-                c2->dec_ref();
-        }
+        for (T* c : m_c2s)
+            if (c) c->dec_ref();
     }
 
     virtual void cancel() {
         if (m_c1)
             m_c1->cancel();
-        unsigned num = m_c2s.size();
-        for (unsigned i = 0; i < num; i++) {
-            if (m_c2s[i])
-                m_c2s[i]->cancel();
-        }
+        for (T* c : m_c2s)
+            if (c) c->cancel();
     }
 
     virtual char const * get_name() const = 0;
     
     virtual void display(std::ostream & out) {
-        out << "(" << get_name() << "\n";
         if (m_c1)
             m_c1->display(out);
-        out << "(\n";
-        unsigned num = m_c2s.size();
-        for (unsigned i = 0; i < num; i++)
-            if (m_c2s[i])
-                m_c2s[i]->display(out);
-        out << "))\n";
+        for (T* c : m_c2s) 
+            if (c) c->display(out);
     }
 };
 
diff --git a/src/tactic/core/elim_uncnstr_tactic.cpp b/src/tactic/core/elim_uncnstr_tactic.cpp
index 6a38f787e..614b20a10 100644
--- a/src/tactic/core/elim_uncnstr_tactic.cpp
+++ b/src/tactic/core/elim_uncnstr_tactic.cpp
@@ -17,7 +17,7 @@ Notes:
 
 --*/
 #include "tactic/tactical.h"
-#include "tactic/extension_model_converter.h"
+#include "tactic/generic_model_converter.h"
 #include "tactic/filter_model_converter.h"
 #include "ast/rewriter/rewriter_def.h"
 #include "ast/arith_decl_plugin.h"
@@ -34,7 +34,7 @@ class elim_uncnstr_tactic : public tactic {
     struct imp {
         // unconstrained vars collector
 
-        typedef extension_model_converter mc;
+        typedef generic_model_converter mc;
 
         struct rw_cfg : public default_rewriter_cfg {
             bool                   m_produce_proofs;
@@ -120,7 +120,7 @@ class elim_uncnstr_tactic : public tactic {
                 SASSERT(uncnstr(v));
                 SASSERT(to_app(v)->get_num_args() == 0);
                 if (m_mc)
-                    m_mc->insert(to_app(v)->get_decl(), def);
+                    m_mc->add(to_app(v)->get_decl(), def);
             }
             
             void add_defs(unsigned num, expr * const * args, expr * u, expr * identity) {
diff --git a/src/tactic/core/pb_preprocess_tactic.cpp b/src/tactic/core/pb_preprocess_tactic.cpp
index 6a0d7205b..c52f0526b 100644
--- a/src/tactic/core/pb_preprocess_tactic.cpp
+++ b/src/tactic/core/pb_preprocess_tactic.cpp
@@ -50,8 +50,8 @@ public:
 
     virtual void operator()(model_ref & mdl, unsigned goal_idx) {
         SASSERT(goal_idx == 0);
-        for (unsigned i = 0; i < m_const.size(); ++i) {
-            mdl->register_decl(m_const[i].first->get_decl(), m_const[i].second);
+        for (auto const& kv : m_const) {
+            mdl->register_decl(kv.first->get_decl(), kv.second);
         }
     }
 
@@ -65,12 +65,18 @@ public:
 
     virtual model_converter * translate(ast_translation & translator) {
         pb_preproc_model_converter* mc = alloc(pb_preproc_model_converter, translator.to());
-        for (unsigned i = 0; i < m_const.size(); ++i) {
-            mc->set_value_p(translator(m_const[i].first), translator(m_const[i].second));
+        for (auto const& kv : m_const) {
+            mc->set_value_p(translator(kv.first), translator(kv.second));
         }
         return mc;
     }
 
+    virtual void display(std::ostream & out) {
+        for (auto const& kv : m_const) {
+            out << "(model-set " << mk_pp(kv.first, m) << " " << mk_pp(kv.second, m) << ")\n";
+        }
+    }
+
 private:
     void set_value_p(app* e, expr* v) {
         SASSERT(e->get_num_args() == 0);  
diff --git a/src/tactic/core/split_clause_tactic.cpp b/src/tactic/core/split_clause_tactic.cpp
index 7a2df81b5..a120f2910 100644
--- a/src/tactic/core/split_clause_tactic.cpp
+++ b/src/tactic/core/split_clause_tactic.cpp
@@ -79,6 +79,8 @@ class split_clause_tactic : public tactic {
         virtual proof_converter * translate(ast_translation & translator) {
             return alloc(split_pc, translator.to(), translator(m_clause), translator(m_clause_pr));
         }
+
+        virtual void display(std::ostream & out) { out << "(split-clause-pc)\n"; }
     };
 
 public:
diff --git a/src/tactic/equiv_proof_converter.h b/src/tactic/equiv_proof_converter.h
index 79f5142b2..0ee44aec2 100644
--- a/src/tactic/equiv_proof_converter.h
+++ b/src/tactic/equiv_proof_converter.h
@@ -47,6 +47,7 @@ public:
 
     ast_manager& get_manager() { return m; }
 
+    virtual void display(std::ostream & out) {}
 };
 
 #endif
diff --git a/src/tactic/extension_model_converter.cpp b/src/tactic/extension_model_converter.cpp
index 38f0100ee..0ae4e1323 100644
--- a/src/tactic/extension_model_converter.cpp
+++ b/src/tactic/extension_model_converter.cpp
@@ -7,7 +7,7 @@ Module Name:
 
 Abstract:
 
-    Model converter that introduces eliminated variables in a model.
+Model converter that introduces eliminated variables in a model.
 
 Author:
 
@@ -16,11 +16,11 @@ Author:
 Notes:
 
 --*/
-#include "tactic/extension_model_converter.h"
-#include "model/model_evaluator.h"
-#include "ast/ast_smt2_pp.h"
-#include "model/model_v2_pp.h"
 #include "ast/ast_pp.h"
+#include "ast/ast_smt2_pp.h"
+#include "model/model_evaluator.h"
+#include "model/model_v2_pp.h"
+#include "tactic/extension_model_converter.h"
 
 extension_model_converter::~extension_model_converter() {
 }
@@ -78,20 +78,17 @@ void extension_model_converter::insert(func_decl * v, expr * def) {
 
 
 void extension_model_converter::display(std::ostream & out) {
-    out << "(extension-model-converter";
     for (unsigned i = 0; i < m_vars.size(); i++) {
-        out << "\n  (" << m_vars.get(i)->get_name() << " ";
-        unsigned indent = m_vars.get(i)->get_name().size() + 4;
-        out << mk_ismt2_pp(m_defs.get(i), m(), indent) << ")";
+        display_add(out, m(), m_vars.get(i), m_defs.get(i));
     }
-    out << ")" << std::endl;
 }
 
 model_converter * extension_model_converter::translate(ast_translation & translator) {
     extension_model_converter * res = alloc(extension_model_converter, translator.to());
-    for (unsigned i = 0; i < m_vars.size(); i++)
-        res->m_vars.push_back(translator(m_vars[i].get()));
-    for (unsigned i = 0; i < m_defs.size(); i++)
-        res->m_defs.push_back(translator(m_defs[i].get()));
+    for (func_decl* v : m_vars)
+        res->m_vars.push_back(translator(v));
+    for (expr* d : m_defs) 
+        res->m_defs.push_back(translator(d));
     return res;
 }
+
diff --git a/src/tactic/extension_model_converter.h b/src/tactic/extension_model_converter.h
index dbd7a7e3b..7ee6c68f5 100644
--- a/src/tactic/extension_model_converter.h
+++ b/src/tactic/extension_model_converter.h
@@ -23,12 +23,11 @@ Notes:
 #include "ast/ast.h"
 #include "tactic/model_converter.h"
 
-
 class extension_model_converter : public model_converter {
     func_decl_ref_vector  m_vars;
     expr_ref_vector       m_defs;
 public:
-    extension_model_converter(ast_manager & m):m_vars(m), m_defs(m) {
+    extension_model_converter(ast_manager & m): m_vars(m), m_defs(m) {
     }
 
     virtual ~extension_model_converter();
@@ -44,6 +43,4 @@ public:
 
     virtual model_converter * translate(ast_translation & translator);
 };
-
-
 #endif
diff --git a/src/tactic/filter_model_converter.cpp b/src/tactic/filter_model_converter.cpp
index 46328186d..40de848be 100644
--- a/src/tactic/filter_model_converter.cpp
+++ b/src/tactic/filter_model_converter.cpp
@@ -55,11 +55,9 @@ void filter_model_converter::operator()(svector<symbol> & labels, unsigned goal_
 }
 
 void filter_model_converter::display(std::ostream & out) {
-    out << "(filter-model-converter";
-    for (unsigned i = 0; i < m_decls.size(); i++) {
-        out << " " << m_decls.get(i)->get_name();
+    for (func_decl* f : m_decls) {
+        display_del(out, f);
     }
-    out << ")" << std::endl;
 }
 
 model_converter * filter_model_converter::translate(ast_translation & translator) {
diff --git a/src/tactic/filter_model_converter.h b/src/tactic/filter_model_converter.h
index b5d6b86f4..1cb6ec056 100644
--- a/src/tactic/filter_model_converter.h
+++ b/src/tactic/filter_model_converter.h
@@ -24,7 +24,7 @@ Notes:
 class filter_model_converter : public model_converter {
     func_decl_ref_vector  m_decls;
 public:
-    filter_model_converter(ast_manager & m):m_decls(m) {}
+    filter_model_converter(ast_manager & m): m_decls(m) {}
     
     virtual ~filter_model_converter();
     
diff --git a/src/tactic/horn_subsume_model_converter.h b/src/tactic/horn_subsume_model_converter.h
index 1c1ae9feb..74d5882a5 100644
--- a/src/tactic/horn_subsume_model_converter.h
+++ b/src/tactic/horn_subsume_model_converter.h
@@ -78,6 +78,7 @@ public:
 
     ast_manager& get_manager() { return m; }
 
+    virtual void display(std::ostream & out) {}
 };
 
 #endif
diff --git a/src/tactic/model_converter.cpp b/src/tactic/model_converter.cpp
index 4269946a1..6984c0536 100644
--- a/src/tactic/model_converter.cpp
+++ b/src/tactic/model_converter.cpp
@@ -18,10 +18,53 @@ Notes:
 --*/
 #include "tactic/model_converter.h"
 #include "model/model_v2_pp.h"
+#include "ast/ast_smt2_pp.h"
+
+/*
+ * Add or overwrite value in model.
+ */
+void model_converter::display_add(std::ostream& out, ast_manager& m, func_decl* f, expr* e) const {
+    // TBD: for arity > 0, requires signature of arguments.
+    if (m_env) {
+        ast_smt2_pp(out, f, e, *m_env, params_ref(), 0, "model-add");        
+    }
+    else {
+        unsigned indent = f->get_name().size() + 4;
+        out << "(model-add " << f->get_name() << " " << mk_ismt2_pp(e, m, indent) << ")\n";
+    }
+}
+
+/*
+ * A value is removed from the model.
+ */
+void model_converter::display_del(std::ostream& out, func_decl* f) const {
+    if (m_env) {
+        ast_smt2_pp(out, f, *m_env, params_ref(), 0, "model-del");
+    }
+    else {
+        out << "(model-del " << f->get_name() << ")\n";
+    }
+}
+
+void model_converter::display_add(std::ostream& out, ast_manager& m) {
+    // default printer for converter that adds entries
+    model_ref mdl = alloc(model, m);
+    (*this)(mdl);
+    for (unsigned i = 0, sz = mdl->get_num_constants(); i < sz; ++i) {
+        func_decl* f = mdl->get_constant(i);
+        display_add(out, m, f, mdl->get_const_interp(f));
+    }
+    for (unsigned i = 0, sz = mdl->get_num_functions(); i < sz; ++i) {
+        func_decl* f = mdl->get_function(i);
+        func_interp* fi = mdl->get_func_interp(f);
+        display_add(out, m, f, fi->get_interp());
+    }
+}
+
 
 class concat_model_converter : public concat_converter<model_converter> {
 public:
-    concat_model_converter(model_converter * mc1, model_converter * mc2):concat_converter<model_converter>(mc1, mc2) {}
+    concat_model_converter(model_converter * mc1, model_converter * mc2): concat_converter<model_converter>(mc1, mc2) {}
 
     virtual void operator()(model_ref & m) {
         this->m_c2->operator()(m);
@@ -37,7 +80,6 @@ public:
         this->m_c2->operator()(r, goal_idx);
         this->m_c1->operator()(r, 0);
     }
-
   
     virtual char const * get_name() const { return "concat-model-converter"; }
 
@@ -90,9 +132,9 @@ public:
                 // found the model converter that should be used
                 model_converter * c2 = this->m_c2s[i];
                 if (c2)
-                  c2->operator()(r, goal_idx);
+                    c2->operator()(r, goal_idx);
                 if (m_c1)
-                  this->m_c1->operator()(r, i);
+                    this->m_c1->operator()(r, i);
                 return;
             }
             // invalid goal
@@ -143,10 +185,10 @@ public:
     }
 
     virtual void operator()(labels_vec & r, unsigned goal_idx) {
-      r.append(m_labels.size(), m_labels.c_ptr());
+        r.append(m_labels.size(), m_labels.c_ptr());
     }
 
-  virtual void cancel() {
+    virtual void cancel() {
     }
     
     virtual void display(std::ostream & out) {
diff --git a/src/tactic/model_converter.h b/src/tactic/model_converter.h
index 5e549344e..02e59f6d5 100644
--- a/src/tactic/model_converter.h
+++ b/src/tactic/model_converter.h
@@ -24,9 +24,19 @@ Notes:
 #include "util/ref.h"
 
 class labels_vec : public svector<symbol> {};
+class smt2_pp_environment; 
 
 class model_converter : public converter {
+protected:
+    smt2_pp_environment* m_env;
+    void display_add(std::ostream& out, ast_manager& m, func_decl* f, expr* e) const;
+    void display_del(std::ostream& out, func_decl* f) const;
+    void display_add(std::ostream& out, ast_manager& m);
+    
 public:
+
+    model_converter(): m_env(0) {}
+
     virtual void operator()(model_ref & m) {}  // TODO: delete
 
     virtual void operator()(model_ref & m, unsigned goal_idx) {
@@ -34,10 +44,12 @@ public:
         SASSERT(goal_idx == 0);
         operator()(m);
     }
-
     virtual void operator()(labels_vec & r, unsigned goal_idx) {}
+
     
     virtual model_converter * translate(ast_translation & translator) = 0;
+
+    void set_pp_env(smt2_pp_environment* env) { m_env = env; }
 };
 
 typedef ref<model_converter> model_converter_ref;
diff --git a/src/tactic/portfolio/bounded_int2bv_solver.cpp b/src/tactic/portfolio/bounded_int2bv_solver.cpp
index db8a1fe53..9e4a0c547 100644
--- a/src/tactic/portfolio/bounded_int2bv_solver.cpp
+++ b/src/tactic/portfolio/bounded_int2bv_solver.cpp
@@ -150,7 +150,7 @@ public:
     virtual void set_progress_callback(progress_callback * callback) { m_solver->set_progress_callback(callback);  }
     virtual void collect_statistics(statistics & st) const { m_solver->collect_statistics(st); }
     virtual void get_unsat_core(ptr_vector<expr> & r) { m_solver->get_unsat_core(r); }
-    virtual void get_model(model_ref & mdl) {
+    virtual void get_model_core(model_ref & mdl) {
         m_solver->get_model(mdl);
         if (mdl) {
             extend_model(mdl);
diff --git a/src/tactic/portfolio/enum2bv_solver.cpp b/src/tactic/portfolio/enum2bv_solver.cpp
index c5c7e3028..1df7a000c 100644
--- a/src/tactic/portfolio/enum2bv_solver.cpp
+++ b/src/tactic/portfolio/enum2bv_solver.cpp
@@ -95,7 +95,7 @@ public:
     virtual void set_progress_callback(progress_callback * callback) { m_solver->set_progress_callback(callback);  }
     virtual void collect_statistics(statistics & st) const { m_solver->collect_statistics(st); }
     virtual void get_unsat_core(ptr_vector<expr> & r) { m_solver->get_unsat_core(r); }
-    virtual void get_model(model_ref & mdl) { 
+    virtual void get_model_core(model_ref & mdl) { 
         m_solver->get_model(mdl);
         if (mdl) {
             extend_model(mdl);
diff --git a/src/tactic/portfolio/pb2bv_solver.cpp b/src/tactic/portfolio/pb2bv_solver.cpp
index 4ff7251be..44898a578 100644
--- a/src/tactic/portfolio/pb2bv_solver.cpp
+++ b/src/tactic/portfolio/pb2bv_solver.cpp
@@ -87,7 +87,7 @@ public:
         m_solver->collect_statistics(st); 
     }
     virtual void get_unsat_core(ptr_vector<expr> & r) { m_solver->get_unsat_core(r); }
-    virtual void get_model(model_ref & mdl) { 
+    virtual void get_model_core(model_ref & mdl) { 
         m_solver->get_model(mdl);
         if (mdl) {
             filter_model(mdl);            
diff --git a/src/tactic/replace_proof_converter.h b/src/tactic/replace_proof_converter.h
index b768a18a0..d5cf7dc31 100644
--- a/src/tactic/replace_proof_converter.h
+++ b/src/tactic/replace_proof_converter.h
@@ -45,6 +45,8 @@ public:
     // run the replacements the inverse direction.
     void invert() { m_proofs.reverse(); }
 
+    virtual void display(std::ostream & out) {}
+
 };
 
 #endif
diff --git a/src/tactic/tactic.cpp b/src/tactic/tactic.cpp
index 6c4ca7476..7610c420a 100644
--- a/src/tactic/tactic.cpp
+++ b/src/tactic/tactic.cpp
@@ -175,7 +175,7 @@ void exec(tactic & t, goal_ref const & in, goal_ref_buffer & result, model_conve
 }
 
 
-lbool check_sat(tactic & t, goal_ref & g, model_ref & md, labels_vec & labels, proof_ref & pr, expr_dependency_ref & core, std::string & reason_unknown) {
+lbool check_sat(tactic & t, goal_ref & g, model_ref & md, model_converter_ref& mc, labels_vec & labels, proof_ref & pr, expr_dependency_ref & core, std::string & reason_unknown) {
     bool models_enabled = g->models_enabled();
     bool proofs_enabled = g->proofs_enabled();
     bool cores_enabled  = g->unsat_core_enabled();
@@ -184,7 +184,6 @@ lbool check_sat(tactic & t, goal_ref & g, model_ref & md, labels_vec & labels, p
     core = 0;
     ast_manager & m = g->m();
     goal_ref_buffer r;
-    model_converter_ref mc;
     proof_converter_ref pc;
     try {
         exec(t, g, r, mc, pc, core);
@@ -219,9 +218,9 @@ lbool check_sat(tactic & t, goal_ref & g, model_ref & md, labels_vec & labels, p
     }
     else {
         if (models_enabled) {
-          model_converter2model(m, mc.get(), md);
-          if (mc)
-              (*mc)(labels, 0);
+            model_converter2model(m, mc.get(), md);
+            if (mc)
+                (*mc)(labels, 0);
         }
         reason_unknown = "incomplete";
         return l_undef;
diff --git a/src/tactic/tactic.h b/src/tactic/tactic.h
index 0e4c61611..93da52366 100644
--- a/src/tactic/tactic.h
+++ b/src/tactic/tactic.h
@@ -153,7 +153,7 @@ public:
 #define MK_SIMPLE_TACTIC_FACTORY(NAME, ST)  MK_TACTIC_FACTORY(NAME, return ST;)
 
 void exec(tactic & t, goal_ref const & in, goal_ref_buffer & result, model_converter_ref & mc, proof_converter_ref & pc, expr_dependency_ref & core);
-lbool check_sat(tactic & t, goal_ref & g, model_ref & md, labels_vec & labels, proof_ref & pr, expr_dependency_ref & core, std::string & reason_unknown);
+lbool check_sat(tactic & t, goal_ref & g, model_ref & md, model_converter_ref& mc, labels_vec & labels, proof_ref & pr, expr_dependency_ref & core, std::string & reason_unknown);
 
 // Throws an exception if goal \c in requires proof generation.
 void fail_if_proof_generation(char const * tactic_name, goal_ref const & in);