diff --git a/scripts/mk_genfile_common.py b/scripts/mk_genfile_common.py
index 3b19b8c25..e242fa443 100644
--- a/scripts/mk_genfile_common.py
+++ b/scripts/mk_genfile_common.py
@@ -672,6 +672,7 @@ def mk_install_tactic_cpp_internal(h_files_full_path, path):
         components.
     """
     ADD_TACTIC_DATA = []
+    ADD_SIMPLIFIER_DATA = []
     ADD_PROBE_DATA = []
     def ADD_TACTIC(name, descr, cmd):
         ADD_TACTIC_DATA.append((name, descr, cmd))
@@ -679,9 +680,13 @@ def mk_install_tactic_cpp_internal(h_files_full_path, path):
     def ADD_PROBE(name, descr, cmd):
         ADD_PROBE_DATA.append((name, descr, cmd))
 
+    def ADD_SIMPLIFIER(name, descr, cmd):
+        ADD_SIMPLIFIER_DATA.append((name, descr, cmd))
+
     eval_globals = {
         'ADD_TACTIC': ADD_TACTIC,
         'ADD_PROBE': ADD_PROBE,
+        'ADD_SIMPLIFIER': ADD_SIMPLIFIER
     }
 
     assert isinstance(h_files_full_path, list)
@@ -691,9 +696,11 @@ def mk_install_tactic_cpp_internal(h_files_full_path, path):
     fout.write('// Automatically generated file.\n')
     fout.write('#include "tactic/tactic.h"\n')
     fout.write('#include "cmd_context/tactic_cmds.h"\n')
+    fout.write('#include "cmd_context/simplifier_cmds.h"\n')
     fout.write('#include "cmd_context/cmd_context.h"\n')
     tactic_pat   = re.compile('[ \t]*ADD_TACTIC\(.*\)')
-    probe_pat    = re.compile('[ \t]*ADD_PROBE\(.*\)')   
+    probe_pat    = re.compile('[ \t]*ADD_PROBE\(.*\)')
+    simplifier_pat = re.compile('[ \t]*ADD_SIMPLIFIER\(.*\)')
     for h_file in sorted_headers_by_component(h_files_full_path):
         added_include = False
         try:
@@ -719,17 +726,31 @@ def mk_install_tactic_cpp_internal(h_files_full_path, path):
                             _logger.error("Failed processing ADD_PROBE command at '{}'\n{}".format(
                                 fullname, line))
                             raise e
+                    if simplifier_pat.match(line):
+                        if not added_include:
+                            added_include = True
+                            fout.write('#include "%s"\n' % path_after_src(h_file))
+                        try:
+                            eval(line.strip('\n '), eval_globals, None)
+                        except Exception as e:
+                            _logger.error("Failed processing ADD_SIMPLIFIER command at '{}'\n{}".format(
+                                fullname, line))
+                            raise e
+                        
         except Exception as e:
            _logger.error("Failed to read file {}\n".format(h_file))
            raise e
     # First pass will just generate the tactic factories
     fout.write('#define ADD_TACTIC_CMD(NAME, DESCR, CODE) ctx.insert(alloc(tactic_cmd, symbol(NAME), DESCR, [](ast_manager &m, const params_ref &p) { return CODE; }))\n')
     fout.write('#define ADD_PROBE(NAME, DESCR, PROBE) ctx.insert(alloc(probe_info, symbol(NAME), DESCR, PROBE))\n')
+    fout.write('#define ADD_SIMPLIFIER_CMD(NAME, DESCR, FUNCTION) ctx.insert(alloc(simplifier_cmd, symbol(NAME), DESCR, FUNCTION))\n')
     fout.write('void install_tactics(tactic_manager & ctx) {\n')
     for data in ADD_TACTIC_DATA:
         fout.write('  ADD_TACTIC_CMD("%s", "%s", %s);\n' % data)
     for data in ADD_PROBE_DATA:
         fout.write('  ADD_PROBE("%s", "%s", %s);\n' % data)
+    for data in ADD_SIMPLIFIER_DATA:
+        fout.write('  ADD_SIMPLIFIER_CMD("%s", "%s", %s);\n' % data)
     fout.write('}\n')
     fout.close()
     return fullname
diff --git a/src/ast/simplifiers/CMakeLists.txt b/src/ast/simplifiers/CMakeLists.txt
index 127db786a..e30224402 100644
--- a/src/ast/simplifiers/CMakeLists.txt
+++ b/src/ast/simplifiers/CMakeLists.txt
@@ -29,4 +29,8 @@ z3_add_component(simplifiers
     normal_forms
     rewriter
     substitution
+  TACTIC_HEADERS
+    bit_blaster.h
+    rewriter_simplifier.h
+
 )
diff --git a/src/ast/simplifiers/bit_blaster.h b/src/ast/simplifiers/bit_blaster.h
index 5724cc075..820431706 100644
--- a/src/ast/simplifiers/bit_blaster.h
+++ b/src/ast/simplifiers/bit_blaster.h
@@ -49,3 +49,6 @@ public:
 
 };
 
+/*
+  ADD_SIMPLIFIER("bit-blaster", "reduce bit-vector expressions into SAT.", "[](auto& m, auto& p, auto &s) -> dependent_expr_simplifier* { return alloc(bit_blaster_simplifier, m, p, s); }")
+*/
diff --git a/src/ast/simplifiers/dependent_expr_state.h b/src/ast/simplifiers/dependent_expr_state.h
index 0fedf484c..d4d449cf8 100644
--- a/src/ast/simplifiers/dependent_expr_state.h
+++ b/src/ast/simplifiers/dependent_expr_state.h
@@ -32,6 +32,7 @@ Author:
 #include "util/trail.h"
 #include "util/statistics.h"
 #include "util/params.h"
+#include "util/z3_exception.h"
 #include "ast/converters/model_converter.h"
 #include "ast/simplifiers/dependent_expr.h"
 #include "ast/simplifiers/model_reconstruction_trail.h"
@@ -98,6 +99,17 @@ public:
     bool has_quantifiers();
 };
 
+class default_dependent_expr_state : public dependent_expr_state {
+public:
+    default_dependent_expr_state(ast_manager& m): dependent_expr_state(m) {}
+    virtual unsigned qtail() const { return 0; }
+    virtual dependent_expr const& operator[](unsigned i) { throw default_exception("unexpected access"); }
+    virtual void update(unsigned i, dependent_expr const& j) { throw default_exception("unexpected update"); }
+    virtual void add(dependent_expr const& j) { throw default_exception("unexpected addition"); }
+    virtual bool inconsistent() { return false; }
+    virtual model_reconstruction_trail& model_trail() { throw default_exception("unexpected access to model reconstruction"); }
+};
+
 inline std::ostream& operator<<(std::ostream& out, dependent_expr_state& st) {
     return st.display(out);
 }
@@ -150,3 +162,5 @@ public:
     ast_manager& get_manager() { return m; }
     dependent_expr_state& get_fmls() { return m_fmls; }
 };
+
+typedef std::function<dependent_expr_simplifier*(ast_manager&, const params_ref&, dependent_expr_state& s)> simplifier_factory;
diff --git a/src/ast/simplifiers/model_reconstruction_trail.cpp b/src/ast/simplifiers/model_reconstruction_trail.cpp
index 82d56f491..22b600ded 100644
--- a/src/ast/simplifiers/model_reconstruction_trail.cpp
+++ b/src/ast/simplifiers/model_reconstruction_trail.cpp
@@ -139,18 +139,15 @@ void model_reconstruction_trail::replay(unsigned qhead, expr_ref_vector& assumpt
  */
 model_converter_ref model_reconstruction_trail::get_model_converter() {
     generic_model_converter_ref mc = alloc(generic_model_converter, m, "dependent-expr-model");
-    unsigned i = 0;
-    append(*mc, i);
+    append(*mc);
     return model_converter_ref(mc.get());
 }
 
 /**
 * Append model conversions starting at index i
 */
-void model_reconstruction_trail::append(generic_model_converter& mc, unsigned& i) {
-    TRACE("simplifier", display(tout));
-    for (; i < m_trail.size(); ++i) {
-        auto* t = m_trail[i];
+void model_reconstruction_trail::append(generic_model_converter& mc) {
+    for (auto* t : m_trail) {
         if (!t->m_active)
             continue;
         else if (t->is_hide())
@@ -163,13 +160,10 @@ void model_reconstruction_trail::append(generic_model_converter& mc, unsigned& i
                 mc.add(v, def);
         }
     }
+    TRACE("simplifier", display(tout); mc.display(tout));
 }
 
 
-void model_reconstruction_trail::append(generic_model_converter& mc) {
-    m_trail_stack.push(value_trail(m_trail_index));
-    append(mc, m_trail_index);
-}
 
 std::ostream& model_reconstruction_trail::display(std::ostream& out) const {
     for (auto* t : m_trail) {
diff --git a/src/ast/simplifiers/model_reconstruction_trail.h b/src/ast/simplifiers/model_reconstruction_trail.h
index 36ddde9ff..89a112c24 100644
--- a/src/ast/simplifiers/model_reconstruction_trail.h
+++ b/src/ast/simplifiers/model_reconstruction_trail.h
@@ -84,7 +84,6 @@ class model_reconstruction_trail {
     ast_manager&             m;
     trail_stack&             m_trail_stack;
     scoped_ptr_vector<entry> m_trail;
-    unsigned                 m_trail_index = 0;
 
     void add_vars(expr* e, ast_mark& free_vars) {
         for (expr* t : subterms::all(expr_ref(e, m)))
@@ -108,10 +107,6 @@ class model_reconstruction_trail {
         return any_of(added, [&](dependent_expr const& d) { return intersects(free_vars, d); });
     }
 
-    /**
-    * Append new updates to model converter, update the current index into the trail in the process.
-    */
-    void append(generic_model_converter& mc, unsigned& index);
 public:
 
     model_reconstruction_trail(ast_manager& m, trail_stack& tr): 
diff --git a/src/ast/simplifiers/rewriter_simplifier.h b/src/ast/simplifiers/rewriter_simplifier.h
index f3dc91a51..f74c213d4 100644
--- a/src/ast/simplifiers/rewriter_simplifier.h
+++ b/src/ast/simplifiers/rewriter_simplifier.h
@@ -53,3 +53,7 @@ public:
     void updt_params(params_ref const& p) override { m_params.append(p); m_rewriter.updt_params(m_params); }
     void collect_param_descrs(param_descrs& r) override { th_rewriter::get_param_descrs(r); }
 };
+
+/*
+  ADD_SIMPLIFIER("simplify", "apply simplification rules.", "[](auto& m, auto& p, auto &s) -> dependent_expr_simplifier* { return alloc(rewriter_simplifier, m, p, s); }")
+ */
diff --git a/src/cmd_context/CMakeLists.txt b/src/cmd_context/CMakeLists.txt
index f8c1aa38f..f3cdb3c03 100644
--- a/src/cmd_context/CMakeLists.txt
+++ b/src/cmd_context/CMakeLists.txt
@@ -9,6 +9,7 @@ z3_add_component(cmd_context
     parametric_cmd.cpp
     pdecl.cpp
     simplify_cmd.cpp
+    simplifier_cmds.cpp
     tactic_cmds.cpp
     tactic_manager.cpp
   COMPONENT_DEPENDENCIES
diff --git a/src/cmd_context/cmd_context.cpp b/src/cmd_context/cmd_context.cpp
index 5602f53a3..89733a7ea 100644
--- a/src/cmd_context/cmd_context.cpp
+++ b/src/cmd_context/cmd_context.cpp
@@ -546,6 +546,7 @@ cmd_context::cmd_context(bool main_ctx, ast_manager * m, symbol const & l):
     install_basic_cmds(*this);
     install_ext_basic_cmds(*this);
     install_core_tactic_cmds(*this);
+    install_core_simplifier_cmds(*this);
     m_mcs.push_back(nullptr);
     SASSERT(m != 0 || !has_manager());
     if (m_main_ctx) {
@@ -559,8 +560,7 @@ cmd_context::~cmd_context() {
     }
     pop(m_scopes.size());
     finalize_cmds();
-    finalize_tactic_cmds();
-    finalize_probes();
+    finalize_tactic_manager();
     m_proof_cmds = nullptr;
     reset(true);
     m_mcs.reset();
diff --git a/src/cmd_context/cmd_context.h b/src/cmd_context/cmd_context.h
index 93d2c0d3e..f5a247794 100644
--- a/src/cmd_context/cmd_context.h
+++ b/src/cmd_context/cmd_context.h
@@ -318,7 +318,7 @@ protected:
     void register_builtin_ops(decl_plugin * p);
     void load_plugin(symbol const & name, bool install_names, svector<family_id>& fids);
     void init_manager_core(bool new_manager);
-    void init_manager();
+
     void init_external_manager();
     void reset_cmds();
     void finalize_cmds();
@@ -414,7 +414,9 @@ public:
     sexpr_manager & sm() const { if (!m_sexpr_manager) const_cast<cmd_context*>(this)->m_sexpr_manager = alloc(sexpr_manager); return *m_sexpr_manager; }
 
     proof_cmds* get_proof_cmds() { return m_proof_cmds.get(); }
+    void init_manager();
     solver* get_solver() { return m_solver.get(); }
+    void set_solver(solver* s) { m_solver = s; }
     void set_proof_cmds(proof_cmds* pc) { m_proof_cmds = pc; }
 
     void set_solver_factory(solver_factory * s);
diff --git a/src/cmd_context/simplifier_cmds.cpp b/src/cmd_context/simplifier_cmds.cpp
new file mode 100644
index 000000000..b8ce15081
--- /dev/null
+++ b/src/cmd_context/simplifier_cmds.cpp
@@ -0,0 +1,158 @@
+/*++
+Copyright (c) 2023 Microsoft Corporation
+
+Module Name:
+
+    simplifier_cmds.h
+
+Abstract:
+    Support for simplifier commands in SMT 2.0 front-end
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2023-01-30
+
+--*/
+#include<sstream>
+#include "cmd_context/simplifier_cmds.h"
+#include "cmd_context/cmd_context.h"
+#include "cmd_context/cmd_util.h"
+#include "cmd_context/parametric_cmd.h"
+#include "model/model_smt2_pp.h"
+#include "ast/ast_smt2_pp.h"
+#include "ast/simplifiers/seq_simplifier.h"
+#include "solver/simplifier_solver.h"
+
+typedef dependent_expr_simplifier simplifier;
+
+static simplifier_factory mk_and_then(cmd_context & ctx, sexpr * n) {
+    SASSERT(n->is_composite());
+    unsigned num_children = n->get_num_children();
+    if (num_children < 2)
+        throw cmd_exception("invalid and-then combinator, at least one argument expected", n->get_line(), n->get_pos());
+    if (num_children == 2)
+        return sexpr2simplifier(ctx, n->get_child(1));
+    vector<simplifier_factory> args;
+    for (unsigned i = 1; i < num_children; i++)
+        args.push_back(sexpr2simplifier(ctx, n->get_child(i)));
+    simplifier_factory result = [args](ast_manager& m, const params_ref& p, dependent_expr_state& st) {
+        scoped_ptr<seq_simplifier> s = alloc(seq_simplifier, m, p, st);
+        for (auto &  simp : args)
+            s->add_simplifier(simp(m, p, st));
+        return s.detach();
+    };
+    return result;
+}
+
+static simplifier_factory mk_using_params(cmd_context & ctx, sexpr * n) {
+    SASSERT(n->is_composite());
+    unsigned num_children = n->get_num_children();
+    if (num_children < 2)
+        throw cmd_exception("invalid using-params combinator, at least one argument expected", n->get_line(), n->get_pos());
+    if (num_children == 2)
+        return sexpr2simplifier(ctx, n->get_child(1));
+    simplifier_factory t = sexpr2simplifier(ctx, n->get_child(1));
+#if 0
+    // hoist parameter parsing code from tactic_cmds to share.
+    param_descrs descrs;
+    t->collect_param_descrs(descrs);
+       
+#endif
+    return t;
+//    return using_params(t.detach(), p);
+}
+
+
+simplifier_factory sexpr2simplifier(cmd_context & ctx, sexpr * n) {
+    if (n->is_symbol()) {
+        simplifier_cmd * cmd = ctx.find_simplifier_cmd(n->get_symbol());
+        if (cmd != nullptr)
+            return cmd->factory();
+        throw cmd_exception("invalid tactic, unknown tactic ", n->get_symbol(), n->get_line(), n->get_pos());
+    }
+    else if (n->is_composite()) {
+        unsigned num_children = n->get_num_children();
+        if (num_children == 0)
+            throw cmd_exception("invalid tactic, arguments expected", n->get_line(), n->get_pos());
+        sexpr * head = n->get_child(0);
+        if (!head->is_symbol())
+            throw cmd_exception("invalid tactic, symbol expected", n->get_line(), n->get_pos());
+        symbol const & cmd_name = head->get_symbol();
+        if (cmd_name == "and-then" || cmd_name == "then")
+            return mk_and_then(ctx, n);
+        else
+            throw cmd_exception("invalid tactic, unknown tactic combinator ", cmd_name, n->get_line(), n->get_pos());
+    }
+    else {
+        throw cmd_exception("invalid tactic, unexpected input", n->get_line(), n->get_pos());
+    }
+}
+
+
+void help_simplifier(cmd_context & ctx) {
+    std::ostringstream buf;
+    buf << "combinators:\n";
+    buf << "- (and-then <simplifier>+) executes the given simplifiers sequentially.\n";
+    // buf << "- (using-params <tactic> <attribute>*) executes the given tactic using the given attributes, where <attribute> ::= <keyword> <value>. ! is a syntax sugar for using-params.\n";
+    buf << "builtin simplifiers:\n";
+    for (simplifier_cmd* cmd : ctx.simplifiers()) {
+        buf << "- " << cmd->get_name() << " " << cmd->get_descr() << "\n";
+        auto fac = cmd->factory();
+        param_descrs descrs;
+        ast_manager& m = ctx.get_ast_manager();
+        default_dependent_expr_state st(m);
+        params_ref p;
+        scoped_ptr<dependent_expr_simplifier> s = fac(m, p, st);
+        s->collect_param_descrs(descrs);
+        descrs.display(buf, 4);
+    }
+    ctx.regular_stream() << '"' << escaped(buf.str()) << "\"\n";
+}
+
+ATOMIC_CMD(help_simplifier_cmd, "help-simplifier", "display the simplifier combinators and primitives.", help_simplifier(ctx););
+
+class set_simplifier_cmd : public parametric_cmd {
+protected:
+    sexpr * m_simplifier;
+public:
+    set_simplifier_cmd():
+        parametric_cmd("set-simplifier") {}
+    
+    char const * get_usage() const override { return "<tactic> (<keyword> <value>)*"; }
+
+    void prepare(cmd_context & ctx) override {
+        parametric_cmd::prepare(ctx);
+        m_simplifier = nullptr;
+    }
+
+    cmd_arg_kind next_arg_kind(cmd_context & ctx) const override {
+        if (m_simplifier == nullptr) return CPK_SEXPR;
+        return parametric_cmd::next_arg_kind(ctx);
+    }
+
+    void set_next_arg(cmd_context & ctx, sexpr * arg) override {
+        m_simplifier = arg;
+    }
+
+    char const * get_main_descr() const override { return "update main solver with simplification pre-processing."; }
+
+    void init_pdescrs(cmd_context & ctx, param_descrs & p) override {
+    }
+
+    void execute(cmd_context & ctx) override {
+        if (!m_simplifier) 
+            throw cmd_exception("set-simplifier needs a simplifier argument");
+        
+        auto simplifier_factory = sexpr2simplifier(ctx, m_simplifier);
+        ctx.init_manager();
+        auto* s = ctx.get_solver();
+        if (s)
+            ctx.set_solver(mk_simplifier_solver(s, &simplifier_factory));        
+    }
+};
+
+
+void install_core_simplifier_cmds(cmd_context & ctx) {
+    ctx.insert(alloc(set_simplifier_cmd));    
+    ctx.insert(alloc(help_simplifier_cmd));
+}
diff --git a/src/cmd_context/simplifier_cmds.h b/src/cmd_context/simplifier_cmds.h
new file mode 100644
index 000000000..e75376dfb
--- /dev/null
+++ b/src/cmd_context/simplifier_cmds.h
@@ -0,0 +1,42 @@
+/*++
+Copyright (c) 2023 Microsoft Corporation
+
+Module Name:
+
+    simplifier_cmds.h
+
+Abstract:
+    Support for simplifier commands in SMT 2.0 front-end
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2023-01-30
+
+--*/
+#pragma once
+
+#include "ast/ast.h"
+#include "ast/simplifiers/dependent_expr_state.h"
+#include "util/params.h"
+#include "util/cmd_context_types.h"
+#include "util/ref.h"
+
+
+class simplifier_cmd {
+    symbol             m_name;
+    char const *       m_descr;
+    simplifier_factory m_factory;
+public:
+    simplifier_cmd(symbol const & n, char const * d, simplifier_factory f):
+        m_name(n), m_descr(d), m_factory(f) {}
+
+    symbol get_name() const { return m_name; }
+    
+    char const * get_descr() const { return m_descr; }
+    
+    simplifier_factory factory() { return m_factory; }
+};
+
+simplifier_factory sexpr2simplifier(cmd_context & ctx, sexpr * n);
+
+void install_core_simplifier_cmds(cmd_context & ctx);
diff --git a/src/cmd_context/tactic_manager.cpp b/src/cmd_context/tactic_manager.cpp
index d4b3374b4..1691f5b45 100644
--- a/src/cmd_context/tactic_manager.cpp
+++ b/src/cmd_context/tactic_manager.cpp
@@ -7,7 +7,7 @@ Module Name:
 
 Abstract:
 
-    Collection of tactics & probes
+    Collection of tactics, simplifiers & probes
 
 Author:
 
@@ -19,8 +19,21 @@ Notes:
 #include "cmd_context/tactic_manager.h"
 
 tactic_manager::~tactic_manager() {
-    finalize_tactic_cmds();
-    finalize_probes();
+    finalize_tactic_manager();
+}
+
+void tactic_manager::finalize_tactic_manager() {
+    std::for_each(m_tactics.begin(), m_tactics.end(), delete_proc<tactic_cmd>());
+    m_tactics.reset();
+    m_name2tactic.reset();
+
+    std::for_each(m_simplifiers.begin(), m_simplifiers.end(), delete_proc<simplifier_cmd>());
+    m_simplifiers.reset();
+    m_name2simplifier.reset();
+
+    std::for_each(m_probes.begin(), m_probes.end(), delete_proc<probe_info>());
+    m_probes.reset();
+    m_name2probe.reset();
 }
 
 void tactic_manager::insert(tactic_cmd * c) {
@@ -30,6 +43,13 @@ void tactic_manager::insert(tactic_cmd * c) {
     m_tactics.push_back(c);
 }
 
+void tactic_manager::insert(simplifier_cmd * c) {
+    symbol const & s = c->get_name();
+    SASSERT(!m_name2simplifier.contains(s));
+    m_name2simplifier.insert(s, c);
+    m_simplifiers.push_back(c);
+}
+
 void tactic_manager::insert(probe_info * p) {
     symbol const & s = p->get_name();
     SASSERT(!m_name2probe.contains(s));
@@ -43,20 +63,15 @@ tactic_cmd * tactic_manager::find_tactic_cmd(symbol const & s) const {
     return c;
 }
 
+simplifier_cmd * tactic_manager::find_simplifier_cmd(symbol const & s) const {
+    simplifier_cmd * c = nullptr;
+    m_name2simplifier.find(s, c);
+    return c;
+}
+
 probe_info * tactic_manager::find_probe(symbol const & s) const {
     probe_info * p = nullptr;
     m_name2probe.find(s, p);
     return p;
 }
 
-void tactic_manager::finalize_tactic_cmds() {
-    std::for_each(m_tactics.begin(), m_tactics.end(), delete_proc<tactic_cmd>());
-    m_tactics.reset();
-    m_name2tactic.reset();
-}
-
-void tactic_manager::finalize_probes() {
-    std::for_each(m_probes.begin(), m_probes.end(), delete_proc<probe_info>());
-    m_probes.reset();
-    m_name2probe.reset();
-}
diff --git a/src/cmd_context/tactic_manager.h b/src/cmd_context/tactic_manager.h
index 3a57d6297..ec60b0873 100644
--- a/src/cmd_context/tactic_manager.h
+++ b/src/cmd_context/tactic_manager.h
@@ -18,54 +18,37 @@ Notes:
 #pragma once
 
 #include "cmd_context/tactic_cmds.h"
+#include "cmd_context/simplifier_cmds.h"
 #include "util/dictionary.h"
 
 class tactic_manager {
 protected:
     dictionary<tactic_cmd*>  m_name2tactic;
     dictionary<probe_info*>  m_name2probe;
+    dictionary<simplifier_cmd*> m_name2simplifier;
     ptr_vector<tactic_cmd>   m_tactics;
+    ptr_vector<simplifier_cmd> m_simplifiers;
     ptr_vector<probe_info>   m_probes;
-    void finalize_tactic_cmds();
-    void finalize_probes();
+    void finalize_tactic_manager();
 public:
     ~tactic_manager();
 
     void insert(tactic_cmd * c);
+    void insert(simplifier_cmd* c);
     void insert(probe_info * p);
     tactic_cmd * find_tactic_cmd(symbol const & s) const; 
     probe_info * find_probe(symbol const & s) const; 
+    simplifier_cmd* find_simplifier_cmd(symbol const& s) const;
 
     unsigned num_tactics() const { return m_tactics.size(); }
     unsigned num_probes() const { return m_probes.size(); }
     tactic_cmd * get_tactic(unsigned i) const { return m_tactics[i]; }
     probe_info * get_probe(unsigned i) const { return m_probes[i]; }
+
+    ptr_vector<simplifier_cmd> const& simplifiers() const { return m_simplifiers; }
+    ptr_vector<tactic_cmd> const& tactics() const { return m_tactics; }
+    ptr_vector<probe_info> const& probes() const { return m_probes; }
     
-    typedef ptr_vector<tactic_cmd>::const_iterator tactic_cmd_iterator;
-    tactic_cmd_iterator begin_tactic_cmds() const { return m_tactics.begin(); }
-    tactic_cmd_iterator end_tactic_cmds() const { return m_tactics.end(); }
-    class tactics_iterator {
-        tactic_manager const& m;
-    public:
-        tactics_iterator(tactic_manager const& m):m(m) {}
-        tactic_cmd_iterator begin() const { return m.begin_tactic_cmds(); }
-        tactic_cmd_iterator end() const { return m.end_tactic_cmds(); }
-    };
-    tactics_iterator tactics() const { return tactics_iterator(*this); }
-
-    typedef ptr_vector<probe_info>::const_iterator probe_iterator;
-    probe_iterator begin_probes() const { return m_probes.begin(); }
-    probe_iterator end_probes() const { return m_probes.end(); }
-
-    class probes_iterator {
-        tactic_manager const& m;
-    public:
-        probes_iterator(tactic_manager const& m):m(m) {}
-        probe_iterator begin() const { return m.begin_probes(); }
-        probe_iterator end() const { return m.end_probes(); }
-    };
-
-    probes_iterator probes() const { return probes_iterator(*this); }
         
 };
 
diff --git a/src/sat/sat_solver/sat_smt_solver.cpp b/src/sat/sat_solver/sat_smt_solver.cpp
index dbc2d9505..82aeded6f 100644
--- a/src/sat/sat_solver/sat_smt_solver.cpp
+++ b/src/sat/sat_solver/sat_smt_solver.cpp
@@ -700,6 +700,6 @@ private:
 
 
 solver* mk_sat_smt_solver(ast_manager& m, params_ref const& p) {
-    return mk_simplifier_solver(alloc(sat_smt_solver, m, p));
+    return mk_simplifier_solver(alloc(sat_smt_solver, m, p), nullptr);
 }
 
diff --git a/src/shell/main.cpp b/src/shell/main.cpp
index 2fdd95d79..4c26d91d9 100644
--- a/src/shell/main.cpp
+++ b/src/shell/main.cpp
@@ -98,6 +98,7 @@ void display_usage() {
     std::cout << "  -pmmd:name  display Z3 module ('name') parameters in Markdown format.\n";
     std::cout << "  -pp:name    display Z3 parameter description, if 'name' is not provided, then all module names are listed.\n";
     std::cout << "  -tactics[:name]  display built-in tactics or if argument is given, display detailed information on tactic.\n";
+    std::cout << "  -simplifiers[:name]  display built-in simplifiers or if argument is given, display detailed information on simplifier.\n";
     std::cout << "  -probes     display avilable probes.\n";
     std::cout << "  --"      << "          all remaining arguments are assumed to be part of the input file name. This option allows Z3 to read files with strange names such as: -foo.smt2.\n";
     std::cout << "\nResources:\n";
@@ -295,6 +296,12 @@ static void parse_cmd_line_args(std::string& input_file, int argc, char ** argv)
                 else
                     help_tactic(opt_arg, false);
             }
+            else if (strcmp(opt_name, "simplifiers") == 0) {
+                if (!opt_arg)
+                    help_simplifiers();
+                else
+                    help_simplifier(opt_arg, false);
+            }
             else if (strcmp(opt_name, "tacticsmd") == 0 && opt_arg) 
                 help_tactic(opt_arg, true);
             else if (strcmp(opt_name, "probes") == 0) 
diff --git a/src/shell/smtlib_frontend.cpp b/src/shell/smtlib_frontend.cpp
index 698f0f239..008142c1a 100644
--- a/src/shell/smtlib_frontend.cpp
+++ b/src/shell/smtlib_frontend.cpp
@@ -88,6 +88,22 @@ void help_tactics() {
         std::cout << "- " << cmd->get_name() << " " << cmd->get_descr() << "\n";
 }
 
+void help_simplifiers() {
+    struct cmp {
+        bool operator()(simplifier_cmd* a, simplifier_cmd* b) const {
+            return a->get_name().str() < b->get_name().str();
+        }
+    };
+    cmd_context ctx;
+    ptr_vector<simplifier_cmd> cmds;
+    for (auto cmd : ctx.simplifiers()) 
+        cmds.push_back(cmd);
+    cmp lt;
+    std::sort(cmds.begin(), cmds.end(), lt);
+    for (auto cmd : cmds) 
+        std::cout << "- " << cmd->get_name() << " " << cmd->get_descr() << "\n";
+}
+
 void help_tactic(char const* name, bool markdown) {
     cmd_context ctx;
     for (auto cmd : ctx.tactics()) {
@@ -103,6 +119,25 @@ void help_tactic(char const* name, bool markdown) {
     }
 }
 
+void help_simplifier(char const* name, bool markdown) {
+    cmd_context ctx;
+    for (auto cmd : ctx.simplifiers()) {
+        if (cmd->get_name() == name) {
+            auto fac = cmd->factory();
+            param_descrs descrs;
+            ast_manager& m = ctx.m();
+            default_dependent_expr_state st(m);
+            params_ref p;
+            scoped_ptr<dependent_expr_simplifier> s = fac(m, p, st);
+            s->collect_param_descrs(descrs);
+            if (markdown)
+                descrs.display_markdown(std::cout);
+            else
+                descrs.display(std::cout, 4);
+        }
+    }
+}
+
 void help_probes() {
     struct cmp {
         bool operator()(probe_info* a, probe_info* b) const {
diff --git a/src/shell/smtlib_frontend.h b/src/shell/smtlib_frontend.h
index 9769472f2..36818f3f6 100644
--- a/src/shell/smtlib_frontend.h
+++ b/src/shell/smtlib_frontend.h
@@ -21,7 +21,9 @@ Revision History:
 unsigned read_smtlib_file(char const * benchmark_file);
 unsigned read_smtlib2_commands(char const * command_file);
 void help_tactics();
+void help_simplifiers();
 void help_probes();
 void help_tactic(char const* name, bool markdown);
+void help_simplifier(char const* name, bool markdown);
 
 
diff --git a/src/solver/simplifier_solver.cpp b/src/solver/simplifier_solver.cpp
index 17a39509e..faaf5b28f 100644
--- a/src/solver/simplifier_solver.cpp
+++ b/src/solver/simplifier_solver.cpp
@@ -89,7 +89,7 @@ class simplifier_solver : public solver {
     };   
 
     ast_manager& m;
-    scoped_ptr<solver> s;
+    solver_ref  s;
     vector<dependent_expr>      m_fmls;
     dep_expr_state              m_preprocess_state;
     seq_simplifier              m_preprocess;
@@ -143,7 +143,7 @@ class simplifier_solver : public solver {
 
 public:
 
-    simplifier_solver(solver* s) : 
+    simplifier_solver(solver* s, simplifier_factory* fac) : 
         solver(s->get_manager()), 
         m(s->get_manager()), 
         s(s),
@@ -152,7 +152,10 @@ public:
         m_assumptions(m),
         m_proof(m)
     {
-        init_preprocess(m, s->get_params(), m_preprocess, m_preprocess_state);
+        if (fac) 
+            m_preprocess.add_simplifier((*fac)(m, s->get_params(), m_preprocess_state));
+        else 
+            init_preprocess(m, s->get_params(), m_preprocess, m_preprocess_state);
     }
 
     void assert_expr_core2(expr* t, expr* a) override {
@@ -197,7 +200,8 @@ public:
     }
 
     model_ref m_cached_model;
-    void get_model_core(model_ref& m) override {        
+    void get_model_core(model_ref& m) override {       
+        CTRACE("simplifier", m_mc.get(), m_mc->display(tout));
         if (m_cached_model) {
             m = m_cached_model;
             return;
@@ -229,7 +233,7 @@ public:
     solver* translate(ast_manager& m, params_ref const& p) override { 
         solver* new_s = s->translate(m, p);
         ast_translation tr(get_manager(), m);
-        simplifier_solver* result = alloc(simplifier_solver, new_s);
+        simplifier_solver* result = alloc(simplifier_solver, new_s, nullptr); // factory?
         for (dependent_expr const& f : m_fmls) 
             result->m_fmls.push_back(dependent_expr(tr, f));
         if (m_mc) 
@@ -311,7 +315,7 @@ public:
 
 };
 
-solver* mk_simplifier_solver(solver* s) {
-    return alloc(simplifier_solver, s);
+solver* mk_simplifier_solver(solver* s, simplifier_factory* fac) {
+    return alloc(simplifier_solver, s, fac);
 }
 
diff --git a/src/solver/simplifier_solver.h b/src/solver/simplifier_solver.h
index 3d97a3869..afc701ca0 100644
--- a/src/solver/simplifier_solver.h
+++ b/src/solver/simplifier_solver.h
@@ -20,6 +20,9 @@ Author:
 
 class solver;
 class solver_factory;
+class dependent_expr_simplifier;
+class dependent_expr_state;
+typedef std::function<dependent_expr_simplifier*(ast_manager&, const params_ref&, dependent_expr_state& s)> simplifier_factory;
 
-solver * mk_simplifier_solver(solver * s);
+solver * mk_simplifier_solver(solver * s, simplifier_factory* fac);
 
diff --git a/src/tactic/arith/bound_simplifier_tactic.h b/src/tactic/arith/bound_simplifier_tactic.h
index c8bc1318c..5451caa20 100644
--- a/src/tactic/arith/bound_simplifier_tactic.h
+++ b/src/tactic/arith/bound_simplifier_tactic.h
@@ -38,4 +38,5 @@ inline tactic* mk_bound_simplifier_tactic(ast_manager& m, params_ref const& p =
 
 /*
   ADD_TACTIC("bound-simplifier", "Simplify arithmetical expressions modulo bounds.", "mk_bound_simplifier_tactic(m, p)")
+  ADD_SIMPLIFIER("bound-simplifier", "Simplify arithmetical expressions modulo bounds.", "[](auto& m, auto& p, auto &s) -> dependent_expr_simplifier* { return alloc(bound_simplifier, m, p, s); }")
 */
diff --git a/src/tactic/arith/card2bv_tactic.h b/src/tactic/arith/card2bv_tactic.h
index 416997d45..032e964f9 100644
--- a/src/tactic/arith/card2bv_tactic.h
+++ b/src/tactic/arith/card2bv_tactic.h
@@ -69,4 +69,5 @@ inline tactic* mk_card2bv_tactic(ast_manager& m, params_ref const& p = params_re
 
 /*
   ADD_TACTIC("card2bv", "convert pseudo-boolean constraints to bit-vectors.", "mk_card2bv_tactic(m, p)")
+  ADD_SIMPLIFIER("card2bv", "convert pseudo-boolean constraints to bit-vectors.", "[](auto& m, auto& p, auto &s) -> dependent_expr_simplifier* { return alloc(card2bv, m, p, s); }")
 */
diff --git a/src/tactic/arith/propagate_ineqs_tactic.h b/src/tactic/arith/propagate_ineqs_tactic.h
index 1dbb0844b..68156c410 100644
--- a/src/tactic/arith/propagate_ineqs_tactic.h
+++ b/src/tactic/arith/propagate_ineqs_tactic.h
@@ -64,5 +64,6 @@ inline tactic* mk_propagate_ineqs_tactic(ast_manager& m, params_ref const& p = p
 
 /*
   ADD_TACTIC("propagate-ineqs", "propagate ineqs/bounds, remove subsumed inequalities.", "mk_propagate_ineqs_tactic(m, p)")
+  ADD_SIMPLIFIER("propagate-ineqs", "propagate ineqs/bounds, remove subsumed inequalities.", "[](auto& m, auto& p, auto &s) -> dependent_expr_simplifier* { return alloc(bound_simplifier, m, p, s); }")
 */
 
diff --git a/src/tactic/bv/bv_bounds_tactic.h b/src/tactic/bv/bv_bounds_tactic.h
index 8153ad52f..eb75ceca7 100644
--- a/src/tactic/bv/bv_bounds_tactic.h
+++ b/src/tactic/bv/bv_bounds_tactic.h
@@ -37,6 +37,7 @@ Contextual bounds simplification tactic.
 --*/
 #pragma once
 #include "tactic/tactic.h"
+#include "ast/simplifiers/bv_bounds_simplifier.h"
 
 tactic * mk_bv_bounds_tactic(ast_manager & m, params_ref const & p = params_ref());
 
@@ -45,6 +46,7 @@ tactic * mk_dom_bv_bounds_tactic(ast_manager & m, params_ref const & p = params_
 /*
   ADD_TACTIC("propagate-bv-bounds", "propagate bit-vector bounds by simplifying implied or contradictory bounds.", "mk_bv_bounds_tactic(m, p)")
 
+  ADD_SIMPLIFIER("propagate-bv-bounds", "propagate bit-vector bounds by simplifying implied or contradictory bounds.", "mk_bv_bounds_simplifier")
 
   ADD_TACTIC("propagate-bv-bounds2", "propagate bit-vector bounds by simplifying implied or contradictory bounds.", "mk_dom_bv_bounds_tactic(m, p)")
 
diff --git a/src/tactic/core/demodulator_tactic.h b/src/tactic/core/demodulator_tactic.h
index 9ffaa6ca9..507b4e5c5 100644
--- a/src/tactic/core/demodulator_tactic.h
+++ b/src/tactic/core/demodulator_tactic.h
@@ -100,4 +100,5 @@ inline tactic * mk_demodulator_tactic(ast_manager& m, params_ref const& p = para
 
 /*
   ADD_TACTIC("demodulator", "extracts equalities from quantifiers and applies them to simplify.", "mk_demodulator_tactic(m, p)")
+  ADD_SIMPLIFIER("demodulator", "extracts equalities from quantifiers and applies them to simplify.", "[](auto& m, auto& p, auto &s) -> dependent_expr_simplifier* { return alloc(demodulator_simplifier, m, p, s); }")
 */
diff --git a/src/tactic/core/distribute_forall_tactic.h b/src/tactic/core/distribute_forall_tactic.h
index 328a62b2f..419eba71e 100644
--- a/src/tactic/core/distribute_forall_tactic.h
+++ b/src/tactic/core/distribute_forall_tactic.h
@@ -50,5 +50,6 @@ inline tactic * mk_distribute_forall_tactic(ast_manager& m, params_ref const& p
 
 /*
   ADD_TACTIC("distribute-forall", "distribute forall over conjunctions.", "mk_distribute_forall_tactic(m, p)")
+  ADD_SIMPLIFIER("distribute-forall", "distribute forall over conjunctions.", "[](auto& m, auto& p, auto &s) -> dependent_expr_simplifier* { return alloc(distribute_forall_simplifier, m, p, s); }")
 */
 
diff --git a/src/tactic/core/dom_simplify_tactic.h b/src/tactic/core/dom_simplify_tactic.h
index 2dba378b7..795db0f26 100644
--- a/src/tactic/core/dom_simplify_tactic.h
+++ b/src/tactic/core/dom_simplify_tactic.h
@@ -56,5 +56,6 @@ inline tactic* mk_dom_simplify_tactic(ast_manager& m, params_ref const& p) {
 
 /*
 ADD_TACTIC("dom-simplify", "apply dominator simplification rules.", "mk_dom_simplify_tactic(m, p)")
+ADD_SIMPLIFIER("dom-simplify", "apply dominator simplification rules.", "[](auto& m, auto& p, auto& s) -> dependent_expr_simplifier* { return alloc(dominator_simplifier, m, s, mk_expr_substitution_simplifier(m), p); }")
 */
 
diff --git a/src/tactic/core/elim_uncnstr2_tactic.h b/src/tactic/core/elim_uncnstr2_tactic.h
index f1c9b9bd7..fc249da64 100644
--- a/src/tactic/core/elim_uncnstr2_tactic.h
+++ b/src/tactic/core/elim_uncnstr2_tactic.h
@@ -118,4 +118,5 @@ inline tactic * mk_elim_uncnstr2_tactic(ast_manager & m, params_ref const & p =
 
 /*
   ADD_TACTIC("elim-uncnstr2", "eliminate unconstrained variables.", "mk_elim_uncnstr2_tactic(m, p)")
+  ADD_SIMPLIFIER("elim-unconstrained", "eliminate unconstrained variables.", "[](auto& m, auto& p, auto &s) -> dependent_expr_simplifier* { return alloc(elim_unconstrained, m, s); }")
 */
diff --git a/src/tactic/core/eliminate_predicates_tactic.h b/src/tactic/core/eliminate_predicates_tactic.h
index 4d90b1acf..b53892e8b 100644
--- a/src/tactic/core/eliminate_predicates_tactic.h
+++ b/src/tactic/core/eliminate_predicates_tactic.h
@@ -64,4 +64,5 @@ inline tactic * mk_eliminate_predicates_tactic(ast_manager& m, params_ref const&
 
 /*
   ADD_TACTIC("elim-predicates", "eliminate predicates.", "mk_eliminate_predicates_tactic(m, p)")
+  ADD_SIMPLIFIER("elim-predicates", "eliminate predicates.", "[](auto& m, auto& p, auto &s) -> dependent_expr_simplifier* { return alloc(eliminate_predicates, m, s); }")
 */
diff --git a/src/tactic/core/propagate_values2_tactic.h b/src/tactic/core/propagate_values2_tactic.h
index e380ce7d3..466ef87a1 100644
--- a/src/tactic/core/propagate_values2_tactic.h
+++ b/src/tactic/core/propagate_values2_tactic.h
@@ -55,4 +55,5 @@ inline tactic * mk_propagate_values2_tactic(ast_manager & m, params_ref const &
 
 /*
   ADD_TACTIC("propagate-values2", "propagate constants.", "mk_propagate_values2_tactic(m, p)")
+  ADD_SIMPLIFIER("propagate-values", "propagate constants.", "[](auto& m, auto& p, auto &s) -> dependent_expr_simplifier* { return alloc(propagate_values, m, p, s); }")
 */
diff --git a/src/tactic/core/reduce_args_tactic.h b/src/tactic/core/reduce_args_tactic.h
index fa90837bf..4bfb7ed2f 100644
--- a/src/tactic/core/reduce_args_tactic.h
+++ b/src/tactic/core/reduce_args_tactic.h
@@ -79,5 +79,7 @@ inline tactic* mk_reduce_args_tactic2(ast_manager& m, params_ref const& p = para
 }
 /*
   ADD_TACTIC("reduce-args2", "reduce the number of arguments of function applications, when for all occurrences of a function f the i-th is a value.", "mk_reduce_args_tactic2(m, p)")
+  ADD_SIMPLIFIER("reduce-args", "reduce the number of arguments of function applications, when for all occurrences of a function f the i-th is a value.", "[](auto& m, auto& p, auto& s) -> dependent_expr_simplifier* { return mk_reduce_args_simplifier(m, s, p); }")
+
 */
 
diff --git a/src/tactic/core/solve_eqs_tactic.h b/src/tactic/core/solve_eqs_tactic.h
index fec46bf04..af27d4576 100644
--- a/src/tactic/core/solve_eqs_tactic.h
+++ b/src/tactic/core/solve_eqs_tactic.h
@@ -79,4 +79,5 @@ inline tactic * mk_solve_eqs_tactic(ast_manager& m, params_ref const& p = params
 
 /*
   ADD_TACTIC("solve-eqs", "solve for variables.", "mk_solve_eqs_tactic(m, p)")
+  ADD_SIMPLIFIER("solve-eqs", "solve for variables.", "[](auto& m, auto& p, auto &s) -> dependent_expr_simplifier* { return alloc(euf::solve_eqs, m, s); }")
 */