diff --git a/src/ast/rewriter/th_rewriter.cpp b/src/ast/rewriter/th_rewriter.cpp
index 96b69dbc3..9604f6d16 100644
--- a/src/ast/rewriter/th_rewriter.cpp
+++ b/src/ast/rewriter/th_rewriter.cpp
@@ -924,6 +924,11 @@ void th_rewriter::get_param_descrs(param_descrs & r) {
     rewriter_params::collect_param_descrs(r);
 }
 
+void th_rewriter::set_flat_and_or(bool f) {
+    m_imp->cfg().m_b_rw.set_flat_and_or(f);
+}
+
+
 th_rewriter::~th_rewriter() {
     dealloc(m_imp);
 }
diff --git a/src/ast/rewriter/th_rewriter.h b/src/ast/rewriter/th_rewriter.h
index e432678a4..b84164abc 100644
--- a/src/ast/rewriter/th_rewriter.h
+++ b/src/ast/rewriter/th_rewriter.h
@@ -38,6 +38,9 @@ public:
 
     void updt_params(params_ref const & p);
     static void get_param_descrs(param_descrs & r);
+
+    void set_flat_and_or(bool f);
+
     unsigned get_cache_size() const;
     unsigned get_num_steps() const;
    
diff --git a/src/ast/simplifiers/extract_eqs.cpp b/src/ast/simplifiers/extract_eqs.cpp
index 543030e91..775eb4d22 100644
--- a/src/ast/simplifiers/extract_eqs.cpp
+++ b/src/ast/simplifiers/extract_eqs.cpp
@@ -29,16 +29,23 @@ namespace euf {
     class basic_extract_eq : public extract_eq {
         ast_manager& m;
         bool m_ite_solver = true;
+        bool m_allow_bool = true;
 
     public:
         basic_extract_eq(ast_manager& m) : m(m) {}
 
+        virtual void set_allow_booleans(bool f) {
+            m_allow_bool = f;
+        }
+
         void get_eqs(dependent_expr const& e, dep_eq_vector& eqs) override {
             auto [f, d] = e();
             expr* x, * y;
             if (m.is_eq(f, x, y)) {
                 if (x == y)
                     return;
+                if (!m_allow_bool && m.is_bool(x))
+                    return;
                 if (is_uninterp_const(x))
                     eqs.push_back(dependent_eq(e.fml(), to_app(x), expr_ref(y, m), d));
                 if (is_uninterp_const(y))
@@ -47,6 +54,8 @@ namespace euf {
             expr* c, * th, * el, * x1, * y1, * x2, * y2;
             if (m_ite_solver && m.is_ite(f, c, th, el)) {
                 if (m.is_eq(th, x1, y1) && m.is_eq(el, x2, y2)) {
+                    if (!m_allow_bool && m.is_bool(x1))
+                        return;
                     if (x1 == y2 && is_uninterp_const(x1))
                         std::swap(x2, y2);
                     if (x2 == y2 && is_uninterp_const(x2))
@@ -57,6 +66,8 @@ namespace euf {
                         eqs.push_back(dependent_eq(e.fml(), to_app(x1), expr_ref(m.mk_ite(c, y1, y2), m), d));
                 }
             }
+            if (!m_allow_bool)
+                return;
             if (is_uninterp_const(f))
                 eqs.push_back(dependent_eq(e.fml(), to_app(f), expr_ref(m.mk_true(), m), d));
             if (m.is_not(f, x) && is_uninterp_const(x))
diff --git a/src/ast/simplifiers/extract_eqs.h b/src/ast/simplifiers/extract_eqs.h
index f38829dfc..724425d6a 100644
--- a/src/ast/simplifiers/extract_eqs.h
+++ b/src/ast/simplifiers/extract_eqs.h
@@ -18,6 +18,7 @@ Author:
 
 #pragma once
 
+#include "ast/ast_pp.h"
 #include "ast/simplifiers/dependent_expr_state.h"
 #include "ast/rewriter/th_rewriter.h"
 #include "ast/expr_substitution.h"
@@ -42,8 +43,13 @@ namespace euf {
         virtual void get_eqs(dependent_expr const& e, dep_eq_vector& eqs) = 0;
         virtual void pre_process(dependent_expr_state& fmls) {}
         virtual void updt_params(params_ref const& p) {}
+        virtual void set_allow_booleans(bool f) {}
     };
 
     void register_extract_eqs(ast_manager& m, scoped_ptr_vector<extract_eq>& ex);
 
 }
+
+inline std::ostream& operator<<(std::ostream& out, euf::dependent_eq const& eq) {
+    return out << mk_pp(eq.var, eq.term.m()) << " = " << eq.term << "\n";
+}
diff --git a/src/ast/simplifiers/model_reconstruction_trail.cpp b/src/ast/simplifiers/model_reconstruction_trail.cpp
index a8e75bfa3..373a500bf 100644
--- a/src/ast/simplifiers/model_reconstruction_trail.cpp
+++ b/src/ast/simplifiers/model_reconstruction_trail.cpp
@@ -26,7 +26,6 @@ void model_reconstruction_trail::replay(dependent_expr const& d, vector<dependen
 
     added.push_back(d);
 
-
     for (auto& t : m_trail) {
         if (!t->m_active)
             continue;
@@ -69,6 +68,7 @@ model_converter_ref model_reconstruction_trail::get_model_converter() {
     // substituted variables by their terms.
     //
 
+    
     scoped_ptr<expr_replacer> rp = mk_default_expr_replacer(m, false);
     expr_substitution subst(m, true, false);
     rp->set_substitution(&subst);
diff --git a/src/ast/simplifiers/solve_context_eqs.cpp b/src/ast/simplifiers/solve_context_eqs.cpp
index c11505726..37836db27 100644
--- a/src/ast/simplifiers/solve_context_eqs.cpp
+++ b/src/ast/simplifiers/solve_context_eqs.cpp
@@ -57,7 +57,7 @@ namespace euf {
         if (!contains_v(f))
             return true;                
         signed_expressions conjuncts;
-        if (contains_conjunctively(f, sign, e, conjuncts))
+        if (contains_conjunctively(f, sign, e, conjuncts)) 
             return true;
         if (recursion_depth > 3)
             return false;
@@ -67,9 +67,9 @@ namespace euf {
     /*
     * Every disjunction in f that contains v also contains the equation e.
     */
-    bool solve_context_eqs::is_disjunctively_safe(unsigned recursion_depth, expr* f, bool sign, expr* e) {
+    bool solve_context_eqs::is_disjunctively_safe(unsigned recursion_depth, expr* f0, bool sign, expr* e) {
         signed_expressions todo;
-        todo.push_back({sign, f});
+        todo.push_back({sign, f0});
         while (!todo.empty()) {
             auto [s, f] = todo.back();
             todo.pop_back();
@@ -93,11 +93,21 @@ namespace euf {
                     todo.push_back({s, arg});            
             else if (m.is_not(f, f))
                 todo.push_back({!s, f});
+            else if (!is_conjunction(s, f))
+                return false;
             else if (!is_safe_eq(recursion_depth + 1, f, s, e))
                 return false;
         }
         return true;
     }
+
+    bool solve_context_eqs::is_conjunction(bool sign, expr* f) const {
+        if (!sign && m.is_and(f))
+            return true;
+        if (sign && m.is_or(f))
+            return true;
+        return false;
+    }
    
     /**
     * Determine whether some conjunction in f contains e. 
@@ -140,29 +150,43 @@ namespace euf {
         for (unsigned i = m_solve_eqs.m_qhead; i < m_fmls.size(); ++i)
             collect_nested_equalities(m_fmls[i], visited, eqs);
 
+        std::stable_sort(eqs.begin(), eqs.end(), [&](dependent_eq const& e1, dependent_eq const& e2) {
+                return e1.var->get_id() < e2.var->get_id(); });
         unsigned j = 0;
+        expr* last_var = nullptr;
         for (auto const& eq : eqs) {
-           
-            m_contains_v.reset();
 
-            // first check if v is in term. If it is, then the substitution candidate is unsafe
-            m_todo.push_back(eq.term);
-            mark_occurs(m_todo, eq.var, m_contains_v);
-            SASSERT(m_todo.empty());
-            if (m_contains_v.is_marked(eq.term))
+            SASSERT(!m.is_bool(eq.var));
+
+            if (eq.var != last_var) {
+
+                m_contains_v.reset();
+                
+                // first check if v is in term. If it is, then the substitution candidate is unsafe
+                m_todo.push_back(eq.term);
+                mark_occurs(m_todo, eq.var, m_contains_v);
+                SASSERT(m_todo.empty());
+                last_var = eq.var;
+                if (m_contains_v.is_marked(eq.term))
+                    continue;
+
+                // then mark occurrences
+                for (unsigned i = 0; i < m_fmls.size(); ++i)
+                    m_todo.push_back(m_fmls[i].fml());
+                mark_occurs(m_todo, eq.var, m_contains_v);
+                SASSERT(m_todo.empty());
+            }
+            else if (m_contains_v.is_marked(eq.term))
                 continue;
 
-            // then mark occurrences
-            for (unsigned i = 0; i < m_fmls.size(); ++i)
-                m_todo.push_back(m_fmls[i].fml());
-            mark_occurs(m_todo, eq.var, m_contains_v);
-            SASSERT(m_todo.empty());
-
             // subject to occurrences, check if equality is safe
-            if (is_safe_eq(eq.orig))
+            if (is_safe_eq(eq.orig)) 
                 eqs[j++] = eq;
         }
         eqs.shrink(j);
+        TRACE("solve_eqs",
+              for (auto const& eq : eqs)
+                  tout << eq << "\n");
     }
 
     void solve_context_eqs::collect_nested_equalities(dependent_expr const& df, expr_mark& visited, dep_eq_vector& eqs) {
@@ -204,8 +228,11 @@ namespace euf {
             else if (m.is_not(f, f))
                 todo.push_back({ !s, depth, f });
             else if (!s && 1 == depth % 2) {
-                for (extract_eq* ex : m_solve_eqs.m_extract_plugins)
+                for (extract_eq* ex : m_solve_eqs.m_extract_plugins) {
+                    ex->set_allow_booleans(false);
                     ex->get_eqs(dependent_expr(m, f, df.dep()), eqs);
+                    ex->set_allow_booleans(true);
+                }
             }
         }
     }
diff --git a/src/ast/simplifiers/solve_context_eqs.h b/src/ast/simplifiers/solve_context_eqs.h
index fb330b57b..8332d3a73 100644
--- a/src/ast/simplifiers/solve_context_eqs.h
+++ b/src/ast/simplifiers/solve_context_eqs.h
@@ -43,6 +43,7 @@ namespace euf {
         bool is_safe_eq(expr* f, expr* e) { return is_safe_eq(0, f, false, e); }
         bool is_disjunctively_safe(unsigned recursion_depth, expr* f, bool sign, expr* e);
         bool contains_conjunctively(expr* f, bool sign, expr* e, signed_expressions& conjuncts);
+        bool is_conjunction(bool sign, expr* f) const;
         
         void collect_nested_equalities(dependent_expr const& f, expr_mark& visited, dep_eq_vector& eqs);        
 
diff --git a/src/ast/simplifiers/solve_eqs.cpp b/src/ast/simplifiers/solve_eqs.cpp
index f364c31e1..96b0427f6 100644
--- a/src/ast/simplifiers/solve_eqs.cpp
+++ b/src/ast/simplifiers/solve_eqs.cpp
@@ -118,6 +118,8 @@ namespace euf {
     }
 
     void solve_eqs::normalize() {
+        if (m_subst_ids.empty())
+            return;
         scoped_ptr<expr_replacer> rp = mk_default_expr_replacer(m, false);
         rp->set_substitution(m_subst.get());
 
@@ -152,15 +154,18 @@ namespace euf {
     void solve_eqs::apply_subst(vector<dependent_expr>& old_fmls) {
         if (!m.inc())
             return;
+        if (m_subst_ids.empty())
+            return;
+        
         scoped_ptr<expr_replacer> rp = mk_default_expr_replacer(m, false);
         rp->set_substitution(m_subst.get());
 
         for (unsigned i = m_qhead; i < m_fmls.size() && !m_fmls.inconsistent(); ++i) {
             auto [f, d] = m_fmls[i]();
             auto [new_f, new_dep] = rp->replace_with_dep(f);
+            m_rewriter(new_f);
             if (new_f == f)
                 continue;
-            m_rewriter(new_f);
             new_dep = m.mk_join(d, new_dep);
             old_fmls.push_back(m_fmls[i]);
             m_fmls.update(i, dependent_expr(m, new_f, new_dep));
@@ -185,14 +190,13 @@ namespace euf {
             normalize();
             apply_subst(old_fmls);
             ++count;
+            save_subst({});
         } 
         while (!m_subst_ids.empty() && count < 20 && m.inc());
 
         if (!m.inc())
             return;
 
-        save_subst({});
-
         if (m_config.m_context_solve) {            
             old_fmls.reset();
             m_subst_ids.reset();
@@ -211,7 +215,7 @@ namespace euf {
 
     void solve_eqs::save_subst(vector<dependent_expr> const& old_fmls) {
         if (!m_subst->empty())   
-            m_fmls.model_trail().push(m_subst.detach(), old_fmls);        
+            m_fmls.model_trail().push(m_subst.detach(), old_fmls);                
     }
 
     void solve_eqs::filter_unsafe_vars() {
@@ -222,11 +226,10 @@ namespace euf {
                 m_unsafe_vars.mark(term);
     }
 
-
-
     solve_eqs::solve_eqs(ast_manager& m, dependent_expr_state& fmls) : 
         dependent_expr_simplifier(m, fmls), m_rewriter(m) {
         register_extract_eqs(m, m_extract_plugins);
+        m_rewriter.set_flat_and_or(false);
     }
 
     void solve_eqs::updt_params(params_ref const& p) {
diff --git a/src/nlsat/tactic/qfnra_nlsat_tactic.cpp b/src/nlsat/tactic/qfnra_nlsat_tactic.cpp
index fc812c4f5..e41347c2b 100644
--- a/src/nlsat/tactic/qfnra_nlsat_tactic.cpp
+++ b/src/nlsat/tactic/qfnra_nlsat_tactic.cpp
@@ -27,6 +27,7 @@ Notes:
 #include "tactic/core/elim_uncnstr_tactic.h"
 #include "tactic/core/propagate_values_tactic.h"
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/core/elim_term_ite_tactic.h"
 
 tactic * mk_qfnra_nlsat_tactic(ast_manager & m, params_ref const & p) {
diff --git a/src/opt/opt_context.cpp b/src/opt/opt_context.cpp
index 5895643bd..66a391cb8 100644
--- a/src/opt/opt_context.cpp
+++ b/src/opt/opt_context.cpp
@@ -31,6 +31,7 @@ Notes:
 #include "tactic/tactic.h"
 #include "tactic/arith/lia2card_tactic.h"
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/core/simplify_tactic.h"
 #include "tactic/core/propagate_values_tactic.h"
 #include "tactic/core/solve_eqs_tactic.h"
diff --git a/src/tactic/core/solve_eqs2_tactic.h b/src/tactic/core/solve_eqs2_tactic.h
index 91b3875ae..fa095aad0 100644
--- a/src/tactic/core/solve_eqs2_tactic.h
+++ b/src/tactic/core/solve_eqs2_tactic.h
@@ -29,13 +29,19 @@ public:
     }
 };
 
-inline tactic * mk_solve_eqs2_tactic(ast_manager& m, params_ref const& p) {
-    return alloc(dependent_expr_state_tactic, m, p, alloc(solve_eqs2_tactic_factory), "solve-eqs2");
+inline tactic * mk_solve_eqs2_tactic(ast_manager& m, params_ref const& p = params_ref()) {
+    return alloc(dependent_expr_state_tactic, m, p, alloc(solve_eqs2_tactic_factory), "solve-eqs");
 }
 
+#if 1
+inline tactic * mk_solve_eqs_tactic(ast_manager & m, params_ref const & p = params_ref()) {
+    return mk_solve_eqs2_tactic(m, p);
+}
+#endif
+
 
 /*
-  ADD_TACTIC("solve-eqs2", "solve for variables.", "mk_solve_eqs2_tactic(m, p)")
+  ADD_TACTIC("solve-eqs", "solve for variables.", "mk_solve_eqs2_tactic(m, p)")
 */
 
 
diff --git a/src/tactic/core/solve_eqs_tactic.cpp b/src/tactic/core/solve_eqs_tactic.cpp
index fdba65b3f..d445b68ac 100644
--- a/src/tactic/core/solve_eqs_tactic.cpp
+++ b/src/tactic/core/solve_eqs_tactic.cpp
@@ -997,6 +997,8 @@ class solve_eqs_tactic : public tactic {
         //
         void operator()(goal_ref const & g, goal_ref_buffer & result) {
             model_converter_ref mc;
+            std::function<void(statistics&)> coll = [&](statistics& st) { collect_statistics(st); };
+            statistics_report sreport(coll);
             tactic_report report("solve_eqs", *g);
             TRACE("goal", g->display(tout););
             m_produce_models = g->models_enabled();
@@ -1042,7 +1044,6 @@ class solve_eqs_tactic : public tactic {
             result.push_back(g.get());
 
             
-            IF_VERBOSE(10, statistics st; collect_statistics(st); st.display_smt2(verbose_stream()));
         }
     };
     
@@ -1103,6 +1104,6 @@ public:
     
 };
 
-tactic * mk_solve_eqs_tactic(ast_manager & m, params_ref const & p) {
+tactic * mk_solve_eqs1_tactic(ast_manager & m, params_ref const & p) {
     return clean(alloc(solve_eqs_tactic, m, p, mk_expr_simp_replacer(m, p), true));
 }
diff --git a/src/tactic/core/solve_eqs_tactic.h b/src/tactic/core/solve_eqs_tactic.h
index d65a33046..4b26254a0 100644
--- a/src/tactic/core/solve_eqs_tactic.h
+++ b/src/tactic/core/solve_eqs_tactic.h
@@ -22,10 +22,16 @@ Revision History:
 class ast_manager;
 class tactic;
 
-tactic * mk_solve_eqs_tactic(ast_manager & m, params_ref const & p = params_ref());
+tactic * mk_solve_eqs1_tactic(ast_manager & m, params_ref const & p = params_ref());
+
+#if 0
+inline tactic * mk_solve_eqs_tactic(ast_manager & m, params_ref const & p = params_ref()) {
+    return mk_solve_eqs1_tactic(m, p);
+}
+#endif
 
 /*
-  ADD_TACTIC("solve-eqs", "eliminate variables by solving equations.", "mk_solve_eqs_tactic(m, p)")
+  ADD_TACTIC("solve-eqs1", "eliminate variables by solving equations.", "mk_solve_eqs1_tactic(m, p)")
 */
 
 
diff --git a/src/tactic/dependent_expr_state_tactic.h b/src/tactic/dependent_expr_state_tactic.h
index 01e135e8a..24f12aeae 100644
--- a/src/tactic/dependent_expr_state_tactic.h
+++ b/src/tactic/dependent_expr_state_tactic.h
@@ -22,16 +22,19 @@ class dependent_expr_state_tactic : public tactic, public dependent_expr_state {
     ast_manager&    m;
     params_ref      m_params;
     std::string     m_name;
-    ref<dependent_expr_simplifier_factory>  m_factory;
-    scoped_ptr<dependent_expr_simplifier>   m_simp;
-    trail_stack                             m_trail;
-    scoped_ptr<model_reconstruction_trail>  m_model_trail;
+    trail_stack     m_trail;
     goal_ref        m_goal;
     dependent_expr  m_dep;
+    statistics      m_st;
+    ref<dependent_expr_simplifier_factory>  m_factory;
+    scoped_ptr<dependent_expr_simplifier>   m_simp;
+    scoped_ptr<model_reconstruction_trail>  m_model_trail;
 
     void init() {
-        if (!m_simp)
+        if (!m_simp) {
             m_simp = m_factory->mk(m, m_params, *this);
+            m_st.reset();
+        }
         if (!m_model_trail)
             m_model_trail = alloc(model_reconstruction_trail, m, m_trail);
     }
@@ -43,7 +46,7 @@ public:
         m_params(p),
         m_name(name),
         m_factory(f),
-        m_simp(f->mk(m, p, *this)),
+        m_simp(nullptr),
         m_dep(m, m.mk_true(), nullptr)
     {}
 
@@ -86,30 +89,34 @@ public:
         if (in->proofs_enabled())
             throw tactic_exception("tactic does not support low level proofs");
         init();
+        statistics_report sreport(*this);
         tactic_report report(name(), *in);
         m_goal = in.get();
         m_simp->reduce();
         m_goal->inc_depth();
         if (in->models_enabled())
-            in->set(m_model_trail->get_model_converter().get());
+            in->add(m_model_trail->get_model_converter().get());
         result.push_back(in.get());        
-
-        statistics st;
-        collect_statistics(st);
-        IF_VERBOSE(10, st.display_smt2(verbose_stream()));
     }
 
     void cleanup() override {
+        if (m_simp) 
+            m_simp->collect_statistics(m_st);
+        m_simp = nullptr;
+        m_model_trail = nullptr;
     }
 
     void collect_statistics(statistics & st) const override {
-        if (m_simp)
+        if (m_simp) 
             m_simp->collect_statistics(st);
+        else
+            st.copy(m_st);
     }
     
     void reset_statistics() override {
         if (m_simp)
             m_simp->reset_statistics();
+        m_st.reset();
     }
 };
 
diff --git a/src/tactic/sls/sls_tactic.cpp b/src/tactic/sls/sls_tactic.cpp
index e631c23e9..a09da60a9 100644
--- a/src/tactic/sls/sls_tactic.cpp
+++ b/src/tactic/sls/sls_tactic.cpp
@@ -18,6 +18,7 @@ Notes:
 --*/
 #include "ast/normal_forms/nnf.h"
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/bv/bv_size_reduction_tactic.h"
 #include "tactic/bv/max_bv_sharing_tactic.h"
 #include "tactic/core/simplify_tactic.h"
diff --git a/src/tactic/smtlogics/qfaufbv_tactic.cpp b/src/tactic/smtlogics/qfaufbv_tactic.cpp
index acad15fd6..6d44addf0 100644
--- a/src/tactic/smtlogics/qfaufbv_tactic.cpp
+++ b/src/tactic/smtlogics/qfaufbv_tactic.cpp
@@ -17,6 +17,7 @@ Notes:
 
 --*/
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/core/simplify_tactic.h"
 #include "tactic/core/propagate_values_tactic.h"
 #include "tactic/bv/bit_blaster_tactic.h"
diff --git a/src/tactic/smtlogics/qfauflia_tactic.cpp b/src/tactic/smtlogics/qfauflia_tactic.cpp
index 2f1879d58..9ca6b70ef 100644
--- a/src/tactic/smtlogics/qfauflia_tactic.cpp
+++ b/src/tactic/smtlogics/qfauflia_tactic.cpp
@@ -21,6 +21,7 @@ Notes:
 #include "tactic/core/propagate_values_tactic.h"
 #include "tactic/arith/propagate_ineqs_tactic.h"
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/core/elim_uncnstr_tactic.h"
 #include "tactic/smtlogics/smt_tactic.h"
 
diff --git a/src/tactic/smtlogics/qfbv_tactic.cpp b/src/tactic/smtlogics/qfbv_tactic.cpp
index 1366b701e..90df4fe42 100644
--- a/src/tactic/smtlogics/qfbv_tactic.cpp
+++ b/src/tactic/smtlogics/qfbv_tactic.cpp
@@ -20,6 +20,7 @@ Notes:
 #include "tactic/core/simplify_tactic.h"
 #include "tactic/core/propagate_values_tactic.h"
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/core/elim_uncnstr_tactic.h"
 #include "tactic/bv/bit_blaster_tactic.h"
 #include "tactic/bv/bv1_blaster_tactic.h"
@@ -39,6 +40,9 @@ static tactic * mk_qfbv_preamble(ast_manager& m, params_ref const& p) {
     // conservative gaussian elimination.
     solve_eq_p.set_uint("solve_eqs_max_occs", 2);
 
+    params_ref flat_and_or_p = p;
+    flat_and_or_p.set_bool("flat_and_or", false);
+
     params_ref simp2_p = p;
     simp2_p.set_bool("som", true);
     simp2_p.set_bool("pull_cheap_ite", true);
@@ -47,15 +51,17 @@ static tactic * mk_qfbv_preamble(ast_manager& m, params_ref const& p) {
     simp2_p.set_uint("local_ctx_limit", 10000000);
     simp2_p.set_bool("flat", true); // required by som
     simp2_p.set_bool("hoist_mul", false); // required by som
+    simp2_p.set_bool("flat_and_or", false);
 
     params_ref hoist_p;
     hoist_p.set_bool("hoist_mul", true);
     hoist_p.set_bool("som", false);
+    hoist_p.set_bool("flat_and_or", false);
 
     return
         and_then(
-            mk_simplify_tactic(m),
-            mk_propagate_values_tactic(m),
+            using_params(mk_simplify_tactic(m), flat_and_or_p),
+            using_params(mk_propagate_values_tactic(m), flat_and_or_p),
             using_params(mk_solve_eqs_tactic(m), solve_eq_p),
             mk_elim_uncnstr_tactic(m),
             if_no_proofs(if_no_unsat_cores(mk_bv_size_reduction_tactic(m))),
@@ -87,6 +93,7 @@ static tactic * mk_qfbv_tactic(ast_manager& m, params_ref const & p, tactic* sat
     params_ref local_ctx_p = p;
     local_ctx_p.set_bool("local_ctx", true);
     local_ctx_p.set_bool("flat", false);
+    local_ctx_p.set_bool("flat_and_or", false);
 
     params_ref solver_p;
     solver_p.set_bool("preprocess", false); // preprocessor of smt::context is not needed.
diff --git a/src/tactic/smtlogics/qfidl_tactic.cpp b/src/tactic/smtlogics/qfidl_tactic.cpp
index c86789ed0..5c1ba5f44 100644
--- a/src/tactic/smtlogics/qfidl_tactic.cpp
+++ b/src/tactic/smtlogics/qfidl_tactic.cpp
@@ -21,6 +21,7 @@ Notes:
 #include "tactic/core/propagate_values_tactic.h"
 #include "tactic/arith/propagate_ineqs_tactic.h"
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/core/elim_uncnstr_tactic.h"
 #include "tactic/arith/normalize_bounds_tactic.h"
 #include "tactic/arith/fix_dl_var_tactic.h"
diff --git a/src/tactic/smtlogics/qflia_tactic.cpp b/src/tactic/smtlogics/qflia_tactic.cpp
index b8ebbd8a9..d116414ea 100644
--- a/src/tactic/smtlogics/qflia_tactic.cpp
+++ b/src/tactic/smtlogics/qflia_tactic.cpp
@@ -22,6 +22,7 @@ Notes:
 #include "tactic/arith/propagate_ineqs_tactic.h"
 #include "tactic/arith/normalize_bounds_tactic.h"
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/core/elim_uncnstr_tactic.h"
 #include "tactic/arith/add_bounds_tactic.h"
 #include "tactic/arith/pb2bv_tactic.h"
diff --git a/src/tactic/smtlogics/qfuf_tactic.cpp b/src/tactic/smtlogics/qfuf_tactic.cpp
index 609107a48..d9f723d67 100644
--- a/src/tactic/smtlogics/qfuf_tactic.cpp
+++ b/src/tactic/smtlogics/qfuf_tactic.cpp
@@ -21,6 +21,7 @@ Notes:
 #include "tactic/core/simplify_tactic.h"
 #include "tactic/core/symmetry_reduce_tactic.h"
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/core/propagate_values_tactic.h"
 #include "tactic/smtlogics/smt_tactic.h"
 
diff --git a/src/tactic/smtlogics/qfufbv_tactic.cpp b/src/tactic/smtlogics/qfufbv_tactic.cpp
index d93a17ce1..98e09b56a 100644
--- a/src/tactic/smtlogics/qfufbv_tactic.cpp
+++ b/src/tactic/smtlogics/qfufbv_tactic.cpp
@@ -21,6 +21,7 @@ Notes:
 #include "tactic/core/simplify_tactic.h"
 #include "tactic/core/propagate_values_tactic.h"
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/core/elim_uncnstr_tactic.h"
 #include "tactic/bv/max_bv_sharing_tactic.h"
 #include "tactic/bv/bv_size_reduction_tactic.h"
@@ -136,22 +137,23 @@ private:
 };
 
 static tactic * mk_qfufbv_preamble1(ast_manager & m, params_ref const & p) {
-    params_ref simp2_p = p;
+    params_ref simp2_p = p, flat_and_or_p = p;
+    flat_and_or_p.set_bool("flat_and_or", false);
     simp2_p.set_bool("pull_cheap_ite", true);
     simp2_p.set_bool("push_ite_bv", false);
     simp2_p.set_bool("local_ctx", true);
     simp2_p.set_uint("local_ctx_limit", 10000000);
-
     simp2_p.set_bool("ite_extra_rules", true);
     simp2_p.set_bool("mul2concat", true);
+    simp2_p.set_bool("flat_and_or", false);
 
     params_ref ctx_simp_p;
     ctx_simp_p.set_uint("max_depth", 32);
     ctx_simp_p.set_uint("max_steps", 5000000);
 
     return and_then(
-        mk_simplify_tactic(m),
-        mk_propagate_values_tactic(m),
+        using_params(mk_simplify_tactic(m), flat_and_or_p),
+        using_params(mk_propagate_values_tactic(m), flat_and_or_p),
         if_no_proofs(if_no_unsat_cores(mk_bv_bound_chk_tactic(m))),
         //using_params(mk_ctx_simplify_tactic(m_m), ctx_simp_p),
         mk_solve_eqs_tactic(m),
@@ -163,8 +165,10 @@ static tactic * mk_qfufbv_preamble1(ast_manager & m, params_ref const & p) {
 }
 
 static tactic * mk_qfufbv_preamble(ast_manager & m, params_ref const & p) {
-    return and_then(mk_simplify_tactic(m),
-                    mk_propagate_values_tactic(m),
+    params_ref simp2_p = p, flat_and_or_p = p;
+    flat_and_or_p.set_bool("flat_and_or", false);
+    return and_then(using_params(mk_simplify_tactic(m), flat_and_or_p),
+                    using_params(mk_propagate_values_tactic(m), flat_and_or_p),
                     mk_solve_eqs_tactic(m),
                     mk_elim_uncnstr_tactic(m),
                     if_no_proofs(if_no_unsat_cores(mk_reduce_args_tactic(m))),
diff --git a/src/tactic/smtlogics/quant_tactics.cpp b/src/tactic/smtlogics/quant_tactics.cpp
index daf020a14..3bf6b658d 100644
--- a/src/tactic/smtlogics/quant_tactics.cpp
+++ b/src/tactic/smtlogics/quant_tactics.cpp
@@ -20,6 +20,7 @@ Revision History:
 #include "tactic/core/simplify_tactic.h"
 #include "tactic/core/propagate_values_tactic.h"
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/core/elim_uncnstr_tactic.h"
 #include "qe/lite/qe_lite.h"
 #include "qe/qsat.h"
diff --git a/src/tactic/ufbv/ufbv_tactic.cpp b/src/tactic/ufbv/ufbv_tactic.cpp
index e8495c013..728e6397d 100644
--- a/src/tactic/ufbv/ufbv_tactic.cpp
+++ b/src/tactic/ufbv/ufbv_tactic.cpp
@@ -20,6 +20,7 @@ Notes:
 #include "tactic/core/simplify_tactic.h"
 #include "tactic/core/propagate_values_tactic.h"
 #include "tactic/core/solve_eqs_tactic.h"
+#include "tactic/core/solve_eqs2_tactic.h"
 #include "tactic/core/distribute_forall_tactic.h"
 #include "tactic/core/der_tactic.h"
 #include "tactic/core/reduce_args_tactic.h"