diff --git a/src/ast/recfun_decl_plugin.cpp b/src/ast/recfun_decl_plugin.cpp
index e63b50700..e26a59b6d 100644
--- a/src/ast/recfun_decl_plugin.cpp
+++ b/src/ast/recfun_decl_plugin.cpp
@@ -513,4 +513,39 @@ namespace recfun {
         }
 
     }
+
+
+    case_expansion::case_expansion(recfun::util& u, app * n) : 
+        m_lhs(n, u.m()), m_def(nullptr), m_args(u.m())  {
+        SASSERT(u.is_defined(n));
+        func_decl * d = n->get_decl();
+        m_def = &u.get_def(d);
+        m_args.append(n->get_num_args(), n->get_args());
+    }
+
+    case_expansion::case_expansion(case_expansion const & from)
+        : m_lhs(from.m_lhs),
+          m_def(from.m_def),
+          m_args(from.m_args) {}
+    case_expansion::case_expansion(case_expansion && from)
+        : m_lhs(from.m_lhs),
+          m_def(from.m_def),
+          m_args(std::move(from.m_args)) {}
+
+    std::ostream& case_expansion::display(std::ostream & out) const {
+        return out << "case_exp(" << m_lhs << ")";
+    }
+
+    std::ostream& body_expansion::display(std::ostream & out) const {
+        ast_manager& m = m_pred.m();
+        out << "body_exp(" << m_cdef->get_decl()->get_name();
+        for (auto* t : m_args) 
+            out << " " << mk_pp(t, m);
+        return out << ")";
+    }
+
+    
+
 }
+
+
diff --git a/src/ast/recfun_decl_plugin.h b/src/ast/recfun_decl_plugin.h
index dec589bd1..fad0fe23e 100644
--- a/src/ast/recfun_decl_plugin.h
+++ b/src/ast/recfun_decl_plugin.h
@@ -20,6 +20,7 @@ Revision History:
 #pragma once
 
 #include "ast/ast.h"
+#include "ast/ast_pp.h"
 #include "util/obj_hashtable.h"
 
 namespace recfun {
@@ -74,7 +75,7 @@ namespace recfun {
     public:
         func_decl* get_decl() const { return m_pred; }
 
-        app_ref apply_case_predicate(ptr_vector<expr> const & args) const {
+        app_ref apply_case_predicate(expr_ref_vector const & args) const {
             ast_manager& m = m_pred.get_manager();
             return app_ref(m.mk_app(m_pred, args.size(), args.c_ptr()), m);
         }
@@ -258,6 +259,10 @@ namespace recfun {
             return mk_fun_defined(d, args.size(), args.c_ptr());
         }
 
+        app* mk_fun_defined(def const & d, expr_ref_vector const & args) {
+            return mk_fun_defined(d, args.size(), args.c_ptr());
+        }
+
         func_decl_ref_vector get_rec_funs() {
             return m_plugin->get_rec_funs();
         }
@@ -265,5 +270,50 @@ namespace recfun {
         app_ref mk_num_rounds_pred(unsigned d);
 
     };
+
+    
+    // one case-expansion of `f(t1...tn)`
+    struct case_expansion {
+        app_ref             m_lhs; // the term to expand
+        recfun::def *       m_def;
+        expr_ref_vector     m_args;
+        case_expansion(recfun::util& u, app * n);
+        case_expansion(case_expansion const & from);
+        case_expansion(case_expansion && from);
+        std::ostream& display(std::ostream& out) const;
+    };
+
+    inline std::ostream& operator<<(std::ostream& out, case_expansion const & e) {
+        return e.display(out);
+    }
+
+    // one body-expansion of `f(t1...tn)` using a `C_f_i(t1...tn)`
+    struct body_expansion {
+        app_ref                  m_pred;
+        recfun::case_def const * m_cdef;
+        expr_ref_vector          m_args;
+        
+        body_expansion(recfun::util& u, app * n) : 
+            m_pred(n, u.m()), m_cdef(nullptr), m_args(u.m()) {
+            m_cdef = &u.get_case_def(n);
+            m_args.append(n->get_num_args(), n->get_args());
+        }
+        body_expansion(app_ref & pred, recfun::case_def const & d, expr_ref_vector & args) : 
+            m_pred(pred), m_cdef(&d), m_args(args) {}
+        body_expansion(body_expansion const & from): 
+            m_pred(from.m_pred), m_cdef(from.m_cdef), m_args(from.m_args) {}
+        body_expansion(body_expansion && from) : 
+            m_pred(from.m_pred), m_cdef(from.m_cdef), m_args(std::move(from.m_args)) {}
+
+        std::ostream& display(std::ostream& out) const;
+    };
+
+    inline std::ostream& operator<<(std::ostream& out, body_expansion const& e) {
+        return e.display(out);
+    }
+
+
+
 }
 
+
diff --git a/src/sat/smt/euf_internalize.cpp b/src/sat/smt/euf_internalize.cpp
index f499de627..9a9f895c9 100644
--- a/src/sat/smt/euf_internalize.cpp
+++ b/src/sat/smt/euf_internalize.cpp
@@ -387,4 +387,25 @@ namespace euf {
             r = m.mk_eq(e1, e2);
         return r;
     }
+
+    unsigned solver::get_max_generation(expr* e) const {
+        unsigned g = 0;
+        expr_fast_mark1 mark;
+        m_todo.push_back(e);
+        while (!m_todo.empty()) {
+            e = m_todo.back();
+            m_todo.pop_back();
+            if (mark.is_marked(e))
+                continue;
+            mark.mark(e);
+            euf::enode* n = m_egraph.find(e);
+            if (n) 
+                g = std::max(g, n->generation());
+            else if (is_app(e)) 
+                for (expr* arg : *to_app(e))
+                    m_todo.push_back(arg);
+        }
+        return g;
+    }
+
 }
diff --git a/src/sat/smt/euf_solver.h b/src/sat/smt/euf_solver.h
index 2f38c7638..aff9d6b55 100644
--- a/src/sat/smt/euf_solver.h
+++ b/src/sat/smt/euf_solver.h
@@ -96,6 +96,7 @@ namespace euf {
         user::solver*          m_user_propagator{ nullptr };
         th_solver*             m_qsolver { nullptr };
         unsigned               m_generation { 0 };
+        mutable ptr_vector<expr> m_todo;
 
         ptr_vector<expr>                                m_bool_var2expr;
         ptr_vector<size_t>                              m_explain;
@@ -228,6 +229,7 @@ namespace euf {
                 s.m_generation = m_g;
             }
         };
+        unsigned get_max_generation(expr* e) const;
 
         // accessors
         
diff --git a/src/sat/smt/q_mbi.cpp b/src/sat/smt/q_mbi.cpp
index 90c74089c..bbaeb0ddf 100644
--- a/src/sat/smt/q_mbi.cpp
+++ b/src/sat/smt/q_mbi.cpp
@@ -213,7 +213,7 @@ namespace q {
             qlit.neg();
         TRACE("q", tout << "project: " << proj << "\n";);
         ++m_stats.m_num_instantiations;        
-        unsigned generation = m_qs.get_max_generation(proj);    
+        unsigned generation = ctx.get_max_generation(proj);    
         m_instantiations.push_back(instantiation_t(qlit, proj, generation));
     }
 
diff --git a/src/sat/smt/q_solver.cpp b/src/sat/smt/q_solver.cpp
index c2139993e..7d6aa3fdc 100644
--- a/src/sat/smt/q_solver.cpp
+++ b/src/sat/smt/q_solver.cpp
@@ -207,26 +207,6 @@ namespace q {
         return val;
     }
 
-    unsigned solver::get_max_generation(expr* e) const {
-        unsigned g = 0;
-        expr_fast_mark1 mark;
-        m_todo.push_back(e);
-        while (!m_todo.empty()) {
-            e = m_todo.back();
-            m_todo.pop_back();
-            if (mark.is_marked(e))
-                continue;
-            mark.mark(e);
-            euf::enode* n = ctx.get_egraph().find(e);
-            if (n) 
-                g = std::max(g, n->generation());
-            else if (is_app(e)) 
-                for (expr* arg : *to_app(e))
-                    m_todo.push_back(arg);
-        }
-        return g;
-    }
-
     expr_ref_vector const& solver::expand(quantifier* q) {
         m_expanded.reset();
         if (is_forall(q)) 
diff --git a/src/sat/smt/q_solver.h b/src/sat/smt/q_solver.h
index 6f1077dc9..9b0301775 100644
--- a/src/sat/smt/q_solver.h
+++ b/src/sat/smt/q_solver.h
@@ -46,7 +46,6 @@ namespace q {
         flat_table             m_flat;
         sat::literal_vector    m_universal;
         obj_map<sort, expr*>   m_unit_table;
-        mutable ptr_vector<expr> m_todo;
         expr_ref_vector        m_expanded;
 
         sat::literal instantiate(quantifier* q, bool negate, std::function<expr* (quantifier*, unsigned)>& mk_var);
@@ -85,6 +84,5 @@ namespace q {
         sat::literal_vector const& universal() const { return m_universal; }
         quantifier* flatten(quantifier* q);
 
-        unsigned get_max_generation(expr* e) const;
     };
 }
diff --git a/src/sat/smt/recfun_solver.cpp b/src/sat/smt/recfun_solver.cpp
index 2a6626382..eec8ea3c8 100644
--- a/src/sat/smt/recfun_solver.cpp
+++ b/src/sat/smt/recfun_solver.cpp
@@ -15,10 +15,13 @@ Author:
 
 --*/
 
+#include "ast/rewriter/var_subst.h"
 #include "sat/smt/recfun_solver.h"
 #include "sat/smt/euf_solver.h"
 
 
+#define TRACEFN(x) TRACE("recfun", tout << x << '\n';)
+
 
 namespace recfun {
 
@@ -29,11 +32,7 @@ namespace recfun {
         m_util(m_plugin.u()), 
         m_disabled_guards(m),
         m_enabled_guards(m),
-        m_preds(m),
-        m_num_rounds(0),
-        m_q_case_expand(), 
-        m_q_body_expand() {
-        m_num_rounds = 0;
+        m_preds(m) {
     }    
 
     solver::~solver() {
@@ -41,34 +40,140 @@ namespace recfun {
     }
 
     void solver::reset() {
-        reset_queues();   
+        m_propagation_queue.reset();
         m_stats.reset();
         m_disabled_guards.reset();
         m_enabled_guards.reset();
-        m_q_guards.reset();
+        m_propagation_queue.reset();
         for (auto & kv : m_guard2pending) 
             dealloc(kv.m_value);
         m_guard2pending.reset();
     }
 
-    void solver::reset_queues() {
-        for (auto* e : m_q_case_expand) {
-            dealloc(e);
+    expr_ref solver::apply_args(vars const & vars, expr_ref_vector const & args, expr * e) {
+        SASSERT(is_standard_order(vars));
+        var_subst subst(m, true);
+        expr_ref new_body = subst(e, args);
+        ctx.get_rewriter()(new_body);
+        return new_body;
+    }
+
+    /**
+     * For functions f(args) that are given as macros f(vs) = rhs
+     * 
+     * 1. substitute `e.args` for `vs` into the macro rhs
+     * 2. add unit clause `f(args) = rhs`
+     */
+    void solver::assert_macro_axiom(case_expansion & e) {
+        m_stats.m_macro_expansions++;
+        SASSERT(e.m_def->is_fun_macro());
+        auto & vars = e.m_def->get_vars();
+        auto lhs = e.m_lhs;
+        auto rhs = apply_args(vars, e.m_args, e.m_def->get_rhs());
+        unsigned generation = std::max(ctx.get_max_generation(lhs), ctx.get_max_generation(rhs));
+        euf::solver::scoped_generation _sgen(ctx, generation + 1);
+        auto eq = eq_internalize(lhs, rhs);
+        add_unit(eq);        
+    }
+
+    /**
+     * Add case axioms for every case expansion path.
+     *
+     * assert `p(args) <=> And(guards)` (with CNF on the fly)
+     *
+     * also body-expand paths that do not depend on any defined fun
+     */
+    void solver::assert_case_axioms(case_expansion & e) {
+        SASSERT(e.m_def->is_fun_defined());
+        // add case-axioms for all case-paths
+        // assert this was not defined before.
+        sat::literal_vector preds;
+        auto & vars = e.m_def->get_vars();
+            
+        for (case_def const & c : e.m_def->get_cases()) {
+            // applied predicate to `args`
+            app_ref pred_applied = c.apply_case_predicate(e.m_args);
+            SASSERT(u().owns_app(pred_applied));
+            preds.push_back(mk_literal(pred_applied));
+            expr_ref_vector guards(m);
+            for (auto & g : c.get_guards()) 
+                guards.push_back(apply_args(vars, e.m_args, g));
+            if (c.is_immediate()) {
+                body_expansion be(pred_applied, c, e.m_args);
+                assert_body_axiom(be);            
+            }
+            else if (!is_enabled_guard(pred_applied)) {
+                disable_guard(pred_applied, guards);
+                continue;
+            }
+            activate_guard(pred_applied, guards);
         }
-        m_q_case_expand.reset();
-        for (auto* e : m_q_body_expand) {
-            dealloc(e);
-        }
-        m_q_body_expand.reset();
-        m_q_clauses.clear();        
+        add_clause(preds);
+    }
+    
+    void solver::activate_guard(expr* pred_applied, expr_ref_vector const& guards) {
+        sat::literal_vector lguards;
+        for (expr* ga : guards) 
+            lguards.push_back(mk_literal(ga));
+        add_equiv_and(mk_literal(pred_applied), lguards);
+    }
+
+    /**
+     * make clause `depth_limit => ~guard`
+     * the guard appears at a depth below the current cutoff.
+     */
+    void solver::disable_guard(expr* guard, expr_ref_vector const& guards) {
+        expr_ref nguard(m.mk_not(guard), m);
+        if (is_disabled_guard(nguard)) 
+            return;
+        SASSERT(!is_enabled_guard(nguard));
+        sat::literal_vector c;
+        app_ref dlimit = m_util.mk_num_rounds_pred(m_num_rounds);
+        c.push_back(~mk_literal(dlimit));
+        c.push_back(~mk_literal(guard)); 
+        m_disabled_guards.push_back(nguard);
+        SASSERT(!m_guard2pending.contains(nguard));
+        m_guard2pending.insert(nguard, alloc(expr_ref_vector, guards));
+        TRACEFN("add clause\n" << c);
+        m_propagation_queue.push_back(alloc(propagation_item, c));
+    }
+
+    /**
+     * For a guarded definition guards => f(vars) = rhs
+     * and occurrence f(args)
+     *
+     * substitute `args` for `vars` in guards, and rhs
+     * add axiom guards[args/vars] => f(args) = rhs[args/vars]
+     *
+     */
+    void solver::assert_body_axiom(body_expansion & e) {
+        recfun::def & d = *e.m_cdef->get_def();
+        auto & vars = d.get_vars();
+        auto & args = e.m_args;
+        SASSERT(is_standard_order(vars));
+        sat::literal_vector clause;
+        for (auto & g : e.m_cdef->get_guards()) {
+            expr_ref guard = apply_args(vars, args, g);
+            if (m.is_false(guard))
+                return;
+            if (m.is_true(guard))
+                continue;
+            clause.push_back(~mk_literal(guard));
+        }        
+        expr_ref lhs(u().mk_fun_defined(d, args), m);
+        expr_ref rhs = apply_args(vars, args, e.m_cdef->get_rhs());
+        clause.push_back(eq_internalize(lhs, rhs));
+        add_clause(clause);
     }
 
     void solver::get_antecedents(sat::literal l, sat::ext_justification_idx idx, sat::literal_vector& r, bool probing) {
-
+        UNREACHABLE();
     }
 
     void solver::asserted(sat::literal l) {
-
+        expr* e = ctx.bool_var2expr(l.var());
+        if (!l.sign() && u().is_case_pred(e)) 
+            push_body_expand(e);
     }
 
     sat::check_result solver::check() {
@@ -76,15 +181,18 @@ namespace recfun {
     }
 
     std::ostream& solver::display(std::ostream& out) const {
-        return out;
+        return out << "disabled guards:\n" << m_disabled_guards << "\n";
     }
 
     std::ostream& solver::display_constraint(std::ostream& out, sat::ext_constraint_idx idx) const {
+        UNREACHABLE();
         return out;
     }
 
     void solver::collect_statistics(statistics& st) const {
-
+        st.update("recfun macro expansion", m_stats.m_macro_expansions);
+        st.update("recfun case expansion", m_stats.m_case_expansions);
+        st.update("recfun body expansion", m_stats.m_body_expansions);
     }
 
     euf::th_solver* solver::clone(euf::solver& ctx) {
@@ -92,13 +200,107 @@ namespace recfun {
     }
 
     bool solver::unit_propagate() {
-        return false;
+        if (m_qhead == m_propagation_queue.size())
+            return false;
+        ctx.push(value_trail<unsigned>(m_qhead));
+        for (; m_qhead < m_propagation_queue.size() && !s().inconsistent(); ++m_qhead) {
+            auto& p = *m_propagation_queue[m_qhead];
+            if (p.is_guard()) {
+                expr* ng = nullptr;
+                VERIFY(m.is_not(p.m_guard, ng));
+                activate_guard(ng, *m_guard2pending[p.m_guard]);
+            }
+            else if (p.is_clause()) {
+                add_clause(p.m_clause);
+            }
+            else if (p.is_case()) {
+                recfun::case_expansion& e = *p.m_case;
+                if (e.m_def->is_fun_macro()) 
+                    assert_macro_axiom(e);
+                else 
+                    assert_case_axioms(e);                
+                ++m_stats.m_case_expansions;
+            } 
+            else {
+                SASSERT(p.is_body());
+                assert_body_axiom(*p.m_body);
+                ++m_stats.m_body_expansions;
+            }                
+        }
+        return true;
     }
 
-    sat::literal solver::internalize(expr* e, bool sign, bool root, bool learned) {
-        return sat::null_literal;
+    void solver::push_body_expand(expr* e) {
+        auto* b = alloc(body_expansion, u(), to_app(e));
+        m_propagation_queue.push_back(alloc(propagation_item, b));
+        ctx.push(push_back_vector<scoped_ptr_vector<propagation_item>>(m_propagation_queue));
     }
 
+    void solver::push_case_expand(expr* e) {
+        auto* c = alloc(case_expansion, u(), to_app(e));
+        m_propagation_queue.push_back(alloc(propagation_item, c));
+        ctx.push(push_back_vector<scoped_ptr_vector<propagation_item>>(m_propagation_queue));        
+    }
+
+    sat::literal solver::internalize(expr* e, bool sign, bool root, bool redundant) {
+        SASSERT(m.is_bool(e));
+        if (!visit_rec(m, e, sign, root, redundant)) {
+            TRACE("array", tout << mk_pp(e, m) << "\n";);
+            return sat::null_literal;
+        }
+        auto lit = expr2literal(e);
+        if (sign)
+            lit.neg();
+        return lit;
+    }
+
+    void solver::internalize(expr* e, bool redundant) {
+        visit_rec(m, e, false, false, redundant);
+    }
+
+    bool solver::visited(expr* e) {
+        euf::enode* n = expr2enode(e);
+        return n && n->is_attached_to(get_id());        
+    }
+
+    bool solver::visit(expr* e) {
+        if (visited(e))
+            return true;
+        if (!is_app(e) || to_app(e)->get_family_id() != get_id()) {
+            ctx.internalize(e, m_is_redundant);
+            euf::enode* n = expr2enode(e);
+            // TODO ensure_var(n);
+            return true;
+        }
+        m_stack.push_back(sat::eframe(e));
+        return false;        
+    }
+
+    bool solver::post_visit(expr* e, bool sign, bool root) {
+        euf::enode* n = expr2enode(e);
+        app* a = to_app(e);        
+        SASSERT(!n || !n->is_attached_to(get_id()));
+        if (!n) 
+            n = mk_enode(e, false);
+        SASSERT(!n->is_attached_to(get_id()));
+        mk_var(n);
+#if 0
+        for (auto* arg : euf::enode_args(n))
+            ensure_var(arg);  
+        switch (a->get_decl_kind()) {
+        default:
+            UNREACHABLE();
+            break;            
+        }
+#endif
+        if (u().is_defined(e) && u().has_defs()) 
+            push_case_expand(e);
+
+        return true;
+    }
+
+
+
     euf::theory_var solver::mk_var(euf::enode* n) {
         return euf::null_theory_var;
     }
diff --git a/src/sat/smt/recfun_solver.h b/src/sat/smt/recfun_solver.h
index 06bf3a1c4..4cc0ef46f 100644
--- a/src/sat/smt/recfun_solver.h
+++ b/src/sat/smt/recfun_solver.h
@@ -35,62 +35,6 @@ namespace recfun {
             void reset() { memset(this, 0, sizeof(stats)); }
             stats() { reset(); }
         };
-
-        // one case-expansion of `f(t1...tn)`
-        struct case_expansion {
-            app *              m_lhs; // the term to expand
-            recfun::def *       m_def;
-            ptr_vector<expr>    m_args;
-            case_expansion(recfun::util& u, app * n) : 
-            m_lhs(n), m_def(nullptr), m_args()  {
-                SASSERT(u.is_defined(n));
-                func_decl * d = n->get_decl();
-                m_def = &u.get_def(d);
-                m_args.append(n->get_num_args(), n->get_args());
-            }
-            case_expansion(case_expansion const & from)
-                : m_lhs(from.m_lhs),
-                  m_def(from.m_def),
-                  m_args(from.m_args) {}
-            case_expansion(case_expansion && from)
-                : m_lhs(from.m_lhs),
-                  m_def(from.m_def),
-                  m_args(std::move(from.m_args)) {}
-        };
-
-        struct pp_case_expansion {
-            case_expansion & e;
-            ast_manager & m;
-            pp_case_expansion(case_expansion & e, ast_manager & m) : e(e), m(m) {}
-        };
-
-        friend std::ostream& operator<<(std::ostream&, pp_case_expansion const &);
-
-        // one body-expansion of `f(t1...tn)` using a `C_f_i(t1...tn)`
-        struct body_expansion {
-            app*                     m_pred;
-            recfun::case_def const * m_cdef;
-            ptr_vector<expr>         m_args;
-
-            body_expansion(recfun::util& u, app * n) : m_pred(n), m_cdef(nullptr), m_args() {
-                m_cdef = &u.get_case_def(n);
-                m_args.append(n->get_num_args(), n->get_args());
-            }
-            body_expansion(app* pred, recfun::case_def const & d, ptr_vector<expr> & args) : 
-                m_pred(pred), m_cdef(&d), m_args(args) {}
-            body_expansion(body_expansion const & from): 
-                m_pred(from.m_pred), m_cdef(from.m_cdef), m_args(from.m_args) {}
-            body_expansion(body_expansion && from) : 
-                m_pred(from.m_pred), m_cdef(from.m_cdef), m_args(std::move(from.m_args)) {}
-        };
-
-        struct pp_body_expansion {
-            body_expansion & e;
-            ast_manager & m;
-            pp_body_expansion(body_expansion & e, ast_manager & m) : e(e), m(m) {}
-        };
-
-        friend std::ostream& operator<<(std::ostream&, pp_body_expansion const &);
         
         recfun::decl::plugin&   m_plugin;
         recfun::util&           m_util;
@@ -103,12 +47,44 @@ namespace recfun {
         obj_map<expr, unsigned>  m_pred_depth;
         expr_ref_vector          m_preds;
         unsigned_vector          m_preds_lim;
-        unsigned                 m_num_rounds;
+        unsigned                 m_num_rounds { 0 };
 
-        ptr_vector<case_expansion>  m_q_case_expand;
-        ptr_vector<body_expansion>  m_q_body_expand;
-        vector<sat::literal_vector> m_q_clauses;
-        ptr_vector<expr>            m_q_guards;
+        struct propagation_item {
+            case_expansion*            m_case { nullptr };
+            body_expansion*            m_body { nullptr };
+            sat::literal_vector        m_clause;
+            expr*                      m_guard { nullptr };
+
+            ~propagation_item() {
+                dealloc(m_case);
+                dealloc(m_body);
+            }
+
+            propagation_item(expr* guard):
+                m_guard(guard) 
+            {}
+
+            propagation_item(sat::literal_vector const& clause):
+                m_clause(clause)
+            {}
+
+            propagation_item(body_expansion* b):
+                m_body(b)
+            {}
+            propagation_item(case_expansion* c):
+                m_case(c)
+            {}
+
+            bool is_guard() const { return m_guard != nullptr; }
+            bool is_clause() const { return !m_clause.empty(); }
+            bool is_case() const { return m_case != nullptr; }
+            bool is_body() const { return m_body != nullptr; }            
+        };
+        scoped_ptr_vector<propagation_item> m_propagation_queue;
+        unsigned                            m_qhead { 0 };
+
+        void push_body_expand(expr* e);
+        void push_case_expand(expr* e);
 
         bool is_enabled_guard(expr* guard) { expr_ref ng(m.mk_not(guard), m); return m_enabled_guards.contains(ng); }
         bool is_disabled_guard(expr* guard) { return m_disabled_guards.contains(guard); }
@@ -122,12 +98,10 @@ namespace recfun {
 
         void activate_guard(expr* guard, expr_ref_vector const& guards);
 
-        void reset_queues();
-        expr_ref apply_args(unsigned depth, recfun::vars const & vars, ptr_vector<expr> const & args, expr * e); //!< substitute variables by args
+        expr_ref apply_args(vars const & vars, expr_ref_vector const & args, expr * e); //!< substitute variables by args
         void assert_macro_axiom(case_expansion & e);
         void assert_case_axioms(case_expansion & e);
         void assert_body_axiom(body_expansion & e);
-        sat::literal mk_literal(expr* e);
 
         void add_induction_lemmas(unsigned depth);
         void disable_guard(expr* guard, expr_ref_vector const& guards);
@@ -141,6 +115,10 @@ namespace recfun {
         }
 
         void reset();
+        bool visit(expr* e) override;
+        bool visited(expr* e) override;
+        bool post_visit(expr* e, bool sign, bool root) override;
+
 
     public:
 
@@ -157,7 +135,7 @@ namespace recfun {
         euf::th_solver* clone(euf::solver& ctx) override;
         bool unit_propagate() override;
         sat::literal internalize(expr* e, bool sign, bool root, bool learned) override;
-        void internalize(expr* e, bool redundant) override { UNREACHABLE(); }
+        void internalize(expr* e, bool redundant) override;
         euf::theory_var mk_var(euf::enode* n) override;
         void init_search() override;
         void finalize_model(model& mdl) override;
diff --git a/src/smt/theory_recfun.cpp b/src/smt/theory_recfun.cpp
index 1348da985..a935b5454 100644
--- a/src/smt/theory_recfun.cpp
+++ b/src/smt/theory_recfun.cpp
@@ -34,10 +34,8 @@ namespace smt {
           m_disabled_guards(m),
           m_enabled_guards(m),
           m_preds(m),
-          m_num_rounds(0),
           m_q_case_expand(), 
           m_q_body_expand() {
-        m_num_rounds = 0;
         }
 
     theory_recfun::~theory_recfun() {
@@ -54,7 +52,6 @@ namespace smt {
     }
 
     bool theory_recfun::internalize_atom(app * atom, bool gate_ctx) {
-        force_push();
         TRACEFN(mk_pp(atom, m));
         if (!u().has_defs()) {
             return false;
@@ -70,13 +67,12 @@ namespace smt {
             ctx.set_var_theory(v, get_id());
         }
         if (!ctx.relevancy() && u().is_defined(atom)) {
-            push_case_expand(alloc(case_expansion, u(), atom));
+            push_case_expand(alloc(recfun::case_expansion, u(), atom));
         }
         return true;
     }
 
     bool theory_recfun::internalize_term(app * term) {
-        force_push();
         if (!u().has_defs()) {
             return false;
         }
@@ -87,7 +83,7 @@ namespace smt {
         if (!ctx.e_internalized(term)) {            
             ctx.mk_enode(term, false, false, true);
             if (!ctx.relevancy() && u().is_defined(term)) {
-                push_case_expand(alloc(case_expansion, u(), term));
+                push_case_expand(alloc(recfun::case_expansion, u(), term));
             }
         }
 
@@ -128,20 +124,16 @@ namespace smt {
         SASSERT(ctx.relevancy());
         TRACEFN("relevant_eh: (defined) " <<  u().is_defined(n) << " " << mk_pp(n, m));        
         if (u().is_defined(n) && u().has_defs()) {
-            push_case_expand(alloc(case_expansion, u(), n));
+            push_case_expand(alloc(recfun::case_expansion, u(), n));
         }
     }
 
     void theory_recfun::push_scope_eh() {
-        if (lazy_push())
-            return;
         theory::push_scope_eh();
         m_preds_lim.push_back(m_preds.size());
     }
 
     void theory_recfun::pop_scope_eh(unsigned num_scopes) {
-        if (lazy_pop(num_scopes))
-            return;
         theory::pop_scope_eh(num_scopes);
         reset_queues();
         
@@ -189,7 +181,7 @@ namespace smt {
         m_q_clauses.clear();
  		
         for (unsigned i = 0; i < m_q_case_expand.size(); ++i) {
-            case_expansion* e = m_q_case_expand[i];
+            recfun::case_expansion* e = m_q_case_expand[i];
             if (e->m_def->is_fun_macro()) {
                 // body expand immediately
                 assert_macro_axiom(*e);
@@ -276,7 +268,7 @@ namespace smt {
         if (is_true && u().is_case_pred(e)) {
             TRACEFN("assign_case_pred_true " << mk_pp(e, m));
             // body-expand
-            push_body_expand(alloc(body_expansion, u(), to_app(e)));            
+            push_body_expand(alloc(recfun::body_expansion, u(), to_app(e)));            
         }
     }
 
@@ -284,12 +276,12 @@ namespace smt {
     expr_ref theory_recfun::apply_args(
         unsigned depth,
         recfun::vars const & vars,
-        ptr_vector<expr> const & args,
+        expr_ref_vector const & args,
         expr * e) {
         SASSERT(is_standard_order(vars));
         var_subst subst(m, true);
         expr_ref new_body(m);
-        new_body = subst(e, args.size(), args.c_ptr());
+        new_body = subst(e, args);
         ctx.get_rewriter()(new_body); // simplify
         set_depth_rec(depth + 1, new_body);
         return new_body;
@@ -329,9 +321,9 @@ namespace smt {
      * 1. substitute `e.args` for `vs` into the macro rhs
      * 2. add unit clause `f(args) = rhs`
      */
-    void theory_recfun::assert_macro_axiom(case_expansion & e) {
+    void theory_recfun::assert_macro_axiom(recfun::case_expansion & e) {
         m_stats.m_macro_expansions++;
-        TRACEFN("case expansion " << pp_case_expansion(e, m));
+        TRACEFN("case expansion " << e);
         SASSERT(e.m_def->is_fun_macro());
         auto & vars = e.m_def->get_vars();
         expr_ref lhs(e.m_lhs, m);
@@ -351,8 +343,8 @@ namespace smt {
      *
      * also body-expand paths that do not depend on any defined fun
      */
-    void theory_recfun::assert_case_axioms(case_expansion & e) {
-        TRACEFN("assert_case_axioms "<< pp_case_expansion(e,m)
+    void theory_recfun::assert_case_axioms(recfun::case_expansion & e) {
+        TRACEFN("assert_case_axioms " << e
                 << " with " << e.m_def->get_cases().size() << " cases");
         SASSERT(e.m_def->is_fun_defined());
         // add case-axioms for all case-paths
@@ -375,7 +367,7 @@ namespace smt {
                 guards.push_back(apply_args(depth, vars, e.m_args, g));
             }
             if (c.is_immediate()) {
-                body_expansion be(pred_applied, c, e.m_args);
+                recfun::body_expansion be(pred_applied, c, e.m_args);
                 assert_body_axiom(be);            
             }
             else if (!is_enabled_guard(pred_applied)) {
@@ -392,13 +384,6 @@ namespace smt {
             ctx.mk_th_axiom(get_id(), preds);
         }
         (void)max_depth;
-        // add_induction_lemmas(max_depth);
-    }
-
-    void theory_recfun::add_induction_lemmas(unsigned depth) {
-        if (depth > 4 && ctx.get_fparams().m_induction && induction::should_try(ctx)) {
-            ctx.get_induction()();
-        }
     }
 
     void theory_recfun::activate_guard(expr* pred_applied, expr_ref_vector const& guards) {
@@ -426,7 +411,7 @@ namespace smt {
      * add axiom guards[args/vars] => f(args) = rhs[args/vars]
      *
      */
-    void theory_recfun::assert_body_axiom(body_expansion & e) {
+    void theory_recfun::assert_body_axiom(recfun::body_expansion & e) {
         recfun::def & d = *e.m_cdef->get_def();
         auto & vars = d.get_vars();
         auto & args = e.m_args;
@@ -439,7 +424,7 @@ namespace smt {
             expr_ref guard = apply_args(depth, vars, args, g);
             clause.push_back(~mk_literal(guard));
             if (clause.back() == true_literal) {
-                TRACEFN("body " << pp_body_expansion(e,m) << "\n" << clause << "\n" << guard);
+                TRACEFN("body " << e << "\n" << clause << "\n" << guard);
                 return;
             }
             if (clause.back() == false_literal) {
@@ -450,7 +435,7 @@ namespace smt {
         std::function<literal_vector(void)> fn = [&]() { return clause; };
         scoped_trace_stream _tr(*this, fn);
         ctx.mk_th_axiom(get_id(), clause);
-        TRACEFN("body " << pp_body_expansion(e,m));
+        TRACEFN("body " << e);
         TRACEFN(pp_lits(ctx, clause));
     }
     
@@ -521,15 +506,4 @@ namespace smt {
         st.update("recfun body expansion", m_stats.m_body_expansions);
     }
 
-    std::ostream& operator<<(std::ostream & out, theory_recfun::pp_case_expansion const & e) {
-        return out << "case_exp(" << mk_pp(e.e.m_lhs, e.m) << ")";
-    }
-
-    std::ostream& operator<<(std::ostream & out, theory_recfun::pp_body_expansion const & e) {
-        out << "body_exp(" << e.e.m_cdef->get_decl()->get_name();
-        for (auto* t : e.e.m_args) {
-            out << " " << mk_pp(t,e.m);
-        }
-        return out << ")";
-    }
 }
diff --git a/src/smt/theory_recfun.h b/src/smt/theory_recfun.h
index 4ee626434..57e163fc1 100644
--- a/src/smt/theory_recfun.h
+++ b/src/smt/theory_recfun.h
@@ -31,62 +31,6 @@ namespace smt {
             void reset() { memset(this, 0, sizeof(stats)); }
             stats() { reset(); }
         };
-
-        // one case-expansion of `f(t1...tn)`
-        struct case_expansion {
-            app *              m_lhs; // the term to expand
-            recfun::def *       m_def;
-            ptr_vector<expr>    m_args;
-            case_expansion(recfun::util& u, app * n) : 
-            m_lhs(n), m_def(nullptr), m_args()  {
-                SASSERT(u.is_defined(n));
-                func_decl * d = n->get_decl();
-                m_def = &u.get_def(d);
-                m_args.append(n->get_num_args(), n->get_args());
-            }
-            case_expansion(case_expansion const & from)
-                : m_lhs(from.m_lhs),
-                  m_def(from.m_def),
-                  m_args(from.m_args) {}
-            case_expansion(case_expansion && from)
-                : m_lhs(from.m_lhs),
-                  m_def(from.m_def),
-                  m_args(std::move(from.m_args)) {}
-        };
-
-        struct pp_case_expansion {
-            case_expansion & e;
-            ast_manager & m;
-            pp_case_expansion(case_expansion & e, ast_manager & m) : e(e), m(m) {}
-        };
-
-        friend std::ostream& operator<<(std::ostream&, pp_case_expansion const &);
-
-        // one body-expansion of `f(t1...tn)` using a `C_f_i(t1...tn)`
-        struct body_expansion {
-            app*                    m_pred;
-            recfun::case_def const * m_cdef;
-            ptr_vector<expr>        m_args;
-
-            body_expansion(recfun::util& u, app * n) : m_pred(n), m_cdef(nullptr), m_args() {
-                m_cdef = &u.get_case_def(n);
-                m_args.append(n->get_num_args(), n->get_args());
-            }
-            body_expansion(app* pred, recfun::case_def const & d, ptr_vector<expr> & args) : 
-                m_pred(pred), m_cdef(&d), m_args(args) {}
-            body_expansion(body_expansion const & from): 
-                m_pred(from.m_pred), m_cdef(from.m_cdef), m_args(from.m_args) {}
-            body_expansion(body_expansion && from) : 
-                m_pred(from.m_pred), m_cdef(from.m_cdef), m_args(std::move(from.m_args)) {}
-        };
-
-        struct pp_body_expansion {
-            body_expansion & e;
-            ast_manager & m;
-            pp_body_expansion(body_expansion & e, ast_manager & m) : e(e), m(m) {}
-        };
-
-        friend std::ostream& operator<<(std::ostream&, pp_body_expansion const &);
         
         recfun::decl::plugin&   m_plugin;
         recfun::util&           m_util;
@@ -99,10 +43,10 @@ namespace smt {
         obj_map<expr, unsigned>  m_pred_depth;
         expr_ref_vector          m_preds;
         unsigned_vector          m_preds_lim;
-        unsigned                 m_num_rounds;
+        unsigned                 m_num_rounds { 0 };
 
-        ptr_vector<case_expansion> m_q_case_expand;
-        ptr_vector<body_expansion> m_q_body_expand;
+        ptr_vector<recfun::case_expansion> m_q_case_expand;
+        ptr_vector<recfun::body_expansion> m_q_body_expand;
         vector<literal_vector>     m_q_clauses;
         ptr_vector<expr>           m_q_guards;
 
@@ -119,13 +63,12 @@ namespace smt {
         void activate_guard(expr* guard, expr_ref_vector const& guards);
 
         void reset_queues();
-        expr_ref apply_args(unsigned depth, recfun::vars const & vars, ptr_vector<expr> const & args, expr * e); //!< substitute variables by args
-        void assert_macro_axiom(case_expansion & e);
-        void assert_case_axioms(case_expansion & e);
-        void assert_body_axiom(body_expansion & e);
+        expr_ref apply_args(unsigned depth, recfun::vars const & vars, expr_ref_vector const & args, expr * e); //!< substitute variables by args
+        void assert_macro_axiom(recfun::case_expansion & e);
+        void assert_case_axioms(recfun::case_expansion & e);
+        void assert_body_axiom(recfun::body_expansion & e);
         literal mk_literal(expr* e);
 
-        void add_induction_lemmas(unsigned depth);
         void disable_guard(expr* guard, expr_ref_vector const& guards);
         unsigned get_depth(expr* e);
         void set_depth(unsigned d, expr* e);
@@ -136,8 +79,8 @@ namespace smt {
             return vars.empty() || vars[vars.size()-1]->get_idx() == 0;
         }
     protected:
-        void push_case_expand(case_expansion* e) { m_q_case_expand.push_back(e); }
-        void push_body_expand(body_expansion* e) { m_q_body_expand.push_back(e); }
+        void push_case_expand(recfun::case_expansion* e) { m_q_case_expand.push_back(e); }
+        void push_body_expand(recfun::body_expansion* e) { m_q_body_expand.push_back(e); }
 
         bool internalize_atom(app * atom, bool gate_ctx) override;
         bool internalize_term(app * term) override;