diff --git a/src/ast/converters/expr_inverter.cpp b/src/ast/converters/expr_inverter.cpp
index bba02b591..f7d59c9e3 100644
--- a/src/ast/converters/expr_inverter.cpp
+++ b/src/ast/converters/expr_inverter.cpp
@@ -21,6 +21,7 @@ Author:
 #include "ast/arith_decl_plugin.h"
 #include "ast/seq_decl_plugin.h"
 #include "ast/pb_decl_plugin.h"
+#include "ast/rewriter/seq_rewriter.h"
 #include "ast/converters/expr_inverter.h"
 
 class basic_expr_inverter : public iexpr_inverter {
@@ -825,8 +826,9 @@ public:
 
 class seq_expr_inverter : public iexpr_inverter {
     seq_util seq;
+    seq_rewriter rw;
 public:
-    seq_expr_inverter(ast_manager& m) : iexpr_inverter(m), seq(m) {}
+    seq_expr_inverter(ast_manager& m) : iexpr_inverter(m), seq(m), rw(m) {}
     
     family_id get_fid() const override { return seq.get_family_id(); }
 
@@ -878,7 +880,42 @@ public:
                 return true;
             }
             return false;
+        case OP_SEQ_IN_RE:
+            if (uncnstr(args[0]) && seq.re.is_ground(args[1])) {
+#if 0
+                // requires auxiliary functions
+                // is_empty
+                // find_member
+                expr* r = args[1];
+                expr_ref not_r(seq.re.mk_complement(r), m);
+                lbool emp_r = rw.is_empty(r);
+
+                if (emp_r == l_undef)
+                    return false;
+                if (emp_r == l_true) {
+                    r = m.mk_false();
+                    return true;
+                }
+                lbool emp_not_r = rw.is_empty(not_r);
+                if (emp_not_r == l_true) {
+                    r = m.mk_true();
+                    return true;
+                }
+                if (emp_not_r == l_false) {
+                    mk_fresh_uncnstr_var_for(f, r);
+                    expr_ref witness1 = rw.find_member(r);
+                    expr_ref witness2 = rw.find_member(not_r);
+                    if (!witness1 || !witness2)
+                        return false;
+                    if (m_mc) 
+                        add_def(args[0], m.mk_ite(r, witness1, witness2));                    
+                    return true;
+                }
+#endif
+            }
+            return false;
         default:
+            verbose_stream() << mk_pp(f, m) << "\n";
             return false;                
             
         }
diff --git a/src/ast/seq_decl_plugin.h b/src/ast/seq_decl_plugin.h
index 4a0b81c7b..03cab284a 100644
--- a/src/ast/seq_decl_plugin.h
+++ b/src/ast/seq_decl_plugin.h
@@ -594,6 +594,7 @@ public:
         info get_info(expr* r) const;
         std::string to_str(expr* r) const;
         std::string to_strh(expr* r) const;
+        bool is_ground(expr* r) const { return get_info(r).interpreted; }
 
         expr_ref mk_ite_simplify(expr* c, expr* t, expr* e)
         {
diff --git a/src/ast/simplifiers/elim_unconstrained.cpp b/src/ast/simplifiers/elim_unconstrained.cpp
index c7aa2f2bc..0680d8b84 100644
--- a/src/ast/simplifiers/elim_unconstrained.cpp
+++ b/src/ast/simplifiers/elim_unconstrained.cpp
@@ -243,6 +243,8 @@ elim_unconstrained::node& elim_unconstrained::get_node(expr* t) {
                 node& ch = get_node(arg);
                 SASSERT(ch.is_root());
                 ch.add_parent(*n);
+                if (is_uninterp_const(arg))
+                    m_heap.increased(arg->get_id());
             }
         }
         else if (is_quantifier(t)) {