diff --git a/src/ast/sls/sls_array_plugin.cpp b/src/ast/sls/sls_array_plugin.cpp
index 913e6bdcf5..70e6335fb0 100644
--- a/src/ast/sls/sls_array_plugin.cpp
+++ b/src/ast/sls/sls_array_plugin.cpp
@@ -166,6 +166,7 @@ namespace sls {
             args.push_back(nsel->get_expr());
         }
         expr_ref f_map(m.mk_app(f, args), m);
+        ctx.add_new_term(f_map);
         auto nsel = mk_select(g, n, sel);
         auto nmap = g.find(f_map);
         if (!nmap) 
@@ -193,6 +194,7 @@ namespace sls {
             args.push_back(idx->get_expr());
         }
         expr_ref esel(a.mk_select(args), m);
+        ctx.add_new_term(esel);
         auto n = g.find(esel);
         return n ? n : g.mk(esel, 0, eargs.size(), eargs.data());
     }
@@ -373,6 +375,11 @@ namespace sls {
                     continue;
                 if (p->get_arg(0)->get_root() != n->get_root())
                     continue;
+#if 1
+                bool is_relevant = any_of(euf::enode_class(p), [&](euf::enode* k) { return ctx.is_relevant(k->get_expr()); });
+                if (!is_relevant)
+                    continue;
+#endif
                 auto val = p->get_root();
                 kv[n].insert(select_args(p), val);
             }
diff --git a/src/ast/sls/sls_context.cpp b/src/ast/sls/sls_context.cpp
index 8ed3619e87..f0acdf4260 100644
--- a/src/ast/sls/sls_context.cpp
+++ b/src/ast/sls/sls_context.cpp
@@ -143,6 +143,7 @@ namespace sls {
                 return l_undef;
 
             if (all_of(m_plugins, [&](auto* p) { return !p || p->is_sat(); })) {
+                VERIFY(unsat().empty() || !m_new_constraint);
                 values2model();
                 return l_true;
             }
@@ -184,11 +185,29 @@ namespace sls {
                 throw default_exception("conflicting assignment");
             }
         }
+
+        validate_model(*mdl);
                 
         s.on_model(mdl);
         // verbose_stream() << *mdl << "\n";
         TRACE("sls", display(tout));
     }
+
+    void context::validate_model(model& mdl) {
+        model_evaluator ev(mdl);
+        for (sat::literal lit : root_literals()) {
+            auto a = atom(lit.var());
+            if (!a)
+                continue;
+            auto eval_a = ev(a);
+            bool bad_model = (m.is_true(eval_a) && lit.sign()) || (m.is_false(eval_a) && !lit.sign());
+
+            if (bad_model) {             
+                IF_VERBOSE(0, verbose_stream() << lit << " " << a->get_id() << " " << mk_bounded_pp(a, m) << " " << eval_a << "\n");
+                throw default_exception("failed to create a well-formed model");
+            }
+        }
+    }
     
     void context::propagate_boolean_assignment() {
     start_propagation:
@@ -286,7 +305,7 @@ namespace sls {
 
     bool context::is_true(expr* e) {
         SASSERT(m.is_bool(e));
-        auto v = m_atom2bool_var.get(e->get_id(), sat::null_bool_var);
+        auto v = m_atom2bool_var.get(e->get_id(), sat::null_bool_var);       
         if (v != sat::null_bool_var)
             return is_true(v);
         if (m.is_and(e))
@@ -342,8 +361,10 @@ namespace sls {
         if (m_visited.contains(id))
             return false;
         m_visited.insert(id);
-        if (m_parents.size() <= id)
-            verbose_stream() << "not in map " << mk_bounded_pp(e, m) << "\n";
+        if (m_parents.size() <= id) // expressions can be temporary created in E-graph but not registered 
+        {
+            return false;
+        }
         for (auto p : m_parents[id]) {
             if (is_relevant(p)) {
                 m_relevant.insert(id);
@@ -353,18 +374,20 @@ namespace sls {
         return false;
     }
 
-    void context::add_constraint(expr* e) {        
+    bool context::add_constraint(expr* e) {        
         if (m_constraint_ids.contains(e->get_id()))
-            return;
+            return false;
         m_constraint_ids.insert(e->get_id());
         m_constraint_trail.push_back(e);
         add_assertion(e, false);     
         m_new_constraint = true;
         IF_VERBOSE(3, verbose_stream() << "add constraint " << mk_bounded_pp(e, m) << "\n");
         ++m_stats.m_num_constraints;
+        return true;
     }
 
     void context::add_assertion(expr* f, bool is_input)  {
+        m_new_constraint = true;
         expr_ref _e(f, m);
         expr* g, * h, * k;
         sat::literal_vector clause;
@@ -676,7 +699,7 @@ namespace sls {
                     has_relevant = true;
                     break;
                 }
-                if (m_rand() % ++n == 0)
+                if (m_rand(++n) == 0)
                     selected_lit = lit;
             }               
             if (!has_relevant && selected_lit != sat::null_literal) {
diff --git a/src/ast/sls/sls_context.h b/src/ast/sls/sls_context.h
index 96958ab0fa..73959e4571 100644
--- a/src/ast/sls/sls_context.h
+++ b/src/ast/sls/sls_context.h
@@ -159,6 +159,8 @@ namespace sls {
 
 
         sat::literal mk_literal();
+
+        void validate_model(model& mdl);
         
     public:
         context(ast_manager& m, sat_solver_context& s);
@@ -221,7 +223,7 @@ namespace sls {
         bool is_true(expr* e);
         bool is_fixed(expr* e);        
         bool is_relevant(expr* e);  
-        void add_constraint(expr* e);
+        bool add_constraint(expr* e);
         ptr_vector<expr> const& subterms();        
         ast_manager& get_manager() { return m; }
         std::ostream& display(std::ostream& out) const;
diff --git a/src/ast/sls/sls_euf_plugin.cpp b/src/ast/sls/sls_euf_plugin.cpp
index b7c2195f08..e4745d02e6 100644
--- a/src/ast/sls/sls_euf_plugin.cpp
+++ b/src/ast/sls/sls_euf_plugin.cpp
@@ -52,11 +52,18 @@ namespace sls {
     void euf_plugin::register_term(expr* e) {
         if (!is_app(e))
             return;
-        if (!is_uninterp(e))
-            return;
         app* a = to_app(e);
         if (a->get_num_args() == 0)
             return;
+        if (!is_uninterp(e)) {
+            return;
+            family_id fid = a->get_family_id();
+            if (fid == basic_family_id)
+                return;
+            if (all_of(*a, [&](expr* arg) { return !is_app(arg) || fid == to_app(arg)->get_family_id(); }))
+                return;            
+        }
+
         auto f = a->get_decl();
         if (!m_app.contains(f))
             m_app.insert(f, ptr_vector<app>());
@@ -341,8 +348,8 @@ namespace sls {
                         verbose_stream() << ctx.get_value(t->get_arg(i)) << " == " << ctx.get_value(u->get_arg(i)) << "\n";
 #endif
                     expr_ref fml(m.mk_or(ors), m);
-                    ctx.add_constraint(fml);
-                    new_constraint = true;
+                    if (ctx.add_constraint(fml))
+                        new_constraint = true;
                     
                 }
                 else
@@ -368,8 +375,8 @@ namespace sls {
                 }
                 // distinct(a, b, c) or a = b or a = c or b = c
                 eqs.push_back(e);
-                ctx.add_constraint(m.mk_or(eqs));
-                new_constraint = true;
+                if (ctx.add_constraint(m.mk_or(eqs)))
+                    new_constraint = true;
             done_distinct:
                 ;
             }