diff --git a/src/math/lp/horner.cpp b/src/math/lp/horner.cpp
index fce8086a0..d146671ac 100644
--- a/src/math/lp/horner.cpp
+++ b/src/math/lp/horner.cpp
@@ -161,10 +161,12 @@ interv horner::interval_of_mul(const nex& e) {
             TRACE("nla_horner_details", tout << "got zero\n"; );
             return b;
         }
-        TRACE("nla_horner_details", tout << "es[k]= "<< es[k] << std::endl << ", "; m_intervals.display(tout, b); );
+        TRACE("nla_horner_details", tout << "es[k]= "<< es[k] << ", "; m_intervals.display(tout, b); );
         interv c;
         m_intervals.mul(a, b, c, comb_rule);
-        m_intervals.combine_deps(a, b, comb_rule, a);
+        m_intervals.combine_deps(a, b, comb_rule, c);
+        TRACE("nla_horner_details", tout << "a "; m_intervals.display(tout, a) << "\n";);
+        TRACE("nla_horner_details", tout << "c "; m_intervals.display(tout, c) << "\n";);
         m_intervals.set(a, c);
         TRACE("nla_horner_details", tout << "part mult "; m_intervals.display(tout, a) << "\n";);
     }
@@ -195,7 +197,7 @@ interv horner::interval_of_sum(const nex& e) {
         interval_deps_combine_rule combine_rule;
         TRACE("nla_horner_details_sum", tout << "a = "; m_intervals.display(tout, a) << "\nb = "; m_intervals.display(tout, b) << "\n";);
         m_intervals.add(a, b, c, combine_rule);
-        m_intervals.combine_deps(a, b, combine_rule, a);
+        m_intervals.combine_deps(a, b, combine_rule, c);
         m_intervals.set(a, c);
         TRACE("nla_horner_details_sum", tout << es[k] << ", ";
               m_intervals.display(tout, a); tout << "\n";);
diff --git a/src/math/lp/nla_intervals.cpp b/src/math/lp/nla_intervals.cpp
index e63b00bbe..50c5d0f0a 100644
--- a/src/math/lp/nla_intervals.cpp
+++ b/src/math/lp/nla_intervals.cpp
@@ -86,7 +86,7 @@ std::ostream& intervals::display(std::ostream& out, const interval& i) const {
     if (m_imanager.upper_is_inf(i)) {
         out << "oo)";
     } else {
-        out << rational(m_imanager.upper(i)) << (m_imanager.lower_is_open(i)? ")":"]");         
+        out << rational(m_imanager.upper(i)) << (m_imanager.upper_is_open(i)? ")":"]");         
     }
     svector<lp::constraint_index> expl;
     m_dep_manager.linearize(i.m_lower_dep, expl);
diff --git a/src/math/lp/nla_intervals.h b/src/math/lp/nla_intervals.h
index 348fc8abc..e60884fcb 100644
--- a/src/math/lp/nla_intervals.h
+++ b/src/math/lp/nla_intervals.h
@@ -174,9 +174,14 @@ public:
     void mul(const interval& a, const interval& b, interval& c) { m_imanager.mul(a, b, c); }
     void add(const interval& a, const interval& b, interval& c) { m_imanager.add(a, b, c); }
     void add(const interval& a, const interval& b, interval& c, interval_deps_combine_rule& deps) { m_imanager.add(a, b, c, deps); }
-    void set(interval& a, const interval& b) { m_imanager.set(a, b); }
+    void set(interval& a, const interval& b) {
+        m_imanager.set(a, b);
+        a.m_lower_dep = b.m_lower_dep;
+        a.m_upper_dep = b.m_upper_dep;
+    }
     void mul(const interval& a, const interval& b, interval& c, interval_deps_combine_rule& deps) { m_imanager.mul(a, b, c, deps); }
     void combine_deps(interval const& a, interval const& b, interval_deps_combine_rule const& deps, interval& i) const {
+        SASSERT(&a != &i && &b != &i);
         m_config.add_deps(a, b, deps, i);
     }