bail out on big rational numbers in nla monotone lemmas

Signed-off-by: Lev Nachmanson <levnach@hotmail.com>

src/math/lp/nla_core.cpp

@@ -1285,7 +1285,7 @@ lbool core::incremental_linearization(bool constraint_derived) {
         SASSERT(elists_are_consistent(true));
         if (search_level == 1) {
             m_order.order_lemma();
-        } else { // search_level == 2
+        } else if (search_level == 2) {
             m_monotone. monotonicity_lemma();
             m_tangents.tangent_lemma();
         }
@@ -1370,6 +1370,21 @@ void core::update_to_refine_of_var(lpvar j) {
     }
 }
 
+bool core::var_is_big(lpvar j) const {
+    if (var_is_int(j))
+        return false;
+    return val(j).is_big();
+}
+
+bool core::has_big_num(const monic& m) const {
+    if (var_is_big(var(m)))
+        return true;
+    for (lpvar j : m.vars())
+        if (var_is_big(j))
+            return true;
+    return false;
+}
+
 bool core::patch_blocker(lpvar u, const monic& m) const {
     SASSERT(m_to_refine.contains(m.var()));
     if (var_is_used_in_a_correct_monic(u)) {

src/math/lp/nla_core.h

@@ -424,6 +424,8 @@ public:
     bool try_to_patch(lpvar, const rational&, const monic&);
     bool to_refine_is_correct() const;
     bool patch_blocker(lpvar u, const monic& m) const;
+    bool has_big_num(const monic&) const;
+    bool var_is_big(lpvar) const;
 };  // end of core
 
 struct pp_mon {

src/math/lp/nla_monotone_lemmas.cpp

@@ -37,6 +37,8 @@ void monotone::monotonicity_lemma(monic const& m) {
     SASSERT(!check_monic(m));
     if (c().mon_has_zero(m.vars()))
         return;
+    if (c().has_big_num(m)) 
+       return;
     const rational prod_val = abs(c().product_value(m));
     const rational m_val = abs(var_val(m));
     if (m_val < prod_val)