Index: interval.hpp
===================================================================
--- interval.hpp	(revision 14329)
+++ interval.hpp	(working copy)
@@ -547,7 +547,8 @@
 typename boost::enable_if<is_static_open<Type>, bool>::type
 is_empty(const Type& object)
 { 
-    return domain_less_equal<Type>(upper(object), domain_next<Type>(lower(object))); 
+    return domain_less_equal<Type>(upper(object), domain_next<Type>(lower(object)))
+        || domain_less_equal<Type>(domain_next<Type>(lower(object)), lower(object));
 }
 
 template<class Type>
@@ -557,7 +558,8 @@
     if(object.bounds() == interval_bounds::closed())
         return domain_less<Type>(upper(object), lower(object)); 
     else if(object.bounds() == interval_bounds::open())
-        return domain_less_equal<Type>(upper(object), domain_next<Type>(lower(object))); 
+        return domain_less_equal<Type>(upper(object), domain_next<Type>(lower(object)))
+            || domain_less_equal<Type>(domain_next<Type>(lower(object)), lower(object));
     else
         return domain_less_equal<Type>(upper(object), lower(object)); 
 }