--- a/src/simulator/scheduler-map.cc	Tue Dec 12 14:30:44 2006 +0100
+++ b/src/simulator/scheduler-map.cc	Tue Dec 12 14:31:16 2006 +0100
@@ -43,6 +43,29 @@
 SchedulerMap::~SchedulerMap ()
 {}
 
+/* Note the invariants which this function must provide:
+ * - irreflexibility: f (x,x) is false)
+ * - antisymmetry: f(x,y) = !f(y,x)
+ * - transitivity: f(x,y) and f(y,z) => f(x,z)
+ */
+bool
+SchedulerMap::EventKeyCompare::operator () (struct EventKey a, struct EventKey b)
+{
+  if (a.m_ns < b.m_ns) 
+    {
+      return true;
+    } 
+  else if (a.m_ns == b.m_ns && a.m_uid < b.m_uid) 
+    {
+      return true;
+    } 
+  else 
+    {
+      return false;
+    }
+}
+
+
 
 EventId
 SchedulerMap::RealInsert (EventImpl *event, Scheduler::EventKey key)