+/**
+ * Check whether 'this' happens before act, according to the memory-model's
+ * happens before relation. This is checked via the ClockVector constructs.
+ * @return true if this action's thread has synchronized with act's thread
+ * since the execution of act, false otherwise.
+ */
+bool ModelAction::happens_before(const ModelAction *act) const
+{
+ return act->cv->synchronized_since(this);
+}
+
+void ModelAction::print(void) const