+/** The is_synchronizing method should only explore interleavings if:
+ * (1) the operations are seq_cst and don't commute or
+ * (2) the reordering may establish or break a synchronization relation.
+ * Other memory operations will be dealt with by using the reads_from
+ * relation.
+ *
+ * @param act is the action to consider exploring a reordering.
+ * @return tells whether we have to explore a reordering.
+ */
+
+bool ModelAction::is_synchronizing(ModelAction *act)