Show that if events e and e are concurrent then neither Ve Ve nor Ve Ve . Hence show that if Ve Ve thene e.

What will be an ideal response?

Let e and e be concurrent and let e occur at pi and e at pj . Because the events are concurrent (not related by happened-before) we know that no message sent from pi at or after event e has propagated its timestamp to pj by the time e occurs at pj , and vice versa. By the reasoning, it follows that Vji Vii Ve Ve . and Vij Vjj (strict inequalities) and therefore that neither Ve Ve nor

Therefore if Ve Ve the two events are not concurrent – they must be related by happened-before. Of the two possibilities, it obviously must be thate e.