3. In a failure-free asynchronous message-passing system of n processes, process Pi learns a fact . (a)

3. In a failure-free asynchronous message-passing system of n processes, process Pi learns a fact φ.

(a) Devise simple noninhibitory protocols using a logical ring along which to pass control messages to achieve the following, and justify your answers. Use timing diagrams to illustrate your answers.

i. A protocol to attain E2(φ) in the system.

ii. A protocol so that each process knows E2(φ).

(b) What is the earliest global time at which all processes know that everyone knows E2(φ)? How can all the processes know about this time?