Q$4.$ A fairness constraint is imposed on $($the scheduler of$)$ the system that it fairly selects the process to

be executed next. One can have three typical fairness constraints.

a$.$ Absolute Fairness, Impartiality: every process should be executed infinitely often

b$.$ Strong Fairness: Every process that is infinitely often enabled should be executed infinitely

often in a state where it is enabled

c$.$ Weak Fairness: Every process that is almost always enabled should be executed infinitely

often

Formulate each of these fairness constraint in LTL$.$ Use the following atomic propositions: ex

denotes process execution. en$,$ denotes process being enabled.

Does absolute Fairness imply Strong Fairness? Does Strong Fairness imply absolute fairness?