In business, strategic situations like the advertising gamepresented are not played once --- the firms evaluate theirstrategies periodically and can repeat these games for many months,quarters, or years into the indefinite future. Even for relativelysimple games like those presented in this chapter (e.g., twoplayers with two possible actions), the Nash equilibria forinfinitely repeated games are very difficult to deriveanalytically. Economists have used numerical tools to simulationthe outcomes from different strategies that the players may use,and the best strategy seems to be the "tit-for-tat" rule in which afirm cooperates with the other firm until the competitor deviates.After one firm deviates from cooperation, the other firm switchesits behavior to non-cooperative actions until the deviating firmreturns to cooperation. As such, firms are rewarded for cooperationand punished for deviation. Our personal relationships may also beexamined in a repeated game framework. Of course, the payoffs inthese situations do not always involve money and may include goodfeelings for favors done or bad feelings for hurtful actions. Doesit make sense to use the "tit-for-tat" rule when dealing withpersonal friends and family members? If not, what is differentabout these personal relationships? Please explain yourresponses.