We study an infinitely-repeated game of oligopolistic price leadership in which one firm, the leader, proposes a supermarkup over Bertrand prices to a coalition of rivals. We estimate the model with aggregate scanner data on the beer industry and find the supermarkup accounts for 6% of price....

We characterize the class of symmetric two-player games in which tit-for-tat cannot be beaten even by very sophisticated opponents in a repeated game. It turns out to be the class of exact potential games. More generally, there is a class of simple imitation rules that includes tit-for-tat but...