We study infinitely repeated anonymous random matching games played by communities of players, who only observe the outcomes of their own matches. It is well known that cooperation can be sustained in equilibrium for the prisoner's dilemma (PD) through grim trigger strategies. Little is known...

When large communities transact with each other and players change rivals over time, players may not recognize each other or may have limited information about past play. Can players cooperate in such anonymous transactions? I analyze an infinitely repeated random matching game between two...