tice sometimes solve the co-ordination problem either via formal or informal agreements. I would focus on the more interesting and complicated case of how collusive outcomes can be sustained by non-co-operative behaviour (informal), i.e. in the absence of explicit, enforceable agreements between firms. We have seen that collusion is not possible in the "one-shot" version of the game and we will now stress upon a question of whether it is possible in a repeated version. The answer depends on at least four factors:1. Whether the game is repeated infinitely or there is some finite number of times;2. Whether there is a full information available to each firm about the objectives of, and opportunities available to, other firms;3. How much weight the firms attach to the future in their calculations;4. Whether the "cheating" can/can not be detected due to the knowledge/lack of knowledge about the prior moves of the firm's rivals. The fact of repetition broadens the strategies available to the players, because they can make their strategy in any currant round contingent on the others' play in previous rounds. This introduction of time dimension permits strategies, which are damaging to be punished in future rounds of the game. This also permits players to choose particular strategies with the explicit purpose of establishing a reputation, e.g. by continuing to co- operate with the other player even when short-term self-interest indicates that an agreement to do so should be breached. b.) Finite game case. But repetition itself does not necessarily resolve the prisoner's dilemma. Suppose that the game is repeated a finite number of times, and that there is complete and perfect information. Again, we assume firms to maximise the (possibly discounted) sum of their profits in the game as a whole. The collusive low output for the firms again, unfortunately for the firms, could not be sustained. Suppose, they play a game for a total of five tim...
