We study two-player discounted repeated games in which one player cannot monitor the other unless he pays a fixed amount. It is well known that in such a model the folk theorem holds when the monitoring cost is on the order of magnitude of the stage payoff. We analyze high frequency games in...

In (Viossat, 2006, The replicator dynamics does not lead to correlated equilibria, forthcoming in Games and Economic Behavior), it was shown that the replicator dynamics may eliminate all pure strategies used in correlated equilibrium, so that only strategies that do not take part in any...

A pure strategy is coherent if it is played with positive probability in at least one correlated equilibrium. A game is pre-tight if in every correlated equilibrium, all incentives constraints for non deviating to a coherent strategy are tight. We show that there exists a Nash equilibrium in the...

We study how the launching of a do-not-spam registry will affect the internet's efficiency. We show that as long as the cost of sending spam messages is not high, having rich users (who have high-quality filters) join the registry has the desirable effect of lowering the number of spam messages...

We consider an example of a Markov game with lack of information on one side, that was .rst introduced by Renault (2002). We compute both the value and optimal strategies for a range of parameter values.

We provide a model to study the effect of improving the quality of the filters that users use, and the increase of the cost of mailing spam messages, on the total number of messages that spammers send. We show that increasing the cost of mailing spam messages have the unequivocal effect of...