FLUCTUATIONS AROUND NASH EQUILIBRIA IN GAME-THEORY

We investigate the fluctuations induced by irrationality in simple gam es with a large number of competing players. We show that Nash equilib ria in such games are ''weakly'' stable: irrationality propagates and amplifies through players' interactions so that huge fluctuations can result from a small amount of irrationality. In the presence of multip le Nash equilibria, our statistical approach allows to establish which is the globally stable equilibrium. However, characteristic times to reach this state can be very large.