A Simple Adaptive Procedure Leading to Correlated Equilibrium (revision of Discussion Paper #126)

Sergiu Hart & Andreu Mas-Colell

We propose a new and simple adaptive procedure for playing a game: " regretmatching." In this procedure, players depart from their current play with probabilities that are proportional to measures of regret for not having used other strategies in the past. It is shown that our adaptive procedure guarantees that, with probability one, the empirical distributions of play converge to the set of correlated equilibria of the game. To compute these regret measures, a player needs to know his payoff function and the history of play. We also offer a variation where every player knows only his own realized payoff history ( but not his payoff function).

March, 1998
Published in: 
Econometrica 68 (2000), 1127-1150