The equivalence of the Dekel-Fudenberg iterative procedure and weakly perfect rationalizability

Two approaches have been proposed in the literature to refine the rationali zability solution concept: either assuming that a player believes that with small probability her opponents choose strategies that are irrational, or assuming that their is a small amount of payoff uncertainty. We show that b oth approaches lead to the same refinement if strategy perturbations are ma de according to the concept of weakly perfect rationalizability, and if the re is payoff uncertainty as in Dekel and Fudenberg [J, of Econ. Theory 52 ( 1990), 243-267], For both cases, the strategies that survive are obtained b y starting with one round of elimination of weakly dominated strategies fol lowed by many rounds of elimination of strictly dominated strategies.