Contemporaneous Perfect Epison Equilibria

Abstract
We examine contemporaneous perfect equilibria, in which a player's actions after every history, evaluated at the point of deviation from the equilibrium, must be within of a best response. This concept implies, but is not implied by Radner's ex ante perfect equilibrium. A strategy profile is a contemporaneous perfect equilibrium of a game if it is a subgame perfect equilibrium in a game achieved by perturbing payoffs by at most e/2, with the converse holding for pure equilibria.