We consider some implications of imperfect recall for existence and subsetting results over various equilibrium concepts in extensive games. Our analysis focuses on commonly time-structured games which allow us to see more clearly in games of imperfect recall. We find that in a game of imperfect recall, a sequential equilibrium may not be a Nash equilibrium, and a perfect equilibrium may not be a sequential equilibrium. A perfect equilibrium exists in every one-player game, but a sequential equilibrium may not exist. We also give su¢ciency conditions weaker than perfect recall, for the standard subsetting results between perfect equilibrium, sequential equilibrium and Nash equilibrium.
Available at: http://works.bepress.com/jeffrey_kline/10/