Absorbing games with a clock and two bits of memory

An absorbing game is a two-person zero-sum repeated game. Some of the entries are “absorbing” in the sense that, following the play of an absorbing entry, with positive probability all future payoffs are equal to that entry's payoff. The outcome of the game is the long-run average payoff. We prove that a two-person zero-sum absorbing game, with either finite or compact action sets, has, for each ε>0, ε-optimal strategies with finite memory. In fact, we show that there is an ε-optimal strategy that depends on the clock and three states of memory.