STOCHASTIC STRATEGIES IN THE PRISONERS-DILEMMA

A complete analysis of all strategies where the probability to cooperate depends only on the opponent's previous move is given for the infinitely iterated Prisoner's Dilemma. All Nash solutions are characterized. A necessary condition for evolutionary stability against invasion by selection pressure is found. A mutation selection model is discussed which enables us to quantify the possibility to succeed over less cooperative strategies by means of reciprocity. © 1990.