Correlation Learning and the Robustness of Cooperation

n the stage game Prisoner's Dilemma one line of research which is pursued to justify the cooperative outcome is based upon some idea of correlation. This paper aims at testing whether correlation could support a cooperative behavior in the long run, by embedding the infinitely repeated game within a simple evolutionary framework. In particular, the main theorem states that just two born cooperative agents might remain cooperative forever with strictly positive probability. This robustness result appears to be particularly strong since the model allows cooperative agents to switch strategy and start defecting from a certain time onward, but not vice versa. (C) 2000 Academic Press