Narrow Results

In this note, the persistence of cooperation in the standard Prisoner's Dilemma is examined under five distinct matching mechanisms. The general model is a birth-and-death process, which is studied using a simple direct method and the mutation-counting technique. Mean matching is discussed first, before two variants of random matching and viscosity are analyzed. Finally payoff assortative matching is considered. In all five cases the stochastic stability of the absorbing sets of the evolutionary process is examined; assortative matching is shown to sustain significant amounts of cooperation.