Voluntarily Separable Repeated Prisoner\u27s Dilemma

Ordinary repeated games do not apply to real societies where one can cheat and run away from partners. We formulate a model of endogenous relationships which one can unilaterally end and start with a randomly-assigned new partner with no information flow. Focusing on two-person, two-action Prisoner\u27s Dilemma, we show that the endogenous duration of partnerships gives rise to a significantly different evolutionary stability structure from ordinary random matching games. Monomorphic equilibria require initial trust-building, while a polymorphic equilibrium includes early cooperators than any strategy in monomorphic equilibria and is thus more efficient. This is due to nonlinearity of average payoffs.revised version subsequently published in The Review of Economic Studies, Vol.76, Issue 3 (July 2009), pp.993-1021本文フィルはリンク先を参照のこ