Boyd R
Department of Anthropology, University of California, Los Angeles, 90024.
J Theor Biol. 1989 Jan 9;136(1):47-56. doi: 10.1016/s0022-5193(89)80188-2.
The repeated prisoner's dilemma game has been widely used in analyses of the evolution of reciprocal altruism. Recently it was shown that no pure strategy could be evolutionarily stable in the repeated prisoner's dilemma. Here I show that if there is always some probability that individuals will make a mistake, then a pure strategy can be evolutionarily stable provided that it is "strong perfect equilibria" against itself. To be a strong perfect equilibrium against itself, a strategy must be the best response to itself after every possible sequence of behavior. I show that both unconditional defection and a modified version of tit-for-tat have this property.
重复囚徒困境博弈已被广泛用于互惠利他主义进化的分析中。最近有研究表明，在重复囚徒困境中没有纯策略能够在进化上保持稳定。在此我表明，如果个体总是存在一定概率会犯错，那么只要一个纯策略是针对自身的“强完美均衡”，它就可以在进化上保持稳定。要成为针对自身的强完美均衡，一个策略必须在每一个可能的行为序列之后都是对自身的最佳回应。我表明无条件背叛和一种修正版的针锋相对策略都具有这一特性。
