We study the evolutionary dynamics of the Prisoner’s Dilemma game in which cooperators and defectors interact with another actor type called exiters. Rather than being exploited by defectors, exiters exit the game in favour of a small pay-off. We find that this simple extension of the game allows cooperation to flourish in well-mixed populations when iterations or reputation are added. In networked populations, however, the exit option is less conducive to cooperation. Instead, it enables the coexistence of cooperators, defectors, and exiters through cyclic dominance. Other outcomes are also possible as the exit pay-off increases or the network structure changes, including network-wide oscillations in actor abundances that may cause the extinction of exiters and the domination of defectors, although game parameters should favour exiting. The complex dynamics that emerges in the wake of a simple option to exit the game implies that nuances matter even if our analyses are restricted to incentives for rational behaviour.

中文翻译：

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退出权为合作开辟了复杂的途径

我们研究囚徒困境博弈的演化动力学，其中合作者和叛逃者与另一种称为退出者的演员类型互动。退出者并没有被叛逃者利用，而是退出游戏以获得小额回报。我们发现，当添加迭代或声誉时，游戏的这种简单扩展允许合作在混合良好的人群中蓬勃发展。然而，在网络化人群中，退出选项不太利于合作。相反，它通过循环支配使合作者、叛逃者和退出者共存。随着退出收益的增加或网络结构的变化，其他结果也是可能的，包括可能导致退出者灭绝和叛逃者统治的参与者丰度的全网络振荡，尽管游戏参数应该有利于退出。