526
个编辑
更改
→Prisoner's dilemma 囚徒困境
A common model of altruism and social cooperation is the Prisoner's dilemma. Here a group of players would collectively be better off if they could play Cooperate, but since Defect fares better each individual player has an incentive to play Defect. One solution to this problem is to introduce the possibility of retaliation by having individuals play the game repeatedly against the same player. In the so-called iterated Prisoner's dilemma, the same two individuals play the prisoner's dilemma over and over. While the Prisoner's dilemma has only two strategies (Cooperate and Defect), the iterated Prisoner's dilemma has a huge number of possible strategies. Since an individual can have different contingency plan for each history and the game may be repeated an indefinite number of times, there may in fact be an infinite number of such contingency plans.
A common model of altruism and social cooperation is the Prisoner's dilemma. Here a group of players would collectively be better off if they could play Cooperate, but since Defect fares better each individual player has an incentive to play Defect. One solution to this problem is to introduce the possibility of retaliation by having individuals play the game repeatedly against the same player. In the so-called iterated Prisoner's dilemma, the same two individuals play the prisoner's dilemma over and over. While the Prisoner's dilemma has only two strategies (Cooperate and Defect), the iterated Prisoner's dilemma has a huge number of possible strategies. Since an individual can have different contingency plan for each history and the game may be repeated an indefinite number of times, there may in fact be an infinite number of such contingency plans.
利他主义和社会合作的普遍模式就是囚徒困境。在这里，如果一群玩家选择“合作”，那么他们这个集体就会生活的更好，但是由于“背叛”为个人带来的利益更大，因此每个玩家都有动机去选择“背叛”。解决该问题的一个可能方案是通过让个体反复与同一玩家来对战，由此引入报复机制。在所谓的囚徒困境迭代过程中，相同的两个人一遍又一遍地扮演着他们的角色。尽管囚犯的困境只有两种策略（合作和背叛），但迭代的囚徒困境游戏却具有大量可能的策略。由于个体对于每个历史可以具有不同的应急计划，并且游戏可以无限次重复，因此实际上可能有无限个此类应急计划。
Three simple contingency plans which have received substantial attention are Always Defect, Always Cooperate, and Tit for Tat. The first two strategies do the same thing regardless of the other player's actions, while the latter responds on the next round by doing what was done to it on the previous round—it responds to Cooperate with Cooperate and Defect with Defect.
Three simple contingency plans which have received substantial attention are Always Defect, Always Cooperate, and Tit for Tat. The first two strategies do the same thing regardless of the other player's actions, while the latter responds on the next round by doing what was done to it on the previous round—it responds to Cooperate with Cooperate and Defect with Defect.
其备受关注的三个简单的应急计划是：“始终背叛”，“始终合作”和“针锋相对”。前两种策略会始终执行相同的操作，而不受另一方行为的影响，而后一种策略则是通过上一轮中执行的操作来对下一轮中的对象做出响应，即“合作对合作”或“背叛对背叛”。
如果整个种群都选择“针锋相对”，并且出现了一个变异者选择了“始终背叛”，那么“针锋相对”将战胜“始终背叛”。如果该变异者的种群太大，则它所占的百分比将保持很小。因此，就这两种策略而言，“针锋相对”就是一种进化均衡策略。另一方面，“始终背叛”的玩家群体可以稳定地抵御少数“针锋相对”玩家的入侵，但不能抵御大量的入侵。
如果整个种群都选择“针锋相对”，并且出现了一个变异者选择了“始终背叛”，那么“针锋相对”将战胜“始终背叛”。如果该变异者的种群太大，则它所占的百分比将保持很小。因此，就这两种策略而言，“针锋相对”就是一种进化均衡策略。另一方面，“始终背叛”的玩家群体可以稳定地抵御少数“针锋相对”玩家的入侵，但不能抵御大量的入侵。
但如果我们使用“始终合作”，那么“针锋相对”就不再是进化均衡策略了。由于大量的“针锋相对”玩家转向选择保持合作，因此“始终合作”策略在这一群体中的表现相同。最终，“始终合作”的变异者将不会被淘汰。当然，即使“始终合作”和“针锋相对”的人群可以共存。但是如果“始终背叛”的玩家只占总量的一小部分时，那么策略选择压力会对“始终合作”不利。而玩家们会倾向于支持“针锋相对”，这是由于合作带来的利益要比背叛来的低。
This demonstrates the difficulties in applying the formal definition of an ESS to games with large strategy spaces, and has motivated some to consider alternatives.
This demonstrates the difficulties in applying the formal definition of an ESS to games with large strategy spaces, and has motivated some to consider alternatives.
这证明了要想将进化均衡策略的正式定义应用于具有较大策略空间的游戏中，是非常困难的，这就促使了一些人去思索替代方案。
== Human behavior 人类行为 ==
== Human behavior 人类行为 ==