TED演讲:著名的绿眼逻辑难题(2)

 　　But on the hundredth morning after your visit, all the prisoners are gone, each having asked to leave the previous night. 但是在你拜访之后的第一百个早上，所有的居民都离开了，每一位居民，都在前一天晚上要求离开。

　　So how did you outsmart the dictator¹? 你是用什么方法智取独裁者的？

　　It might help to realize that the amount of prisoners is arbitrary². 把居民的数目任意化也许可以有所帮助。

　　Let's simplify things by imagining just two, Adria and Bill. 让我们先把情况简化，想像只有两个居民 Adria 和 Bill。

　　Each sees one person with green eyes, and for all they know, that could be the only one. 他们各自看到对方拥有绿色眼睛。所以他们都知道：对方是可以离开岛上的那一位。

　　For the first night, each stays put. 第一天晚上，两个居民都留下来了。

　　But when they see each other still there in the morning, they gain new information. 但是到了隔天早上，当他们看到彼此都还在，他们得到了新的讯息。

　　Adria realizes that if Bill had seen a non-green-eyed person next to him, Adria的想法是：如果Bill看到的人没有绿色眼睛，

　　he would have left the first night after concluding the statement could only refer to himself. 那Bill在第一天晚上就会要求离开。当他得到这个结论的时候，就会推论出：自己有绿色眼睛。

　　Bill simultaneously³ realizes the same thing about Adria. 而Bill也会得到相同的结论。

　　The fact that the other person waited tells each prisoner his or her own eyes must be green. 由于另一个人还在等待，没有离开岛屿，这个事实告诉每位居民：他们自己的眼睛一定是绿色的。

　　And on the second morning, they're both gone. 根据第二天早上的结果，他们两个都会要求离开。

　　Now imagine a third prisoner. 现在，假设岛上有三个居民。

　　Adria, Bill and Carl each see two green-eyed people, Adria，Bill和Carl都看到其他两位拥有绿色眼睛，

　　but aren't sure if each of the others is also seeing two green-eyed people, or just one. 但无法确定其他两位，也同样看到两个绿眼的人，或是只看到一个(绿眼的人)。

　　They wait out the first night as before, but the next morning, they still can't be sure. 他们像之前一样度过第一个晚上，到了隔天早上，他们还是不能确定。

1 dictator   

n.独裁者，爱发号施令的人

参考例句：

• We felt quite impotent to resist the will of the dictator.我们感到无力抗拒独裁者的意志。
• A dictator must have a firm hand.独裁者的手段是很厉害的。

2 arbitrary   

adj.任意的，任性的，主观的；专断的，武断的

参考例句：

• A good judge does not make arbitrary decisions.一个优秀的法官不会作武断的判决。
• You can make an arbitrary choice.你可以随便做选择。

3 simultaneously   

adv.同时发生地，同时进行地

参考例句：

• The radar beam can track a number of targets almost simultaneously.雷达波几乎可以同时追着多个目标。
• The Windows allow a computer user to execute multiple programs simultaneously.Windows允许计算机用户同时运行多个程序。