理发师悖论是个著名的悖论,是大数学家罗素提出来的。在一座小城里,有一位自命不凡的理发师。在他的理发馆门前竖立着一块招牌,上面写着理发师的告示:“城里所有不自己刮胡子的人的胡子都由我来刮,我也只给不自己刮胡子的人刮胡子。”麻烦来了。谁给这位理发师刮胡子呢?如果理发师给自己刮胡子,他就属于自己刮胡子的那类人,但是,在他的告示中明确指出他是不给这类人刮脸的。因此他不能给自己刮。如果由其他人给理发师刮胡子,他就属于不自己刮胡子的那类 Barber paradox is a famous paradox, proposed by the great mathematician Russell. In a small town, there is a pretentious barber. In front of his hairdresser stood a signboard with a sign of the barber: “All the beard of the city who did not shave myself was scraped by me, and I gave it to those who did not shave themselves Beard. ”Trouble is coming. Who shaved the barber? If the barber shaved herself, he belonged to his own group of shaved men, but in his message he made it clear that he did not shave such people. So he can not scratch himself. If someone else shaves a barber, he belongs to the class that does not shave himself