在电影《哪吒2》中，太乙真人复活哪吒为什么要用藕？因为从拓扑学上来说：藕跟人是 同胚 （Homeomorphism）的，所以能够经过连续变换得到一个人。

Since the twin breakthroughs in 1982-83 by Freedman and Donaldson the study of four manifolds has been developing rapidly. Freedman’s work showed that the homeomorphism problem for 4-dimensional ...