The concept of NP-completeness has provided a powerful tool for understanding the complexity of computational problems.

A mathematician is a person who can find analogies between theorems; a better mathematician is one who can see analogies between proofs and the best mathematician can notice analogies between theories.

——从浙江观潮返上海后题词，1916年9月15日

上帝在他的天堂——世界一切安好！

所有的突破在一开始都是看起来很可笑和荒谬的。事实上如果它在一开始看起来不够可笑和荒谬的话，它也称不上是一种突破。