置換

Multiplication of permutations, unlike multiplication of numbers, is not always commutative. 置換的乘法不同于數(shù)的乘法，它并不一定滿足交換律。

It turns out that all these problems can be solved at once, provided we learn enough about the cycle structure of permutations. 結(jié)果是，所有這些問(wèn)題都可以一次解決，只要我們充分地了解各置換的循環(huán)結(jié)構(gòu)。