exchange permutation

• 交换排列

exchange permutation的用法和样例：

例句

1. Such a permutation is called a derangement.
   这样的一个排列称为错位排列。
2. Unique because that particular permutation has not appeared before.
   之所以独一无二，是因为那种独特的基因排列组合以前不曾出现过。