permutation, permute 的名词
1‘数学’排列
~(s) and combination(s)
排列与组合
2 (C)交换,互换,置换 (interchange)[@more@][usually pl.] any of the different ways in which a set of things can be ordered: The possible permutations of x, y and z are xyz, xzy, yxz, yzx, zxy and zyx.