permutationn.交换；排列permutation homeomorphism置换同胚permutation of multi-set多重集的排列permutation transformation变换转换, 换位转换permutation code algorithm排列码算法permutation representation置换表示permutation with repetition重复排列permutation and combinationn.[数]排列组合permutation schedule problems同顺序排序permutation polynomial vector置换多项式向量permutation entropy algorithm排列熵算法