Permutation

A permutation is a bijection of a set onto itself, interpreted either as a new order of the members of a sequence or as the act of changing the linear order of an ordered set; the six permutations of the set {1, 2, 3} are an example of the first interpretation. The number of permutations of n distinct objects is n factorial, and the study of permutations of finite sets is an important topic in combinatorics and group theory, applied across computer science, quantum physics and biology. The collection of all permutations of a set forms a group, called the symmetric group of the set, under the operation of composing permutations. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/