Definition of arrangement: from N different elements, any m(m≤n, m and n are natural numbers, the same below) elements are arranged in a column in a certain order, which is called the arrangement of M elements in N different elements, and is represented by the symbol A(n, m).
Definition of combination: m(m≤n) elements from N different elements are combined into a group, which is called the combination of M elements of N different elements and is represented by symbol C(n, m).
Extended data
Permutation and combination is the most basic concept of species combination in mathematics. Arrangement refers to taking out a specified number of elements from a given number of elements for sorting. Combination is to take out a specified number of elements from a given number of elements, regardless of sorting.
The central problem of permutation and combination is to study the total number of possible situations in a given permutation and combination. Permutation and combination are closely related to classical probability theory.
Refer to Baidu Encyclopedia-permutation and combination