Discrete Mathematics Week9 Combinatorics Part1

Combinatorics is a branch of mathematics that deals with counting, arranging, and selecting objects or elements from a finite set. It focuses on problems related to counting and organizing objects in a systematic and often discrete manner. Combinatorial techniques are widely used in various fields, including computer science, statistics, cryptography, and optimization, among others.

Permutations: Permutations are arrangements of objects in a specific order. For example, the permutations of the letters A, B, and C are ABC, ACB, BAC, BCA, CAB, and CBA.

Combinations: Combinations involve selecting a subset of objects from a larger set without considering the order of selection. For example, the combinations of two letters from the set {A, B, C} are {A, B}, {A, C}, and {B, C}.