
Stirling numbers
Stirling numbers are mathematical tools used to count specific ways of organizing or partitioning objects. There are two types: Stirling numbers of the first kind, which count how many ways to arrange a set of objects into cycles (loops), and Stirling numbers of the second kind, which count how many ways to split a set into non-empty groups. They help solve problems in combinatorics, such as counting permutations with cycles or partitioning sets, and are essential in various fields like algebra, probability, and computer science for understanding the structure and organization of complex systems.