Concepts2
∑MathAdvanced
Stirling Numbers of Second Kind
Stirling numbers of the second kind S(n,k) count how many ways to split n labeled items into k non-empty, unlabeled groups.
#stirling numbers of the second kind#set partitions#bell numbers+12
∑MathIntermediate
Inclusion-Exclusion Principle
The Inclusion-Exclusion Principle (IEP) corrects overcounting by alternately adding and subtracting sizes of intersections of sets.
#inclusion-exclusion#derangements#surjections+12