MathDB

5

Part of 1972 Czech and Slovak Olympiad III A

Problems(1)

Disjoint subsets of an n-element set

Source: Czech and Slovak Olympiad 1972, National Round, Problem 5

7/10/2024
Determine how many unordered pairs {A,B}\{A,B\} is there such that A,B⊆{1,…,n}A,B\subseteq\{1,\ldots,n\} and A∩B=∅.A\cap B=\emptyset.
combinatoricsSubsets