MathDB
Family of sets with a regular property

Source: Kürschák competition 2019 P2

February 17, 2020
combinatorics

Problem Statement

Find all family F\mathcal{F} of subsets of [n][n] such that for any nonempty subset X⊆[n]X\subseteq [n], exactly half of the elements A∈FA\in \mathcal{F} satisfies that ∣A∩X∣|A\cap X| is even.
Back to ProblemsView on AoPS