On Subsets with Intersections of Even Cardinality

Author:
  • EBE.R. Berlekamp
    E.R. Berlekamp
Publisher website
Google Scholar
Abstract
This paper solves a question posed by P. Erdös:If A1, A2, …, A are distinct subsets of n elements and if |Ai ∩ Ai| ≡ 0 mod 2 (i ≠ j), then and for each n, there exists a collection of subsets which achieves this bound with equality.