English

On the maximum number of distinct intersections in an intersecting family

Combinatorics 2021-08-03 v1 Discrete Mathematics

Abstract

For n>2k4n > 2k \geq 4 we consider intersecting families F\mathcal F consisting of kk-subsets of {1,2,,n}\{1, 2, \ldots, n\}. Let I(F)\mathcal I(\mathcal F) denote the family of all distinct intersections FFF \cap F', FFF \neq F' and F,FFF, F'\in \mathcal F. Let A\mathcal A consist of the kk-sets AA satisfying A{1,2,3}2|A \cap \{1, 2, 3\}| \geq 2. We prove that for n50k2n \geq 50 k^2 I(F)|\mathcal I(\mathcal F)| is maximized by A\mathcal A.

Keywords

Cite

@article{arxiv.2108.00479,
  title  = {On the maximum number of distinct intersections in an intersecting family},
  author = {Peter Frankl and Sergei Kiselev and Andrey Kupavskii},
  journal= {arXiv preprint arXiv:2108.00479},
  year   = {2021}
}