English

Maximal $3$-wise intersecting families

Combinatorics 2023-02-28 v2

Abstract

A family F\mathcal{F} on ground set [n]:={1,2,,n}[n]:=\{1,2,\ldots, n\} is maximal kk-wise intersecting if every collection of at most kk sets in F\mathcal{F} has non-empty intersection, and no other set can be added to F\mathcal{F} while maintaining this property. In 1974, Erd\H{o}s and Kleitman asked for the minimum size of a maximal kk-wise intersecting family. We answer their question for k=3k=3 and sufficiently large nn. We show that the unique minimum family is obtained by partitioning the ground set [n][n] into two sets AA and BB with almost equal sizes and taking the family consisting of all the proper supersets of AA and of BB.

Keywords

Cite

@article{arxiv.2110.12708,
  title  = {Maximal $3$-wise intersecting families},
  author = {József Balogh and Ce Chen and Kevin Hendrey and Ben Lund and Haoran Luo and Casey Tompkins and Tuan Tran},
  journal= {arXiv preprint arXiv:2110.12708},
  year   = {2023}
}

Comments

17 pages. This is a combination of the results from arXiv:2110.12708 (version 1) and the results from arXiv:2206.09334, which settled the even and odd case of the problem, respectively

R2 v1 2026-06-24T07:09:05.787Z