A note on the maximum diversity of intersecting families in the symmetric group
Combinatorics
2026-01-05 v2
Abstract
Let be the symmetric group on the set . A family is called intersecting if for every there exists some such that . Deza and Frankl proved that the largest intersecting family of permutations is the full star, that is, the collection of all permutations with a fixed position. The diversity of an intersecting family is defined as the minimum number of permutations in , whose deletion results in a star. In the present paper, by applying the spread approximation method developed recently by Kupavskii and Zakharov, we prove that for the diversity of an intersecting subfamily of is at most , which is best possible.
Cite
@article{arxiv.2501.06731,
title = {A note on the maximum diversity of intersecting families in the symmetric group},
author = {Jian Wang and Jimeng Xiao},
journal= {arXiv preprint arXiv:2501.06731},
year = {2026}
}
Comments
Final version