English

Families with no $s$ pairwise disjoint sets

Combinatorics 2017-12-01 v2 Discrete Mathematics

Abstract

For integers ns2n\ge s\ge 2 let e(n,s)e(n,s) denote the maximum of F,|\mathcal F|, where F\mathcal F is a family of subsets of an nn-element set and F\mathcal F contains no ss pairwise disjoint members. Half a century ago, solving a conjecture of Erd\H os, Kleitman determined e(sm1,s)e(sm-1,s) and e(sm,s)e(sm,s) for all m,s1m,s\ge 1. During the years very little progress in the general case was made. In the present paper we state a general conjecture concerning the value of e(sml,m)e(sm-l,m) for 1<l<s1<l<s and prove its validity for s>s0(l,m).s>s_0(l,m). For l=2l=2 we determine the value of e(sm2,m)e(sm-2,m) for all s5.s\ge 5. Some related results shedding light on the problem from a more general context are proved as well.

Keywords

Cite

@article{arxiv.1607.06122,
  title  = {Families with no $s$ pairwise disjoint sets},
  author = {Peter Frankl and Andrey Kupavskii},
  journal= {arXiv preprint arXiv:1607.06122},
  year   = {2017}
}
R2 v1 2026-06-22T14:59:53.296Z