English

On the ratio of maximum and minimum degree in maximal intersecting families

Combinatorics 2014-06-02 v1

Abstract

To study how balanced or unbalanced a maximal intersecting family F([n]r)\mathcal{F}\subseteq \binom{[n]}{r} is we consider the ratio R(F)=Δ(F)δ(F)\mathcal{R}(\mathcal{F})=\frac{\Delta(\mathcal{F})}{\delta(\mathcal{F})} of its maximum and minimum degree. We determine the order of magnitude of the function m(n,r)m(n,r), the minimum possible value of R(F)\mathcal{R}(\mathcal{F}), and establish some lower and upper bounds on the function M(n,r)M(n,r), the maximum possible value of R(F)\mathcal{R}(\mathcal{F}). To obtain constructions that show the bounds on m(n,r)m(n,r) we use a theorem of Blokhuis on the minimum size of a non-trivial blocking set in projective planes.

Keywords

Cite

@article{arxiv.1109.1079,
  title  = {On the ratio of maximum and minimum degree in maximal intersecting families},
  author = {Zoltán Loránt Nagy and Lale Özkahya and Balázs Patkós and Máté Vizer},
  journal= {arXiv preprint arXiv:1109.1079},
  year   = {2014}
}