English

More Shattering News

Combinatorics 2026-03-20 v1

Abstract

An ordered variant of the well-known set theory concept of shattering was introduced by Anstee, R\'onyai, and Sali. In this paper, we prove several new results related to order shattering. Given a family F\mathcal F of subsets of [n][n], we show that osh(F)\mathrm{osh}(\mathcal F), the family of all sets order shattered by F\mathcal F, coincides with T(F)T(\mathcal F), the family obtained from F\mathcal F by the down-shift operation. We then give a full characterization of all sets that can be order shattered by some \ell-Sperner family. Finally, we completely determine osh(([n]a)([n]b))\mathrm{osh}\left(\binom{[n]}{a}\cup\binom{[n]}{b}\right).

Keywords

Cite

@article{arxiv.2603.18708,
  title  = {More Shattering News},
  author = {Attila Sali and Jun Yan},
  journal= {arXiv preprint arXiv:2603.18708},
  year   = {2026}
}
R2 v1 2026-07-01T11:27:47.220Z