English

Set System Blowups

Combinatorics 2025-06-03 v4

Abstract

We prove that given a constant k2k \ge 2 and a large set system F\mathcal{F} of sets of size at most ww, a typical kk-tuple of sets (S1,,Sk)(S_1, \cdots, S_k) from F\mathcal{F} can be ``blown up" in the following sense: for each 1ik1 \le i \le k, we can find a large subfamily Fi\mathcal{F}_i containing SiS_i so that for iji \neq j, if TiFiT_i \in \mathcal{F}_i and TjFjT_j \in \mathcal{F}_j , then TiTj=SiSjT_i \cap T_j=S_i \cap S_j. We also show that the answer to the multicolor version of the sunflower conjecture is the same as the answer for the original, up to an exponential factor.

Keywords

Cite

@article{arxiv.2003.11202,
  title  = {Set System Blowups},
  author = {Ryan Alweiss},
  journal= {arXiv preprint arXiv:2003.11202},
  year   = {2025}
}

Comments

many edits made, to appear in Combinatorica

R2 v1 2026-06-23T14:26:21.901Z