English

Strict Erd\H{o}s-Ko-Rado theorems for simplicial complexes

Combinatorics 2025-07-02 v2

Abstract

We show that if a simplicial complex is a near-cone of sufficiently high depth, then the only maximum families of small pairwise intersecting faces are those with a common intersection. Thus, near-cones of sufficiently high depth satisfy the strict Erd\H{o}s-Ko-Rado property conjectured by Holroyd and Talbot and by Borg. One consequence is a strict Erd\H{o}s-Ko-Rado theorem for independence complexes of chordal graphs with an isolated vertex. Under stronger shiftedness conditions, we prove a sharper stability theorem of Hilton-Milner type, as well as two cross-intersecting theorems.

Keywords

Cite

@article{arxiv.2503.15608,
  title  = {Strict Erd\H{o}s-Ko-Rado theorems for simplicial complexes},
  author = {Denys Bulavka and Russ Woodroofe},
  journal= {arXiv preprint arXiv:2503.15608},
  year   = {2025}
}

Comments

18 pages. v2 has a minor correction

R2 v1 2026-06-28T22:27:26.679Z