English

Hypergraph Tur\'an problem of the generalized triangle with bounded matching number

Combinatorics 2025-07-24 v2

Abstract

Let H\mathcal{H} be a 3-graph on nn vertices. The matching number ν(H)\nu(\mathcal{H}) is defined as the maximum number of disjoint edges in H\mathcal{H}. The generalized triangle F5F_5 is a 3-graph on the vertex set {a,b,c,d,e}\{a,b,c,d,e\} with the edge set {abc,abd,cde}\{abc, abd,cde\}. In this paper, we showed that an F5F_5-free 3-graph H\mathcal{H} with matching number at most ss has at most s(ns)2/4s\lfloor (n-s)^2/4\rfloor edges for n30(s+1)n\geq 30(s+1) and s3s\geq 3. For the proof, we establish a 2-colored version of Mantel's theorem, which may be of independent interests.

Keywords

Cite

@article{arxiv.2507.04579,
  title  = {Hypergraph Tur\'an problem of the generalized triangle with bounded matching number},
  author = {Jian Wang and Wenbin Wang and Weihua Yang},
  journal= {arXiv preprint arXiv:2507.04579},
  year   = {2025}
}

Comments

A corollary is added

R2 v1 2026-07-01T03:48:41.427Z