English

On degree bounds of $k$-uniform hypergraphs with bounded matching number

Combinatorics 2026-05-28 v2

Abstract

We study the connection between the degree sequence of a kk-uniform hypergraph and the size of its largest matching. Let F\mathcal{F} be a kk-uniform hypergraph on nn vertices and let d1d2dnd_1 \ge d_2 \ge \dots \ge d_n be the vertex degrees arranged in non-increasing order. For integers k2k\ge 2, s2s\ge 2 and n>2skn > 2sk, we prove that if the (2sk+1)(2sk+1)-th largest degree satisfies d2sk+1>(n1k1)(nsk1),d_{2sk+1} > \binom{n-1}{k-1} - \binom{n-s}{k-1}, then F\mathcal{F} contains a matching of size at least ss. This can be viewed as a generalization of theorems by Lu, Guo, and Jiang (2023) and Huang and Rao (2026). Moreover, by relaxing the range of nn, we obtain the same bound for the (k+2s2)(k+2s-2)-th largest degree vertex. Note that the number k+2s2k+2s-2 is optimal. For a kk-set of vertices S[n]S \subseteq [n], the degree of SS is defined as deg(S)=vSdeg(v)\mathrm{deg}(S) = \sum_{v \in S} \mathrm{deg}(v), and the minimum of deg(S)\mathrm{deg}(S) over all non-edge kk-subsets SE(F)S \notin E(\mathcal{F}) of V(F)V(\mathcal{F}) is the Ore-degree of F\mathcal{F}, denoted by σk(F)\sigma_k(\mathcal{F}). Balogh, Palmer and Raeisi proved: for s2s \ge 2 and n3k2(s1)n \ge 3k^2(s-1), if σk(F)>k((n1k1)(nsk1)),\sigma_k(\mathcal{F}) > k\left(\binom{n-1}{k-1} - \binom{n-s}{k-1}\right), then F\mathcal{F} contains a matching of size ss. They also conjectured that the result holds when n>skn > sk. As a corollary, we prove that the bound on nn can be taken to be linear in sksk (n3sk n \geq 3sk ).

Keywords

Cite

@article{arxiv.2605.21208,
  title  = {On degree bounds of $k$-uniform hypergraphs with bounded matching number},
  author = {Haixiang Zhang and Mengyu Cao and Mei Lu},
  journal= {arXiv preprint arXiv:2605.21208},
  year   = {2026}
}