English

The generalizations of Erd\H{o}s matching conjecture for $t$-matching number

Combinatorics 2025-08-19 v1

Abstract

Define a \textit{tt-matching} of size mm in a kk-uniform family as a collection {A1,A2,,Am}([n]k)\{A_1, A_2, \ldots, A_m\} \subseteq \binom{[n]}{k} such that AiAj<t|A_i \cap A_j| < t for all 1i<jm1 \leq i < j \leq m. Let F([n]k)\mathcal{F}\subseteq \binom{[n]}{k}. The \textit{tt-matching number} of F\mathcal{F}, denoted by νt(F)\nu_t(\mathcal{F}), is the maximum size of a tt-matching contained in F\mathcal{F}. We study the maximum cardinality of a family F([n]k)\mathcal{F}\subseteq\binom{[n]}{k} with given tt-matching number, which is a generalization of Erd\H{o}s matching conjecture, and we additionally prove a stability result. We also determine the second largest maximal structure with νt(F)=s\nu_t(\mathcal{F})=s, extending work of Frankl and Kupavskii \cite{frankl2016two}. Finally, we obtain the extremal GG-free induced subgraphs of generalized Kneser graph, generalizing Alishahi's results in \cite{alishahi2018extremal}.

Keywords

Cite

@article{arxiv.2508.12679,
  title  = {The generalizations of Erd\H{o}s matching conjecture for $t$-matching number},
  author = {Haixiang Zhang and Mengyu Cao and Mei Lu},
  journal= {arXiv preprint arXiv:2508.12679},
  year   = {2025}
}