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On stability of rainbow matchings

Published online by Cambridge University Press:  09 December 2025

Hongliang Lu
Affiliation:
School of Mathematics and Statistics, Xi’an Jiaotong University, Xi’an, Shaanxi, China
Yan Wang*
Affiliation:
School of Mathematical Sciences, Shanghai Jiao Tong University, Shanghai, China
Xingxing Yu
Affiliation:
School of Mathematics, Georgia Institute of Technology, Atlanta, GA, USA
*
Corresponding author: Yan Wang; Email: yan.w@sjtu.edu.cn

Abstract

We show that for any integer $k\ge 1$ there exists an integer $t_0(k)$ such that, for integers $t, k_1, \ldots , k_{t+1}, n$ with $t\gt t_0(k)$, $\max \{k_1, \ldots , k_{t+1}\}\le k$, and $n \gt 2k(t+1)$, the following holds: If $F_i$ is a $k_i$-uniform hypergraph with vertex set $[n]$ and more than $ \binom{n}{k_i}-\binom{n-t}{k_i} - \binom{n-t-k}{k_i-1} + 1$ edges for all $i \in [t+1]$, then either $\{F_1,\ldots , F_{t+1}\}$ admits a rainbow matching of size $t+1$ or there exists $W\in \binom{[n]}{t}$ such that $W$ intersects $F_i$ for all $i\in [t+1]$. This may be viewed as a rainbow non-uniform extension of the classical Hilton-Milner theorem. We also show that the same holds for every $t$ and $n \gt 2k^3t$, generalizing a recent stability result of Frankl and Kupavskii on matchings to rainbow matchings.

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Paper
Copyright
© The Author(s), 2025. Published by Cambridge University Press

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Footnotes

*

Partially supported by National Natural Science Foundation of China under grant No. 12271425

Partially supported by National Key R&D Program of China under Grant No. 2022YFA1006400, National Natural Science Foundation of China under grants No. 12571376 and No. 12201400, and Shanghai Municipal Education Commission (No. 2024AIYB003)

Partially supported by NSF grants DMS-1954134 and DMS-2348702

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