Proves that d_{2sk+1} > binom(n-1,k-1) - binom(n-s,k-1) implies matching number at least s in k-uniform hypergraphs (n>2sk), generalizes prior results, shows k+2s-2 is optimal for a relaxed index, and improves the n bound for the Ore-degree condition to 3sk.
On the $\ell$-th largest degree of an intersecting family
2 Pith papers cite this work. Polarity classification is still indexing.
abstract
Let $\mathcal{F}\subset\binom{[n]}{k}$ be an intersecting family. For an element $i\in[n]$, the degree of $i$ is the number of sets in $\mathcal{F}$ that contain $i$. Assume that the degrees are ordered as $d_{1}\ge d_{2}\ge\cdots\ge d_{n}$.Huang and Zhao showed that if $n>2k$, then the minimum degree satisfies $d_{n}\le\binom{n-2}{k-2}$, with the maximum attained by the $1$-star. We strengthen this result by proving that for $n\ge 2k+1$, the $(2k+1)$-th largest degree satisfies $d_{2k+1}\le\binom{n-2}{k-2}$, thereby confirming a conjecture of Frankl and Wang. Furthermore, we prove that for large $k$ and $n>12k$, the $(k+2)$-th largest degree $d_{k+2}$ is already at most $\binom{n-2}{k-2}$. The techniques we developed also yield a tight upper bound for the $(\ell+1)$-th largest degree $d_{\ell+1}$ for $\varepsilon k \le \ell \le k$ and sufficiently large $n>C_{\varepsilon} k$.
fields
math.CO 2years
2026 2verdicts
UNVERDICTED 2representative citing papers
New Ore-degree conditions guarantee matchings and s pairwise disjoint edges in r-uniform hypergraphs under size and intersecting assumptions.
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On degree bounds of $k$-uniform hypergraphs with bounded matching number
Proves that d_{2sk+1} > binom(n-1,k-1) - binom(n-s,k-1) implies matching number at least s in k-uniform hypergraphs (n>2sk), generalizes prior results, shows k+2s-2 is optimal for a relaxed index, and improves the n bound for the Ore-degree condition to 3sk.
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Matchings in hypergraphs via Ore-degree conditions
New Ore-degree conditions guarantee matchings and s pairwise disjoint edges in r-uniform hypergraphs under size and intersecting assumptions.