English

Erdős-Ko-Rado-type problem for hypergraph matchings

Combinatorics 2026-07-16 v1

Abstract

Given integers 1tk1\leq t\leq k, a family of kk-matchings in a complete rr-partite rr-uniform hypergraph is said to be tt-intersecting if any two of its members share at least tt common edges. This concept unifies several well-studied classes of intersecting families, including classical intersecting families, intersecting families of permutations, partial permutations, and generalized permutations, as well as intersecting families of injections. In this paper we employ two approaches to determine the maximum size of tt-intersecting families of kk-matchings and to characterize the extremal families that attain this bound. Using a recent result of Keller, Lifshitz, Minzer, and Sheinfeld on tt-intersecting families of permutations, we obtain Erd\H{o}s-Ko-Rado-type theorems whose thresholds depend only on tt. We also develop a tt-cover-based approach that offers a complementary characterization of the extremal families.

Cite

@article{arxiv.2607.14872,
  title  = {Erdős-Ko-Rado-type problem for hypergraph matchings},
  author = {Binwei Zhao and Tao Feng and Xiaomiao Wang and Menglong Zhang},
  journal= {arXiv preprint arXiv:2607.14872},
  year   = {2026}
}