English

A step towards a general density Corr\'{a}di--Hajnal Theorem

Combinatorics 2023-02-28 v2

Abstract

For a nondegenerate rr-graph FF, large nn, and tt in the regime [0,cFn][0, c_{F} n], where cF>0c_F>0 is a constant depending only on FF, we present a general approach for determining the maximum number of edges in an nn-vertex rr-graph that does not contain t+1t+1 vertex-disjoint copies of FF. In fact, our method results in a rainbow version of the above result and includes a characterization of the extremal constructions. Our approach applies to many well-studied hypergraphs (including graphs) such as the edge-critical graphs, the Fano plane, the generalized triangles, hypergraph expansions, the expanded triangles, and hypergraph books. Our results extend old results of Simonovits~\cite{SI68} and Moon~\cite{Moon68} on complete graphs and can be viewed as a step towards a general density version of the classical Corr\'{a}di--Hajnal Theorem~\cite{CH63}.

Keywords

Cite

@article{arxiv.2302.09849,
  title  = {A step towards a general density Corr\'{a}di--Hajnal Theorem},
  author = {Jianfeng Hou and Heng Li and Xizhi Liu and Long-Tu Yuan and Yixiao Zhang},
  journal= {arXiv preprint arXiv:2302.09849},
  year   = {2023}
}

Comments

corrected some typo and added a theorem (THM 2.7) about expanded Erdos-Sos trees

R2 v1 2026-06-28T08:44:17.192Z