English

Transversal Hamilton cycles in digraph collections

Combinatorics 2026-04-14 v2

Abstract

Given a collection D={D1,D2,,Dm}\mathcal{D} =\{D_1,D_2,\ldots,D_m\} of digraphs on the common vertex set VV, an mm-edge digraph HH with vertices in VV is \textit{transversal} in D\mathcal{D} if there exists a bijection φ:E(H)[m]\varphi :E(H)\rightarrow [m] such that eE(Dφ(e))e \in E(D_{\varphi(e)}) for all eE(H)e\in E(H). Ghouila-Houri proved that any nn-vertex digraph with minimum semi-degree at least n2\frac{n}{2} contains a directed Hamilton cycle. In this paper, we provide a transversal generalization of Ghouila-Houri's theorem, thereby solving a problem proposed by Chakraborti, Kim, Lee and Seo. Our proof utilizes the absorption method for transversals, the regularity method for digraph collections, as well as the transversal blow-up lemma and the related machinery. As an application, when nn is sufficiently large, our result implies the transversal version of Dirac's theorem, which was proved by Joos and Kim.

Keywords

Cite

@article{arxiv.2501.00998,
  title  = {Transversal Hamilton cycles in digraph collections},
  author = {Yangyang Cheng and Heng Li and Wanting Sun and Guanghui Wang},
  journal= {arXiv preprint arXiv:2501.00998},
  year   = {2026}
}

Comments

Accepted by Combinatorics, Probability and Computing

R2 v1 2026-06-28T20:54:12.846Z