English

Cycle tilings and $H$-factors in directed graphs

Combinatorics 2026-02-17 v1

Abstract

We prove several results concerning cycle tilings and HH-factors in digraphs. We provide a minimum semi-degree condition for forcing a digraph to contain a given spanning collection of vertex-disjoint orientations of cycles. Our result is asymptotically best possible for odd cycles and can be viewed as a digraph analogue of the El-Zahar conjecture. In addition, we asymptotically determine the minimum degree threshold for forcing an HH-factor in a digraph for a range of digraphs HH, including the cases when HH is a tree or anti-directed cycle. Furthermore, an asymptotically exact Ore-type result for forcing a transitive tournament factor in a digraph is proven. Several related open problems are also highlighted.

Keywords

Cite

@article{arxiv.2602.13737,
  title  = {Cycle tilings and $H$-factors in directed graphs},
  author = {Theodore Molla and Andrew Treglown},
  journal= {arXiv preprint arXiv:2602.13737},
  year   = {2026}
}

Comments

22 pages

R2 v1 2026-07-01T10:36:47.868Z