English

Tiling directed graphs with tournaments

Combinatorics 2016-03-29 v1

Abstract

The Hajnal--Szemer\'edi theorem states that for any integer r1r \ge 1 and any multiple nn of rr, if GG is a graph on nn vertices and δ(G)(11/r)n\delta(G) \ge (1 - 1/r)n, then GG can be partitioned into n/rn/r vertex-disjoint copies of the complete graph on rr vertices. We prove a very general analogue of this result for directed graphs: for any integer r4r \ge 4 and any sufficiently large multiple nn of rr, if GG is a directed graph on nn vertices and every vertex is incident to at least 2(11/r)n12(1 - 1/r)n - 1 directed edges, then GG can be partitioned into n/rn/r vertex-disjoint subgraphs of size rr each of which contain every tournament on rr vertices. A related Tur\'an-type result is also proven.

Keywords

Cite

@article{arxiv.1603.08198,
  title  = {Tiling directed graphs with tournaments},
  author = {Andrzej Czygrinow and Louis DeBiasio and Theodore Molla and Andrew Treglown},
  journal= {arXiv preprint arXiv:1603.08198},
  year   = {2016}
}

Comments

39 pages, 2 figures

R2 v1 2026-06-22T13:19:18.046Z