English

Oriented coloring of graphs with low maximum degree

Discrete Mathematics 2019-05-30 v1 Combinatorics

Abstract

Duffy et al. [C. Duffy, G. MacGillivray, and \'E. Sopena, Oriented colourings of graphs with maximum degree three and four, Discrete Mathematics, 342(4), p. 959--974, 2019] recently considered the oriented chromatic number of connected oriented graphs with maximum degree 33 and 44, proving it is at most 99 and 6969, respectively. In this paper, we improve these results by showing that the oriented chromatic number of non-necessarily connected oriented graphs with maximum degree 33 (resp. 44) is at most 99 (resp. 2626). The bound of 2626 actually follows from a general result which determines properties of a target graph to be universal for graphs of bounded maximum degree. This generalization also allows us to get the upper bound of 9090 (resp. 306306, 13221322) for the oriented chromatic number of graphs with maximum degree 55 (resp. 66, 77).

Keywords

Cite

@article{arxiv.1905.12484,
  title  = {Oriented coloring of graphs with low maximum degree},
  author = {Pascal Ochem and Alexandre Pinlou},
  journal= {arXiv preprint arXiv:1905.12484},
  year   = {2019}
}
R2 v1 2026-06-23T09:31:44.263Z