Abstract
An odd hole is an induced odd cycle of length at least five. Let \(\ell \ge 2\) be an integer, and let \({\mathcal {G}}_\ell \) denote the family of graphs which have girth \(2\ell + 1\) and have no holes of odd length at least \(2\ell +5\). In this paper, we prove that every graph \(G \in \cup _{\ell \ge 3}{\mathcal {G}}_\ell \) is 4-colourable.
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Acknowledgements
We would like to thank the anonymous referee for his/her careful reading and valuable suggestions. We also would like to thanks Yidong Zhou for inspiring discussions on this subject.
Funding
This research was supported by the NSFC grant 12271170 and Science and Technology Commission of Shanghai Municipality (STCSM) grant 22DZ2229014.
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Lan, K., Liu, F. The Chromatic Number of a Graph with Two Odd Holes and an Odd Girth. Graphs and Combinatorics 39, 125 (2023). https://doi.org/10.1007/s00373-023-02723-y
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DOI: https://doi.org/10.1007/s00373-023-02723-y