Chords of longest cycles in graphs with large circumferences
Abstract
A long-standing conjecture of Thomassen says that every longest cycle of a -connected graph has a chord. Thomassen (2018) proved that if is a -connected cubic graph, then any longest cycle must have a chord. He also showed that in any 3-connected graph with minimum degree at least four, some longest cycle must contain a chord. Harvey proved that every longest cycle has a chord for graphs with a large minimum degree. He also conjectured that any longest cycle in a 2-connected graph with minimum degree at least three has a chord. In this paper, we prove that both Thomassen's and Harvey's conjectures are true for graphs with large circumferences. We also prove a more general result for the existence of chords in longest cycles containing a linear forest.
Cite
@article{arxiv.2511.03422,
title = {Chords of longest cycles in graphs with large circumferences},
author = {Haidong Wu and Shunzhe Zhang},
journal= {arXiv preprint arXiv:2511.03422},
year = {2025}
}