PreprintCC BY 4.0arXiv
Towards a more structured search for Erdős-Gyárfás counter-examples
Abstract
The Erdős-Gyárfás conjecture posits that every graph with minimum degree at least three contains a cycle of length some power of two. We prove a few simple structural properties for any minimal counter-example to this conjecture. In particular, the fraction of its vertices of degree three must be greater than 2/3, thus improving on the prior bound of 4/7 (Carr, 2026). Furthermore, it is either biconnected or the $1$-clique-sum of two biconnected graphs. By exploiting some of these properties, we were able to verify the conjecture for every graph of order at most $40$, every bipartite graph of order at most $66$, and every cubic graph of order at most $48$.
Related
BibTeX
@misc{ducoffe2026towards,
title = {{Towards a more structured search for Erdős-Gyárfás counter-examples}},
author = {Guillaume Ducoffe and Bogdan Dumitru},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.28594},
eprint = {2609.28594},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.28594},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Towards a more structured search for Erdős-Gyárfás counter-examples
AU - Guillaume Ducoffe
AU - Bogdan Dumitru
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.28594
UR - https://arxiv.org/abs/2609.28594
AB - The Erdős-Gyárfás conjecture posits that every graph with minimum degree at least three contains a cycle of length some power of two. We prove a few simple structural properties for any minimal counter-example to this conjecture. In particular, the fraction of its vertices of degree three must be greater than 2/3, thus improving on the prior bound of 4/7 (Carr, 2026). Furthermore, it is either biconnected or the $1$-clique-sum of two biconnected graphs. By exploiting some of these properties, we were able to verify the conjecture for every graph of order at most $40$, every bipartite graph of order at most $66$, and every cubic graph of order at most $48$.
ER -