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arXiv · 2609.28594

Towards a more structured search for Erdős-Gyárfás counter-examples

Guillaume Ducoffe·Bogdan Dumitru
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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 $48$.

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Guillaume Ducoffe, Bogdan Dumitru. 2026-09-23. Towards a more structured search for Erdős-Gyárfás counter-examples. https://arxiv.org/abs/2609.28594

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