Cubic edge-transitive graphs of order ℓ p2
Abstract
A graph is edge-transitive if its automorphism group acts transitively on its edge set. This paper is devoted to a systematic study of cubic edge-transitive graphs of order ℓ p2, where p is a prime and ℓ is an even integer. We first show that either Γ is the unique cubic edge-transitive graph of order $18$, or its full automorphism group Aut(Γ) contains a normal Sylow p-subgroup P which is isomorphic to either Zp2 or Zp2. For the case P≅ Zp2, we prove that Γ is either arc-regular or edge-regular, and provide a complete classification of such graphs. For the case P≅ Zp2, we prove that Γ is a normal cover of certain known graphs. This work generalizes previous classifications by Zhou and Feng (2024), Lu et al.~(2004), and others. As an application, we obtain a classification of cubic edge-transitive graphs of order ℓ p2 in the case where ℓ is square-free.
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BibTeX
@misc{wang2026cubic,
title = {{Cubic edge-transitive graphs of order $\ell p^2$}},
author = {Xue Wang and Jun-Jie Huang and Da-Wei Yang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.32351},
eprint = {2610.32351},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.32351},
}
RIS
TY - UNPB
TI - Cubic edge-transitive graphs of order ℓ p^2
AU - Xue Wang
AU - Jun-Jie Huang
AU - Da-Wei Yang
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.32351
UR - https://arxiv.org/abs/2610.32351
AB - A graph is edge-transitive if its automorphism group acts transitively on its edge set. This paper is devoted to a systematic study of cubic edge-transitive graphs of order ℓ p^2, where p is a prime and ℓ is an even integer. We first show that either Γ is the unique cubic edge-transitive graph of order $18$, or its full automorphism group Aut(Γ) contains a normal Sylow p-subgroup P which is isomorphic to either Z_p^2 or Z_p^2. For the case P≅ Z_p^2, we prove that Γ is either arc-regular or edge-regular, and provide a complete classification of such graphs. For the case P≅ Z_p^2, we prove that Γ is a normal cover of certain known graphs. This work generalizes previous classifications by Zhou and Feng (2024), Lu et al.~(2004), and others. As an application, we obtain a classification of cubic edge-transitive graphs of order ℓ p^2 in the case where ℓ is square-free.
ER -