English

The square of a subcubic planar graph without a 5-cycle is 7-choosable

Combinatorics 2026-01-01 v1

Abstract

The square of a graph GG, denoted G2G^2, has the same vertex set as GG and has an edge between two vertices if the distance between them in GG is at most 22. Thomassen [12] showed that χ(G2)7\chi(G^2) \leq 7 if GG is a subcubic planar graph. A natural question is whether χ(G2)7\chi_{\ell}(G^2) \leq 7 or not if GG is a subcubic planar graph. Recently Kim and Lian [11] showed that χ(G2)7\chi_{\ell}(G^2) \leq 7 if GG is a subcubic planar graph of girth at least 6. And Jin, Kang, and Kim [10] showed that χ(G2)7\chi_{\ell}(G^2) \leq 7 if GG is a subcubic planar graph without 4-cycles and 5-cycles. In this paper, we show that the square of a subcubic planar graph without 5-cycles is 7-choosable, which improves the results of [10] and [11].

Keywords

Cite

@article{arxiv.2512.24536,
  title  = {The square of a subcubic planar graph without a 5-cycle is 7-choosable},
  author = {Seog-Jin Kim and Xiaopan Lian and Atsuhiro Nakamoto and Kenta Ozeki},
  journal= {arXiv preprint arXiv:2512.24536},
  year   = {2026}
}

Comments

49 pages and 39 figures