English

The square of every subcubic planar graph without 4-cycles and 5-cycles is 7-choosable

Combinatorics 2025-07-02 v1

Abstract

The square of a graph GG, denoted by 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 (2018) and independently, Hartke, Jahanbekam and Thomas (2016) proved 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 (2024) proved that χ(G2)7\chi_{\ell}(G^2) \leq 7 if GG is a subcubic planar graph of girth at least 6. In this paper, we prove that χ(G2)7\chi_{\ell}(G^2) \leq 7 if GG is a subcubic planar graph without 4-cycles and 5-cycles, which improves the result of Kim and Lian.

Keywords

Cite

@article{arxiv.2507.00426,
  title  = {The square of every subcubic planar graph without 4-cycles and 5-cycles is 7-choosable},
  author = {Ligang Jin and Yingli Kang and Seog-Jin Kim},
  journal= {arXiv preprint arXiv:2507.00426},
  year   = {2025}
}

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10 pages