English

A note on cycles in cyclically $4$-edge-connected cubic planar graphs

Combinatorics 2026-05-12 v2

Abstract

Let HH be obtained from a cyclically 44-edge-connected cubic planar graph YY other than K4K_4 by deleting two adjacent vertices. We provide a short proof that if HH has circumference at least kk for some even integer k4k \ge 4, then HH contains a cycle of length between kk and 3k/23k/2. As a consequence, we show that the line graph GG of YY contains a cycle of length ll avoiding any prescribed vertex of GG, for every l{3}{5,,V(G)1}l \in \{3\} \cup \{5, \dots, |V(G)| - 1\}. The proofs integrate Euler's formula and the Three Edge Lemma, established by Thomas and Yu, and independently by Sanders, in a novel way. This work was partially motivated by conjectures of Bondy and Malkevitch.

Keywords

Cite

@article{arxiv.2605.03786,
  title  = {A note on cycles in cyclically $4$-edge-connected cubic planar graphs},
  author = {On-Hei Solomon Lo},
  journal= {arXiv preprint arXiv:2605.03786},
  year   = {2026}
}
R2 v1 2026-07-01T12:50:52.623Z