English

Every signed planar graph without cycles of length from 4 to 7 is 3-colorable

Combinatorics 2022-05-04 v2

Abstract

Hu and Li investigate the signed graph version of Erdo¨\ddot{\mathrm{o}}s problem: Is there a constant cc such that every signed planar graph without kk-cycles, where 4kc4\leq k\leq c, is 33-colorable and prove that each signed planar graph without cycles of length from 4 to 8 is 3-colorable. We give a very short and simple proof of this result and improve it, based on a recent observation.

Keywords

Cite

@article{arxiv.2205.00887,
  title  = {Every signed planar graph without cycles of length from 4 to 7 is 3-colorable},
  author = {Lan Kaiyang and Liu Feng},
  journal= {arXiv preprint arXiv:2205.00887},
  year   = {2022}
}

Comments

incomplete proof