English

On a problem concerning integer distance graphs

Combinatorics 2024-01-24 v1

Abstract

For DD being a subset of positive integers, the integer distance graph is the graph G(D)G(D), whose vertex set is the set of integers, and edge set is the set of all pairs uvuv with uvD|u-v| \in D. It is known that χ(G(D))D+1\chi(G(D)) \leq |D|+1. This article studies the problem (which is motivated by a conjecture of Zhu): "Is it true that χ(G(D))=D+1\chi(G(D)) = |D|+1 implies ω(G(D))D+1\omega(G(D)) \geq |D|+1, where ω(H)\omega(H) is the clique number of HH?". We give a negative answer to this question, by showing an infinite class of integer distance graphs with χ(G(D))=D+1\chi(G(D))=|D|+1 but ω(G(D))=D1\omega(G(D))=|D|-1.

Keywords

Cite

@article{arxiv.2401.12347,
  title  = {On a problem concerning integer distance graphs},
  author = {Janka Oravcová and Roman Soták},
  journal= {arXiv preprint arXiv:2401.12347},
  year   = {2024}
}
R2 v1 2026-06-28T14:24:06.107Z