English

Verifying Hadwiger's Conjecture for Examples of Graphs with $\alpha(G) = 2$

Combinatorics 2025-12-23 v2

Abstract

Hadwiger's Conjecture states that every graph with chromatic number kk contains a complete graph on kk vertices as a minor. This conjecture is a tremendous strengthening of the Four-Colour Theorem and is regarded as one of the most important open problems in graph theory. The case of Hadwiger's Conjecture for graphs with α(G)=2\alpha(G) = 2 has garnered much attention. Seymour writes: ``My own belief is, if Hadwiger's Conjecture is true for graphs with stability number two then it is probably true in general, so it would be very nice to decide this case.'' This paper presents several tools useful for proving that a graph GG with α(G)=2\alpha(G) = 2 satisfies Hadwiger's Conjecture. In doing so, we survey and generalise several classical results on the α(G)=2\alpha(G) = 2 case of Hadwiger's Conjecture. Further, we apply these tools to prove variants of Hadwiger's Conjecture for several noteworthy classes of graphs with α(G)=2\alpha(G) = 2. In particular, we prove Hadwiger's Conjecture for inflations of the complements of the following graphs: graphs with girth at least 55, triangle-free Kneser graphs, and the Clebsch, Mesner, and Gewirtz graphs. This paper also highlights classes of graphs with α(G)=2\alpha(G) = 2 where it is unknown if Hadwiger's Conjecture holds.

Keywords

Cite

@article{arxiv.2512.17114,
  title  = {Verifying Hadwiger's Conjecture for Examples of Graphs with $\alpha(G) = 2$},
  author = {Jofre Costa and Eric Luu and David R. Wood and Jung Hon Yip},
  journal= {arXiv preprint arXiv:2512.17114},
  year   = {2025}
}

Comments

v1. Comments welcome!