Odd clique minors in graphs with independence number two
Abstract
A -expansion consists of vertex-disjoint trees, every two of which are joined by an edge. We call such an expansion odd if its vertices can be two-colored so that the edges of the trees are bichromatic but the edges between trees are monochromatic. A graph contains an odd minor or an odd clique minor of order if it contains an odd -expansion. Gerards and Seymour from 1995 conjectured that every graph contains an odd minor, where denotes the chromatic number of . This conjecture is referred to as ``Odd Hadwiger's Conjecture". Let denote the independence number of a graph . In this paper we investigate the Odd Hadwiger's Conjecture for graphs with . We first observe that a graph on vertices with contains an odd minor if and only if contains an odd clique minor of order . We then prove that every graph on vertices with contains an odd clique minor of order if contains a clique of order when is even and when is odd, or does not contain as an induced subgraph, where and is an induced subgraph of , , , , , or the kite graph.
Keywords
Cite
@article{arxiv.2505.07727,
title = {Odd clique minors in graphs with independence number two},
author = {Yuqing Ji and Zi-Xia Song and Evan Weiss and Xia Zhang},
journal= {arXiv preprint arXiv:2505.07727},
year = {2025}
}