{ "id": "2107.04998", "version": "v1", "published": "2021-07-11T09:00:01.000Z", "updated": "2021-07-11T09:00:01.000Z", "title": "Counterexamples to a conjecture on matching Kneser graphs", "authors": [ "Moharram N. Iradmusa" ], "comment": "1 page", "categories": [ "math.CO" ], "abstract": "Let $G$ be a graph and $r\\in\\mathbb{N}$. The matching Kneser graph $\\textsf{KG}(G, rK_2)$ is a graph whose vertex set is the set of $r$-matchings in $G$ and two vertices are adjacent if their corresponding matchings are edge-disjoint. In [Alishahi, M. and Hajiabolhassan, H., On the Chromatic Number of Matching Kneser Graphs, Combin. Probab. and Comput. 29 (2020), no. 1, 1--21.] it was conjectured that for any connected graph $G$ and positive integer $r\\geq 2$, the chromatic number of $\\textsf{KG}(G, rK_2)$ is equal to $|E(G)|-\\textsf{ex}(G,rK_2)$, where $\\textsf{ex}(G,rK_2)$ denotes the largest number of edges in $G$ avoiding a matching of size $r$. In this note, we show that the conjecture is not true for snarks.", "revisions": [ { "version": "v1", "updated": "2021-07-11T09:00:01.000Z" } ], "analyses": { "subjects": [ "05C15", "05C65" ], "keywords": [ "matching kneser graph", "conjecture", "counterexamples", "chromatic number", "largest number" ], "note": { "typesetting": "TeX", "pages": 1, "language": "en", "license": "arXiv", "status": "editable" } } }