{ "id": "0812.1345", "version": "v4", "published": "2008-12-07T13:38:29.000Z", "updated": "2012-05-06T16:23:30.000Z", "title": "A Unified Approach to Distance-Two Colouring of Graphs on Surfaces", "authors": [ "Omid Amini", "Louis Esperet", "Jan van den Heuvel" ], "comment": "36 pages", "categories": [ "math.CO" ], "abstract": "In this paper we introduce the notion of $\\Sigma$-colouring of a graph $G$: For given subsets $\\Sigma(v)$ of neighbours of $v$, for every $v\\in V(G)$, this is a proper colouring of the vertices of $G$ such that, in addition, vertices that appear together in some $\\Sigma(v)$ receive different colours. This concept generalises the notion of colouring the square of graphs and of cyclic colouring of graphs embedded in a surface. We prove a general result for graphs embeddable in a fixed surface, which implies asymptotic versions of Wegner's and Borodin's Conjecture on the planar version of these two colourings. Using a recent approach of Havet et al., we reduce the problem to edge-colouring of multigraphs, and then use Kahn's result that the list chromatic index is close to the fractional chromatic index. Our results are based on a strong structural lemma for graphs embeddable in a fixed surface, which also implies that the size of a clique in the square of a graph of maximum degree $\\Delta$ embeddable in some fixed surface is at most $\\frac32\\,\\Delta$ plus a constant.", "revisions": [ { "version": "v4", "updated": "2012-05-06T16:23:30.000Z" } ], "analyses": { "subjects": [ "05C15", "05C10" ], "keywords": [ "unified approach", "distance-two colouring", "fixed surface", "implies asymptotic versions", "list chromatic index" ], "note": { "typesetting": "TeX", "pages": 36, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2008arXiv0812.1345A" } } }