{ "id": "1708.02264", "version": "v1", "published": "2017-08-07T18:50:27.000Z", "updated": "2017-08-07T18:50:27.000Z", "title": "On the clique number of the square of a line graph and its relation to Ore-degree", "authors": [ "Maxime Faron", "Luke Postle" ], "comment": "11 pages", "categories": [ "math.CO" ], "abstract": "In 1985, Erd\\H{o}s and Ne\\v{s}et\\v{r}il conjectured that the square of the line graph of a graph $G$, that is $L(G)^2$, can be colored with $\\frac{5}{4}\\Delta(G)^2$ colors. This conjecture implies the weaker conjecture that the clique number of such a graph, that is $\\omega(L(G)^2)$, is at most $\\frac{5}{4}\\Delta(G)^2$. In 2015, \\'Sleszy\\'nska-Nowak proved that $\\omega(L(G)^2)\\le \\frac{3}{2}\\Delta(G)^2$. In this paper, we prove that $\\omega(L(G)^2)\\le \\frac{4}{3}\\Delta(G)^2$. This theorem follows from our stronger result that $\\omega(L(G)^2)\\le \\frac{\\sigma(G)^2}{3}$ where $\\sigma(G) := \\max_{uv\\in E(G)} d(u) + d(v)$, is the Ore-degree of the graph $G$.", "revisions": [ { "version": "v1", "updated": "2017-08-07T18:50:27.000Z" } ], "analyses": { "keywords": [ "line graph", "clique number", "ore-degree", "stronger result", "conjecture implies" ], "note": { "typesetting": "TeX", "pages": 11, "language": "en", "license": "arXiv", "status": "editable" } } }