{ "id": "1602.03098", "version": "v1", "published": "2016-02-09T18:01:16.000Z", "updated": "2016-02-09T18:01:16.000Z", "title": "On the Minimum Number of Edges in Triangle-Free 5-Critical Graphs", "authors": [ "Luke Postle" ], "comment": "22 pages", "categories": [ "math.CO" ], "abstract": "Kostochka and Yancey proved that every 5-critical graph G satisfies: |E(G)|>= (9/4)|V(G)| - 5/4. A construction of Ore gives an infinite family of graphs meeting this bound. We prove that there exists e,d > 0 such that if G is a 5-critical graph, then |E(G)| >= (9/4 + e)|V(G)|- 5/4 - dT(G), where T(G) is the maximum number of vertex-disjoint cliques of size three or four where cliques of size four have twice the weight of a clique of size three. As a corollary, a triangle-free 5-critical graph G satisfies: |E(G)|>=(9/4 + e)|V(G)| - 5/4.", "revisions": [ { "version": "v1", "updated": "2016-02-09T18:01:16.000Z" } ], "analyses": { "subjects": [ "05C15" ], "keywords": [ "minimum number", "triangle-free", "maximum number", "vertex-disjoint cliques", "construction" ], "note": { "typesetting": "TeX", "pages": 22, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2016arXiv160203098P" } } }