{ "id": "2408.09081", "version": "v1", "published": "2024-08-17T03:19:48.000Z", "updated": "2024-08-17T03:19:48.000Z", "title": "B-colorings of planar and outerplanar graphs", "authors": [ "Ryan R. Martin", "Miklós Ruszinkó", "Gábor N. Sárközy" ], "comment": "15 pages, 4 figures", "categories": [ "math.CO" ], "abstract": "A coloring of the edges of a graph $G$ in which every $K_{1,2}$ is totally multicolored is known as a proper coloring and a coloring of the edges of $G$ in which every $K_{1,2}$ and every $K_{2,2}$ is totally multicolored is called a B-coloring. In this paper, we establish that a planar graph with maximum degree $\\Delta$ can be B-colored with $\\max\\{2\\Delta,32\\}$ colors. This is best-possible for large $\\Delta$ because $K_{2,\\Delta}$ requires $2\\Delta$ colors. In addition, there is an example with $\\Delta=4$ that requires $12$ colors. We also establish that an outerplanar graph with maximum degree $\\Delta$ can be B-colored with $\\max\\{\\Delta,6\\}$ colors. This is almost best-possible because $\\Delta$ colors are necessary and there is an example with $\\Delta=4$ that requires $5$ colors.", "revisions": [ { "version": "v1", "updated": "2024-08-17T03:19:48.000Z" } ], "analyses": { "subjects": [ "05C15", "05C10", "05C35" ], "keywords": [ "outerplanar graph", "maximum degree", "b-coloring" ], "note": { "typesetting": "TeX", "pages": 15, "language": "en", "license": "arXiv", "status": "editable" } } }