{ "id": "2408.04942", "version": "v1", "published": "2024-08-09T08:48:29.000Z", "updated": "2024-08-09T08:48:29.000Z", "title": "On local antimagic chromatic numbers of the join of two special families of graphs", "authors": [ "Gee-Choon Lau", "Wai Chee Shiu" ], "comment": "15 pages, 8 figures", "categories": [ "math.CO" ], "abstract": "It is known that null graphs and 1-regular graphs are the only regular graphs without local antimagic chromatic number. In this paper, we use matrices of size $(2m+1) \\times (2k+1)$ to completely determine the local antimagic chromatic number of the join of null graphs, $O_m, m\\ge 1,$ and 1-regular graphs of odd components, $(2k+1)P_2$, $k\\ge 1$. Consequently, we obtained infinitely many (possibly disconnected or regular) tripartite graphs with local antimagic chromatic number 3.", "revisions": [ { "version": "v1", "updated": "2024-08-09T08:48:29.000Z" } ], "analyses": { "subjects": [ "05C78", "05C69" ], "keywords": [ "local antimagic chromatic number", "special families", "null graphs", "regular graphs", "tripartite graphs" ], "note": { "typesetting": "TeX", "pages": 15, "language": "en", "license": "arXiv", "status": "editable" } } }