{ "id": "2311.01672", "version": "v1", "published": "2023-11-03T02:37:38.000Z", "updated": "2023-11-03T02:37:38.000Z", "title": "Counterexamples to Negami's Conjecture have ply at least 14", "authors": [ "Dickson Y. B. Annor", "Yuri Nikolayevsky", "Michael S. Payne" ], "categories": [ "math.CO" ], "abstract": "S. Negami conjectured in $1988$ that a connected graph has a finite planar cover if and only if it embeds in the projective plane. It follows from the works of D. Archdeacon, M. Fellows, P. Hlin\\v{e}n\\'{y}, and S. Negami that the conjecture is true if the graph $K_{2, 2, 2, 1}$ has no finite planar cover. We prove that $K_{2, 2, 2, 1}$ has no planar cover of ply less than $14$ and consequently, any counterexample to Negami's conjecture has ply at least 14 and at least $98$ vertices.", "revisions": [ { "version": "v1", "updated": "2023-11-03T02:37:38.000Z" } ], "analyses": { "subjects": [ "05C10", "57M15" ], "keywords": [ "negamis conjecture", "finite planar cover", "counterexample", "projective plane" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }