{ "id": "2009.00693", "version": "v1", "published": "2020-09-01T20:55:33.000Z", "updated": "2020-09-01T20:55:33.000Z", "title": "Most Generalized Petersen graphs of girth 8 have cop number 4", "authors": [ "Joy Morris", "Tigana Runte", "Adrian Skelton" ], "comment": "19 pages plus 11 pages of data in appendix. 11 figures", "categories": [ "math.CO" ], "abstract": "A generalized Petersen graph $GP(n,k)$ is a regular cubic graph on $2n$ vertices (the parameter $k$ is used to define some of the edges). It was previously shown (Ball et al., 2015) that the cop number of $GP(n,k)$ is at most $4$, for all permissible values of $n$ and $k$. In this paper we prove that the cop number of \"most\" generalized Petersen graphs is exactly $4$. More precisely, we show that unless $n$ and $k$ fall into certain specified categories, then the cop number of $GP(n,k)$ is $4$. The graphs to which our result applies all have girth $8$. In fact, our argument is slightly more general: we show that in any cubic graph of girth at least $8$, unless there exist two cycles of length $8$ whose intersection is a path of length $2$, then the cop number of the graph is at least $4$. Even more generally, in a graph of girth at least $9$ and minimum valency $\\delta$, the cop number is at least $\\delta+1$.", "revisions": [ { "version": "v1", "updated": "2020-09-01T20:55:33.000Z" } ], "analyses": { "subjects": [ "05C57", "91A46" ], "keywords": [ "cop number", "generalized petersen graph", "regular cubic graph", "minimum valency", "result applies" ], "note": { "typesetting": "TeX", "pages": 19, "language": "en", "license": "arXiv", "status": "editable" } } }