{ "id": "1811.08334", "version": "v2", "published": "2018-11-20T16:03:01.000Z", "updated": "2020-06-17T13:58:23.000Z", "title": "An asymptotic resolution of a problem of Plesník", "authors": [ "Stijn Cambie" ], "comment": "16 pages, 5 figures revised version as accepted at JCTB", "categories": [ "math.CO" ], "abstract": "Fix $d \\ge 3$. We show the existence of a constant $c>0$ such that any graph of diameter at most $d$ has average distance at most $d-c \\frac{d^{3/2}}{\\sqrt n}$, where $n$ is the number of vertices. Moreover, we exhibit graphs certifying sharpness of this bound up to the choice of $c$. This constitutes an asymptotic solution to a longstanding open problem of Plesn\\'{i}k. Furthermore we solve the problem exactly for digraphs if the order is large compared with the diameter.", "revisions": [ { "version": "v2", "updated": "2020-06-17T13:58:23.000Z" } ], "analyses": { "subjects": [ "05C12", "05C20", "05C35" ], "keywords": [ "asymptotic resolution", "longstanding open problem", "asymptotic solution", "graphs certifying sharpness", "average distance" ], "note": { "typesetting": "TeX", "pages": 16, "language": "en", "license": "arXiv", "status": "editable" } } }