{ "id": "2309.10866", "version": "v1", "published": "2023-09-19T18:26:35.000Z", "updated": "2023-09-19T18:26:35.000Z", "title": "Determination of hyperovals by lines through a few points", "authors": [ "Zhiguo Ding", "Michael E. Zieve" ], "comment": "20 pages", "categories": [ "math.CO" ], "abstract": "If S is a set of q+2 points in P^2(F_q) such that some point of S is not on any line containing two other points of S, then in suitable coordinates S has the form S_f:={(c:f(c):1) : c in F_q} U {(1:0:0),(0:1:0)} for some f(X) in F_q[X]. Let T be a subset of S_f which contains the two infinite points and at least 3+log_3(q)/4 finite points. We show that if there is no line passing through a point of T and two other points of S_f, and deg(f)<=q^{1/4}, then no three points of S_f are collinear, so that S_f is a hyperoval. We also determine all f(X) with deg(f)<=q^{1/4} for which S_f is a hyperoval, which strengthens a result that was proved by Caullery and Schmidt using entirely different methods.", "revisions": [ { "version": "v1", "updated": "2023-09-19T18:26:35.000Z" } ], "analyses": { "subjects": [ "05B25", "11T06", "51E20" ], "keywords": [ "determination", "infinite points", "suitable coordinates", "strengthens" ], "note": { "typesetting": "TeX", "pages": 20, "language": "en", "license": "arXiv", "status": "editable" } } }