{ "id": "1707.08996", "version": "v1", "published": "2017-07-27T18:43:49.000Z", "updated": "2017-07-27T18:43:49.000Z", "title": "One-point covers of elliptic curves and good reduction", "authors": [ "James Phillips" ], "comment": "11 pages", "categories": [ "math.AG", "math.NT" ], "abstract": "Raynaud gave a criterion for a branched $G$-cover of curves defined over a mixed-characteristic discretely valued field $K$ with residue characteristic $p$ to have good reduction in the case of either a three-point cover of $\\mathbb{P}^1$ or a one-point cover of an elliptic curve. Specifically, such a cover has potentially good reduction whenever $G$ has a Sylow $p$-subgroup of order $p$ and the absolute ramification index of $K$ is less than the number of conjugacy classes of order $p$ in $G$. In the case of an elliptic curve, we generalize this to the case in which $G$ has an arbitrarily large cyclic Sylow $p$-subgroup.", "revisions": [ { "version": "v1", "updated": "2017-07-27T18:43:49.000Z" } ], "analyses": { "keywords": [ "elliptic curve", "one-point cover", "absolute ramification index", "arbitrarily large cyclic sylow", "three-point cover" ], "note": { "typesetting": "TeX", "pages": 11, "language": "en", "license": "arXiv", "status": "editable" } } }