{ "id": "1801.05320", "version": "v1", "published": "2018-01-16T15:45:43.000Z", "updated": "2018-01-16T15:45:43.000Z", "title": "Presentations of parabolics in some elementary Chevalley-Demazure groups", "authors": [ "Yuri Santos Rego" ], "comment": "45 pages", "categories": [ "math.GR" ], "abstract": "Given a universal elementary Chevalley-Demazure group $E_\\Phi^{sc}(R)$ for which its (standard) parabolic subgroups are finitely generated, we consider the problem of classifying which parabolics $P(R) \\subset E_\\Phi^{sc}(R)$ are finitely presented. We show that, under mild assumptions, this is equivalent to the finite presentability of a suitable retract of $P$ which contains the Levi factor. If the base ring $R$ is a Dedekind domain of arithmetic type, we combine our results with well-known theorems due to Borel-Serre, Abels, Behr and Bux to give a partial classification of finitely presentable $S$-arithmetic subgroups of parabolics in split reductive linear algebraic groups.", "revisions": [ { "version": "v1", "updated": "2018-01-16T15:45:43.000Z" } ], "analyses": { "subjects": [ "20F05", "20H25", "20G30" ], "keywords": [ "presentations", "split reductive linear algebraic groups", "universal elementary chevalley-demazure group", "partial classification", "dedekind domain" ], "note": { "typesetting": "TeX", "pages": 45, "language": "en", "license": "arXiv", "status": "editable" } } }