{ "id": "0809.2408", "version": "v4", "published": "2008-09-14T17:30:35.000Z", "updated": "2010-06-16T11:29:19.000Z", "title": "Normal automorphisms of relatively hyperbolic groups", "authors": [ "A. Minasyan", "D. Osin" ], "comment": "Version 4: final (27 pages, 2 figures)", "journal": "Trans. Amer. Math. Soc. 362 (2010), no. 11, 6079-6103", "categories": [ "math.GR", "math.GT" ], "abstract": "An automorphism $\\alpha$ of a group $G$ is normal if it fixes every normal subgroup of $G$ setwise. We give an algebraic description of normal automorphisms of relatively hyperbolic groups. In particular, we prove that for any relatively hyperbolic group $G$, $Inn(G)$ has finite index in the subgroup $Aut_n(G)$ of normal automorphisms. If, in addition, $G$ is non-elementary and has no non-trivial finite normal subgroups, then $Aut_n(G)=Inn(G)$. As an application, we show that $Out(G)$ is residually finite for every finitely generated residually finite group $G$ with more than one end.", "revisions": [ { "version": "v4", "updated": "2010-06-16T11:29:19.000Z" } ], "analyses": { "subjects": [ "20F65", "20F67", "20E26" ], "keywords": [ "relatively hyperbolic group", "normal automorphisms", "non-trivial finite normal subgroups", "finitely generated residually finite group", "algebraic description" ], "tags": [ "journal article" ], "publication": { "publisher": "AMS", "journal": "Trans. Amer. Math. Soc." }, "note": { "typesetting": "TeX", "pages": 27, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2008arXiv0809.2408M" } } }