{ "id": "1010.4753", "version": "v2", "published": "2010-10-22T16:39:23.000Z", "updated": "2011-04-20T16:29:15.000Z", "title": "Relative outer automorphisms of free groups", "authors": [ "Erika Meucci" ], "comment": "24 pages, 16 figures, corrected typos, revised argument in section 5, results unchanged", "categories": [ "math.GT", "math.GR" ], "abstract": "Let $A_1,...,A_k$ be a system of free factors of $F_n$. The group of relative automorphisms $Aut(F_n;A_1,...,A_k)$ is the group given by the automorphisms of $F_n$ that restricted to each $A_i$ are conjugations by elements in $F_n$. The group of relative outer automorphisms is defined as $Out(F_n;A_1,...,A_k) = Aut(F_n;A_1,...,A_k)/Inn(F_n)$, where $Inn(F_n)$ is the normal subgroup of $Aut(F_n)$ given by all the inner automorphisms. We define a contractible space on which $Out(F_n;A_1,...,A_k)$ acts with finite stabilizers and we compute the virtual cohomological dimension of this group.", "revisions": [ { "version": "v2", "updated": "2011-04-20T16:29:15.000Z" } ], "analyses": { "keywords": [ "relative outer automorphisms", "free groups", "virtual cohomological dimension", "normal subgroup", "inner automorphisms" ], "note": { "typesetting": "TeX", "pages": 24, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2010arXiv1010.4753M" } } }