{ "id": "math/0603177", "version": "v1", "published": "2006-03-08T06:38:47.000Z", "updated": "2006-03-08T06:38:47.000Z", "title": "Dimension of the Torelli group for Out(F_n)", "authors": [ "Mladen Bestvina", "Kai-Uwe Bux", "Dan Margalit" ], "comment": "27 pages, 9 figures", "doi": "10.1007/s00222-007-0055-0", "categories": [ "math.GT", "math.GR" ], "abstract": "Let T_n be the kernel of the natural map from Out(F_n) to GL(n,Z). We use combinatorial Morse theory to prove that T_n has an Eilenberg-MacLane space which is (2n-4)-dimensional and that H_{2n-4}(T_n,Z) is not finitely generated (n at least 3). In particular, this recovers the result of Krstic-McCool that T_3 is not finitely presented. We also give a new proof of the fact, due to Magnus, that T_n is finitely generated.", "revisions": [ { "version": "v1", "updated": "2006-03-08T06:38:47.000Z" } ], "analyses": { "subjects": [ "20F36", "20F28" ], "keywords": [ "torelli group", "combinatorial morse theory", "natural map", "eilenberg-maclane space" ], "tags": [ "journal article" ], "publication": { "journal": "Inventiones Mathematicae", "year": 2007, "month": "May", "volume": 170, "number": 1, "pages": 1 }, "note": { "typesetting": "TeX", "pages": 27, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2007InMat.170....1B" } } }