We prove that the quotient map from Aut(Fn) to Out(Fn) induces an isomorphism on homology in dimension i for n at least 2i + 4. This corrects an earlier proof by the first author and significantly improves the stability range. In the course of the proof, we also prove homology stability for a sequence of groups which are natural analogs of mapping class groups of surfaces with punctures. In particular, this leads to a slight improvement on the known stability range for Aut(Fn), showing that its ith homology is independent of n for n at least 2i + 2.
Hatcher, Allen  1 ; Vogtmann, Karen  1
@article{10_2140_agt_2004_4_1253,
author = {Hatcher, Allen and Vogtmann, Karen},
title = {Homology stability for outer automorphism groups of free groups},
journal = {Algebraic and Geometric Topology},
pages = {1253--1272},
year = {2004},
volume = {4},
number = {2},
doi = {10.2140/agt.2004.4.1253},
url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2004.4.1253/}
}
TY - JOUR AU - Hatcher, Allen AU - Vogtmann, Karen TI - Homology stability for outer automorphism groups of free groups JO - Algebraic and Geometric Topology PY - 2004 SP - 1253 EP - 1272 VL - 4 IS - 2 UR - http://geodesic.mathdoc.fr/articles/10.2140/agt.2004.4.1253/ DO - 10.2140/agt.2004.4.1253 ID - 10_2140_agt_2004_4_1253 ER -
%0 Journal Article %A Hatcher, Allen %A Vogtmann, Karen %T Homology stability for outer automorphism groups of free groups %J Algebraic and Geometric Topology %D 2004 %P 1253-1272 %V 4 %N 2 %U http://geodesic.mathdoc.fr/articles/10.2140/agt.2004.4.1253/ %R 10.2140/agt.2004.4.1253 %F 10_2140_agt_2004_4_1253
Hatcher, Allen; Vogtmann, Karen. Homology stability for outer automorphism groups of free groups. Algebraic and Geometric Topology, Tome 4 (2004) no. 2, pp. 1253-1272. doi: 10.2140/agt.2004.4.1253
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