Commensurations of Out(F_n)
| dc.creator | Farb, Benson | |
| dc.creator | Handel, Michael | |
| dc.date | 2006-07-21 | |
| dc.date | 2007-07-26 | |
| dc.date.accessioned | 2026-07-07T08:20:19Z | |
| dc.date.available | 2026-07-07T08:20:19Z | |
| dc.description | Let $\Out(F_n)$ denote the outer automorphism group of the free group $F_n$ with $n>3$. We prove that for any finite index subgroup $Γ<\Out(F_n)$, the group $\Aut(Γ)$ is isomorphic to the normalizer of $Γ$ in $\Out(F_n)$. We prove that $Γ$ is {\em co-Hopfian} : every injective homomorphism $Γ\to Γ$ is surjective. Finally, we prove that the abstract commensurator $\Comm(\Out(F_n))$ is isomorphic to $\Out(F_n)$. | |
| dc.description | Revised version, 43 pages. To appear in Publ. Math. IHES | |
| dc.identifier | https://arxiv.org/abs/math/0607556 | |
| dc.identifier | http://arxiv.org/abs/math/0607556 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/135041 | |
| dc.subject | Group Theory | |
| dc.subject | 20F28 | |
| dc.title | Commensurations of Out(F_n) | |
| dc.type | text |