The outer space of a free product

dc.creatorGuirardel, Vincent
dc.creatorLevitt, Gilbert
dc.date2005-01-19
dc.date2006-08-29
dc.date.accessioned2026-07-07T08:57:21Z
dc.date.available2026-07-07T08:57:21Z
dc.descriptionWe associate a contractible ``outer space'' to any free product of groups G=G_1*...*G_q. It equals Culler-Vogtmann space when G is free, McCullough-Miller space when no G_i is Z. Our proof of contractibility (given when G is not free) is based on Skora's idea of deforming morphisms between trees. Using the action of Out(G) on this space, we show that Out(G) has finite virtual cohomological dimension, or is VFL (it has a finite index subgroup with a finite classifying space), if the groups G_i and Out(G_i) have similar properties. We deduce that Out(G) is VFL if G is a torsion-free hyperbolic group, or a limit group (finitely generated fully residually free group).
dc.descriptionUpdated reference. To appear in Proc. L.M.S
dc.identifierhttps://arxiv.org/abs/math/0501288
dc.identifierhttp://arxiv.org/abs/math/0501288
dc.identifierProc. Lond. Math. Soc. (3) 94 (2007), no. 3, 695--714.
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/146938
dc.subjectGroup Theory
dc.subjectGeometric Topology
dc.subject20E08; 20E06; 20F28;20J06
dc.titleThe outer space of a free product
dc.typetext

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