Curve complexes and finite index subgroups of mapping class groups

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dc.creatorBehrstock, Jason
dc.creatorMargalit, Dan
dc.date2005-04-15
dc.date2005-04-21
dc.date.accessioned2026-07-07T10:18:11Z
dc.date.available2026-07-07T10:18:11Z
dc.descriptionLet Mod(S) be the extended mapping class group of a surface S. For S the twice-punctured torus, we show that there exists an isomorphism of finite index subgroups of Mod(S) which is not the restriction of an inner automorphism. For S a torus with at least three punctures, we show that every injection of a finite index subgroup of Mod(S) into Mod(S) is the restriction of an inner automorphism; this completes a program begun by Irmak. For all of the above surfaces, we establish the co-Hopf property for finite index subgroups of Mod(S).
dc.description17 pages, 1 figure, minor mistake in closed genus 2 case corrected, references updated
dc.identifierhttps://arxiv.org/abs/math/0504328
dc.identifierhttp://arxiv.org/abs/math/0504328
dc.identifierGeometriae Dedicata, 118, (2006), 71-85
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/174107
dc.subjectGeometric Topology
dc.subjectGroup Theory
dc.subject57M99; 20F38
dc.titleCurve complexes and finite index subgroups of mapping class groups
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