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shupp_01

### Prof. Dr. Alexander Lubotzky, Einstein Institute Jerusalem, Vortrag: Fritz Grunewald memorial talk: Arithmetic quotients of the mapping class group

##### Mittwoch, 17.06.2015 16:30 im Raum M6

Let M=M(g) be the mapping class group of a surface of genus g > 1 (resp. M=Aut(F_g) the automorphism group of the Free group on g generators ). As it is well known, M is mapped onto the symplectic group Sp(2g,Z) (resp. the general linear group GL(g,Z) ). We will show that this is only a first case in a series: in fact, for every pair (S,r) when S is a finite group with less than g generators and r is a Q-irreducible representation of S, we associate an arithmetic group which is then shown to be a virtual quotient of M. The case when S is the trivial group gives the above Sp(2g,Z) ( resp. GL(g,Z) ) but many new quotients are obtained. For example it is used to show that M(2) (resp. Aut(F_3) ) is virtually mapped onto a non-abelian free group. Another application is an answer to a question of Kowalski: generic elements in the Torelli groups are hyperbolic and fully irreducible. Joint work with Fritz Gruenwald, Michael Larsen and Justin Malestein .

Angelegt am Mittwoch, 18.03.2015 14:48 von shupp_01
Geändert am Mittwoch, 06.05.2015 09:29 von shupp_01
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Kolloquium Wilhelm Killing