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Department of Mathematical Sciences

Seminar Archives

On this page you can find information about seminars in this and previous academic years, where available on the database.

Pure Maths Colloquium: Cycles in Outer space

Presented by Karen Vogtmann, Cornell University and University of Warwick

10 November 2014 16:00 in CM221

Groups are of central importance throughout mathematics because they
measure symmetry. Groups themselves have symmetry, which is measured
by their automorphism groups. This talk is about the automorphism
group of a finitely
generated free group, which is surprisingly complex given that the free
group itself is so simple. We study this group by studying
its action on a geometric object called Outer space. Topological invariants of
the associated quotient space, such as homology groups, are algebraic invariants
of the group. I will describe Outer space and show how to study the
homology of the quotient space. Recent investigations have turned up
a surprising
connection of this homology with classical modular forms for SL(2,Z).

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