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Emmy-Noether-Seminar

Feb 07
07-02-2020 14:30 Uhr bis 15:30 Uhr
Raum 04.363, Cauerstraße 11, Erlangen

The Euler characteristic of Out(F_n)

Michael Borinsky (Amsterdam)

Abstract: I will report on recent joint work with Karen Vogtmann on the Euler characteristic of Out(F_n) and the moduli space of graphs. A similar study has been performed in the seminal 1986 work of Harer and Zagier on the Euler characteristic of the mapping class group and the moduli space of curves. I will review a topological field theory proof, due to Kontsevich, of Harer and Zagier’s result and illustrate how an analogous „renormalized“ topological field theory argument can be applied to Out(F_n).