Published on *Max-Planck-Institut für Mathematik* (http://www.mpim-bonn.mpg.de)

Posted in

- Vortrag [1]

Speaker:

Gerhard Röhrle
Zugehörigkeit:

Ruhr-Universität Bochum
Datum:

Don, 2018-11-22 16:30 - 17:30 We first review some basic results related to Serre's notion of $G$-complete reducibility for a reductive algebraic group $G$. We then discuss a relative variant of this concept where we let $K$ be a reductive subgroup of $G$, and consider subgroups of $G$ which normalise the identity component $K^o$ of $K$. We show that such a subgroup is relatively $G$-completely reducible with respect to $K$ if and only if its image in the automorphism group of $K^o$ is completely reducible in the sense of Serre. This allows us to generalise a number of fundamental results from the absolute to the relative setting. This is a report on recent joint work with M. Gruchot and A. Litterick.

**Links:**

[1] http://www.mpim-bonn.mpg.de/de/taxonomy/term/39

[2] http://www.mpim-bonn.mpg.de/de/node/3444

[3] http://www.mpim-bonn.mpg.de/de/node/8209