## [PAST EVENT] Mathematics Colloquium:  Stephen Trefethen (William & Mary)

October 4, 2019
2pm - 3pm
##### Location
Jones Hall, Room 301
200 Ukrop Way
Williamsburg, VA 23185Map this location
##### Access & Features
• Open to the public

Title:  Frobenius--Schur indicators of finite exceptional groups.

Abstract: Let G be a finite group. The Frobenius--Schur indicator of an irreducible character $\chi$, denoted $\varepsilon(\chi)$, is defined as $\varepsilon(\chi) = \frac{1}{|G|} \sum_{g \in G} \chi(g^2)$. It is known that $\varepsilon(\chi)=1, -1,$ or $0$, where $\varepsilon(\chi) = 0$ precisely when $\chi$ is not real-valued. When $\chi$ is real-valued, $\varepsilon(\chi) = 1$ if $\chi$ is afforded by a representation that may be defined over the real numbers, otherwise $\varepsilon(\chi) = -1$. In this talk we outline a computational method used to prove that the exceptional groups $F_4(q)$, $E_7(q)_{\textrm{ad}}$, and $E_8(q)$ have no irreducible characters with Frobenius--Schur indicator -1.

##### Contact

Stephen Trefethen