Jon McCammond (UC Santa Barbara)

Title: Reflection groups beyond Coxeter groups.

Abstract: All Coxeter groups are reflection groups. And there are many contexts where "reflection group" and "Coxeter group" mean essentially the same thing. In this talk I will

highlight a case where these notions are different. Concretely, a discrete group generated by finitely many reflections preserving a non-singular quadratic form on a real metric vector space

need not be a Coxeter group.

Note that there will not be teatime in the lounge at 4pm after Jon's talk due to the McGill departmental potluck from 4:30pm-6:30pm in the lounge. We will go for dinner with Jon after the talk. Please email Piotr (piotr.przytycki [at] mcgill.ca) if you are interested in joining for dinner.