Groups and Operator Algebras Seminar

Speaker: Nadia Larsen (University of Oslo)

Title: Simplicity of groupoid algebras associated to Z_2-multispinal groups

Abstract: I will present an approach to showing simplicity of groupoid *-algebras associated to multispinal groups over Z_2 extending the method by Clark-Exel-Pardo-Starling-Sims for the case of the Grigorchuk group (the first example inspiring the constructions of multispinal groups). Along the way we come across a class of full-rank matrices of a kind appearing in the theory of 2-designs. This is joint work with Carla Farsi, Judith Packer and Nathaniel Thiem at UC Boulder, Colorado, USA.