XXXVI Workshop on Geometric Methods in Physics 2-8.07.2017
VI School on Geometry and Physics 26-30.06.2017

Bartosz Kwaśniewski

Aperiodicity, topological freeness and pure outerness: from group actions to Fell bundles

Several deep results on the relationship between various non-triviality conditions for group actions and the simplicity of reduced crossed products were proved around~1980 by Olesen-Pedersen, Kishimoto and Rieffel. They are applied by a number of authors in the study of the ideal structure and pure infiniteness of crossed products by actions of discrete groups.

We collect a number of this kind of results and generalize them to Fell bundles over discrete groups. We discuss conditions under which aperiodicity, topological freeness and pure outerness are equivalent, and also when they are necessary for the unit fibre of a Fell bundle to detect ideals in the reduced cross sectional C*-algebra. (Based on joint work with Ralf Meyer.)

Event sponsored by:
Centre de recherches mathématiques          University
of Bialystok
University of Bialystok

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