BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Siegfried Echterhoff (University of Münster) DTSTART:20210927T063000Z DTEND:20210927T073000Z DTSTAMP:20260423T052838Z UID:SiN/30 DESCRIPTION:Title: Ame nable group actions on C*-algebras and the weak containment problem\nb y Siegfried Echterhoff (University of Münster) as part of Symmetry in New castle\n\n\nAbstract\nThe notion of amenable actions by discrete groups on C*-algebras has been introduced by Claire Amantharaman-Delaroche more tha n thirty years ago\, and has become a well understood theory with many app lications. So it is somewhat surprising that an established theory of amen able actions by general locally compact groups has been missed for a very long time. We now present a theory which extends the discrete case and uni fies several notions of approximation properties of actions which have bee n discussed in the literature. We also discuss the weak containment proble m which asks wether an action $\\alpha:G\\to \\Aut(A)$ is amenable if and only if the maximal and reduced crossed products coincide.\n\nIn this lect ure we report on joint work with Alcides Buss and Rufus Willett\n LOCATION:https://researchseminars.org/talk/SiN/30/ END:VEVENT END:VCALENDAR