Spectral gaps, higher Kazhdan projections and L^2-Betti numbers

Piotr Nowak  (University of Warsaw)

8:00-9:00,August 3,2023   文附楼 (Wenfu Building) 219

Abstract:

I will define the notion of a higher Kazdhan projection, which is an idempotent over the maximal C*-algebra, and discuss how it is relevant in the context of higher index theory. More precisely, I will show how these projections can be used as a strategy to construct new counterexamples to the coarse Baum-Connes conjecture, in the spirit of high-dimensional expanders. This is joint work with Kang Li and Sanaz Pooya.

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