Alcides Buss (Florianopolis): Deformation of C*-algebras. Oberseminar C*-Algebren.
Tuesday, 17.10.2023 16:15 im Raum SRZ 216/217
In this talk we revisit the procedure of deforming C*-algebras endowed coactions of locally compact groups, generalizing Rieffel deformation for actions of R^n. The main deformation parameters used to deform those co-systems are Borel 2-cocycles on the underlying group G. The main difficulty relies on Borel 2-cocycles that are not continuous. We introduce a new approach that gives a systematic way to deform arbitrary co-systems via Borel 2-cocycles that applies not only to reduced (i.e. normal) coactions, but also maximal and other exotic forms of coactions, generalizing previous work by Bhowmick, Neshveyev, and Sangha for reduced coactions of groups, that is, coactions that belong to the reduced group C*-algebra of G. The main idea is to use exotic versions of Landstad duality for coactions of G. This works for any crossed-product functor for G that respects Morita equivalences. Our approach yields a new realization of the deformed C*-algebras and many of the previous results carry over to this more general setting, including invariance of K-theory for defomations via homotopic 2-cocycles.
This is based on joint work with Siegfried Echterhoff.
Angelegt am Tuesday, 29.08.2023 09:49 von Elke Enning
Geändert am Monday, 09.10.2023 09:38 von Elke Enning
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