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Elke Enning

Ebrahim Sawei (Saskatoon, z.Zt. Warschau): Exotic C*-algebras of geometric groups. Oberseminar C*-Algebren.

Tuesday, 16.04.2019 15:15

Mathematik und Informatik

We consider a new class of potentially exotic group C*-algebras C(PFp(G)) for a locally compact group G, and its connection with the class of potentially exotic group C*-algebras CLp(G) introduced by Brown and Guentner \cite{BG}. Surprisingly, these two classes of C*-algebras are intimately related. By exploiting this connection, we show CLp(G)=C(PFp(G)) for p(2,), and the C*-algebras CLp(G) are pairwise distinct for p(2,) when G belongs to a large class of nonamenable groups possessing the Haagerup property and either the rapid decay property or Kunze-Stein phenomenon by characterizing the positive definite functions that extend to positive linear functionals of CLp(G) and C(PFp(G)). This greatly generalizes earlier results of Okayasu \cite{Okay} and Wiersma on the pairwise distinctness of CLp(G) for $20(recallA_\pi\subseteq B_\pi).HereA_\piandB_\piaretheclosedspanofcoefficientsof\piinthenormandw^*topologyoftheFourierStieljesalgebraB(G)=C^*(G)^*,respectively.Inparticular,wehaveA_\pi\subseteq B_\pi$.\\ This is based on a joint work with M. Wiersma.



Angelegt am 15.03.2019 von Elke Enning
Geändert am 15.03.2019 von Elke Enning
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