Thomas Timmermann
The Fell compactification and non-Hausdorff groupoids.
Mon, 11/16/2009 - 16:01 — SomNambulAuthors: Thomas Timmermann
Subjects: Operator Algebras
AbstractA compactification of Fell is applied to locally compact non-Hausdorff
groupoids and yields locally compact Hausdorff groupoids. In the etale case,
this construction provides a geometric picture for the left-regular
representations introduced by Khoshkam and Skandalis.Coactions of Hopf C*-bimodules.
Wed, 11/04/2009 - 16:01 — SomNambulAuthors: Thomas Timmermann
Subjects: Operator Algebras
AbstractCoactions of Hopf C*-bimodules simultaneously generalize coactions of Hopf
C*-algebras and actions of groupoids. Following an approach of Baaj and
Skandalis, we construct reduced crossed products and establish a duality for
fine coactions. Examples of coactions arise from Fell bundles on groupoids and
actions of a groupoid on bundles of C*-algebras. Continuous Fell bundles on an
etale groupoid correspond to coactions of the reduced groupoid algebra, and
actions of a groupoid on a continuous bundle of C*-algebras correspond to
coactions of the function algebra.C*-pseudo-multiplicative unitaries and Hopf C*-bimodules.
Fri, 08/14/2009 - 21:09 — SomNambulAuthors: Thomas Timmermann
Subjects: Operator Algebras
AbstractWe introduce C*-pseudo-multiplicative unitaries and concrete Hopf
C*-bimodules for the study of quantum groupoids in the setting of C*-algebras.
These unitaries and Hopf C*-bimodules generalize multiplicative unitaries and
Hopf C*-algebras and are analogues of the pseudo-multiplicative unitaries and
Hopf--von Neumann-bimod-ules studied by Enock, Lesieur and Vallin. To each
C*-pseudo-multiplicative unitary, we associate two Fourier algebras with a
duality pairing, a C*-tensor category of representations, and in the regular
case two reduced and two universal Hopf C*-bimodules.- Read more
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