Guest lectures and seminars - Page 114

Ulrik Bo Rufus Enstad (Oslo) will give a talk with title: Connections between Gabor frames and Noncommutative Tori

Abstract: A Gabor frame is a special type of frame in the Hilbert space of square-integrable functions on the real line. Gabor frames provide robust, basis-like representations of functions, and have applications in a wide range of areas. They have a duality theory which is deeply linked to Rieffel’s work on imprimitivity bimodules over noncommutative tori. We explore several links between Gabor frames and noncommutative tori, and show how operator algebras can be used to give alternative proofs of theorems from time-frequency analysis.  This talk is based on my Master’s thesis written at NTNU, which reviews Franz Luef’s work on the connections between Gabor frames and modules over noncommutative tori, as well as some joint work with Franz Luef.

Nacira Agram (University of Oslo) gives a lecture with the title: Model Uncertainty Stochastic Mean-Field Control.

A continuation of part I.

John Quigg, Arizona State University (Tempe), USA, will give a talk with title "The Pedersen rigidity problem".

University of Abstract: If \alpha is an action of a locally compact abelian group G on a C*-algebra A, Takesaki-Takai duality recovers (A,\alpha) up to Morita equivalence from the dual action of \widehat{G} on the crossed product A\rtimes_\alpha G. Given a bit more information, Landstad duality recovers (A,\alpha) up to isomorphism. In between these, by modifying a theorem of Pedersen, (A,\alpha) is recovered up to outer conjugacy from the dual action and the position of A in M(A\rtimes_\alpha G). Our search (still unsuccessful, somehow irritating) for examples showing the necessity of this latter condition has led us to formulate the "Pedersen rigidity problem". We present numerous situations where the condition is redundant, including G discrete or A stable or commutative. The most interesting of these "no-go theorems" is for locally unitary actions on continuous-trace algebras. This is joint work with Steve Kaliszewski and Tron Omland.