Tidligere gjesteforelesninger og seminarer - Side 71

Magnus Dahler Norling, UiO, will give a talk with title: The K-theory of some reduced inverse semigroup C*-algebras

Abstract: We use a recent result by Cuntz, Echterhoff and Li about the K-theory of certain reduced C*-crossed products to describe the K-theory of C*_r(S) when S is an inverse semigroup satisfying certain requirements. A result of Milan and Steinberg allows us to show that C*_r(S) is Morita equivalent to a crossed product of the type handled by Cuntz, Echterhoff and Li. We apply the results to graph inverse semigroups and the inverse semigroups of one-dimensional tilings.

Michael Scheuerer will talk about (Institute of Applied Mathematics, Heidelberg University)

Statistical post-processing of weather forecasts: The importance of spatial modeling

Dette semesteret arrangerer vi et seminar om 4-mangfoldigheter, et felt som burde interessere både topologer og algebraiskgeometere. Dessuten, siden vi nå er i samme avdeling, bør vi jo ha noe felles aktivitet. Et overordnet mål er å studere komplekse flater opp til diffeomorfi. Det konkrete programmet vil bli til underveis, men emner vi regner med å komme innom inkluderer - Topologisk klassifikasjon av enkeltsammenhengende, kompakte   4-mangfoldigheter (Freedman) - Donaldsons teorem om snittformen til differensiable 4-mangfoldigheter - Enriques-Kodaira klassifikasjon av komplekse flater - Seiberg-Witten teori.

Vi starter opp mandag 28. januar 1415-1600 i B70 med at Bjørn snakker om snittformen og den topologiske teorien. Bjørn Jahren og Geir Ellingsrud

Program for the seminar in Logic, Spring 2013

Førsteamanuensis Luc Rouppe van der Voort, Institutt for teoretisk astrofysikk

Donna Mary Salopek (Uni. South Wales) holder et seminar med tittelen: Stochastic Evolution Equations driven by Liouville Fractional Brownian motion

Benedykt Szozda (Uni. Aarhus) holder et seminar med tittelen: Anticipative extension of the Ito integral

Thomas Jaki (Department of Mathematics and Statistics, Lancaster University) will talk about

Designing multi-arm multi-stage clinical studies

Matthew Sperrin (Department of Mathematics and Statistics, Lancaster University) will talk about

Modelling the effect of interventions on onset and progression of chronic disease

Friday seminar by Jeffrey Hutchings

Fred Shultz, Wellesley College, USA will give a talk with title "Decomposing separable states".

This is the first in a joint seminar series organised by the Operator Algebra group (UiO), Several Complex Variable group (UiO) and the CAS group.  The plan is to have seminars every other week.  

Abstract: This talk will begin with a brief introduction to entanglement and its applications, since that motivates the mathematics to be discussed.  In the title of this talk, a state is a positive linear functional on the tensor product of the algebras of m x m and n x n complex matrices.  Such a state is separable if it is a convex combination of product states. An interesting open problem is to give a useful criterion for a state to be separable. A related problem is to give a systematic way to find a decomposition of a separable state into a convex combination of product states.  This talk will describe such a decomposition for a class of separable states that is of both physical and mathematical interest.  This decomposition is also applicable to a class of completely positive maps (which correspond to certain quantum channels). This is joint work with Erik Alfsen.  

Paul Kruehner, MAWREM/CMA, holder et seminar med tittelen: Subordination of Hilbert space valued Lévy processes

Magnus Landstad (NTNU) will give a talk with title: Exotic group C*-algebras and noncommutative duality.

Abstract: It  has long been known that for a (non-amenable) locally compact group G there are many C*-algebras between the full and reduced group C*-algebra. First I will discuss to what extent these intermediate algebras can be called group C*-algebras. Then I will look at algebras between the full and reduced crossed product, and the various types of coactions (full, maximal, normal) a group can have. To make arguments a little simpler, we shall assume G to be discrete.

Friday seminar by Barbara Bramanti

CEES Extra seminar by Ulf Büntgen

Friday seminar by Torstein Tengs

Håkon Dahle, forsker, Institutt for teoretisk astrofysikk.

Abstract: In groundbreaking work Thomason establishes a fundamental comparison between Bott-inverted algebraic K-theory and étale K-theory with finite coefficients. Over the complex numbers, Walker has shown how to deduce Thomason's theorem using a semi-topological K-homology theory. In joint work with J. Hornbostel we establish an equivariant generalization of Walker's Fundamental Comparison Theorem and use it to deduce the equivariant version of Thomason's theorem for complex varieties with action by a finite group. 

Salvador Ortiz-Latorre, EMMOS/CMA, holder et seminar med tittelen: A second order approximation of the continuous time filtering problem

Friday seminar by Thorsten Reusch

Claus Madsen, senior advisor at the European Southern Observatory (ESO).

Yoshiko Ogata, University of Tokyo, will give a talk with title: Approximating macroscopic observables in quantum spin systems with commuting matrices

Abstract: Macroscopic observables in a quantum spin system are spatial means of local observables in a UHF algebra. One of their properties is that they commute asymptotically as the system size goes to infinity. It is not true that any given set of asymptotically commuting matrices can be approximated by commuting ones in the norm topology. The main statement of this talk is that this is true for macroscopic observables.