Events - Page 24

Noncommutative geometry aims to use geometric insight in studying phenomena that are beyond the reach of classical geometry and analysis, using functional analysis and algebra as primary rigorous tools. Over the years it has been applied to a variety of problems, from index theory for foliations, to the Novikov conjecture, quantum Hall effect, standard model, analysis on quantum groups, and many more. The goal of the one-day seminar is to use the opportunity provided by the visit of Adam Rennie from Australia to report on recent advances in the area. Another goal is to strengthen ties between the operator algebra groups in Oslo and Trondheim.

The seminar is part of the project "Pure Mathematics in Norway, 2018-2022", supported by the Trond Mohn Stiftelse (earlier called Bergen Research Foundation) and the Tromsø Research Foundation.     

Valeriya Naumova (Machine Intelligence Department, Simula Research Laboratory) will give a talk on October 23th at 14:15 in the Seminar Room 819, Niels Henrik Abels hus, 8th floor.

Professor Andrey Pilipenko from the Kiev Polytechnic Institute will give a talk with title "On perturbations of ordinary differential equations with non-Lipschitz coefficients by a small-noise".

The genuine analog of an E_\infty-ring spectrum in algebraic geometry is the notion of a normed motivic spectrum, which carries multiplicative transfers along finite etale morphisms. The homological shadows of an E_\infty-ring structure are the Dyer-Lashof operations which acts on the homology an E_\infty-ring spectrum. We will construct analogs of these operations in motivic homotopy theory, state their basic properties and discuss some consequences such as splitting results for normed motivic spectra. The construction mixes two ingredients: the theory of motivic colimits and equivariant motivic homotopy theory. This is joint work with Tom Bachmann and Jeremiah Heller.  

Let C be a generalised based category (to be defined) and R a commutative ring with identity. In this talk, we construct a cohomology theory in the category B_R(C) of contravariant functors from C to the category of R-modules in an axiomatic way, This cohomology theory generalises simultaneously Bredon cohomology involving finite, profinite, and discrete groups. We also study higher K-theory of the categories of finitely generated projective objects and and finitely generated objects in B_R(C) and obtain some finiteness and other results.  

This is a partial report on a joint work with G. Garkusha. The triangulated category of framed bispectra SH^fr_nis(k) is introduced. This triangulated category only uses Nisnevich local equivalences and has nothing to do with any kind of motivic equivalences. It is proved that SH^fr_nis(k) recovers the classical Morel-Voevodsky triangulated categories of bispectra SH(k), provided the base field k is infinite and perfect.

Emanuele Gramuglia (Department of Mathematics, University of Oslo) will give a talk on October 9th at 14:15 in the Seminar Room 819, Niels Henrik Abels hus, 8th floor.

Ingrid Van Keilegom (Department of OR and Business Statistics, Catholic University of Leuven) will give a talk on Monday, October 1st at 14:15 in the Seminar Room 819, Niels Henrik Abels hus, 8th floor.

Rebecka Jörnsten (Division of Applied Mathematics and Statistics, University of Gothenburg / Chalmers University of Techology) will give a talk on September 28th at 9:15 in the Seminar Room 819, Niels Henrik Abels hus, 8th floor.

Giuliana Cortese (Department of Statistical Sciences, University of Padova) will give a talk on September 25th at 14:15 in the Seminar Room 819, Niels Henrik Abels hus, 8th floor.

Prof. Masaki Izumi, Kyoto University, Japan, will give a talk with title:

The classification of poly-Z group actions on Kirchberg algebras

Abstract: We completely classify outer actions of a poly-Z group G on any Kirchberg algebra A in terms of a principal Aut(A x K)-bundle over the classifying space BG. This is joint work with Hiroki Matui.

Becky Armstrong, University of Sydney, Australia, will give a talk with title:

Simple graph algebras

Abstract: Since their introduction twenty years ago, C*-algebras associated to directed graphs have become a popular tool for investigating various classes of C*-algebras, because analytical properties of these C*-algebras depend on much simpler combinatorial properties of the underlying graphs. One such analytical property is simplicity, which plays a fundamental role in the classification program for C*-algebras. In this talk I will first recall the characterisation of simplicity for directed graph C*-algebras. I will then describe the results of my PhD research, in which I characterise simplicity of twisted C*-algebras of topological higher-rank graphs in terms of the underlying graphical and cohomological data. These C*-algebras are constructed using groupoid techniques for the purpose of this simplicity characterisation, but I will also briefly describe two product-system models for twisted C*-algebras of topological higher-rank graphs. (This is joint work with my PhD supervisors, Nathan Brownlowe and Aidan Sims.)

Geoff Nicholls (Department of Statistics, University of Oxford) and Idris Eckley (Mathematics and Statistics, Lancaster University) will both give a talk on September 17th, at 13:45 and 14:45, respectively, in the Seminar Room 819, Niels Henrik Abels hus, 8th floor.

Paolo Vidoni (Department of Economics and Statistics, University of Udine) will give a talk on September 4th at 14:15 in the Seminar Room 819, Niels Henrik Abels hus, 8th floor.

The Mahowald invariant is a method for constructing nontrivial classes in the stable homotopy groups of spheres from lower dimensional classes. I will introduce this construction and recall Mahowald and Ravenel's computation of the Mahowald invariant of 2^i for all i . I'll then introduce motivic and equivariant analogs of the Mahowald invariant, outline the computation of the generalized Mahowald invariants of 2^i and \eta^i for all i , and discuss the relationship between these generalized computations and exotic periodicity in the equivariant and motivic stable homotopy groups of spheres.

Christophe Henry

Post doc at Observatoire de la Cote d'Azur, Laboratoire Lagrange

Nordfjordeid Summer school 2018