# Gjesteforelesninger, seminarer og konferanser

## Kommende

Paul Krühner (TU Wien) holds a lecture with the title: Affine processes with compact state space and counter-examples for polynomial processes.

Welcome to the first FINEWSTOCH Networkshop. The workshop will bring together leading researchers in stochastics and probability theory to discuss recent developments with a particular focus on finance, insurance, energy and weather.

The conference is part of a joint French-Norwegian conference series on curves and surfaces. In Norway previous meetings were held in Oslo 1988, Biri 1991, Ulvik 1994, Lillehammer 1997, Oslo 2000, Tromsø 2004, Tønsberg 2008, and Oslo 2012. In France the last meeting was in Paris 2014.

## Tidligere

Nicolai Stammeier (Münster) will give a talk with title "Aiming for accuracy - boundary quotients of right LCM semigroups revisited "

Abstract: I will recall the notions of foundation sets and the boundary quotient for right LCM semigroups. This C*-algebra is obtained by modding out products of defect projections over foundation sets in the full semigroup C*-algebra of the right LCM semigroup. Observing that this is in stark contrast to the standard presentations of C*-algebras in the spirit of Cuntz algebras, where a summation relation gets used, we will discuss the possibility of replacing the product relation by a summation relation and arrive at the accurate refinement property. This feature turns out to be quite common among right LCM semigroups. In fact, we are yet to see an example of a right LCM semigroup that has an insufficient supply of accurate foundation sets. Time permitting, we will leave the realm of right LCM semigroups for the sake of finding semigroups without the accurate refinement property.

Valeria Vitelli (Dept. of Biostatistics, UiO) will give a seminar in room 801 (B81), 8th floor N.H. Abels House at 14:15 September 1st: Probabilistic preference learning with the Mallows rank model

Felipe Rincon, UiO, gives the Seminar in Algebra and Algebraic Geometry

An introduction to tropical geometry

The seminar will be at the same time and location as during the spring.

Andrey Pilipenko (Ukrainian National Academy of Sciences) gives a lecture with the title: Limits of Markov processes with irregular behavior at a fixed point.

Tijana Levajkovic (University of Innsbruck) holds a lecture with the title: Chaos expansions for stochastic evolution equations.

Please note that participation is by invitation only. Note also that there is an official homepage of the Abel Symposium 2015.

The Abel Symposium is administrated by the Norwegian Mathematical Society.

Klaus Thomsen, Aarhus Universitet, Denmark, will give a talk with title "KMS states and ground states for generalized gauge actions on graph C*-algebras"

John Quigg, Arizona State University at Tempe, USA, will give a talk with title: Landstad duality and a theorem of Pedersen

Abstract:

In joint work with Steve Kaliszewski and Tron Omland, we show how a theorem of Pedersen characterizing exterior equivalent actions on a C*-algebra can be parlayed into an equivalence between two equivariant categories of C*-algebras. In one category, isomorphisms correspond to outer conjugacies of actions, while isomorphisms in the other category are equivariant isomorphisms of the crossed products that respect the generalized fixed point algebras. This category equivalence is a variation of Landstad's original characterization of actions up to equivariant isomorphism, where we now allow more morphisms. Time permitting, we will compare our "outer duality" with Landstad duality and also with Imai-Takai crossed-product duality.

Alfons van Daele (University of Leuven, Belgium) will give a talk with title: Constructing locally compact quantum groups from pairs of *-algebras

Abstract: Let (A,\Delta) be a finite-dimensional Hopf *-algebra. The dual B of A is again a finite-dimensional Hopf *-algebra. The entire structure of these two Hopf *-algebras is encoded in the *-algebras A and B and the pairing between the two. We will explain how this works. This is in fact true in many more, and more general situations. In particular, we give an example constructed from a pair of subroups H,K of a group G with the property that the map (h,k)-> hk is a bijection from HxK to G. This method is used in a joined paper with Magnus Landstad where we construct a pair of locally compact quantum groups from such pairs of subgroups of a locally compact group G.

The statistics groups at the University of Oslo and the Norwegian University of Life Sciences invite all PhD-students and postdocs within statistics in the Oslo-region as well as their teachers and supervisors to a 2-days workshop.

Computable error estimates for Monte Carlo finite element approximation of elliptic PDE with lognormal diffusion coefficients

Adam Sørensen (UiO) will give a talk with title "Leavitt path algebras - a connection between pure algebra and operator algebras"

Abstract: We will discuss Leavitt path algebras, the purely algebraic cousins of the analytic graph C*-algebras. We will discuss similarities and differences, in particular recent work with Brownlowe on a purely algebraic version of Kirchberg's theorem that all exact C*-algebras embed into O_2.

Stein Andreas Bethuelsen (Universiteit Leiden) gives a lecture with the title: Random walks in (dynamic) random environment

Marco Matassa (UiO) will give a talk with title The Dolbeault-Dirac operator on quantized projective spaces, revisited

Abstract: In this talk I will present a new construction for the Dolbeault-Dirac operator on quantum projective spaces, the main result being the computation of its square. This clarifies and generalizes some results of D'Andrea-Dąbrowski. Moreover it gives a class of explicit examples of the general construction of Krähmer-Tucker Simmons, which deals with such operators on irreducible generalized flag manifolds.

Fourteenth International Workshop

Carsten Lütken, UiO, gives the Seminar in Algebra and Algebraic Geometry:

Modular curves VIII

The Skolem Lecture is an annual event in honor of the Norwegian mathematician and logician Thoralf Skolem.

This years Skolem Lecturer will be

Michael Rathjen, The University of Leeds:

"On relating strong type theories and set theories"

Roberto Conti (La Sapienza, Rome) will give a talk with title "C*-algebras and Fourier theory"

Robert Yuncken (Univ. Clermont-Ferrand II, France) will give a talk with title: A groupoid approach to pseudodifferential operators

Abstract: Connes introduced the "tangent groupoid" of a manifold as a geometric device for linking a classical pseudodifferential operator to its symbol, yielding a novel proof of the Atiyah-Singer index theorem. Since then, numerous variations on the tangent groupoid have been produced, each adapted to a different class of pseudodifferential operators. In this talk we will consider the reverse problem: associating to a given tangent groupoid a pseudodifferential calculus. We shall show that the kernels of classical pseudodifferential operators are precisely the essentially homogeneous fibrewise distributions on Connes' tangent groupoid. This leads to a natural pseudodifferential calculus of subelliptic type on a manifold with a filtration on its Lie algebra of vector fields.