# Gjesteforelesninger, seminarer og konferanser

## Kommende

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

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

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.

Fredrik Meyer, UiO, gives the Seminar in Algebra and Algebraic Geometry:

Modular curves VII

**Comments on the Galilean limits of Maxwell's equations**

Convex relaxation, graph cut and continuous max-flow algorithms for image processing and computer vision.

Pietro De Poi (Udine), gives the Seminar in Algebra and Algebraic Geometry:

A Severi type theorem on surfaces in P^6

Welcome to the SECOND conference on Stochastics of Environmental and Financial Economics. The conference will bring together leading researchers in the fields of stochastic analysis and finance to discuss recent developments and challenges with an edge towards energy, environmental and financial markets.

The conference is also a celebration of professor Bernt Øksendal's 70th anniversary. On Thursday April 23 the program of the conference will mark this big event with a selected list of speakers.

The conference is organized by the Center of Advanced Studies (CAS), Stochastics of Environmental and Financial Economics. Scientific organizers: Fred Espen Benth and Giulia Di Nunno (UiO)

Kristian Ranestad, UiO, gives the Seminar in Algebra and Algebraic Geometry:

Modular curves VI

Prof. Dr. Alois Gisler (ETH Zurich, RiskLab Switzerland) holds a seminar with the title "On the Development of the Swiss Solvency Test"

Prof. Dr. Alois Gisler (ETH Zurich, RiskLab Switzerland) holds a seminar with the title "The Reserve Risk of the Chain-Ladder Reserving Method from a New Perspective"

Réamonn Ó Buachalla (IMPAN) will give a talk with title: Noncommutative Kähler structures on quantum homogeneous spaces

Abstract:

Building on the definition of a noncommutative complex structure for a general algebra A, I will introduce the notion of a noncommutative Kähler structure for A. In the special case where A is a quantum homogeneous space, I show that many of the fundamental results of classical Kähler geometry follow from the existence of such a structure: Hodge decomposition, Serre duality, the Hard Lefschetz theorem, the Kähler identities, and collapse of the Frölicher spectral sequence at the first page. We then apply these results to Heckenberger and Kolb's differential calculus for quantum projective space, and show that they have cohomology groups of at least classical dimension. Time permitting, I will also discuss the relationship of this work to Connes proposal to study positive Hochschild cocycles as a starting point for noncommutative complex geometry, and Fröchlich, Grandjean, and Recknagel's definition of a Kähler spectral tuple.