Gjesteforelesninger og seminarer - Side 27

Håvard Kvamme (UiO, Dept. of mathematics) will give a seminar in the lunch area, 8th floor Niels Henrik Abels hus at 14:15.

We will discuss the motivic May spectral sequence and demonstrate how to  use it to identify Massey products in the motivic Adams spectral sequence.  We will then investigate what is known about the motivic homotopy groups  of the eta-local sphere over the complex numbers and discuss how these  calculations may work over other base fields.  

Francesco Galuppi (UiO/Ferrara) gives the algebraic geometry seminar:

"Identifiability of polynomials and Cremona transformations."

Certain 3-dimensional lens spaces are known to smoothly bound 4-manifolds with the rational homology of a ball. These can sometimes be useful in cut-and-paste constructions of interesting (exotic) smooth 4-manifolds. To this end it is interesting to identify 4-manifolds which contain these rational balls. Khodorovskiy used Kirby calculus to exhibit embeddings of rational balls in certain linear plumbed 4-manifolds, and recently Park-Park-Shin used methods from the minimal model program in 3-dimensional complex algebraic geometry to generalise Khodorovskiy's result. The goal of this talk is to give an accessible introduction to the objects mentioned above and also to describe a much easier topological proof of Park-Park-Shin's theorem.  

Bartosz Kwasniewski (Odense) will give a talk with title: Paradoxicality and pure infiniteness of  C*-algebras associated to Fell bundles

Abstract: Abstract: In this talk we present conditions implying  pure infiniteness of the reduced cross-sectional $C^*$-algebra $C^*_r(\mathcal{B})$ of a Fell bundle $\mathcal{B}$ over a discrete group $G$. We introduce notions of aperiodicity, $\mathcal{B}$-paradoxicality and  residual $\mathcal{B}$-infiniteness.  We discuss their relationship with similar conditions studied, in the context of crossed products, by the following duos: Laca, Spielberg; Jolissaint, Robertson; Sierakowski, R{\o}rdam;  Giordano, Sierakowski and Kirchberg, Sierakowski.    (based on  joint work with Wojciech Szyma{\'n}ski)

Francesca Biagini, professor in mathematical finance from Ludwig-Maximillian University of Munich, will give an intensive course from Tuesday Sept 13 to Friday Sept 16.

Seckin Adali (UiO), gives the Seminar in Algebra and Algebraic Geometry:

Singularities of Restriction Varieties in OG(k,n)

In the nineties, Deninger gave a detailed description of a conjectural cohomological interpretation of the (completed) Hasse-Weil zeta function of a regular scheme proper over the ring of rational integers. He envisioned the cohomology theory to take values in countably infinite dimensional complex vector spaces and the zeta function to emerge as the regularized determinant of the infinitesimal generator of a Frobenius flow. In this talk, I will explain that for a scheme smooth and proper over a finite field, the desired cohomology theory naturally appears from the Tate cohomology of the action by the circle group on the topological Hochschild homology of the scheme in question.  

Abstract: Exploring connections between subfactors and conformal field theories, Vaughan Jones recently observed that planar algebras give rise to unitary representations of the Thompson group F, and more generally,  to unitary representations of the group of fractions of certain categories. Remarkably, this procedure applies to oriented link invariants. In particular, a suitably normalized HOMFLYPT polynomial is a positive definite function on the oriented Thompson group. (Based on joint work with V. Aiello and V. Jones.)

The motivic Adams spectral sequence is a general tool for calculating homotopy groups of a motivic spectrum X. We will investigate the construction of the motivic Adams spectral sequence, determine the second page of the spectral sequence, and identify what it converges to in good cases. If time permits, we will show how to use the motivic Adams spectral sequence to obtain explicit calculations of the motivic homotopy groups of spheres and other spectra. 

On 5-7 September the first STORE PHD Gathering will take place, with two intensive courses. The first is on the new class of stochastic processes called Trawl processes and instructed by Almut Veraart from Imperial College London, UK. The second is led by Rudiger Kiesel from University of Duisburg-Essen, Germany, and focuses on intra-day trading of electricity. 

A class of nonlinear evolution equations of second order

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

"Kummer surfaces and hyperkähler fourfolds, as degeneracy loci"

Arturo Kohatsu-Higa (Ritsumeikan University, Kusatsu, Japan) gives a lecture with the title: Probabilistic interpretation of the parametrix method

Prof. Yasunori Fujikoshi​ (Hiroshima University​) will give a seminar in Sverdrups plass (lunch area), 8th floor, Niels Henrik Abels hus at 14:15.

The Logic Seminar will take place at the same time and location as in previous terms.

Andrea Cremaschi (earlier University of Kent, now UiO) will give a seminar in the lunch area, 8th floor Niels Henrik Abels hus at 14:15.

Bloch constructed higher cycle class maps from higher Chow groups to Deligne cohomology and étale cohomology. I will define a map from the motivic Eilenberg-Mac Lane spectrum to the spectrum representing Deligne cohomology in the motivic stable homotopy category over C such that it gives Bloch's higher cycle class map on cohomology. The map is induced by the map from Voevodsky's algebraic cobordism spectrum MGL to the Hodge-filtered complex cobordism spectrum defined by Hopkins-Quick. This extends a result of Totaro showing that the usual cycle class map to singular cohomology factors through complex cobordism modulo the coefficients of the Lazard ring MU^{2*} tensor_L Z. This is joint work with Amit Hogadi.

Yaozhong Hu (University of Kansas, USA) gives a lecture with the title: Rate of convergence and asymptotic error distribution of Euler approximation schemes for fractional diffusions

Olfa Draouil (University of Tunis El Manar, Tunisia) gives a lecture with the title: Optimal insider control of stochastic partial differential equations

Multi-index Monte Carlo and Multi-index Stochastic Collocation

In this talk I will present a paper by D. Bisch, R. Nicoara and S. Popa where continuous families of irreducible subfactors of the hyperfinite II_1 factor which are non-isomorphic, but have all the same standard invariant are constructed. In particular, they obtain 1-parameter families of irreducible, non-isomorphic subfactors of the hyperfinite II_1 factor with Jones index 6, which have all the same standard invariant with property (T).

Igor Barros Barbosa (PhD candidate at Department of Computer and Information Science at NTNU) gives a seminar on deep learning at Department of Mathematics on the 8th floor of Niels Henrik Abels hus.

Ritwik Mukherjee (TIFR) gives the Seminar in Algebra and Algebraic Geometry:

Title: Enumerative Geometry of singular curves in a Linear System

Abstract: Enumerative geometry is a branch of mathematics that deals with the following question: "How many geometric objects satisfy certain constraints". A well known class of enumerative question is to count curves in a linear system H^0(X,L) that have some prescribed singularities. In this talk we will describe a topological method to approach this problem. We will express the enumerative numbers as the Euler class of an appropriate bundle. We will then go on to explain how we compute the degenerate contribution of the Euler class using a topological method.