# Talk

Talks and seminars, possibly part of a conference or series.

## tba

Posted in
Speaker:
Néstor León Delgado
Affiliation:
MPIM
Date:
Fri, 2018-05-04 10:00 - 12:00
Location:
MPIM Lecture Hall
Parent event:
Promotionskolloquium

## Quantum versions of Deligne categories

Posted in
Speaker:
Hans Wenzl
Affiliation:
University of California at San Diego/ MPIM
Date:
Fri, 2018-05-04 14:15 - 16:00
Location:
MPIM Lecture Hall

## Truncated current Lie algebras with polynomial rings of symmetric invariants

Posted in
Speaker:
Dmitri Panyushev
Affiliation:
IITP Moscow/MPIM
Date:
Thu, 2018-05-03 15:00 - 16:00
Location:
MPIM Lecture Hall
Parent event:
MPI-Oberseminar

We prove that under mild restrictions on the Lie algebra $q$ having a polynomial ring of symmetric invariants, the truncated current algebras of $q$ also have a polynomial ring of symmetric invariants.

## Bott-periodicity - first proof II

Posted in
Speaker:
Ivo Slegers
Affiliation:
MPIM
Date:
Wed, 2018-05-02 16:30 - 18:00
Location:
MPIM Seminar Room
Parent event:
IMPRS seminar on K-theory

## Stable cohomology of arithmetic groups, algebraic K-groups of number fields and special values of Dedekind zeta functions

Posted in
Speaker:
Christian Kaiser
Affiliation:
MPIM
Date:
Mon, 2018-04-30 14:15 - 15:45
Location:
MPIM Lecture Hall
Parent event:
IMPRS Minicourse

## Introduction to Knots and Links

Posted in
Speaker:
Peter Teichner
Organiser(s):
Wolfgang Lück, Peter Teichner
Date:
Thu, 2018-05-03 13:15 - 15:00
Location:
MPIM Lecture Hall

## Local-global properties of word varieties

Posted in
Speaker:
Boris Kunyavskii
Affiliation:
Bar-Ilan University/MPIM
Date:
Tue, 2018-04-24 11:00 - 12:00
Location:
MPIM Lecture Hall
Parent event:
Number theory lunch seminar

We consider equations of the form w(x,y)=g where w
is a group word in two letters (= an element of the free
group on two generators), g is a fixed element of a fixed
group G, and solutions are sought among pairs of elements
of G. Our focus is on the case where G is a simple linear
algebraic group. In this talk we consider the case
G=SL(2,K) where K is a number field. We discuss approximation
properties of the corresponding algebraic K-variety.

## Local asymptotic Diophantine approximations

Posted in
Speaker:
Zhizhong Huang
Affiliation:
Université Grenoble Alpes/MPIM
Date:
Wed, 2018-04-25 16:30 - 17:30
Location:
MPIM Lecture Hall

The irrationality measure of a real number characterizes its Diophantine approximation property. The problem of counting the number of approximates to a given real number with respect to certain approximation order has been considered by a number of authors such as S. Lang, W. Adams,... We propose a local version of this problem and show that in certain cases the approximates are uniformly distributed, by using standard tools from analytic number theory.

## The blocks and abelian envelope of Deligne's Rep S_t

Posted in
Speaker:
Hankyung Ko
Affiliation:
MPIM
Date:
Fri, 2018-04-27 14:15 - 16:00
Location:
MPIM Seminar Room

## L^2-Betti numbers, II

Posted in
Speaker:
Wolfgang Lück
Affiliation:
Universität Bonn
Date:
Thu, 2018-04-26 13:15 - 15:00
Location:
MPIM Lecture Hall

## Enumeration of meanders and volumes of moduli spaces of quadratic differentials

Posted in
Speaker:
Peter Zograf
Affiliation:
Steklov Math. Institute, St. Petersburg
Date:
Thu, 2018-04-26 15:00 - 16:00
Location:
MPIM Lecture Hall
Parent event:
MPI-Oberseminar

A meander is a topological configuration of a line and a simple closed curve in the plane (or a pair of simple closed curves on the 2-sphere) intersecting transversely. In physics, meanders provide a model of polymer folding, and their enumeration is directly related to the entropy of the associated dynamical systems.

## Bott-periodicity - first proof

Posted in
Speaker:
Johannes Schaefer
Affiliation:
MPIM
Date:
Wed, 2018-04-25 16:30 - 18:00
Location:
MPIM Seminar Room
Parent event:
IMPRS seminar on K-theory

## On the Hasse Principle for Divisibility in commutative algebraic groups, III

Posted in
Speaker:
Laura Paladino
Affiliation:
University of Calabria/MPIM
Date:
Fri, 2018-04-27 10:15 - 12:00
Location:
MPIM Lecture Hall

## Kaehler groups and surface bundles

Posted in
Speaker:
Corey Bregman
Affiliation:
Brandeis University
Date:
Mon, 2018-04-23 16:30 - 18:00
Location:
MPIM Lecture Hall
Parent event:
MPIM Topology Seminar

A question going back to Serre asks which groups arise as fundamental groups of smooth complex projective varieties, or more generally, compact Kaehler manifolds.

## Spectral invariants for hyperbolic polygons

Posted in
Speaker:
Eren Ucar
Affiliation:
Humboldt Universität, Berlin
Date:
Thu, 2018-04-26 16:30 - 17:30
Location:
MPIM Lecture Hall

In 1966, M. Kac published his seminal article ''Can one hear the shape of a drum?'', which deals with the so-called inverse spectral problem: to determine geometric information from spectral data.

## Counting rational points in arithmetic varieties by the determinant

Posted in
Speaker:
Chunhui Liu
Affiliation:
Kyoto University
Date:
Fri, 2018-06-08 14:30 - 15:30
Location:
MPIM Lecture Hall
Parent event:
Number theory lunch seminar

By the slope method in Arakelov geometry, we can construct a
family of hypersurfaces which cover the rational points of bounded height on
an arithmetic variety, but do not contain the generic point of this variety.
By estimating some invariants of Arakelov geometry, we can control the
number and the maximal degree of this family of auxiliary hypersurfaces
explicitly. In this talk, I will explain the method of studying the problem
of counting rational points by using methods from Arakelov geometry.

## Vector bundles and K-theory

Posted in
Speaker:
Julia Semikina
Affiliation:
MPIM
Date:
Wed, 2018-04-18 16:30 - 18:00
Location:
MPIM Lecture Hall
Parent event:
IMPRS seminar on K-theory

## Tensor ideals in Deligne's interpolating categories

Posted in
Speaker:
Thorsten Heidersdorf
Affiliation:
The Ohio State University/MPIM
Date:
Fri, 2018-04-20 14:15 - 16:00
Location:
MPIM Lecture Hall

I will talk about the classification of tensor ideals in the Deligne categories attached to the symmetric, orthogonal and general linear group and give some applications.

## Polyak sections 3.1-3.3. Gauge fixing, Faddeev-Popov ghost, Cattaneo section 12.2. BRST cohomology

Posted in
Speaker:
Alessandro Giacchetto
Affiliation:
SISSA Trieste/MPIM
Date:
Thu, 2018-04-26 10:15 - 12:00
Location:
MPIM Seminar Room

## Nodal geometry of Laplace eigenfunctions

Posted in
Speaker:
Mayukh Mukherjee
Affiliation:
Technion, Haifa/MPIM
Date:
Thu, 2018-04-19 15:00 - 16:00
Location:
MPIM Lecture Hall
Parent event:
MPI-Oberseminar

Let $M$ be a compact Riemannian manifold and $\varphi_\lambda$ be an eigenfunction of the Laplacian corresponding to the eigenvalue $\lambda$. We will survey a few recent results in the area regarding the geometry of nodal sets and nodal domains of $\varphi_\lambda$. We will also mention joint work with Bogdan Georgiev and Stefan Steinerberger.

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