# Talk

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

## tba

Posted in
Speaker:
Mingjia Zhang
Affiliation:
Universität Bonn/MPIM
Date:
Wed, 2021-05-05 16:15 - 17:45

Zoom Meeting-ID: 994 2805 4844

## Perverse Sheaves and Morse Theory

Posted in
Speaker:
Axel Koelschbach
Affiliation:
Universität Bonn/MPIM
Date:
Wed, 2021-04-28 16:15 - 17:45

Zoom Meeting-ID: 994 2805 4844

## Formalism of Perverse Sheaves

Posted in
Speaker:
Gregory Andreychev
Affiliation:
Universität Bonn/MPIM
Date:
Wed, 2021-04-21 16:15 - 17:45

Zoom Meeting-ID: 994 2805 4844

## Maxima of a Random Model of the Riemann Zeta Function over Intervals of Varying Length

Posted in
Speaker:
Lisa Hartung
Affiliation:
Universität Mainz
Date:
Wed, 2021-04-21 14:30 - 15:30
Parent event:
Number theory lunch seminar

Zoom Meeting ID: 919 6497 4060
For password see the email or contact Pieter Moree (moree@mpim...).

## tba

Posted in
Speaker:
Will Sawin
Affiliation:
Columbia University
Date:
Tue, 2021-05-25 14:00 - 14:30

## The Yang Baxter equation: origins and connection to symmetric functions

Posted in
Speaker:
Till Wehrhan
Affiliation:
MPIM/Universität Bonn
Date:
Thu, 2021-04-15 13:15 - 14:45

Please note the time!

For meeting ID and passcode please contact Christian Kaiser (kaiser@mpim...).

## Pair correlation of sequences: metric results and a modified additive energy.

Posted in
Speaker:
Marc Munsch
Affiliation:
TU Graz
Date:
Wed, 2021-04-14 14:30 - 15:30
Parent event:
Number theory lunch seminar

The uniform distribution of a sequence $\{x_n\}_{n\geq 1}$ measures the pseudo-random behavior at a global scale. At a more localized scale, we can study the pair correlation for sequences in the unit interval. Pseudo-random behavior with respect to this statistic is called Poissonian behavior.

## tba

Posted in
Speaker:
Martina Joergensen
Affiliation:
ETH Zürich
Date:
Thu, 2021-06-10 16:30 - 18:00

The seminar is virtual via Zoom.

## tba

Posted in
Speaker:
Fedor Manin
Affiliation:
University of California, Santa Barbara
Date:
Thu, 2021-05-27 18:30 - 20:00

Please note the time.

## tba

Posted in
Speaker:
David Bate
Affiliation:
University of Warwick
Date:
Thu, 2021-05-20 16:30 - 18:00

The seminar is virtual via Zoom.

## tba

Posted in
Speaker:
Matthias Kreck
Affiliation:
Universität Bonn
Date:
Mon, 2021-05-03 14:00 - 15:00
Parent event:
MPIM Topology Seminar

Meeting ID: 916 5855 1117
Contact: Aru Ray and Tobias Barthel.

## Topological rigidity and low dimensional topology

Posted in
Speaker:
Jim Davis
Affiliation:
Bloomington/MPIM
Date:
Mon, 2021-04-26 14:00 - 15:00
Parent event:
MPIM Topology Seminar
An aspherical manifold is a manifold whose universal cover is contractible, i.e. a K(\pi,1)-manifold. Borel conjectured that any two closed aspherical manifolds with isomorphic fundamental groups are homeomorphic, in fact, that the structure set of an aspherical manifold is trivial. Wall asked if a K(\pi,1)-space which satisfies Poincare duality is homotopy equivalent to a closed manifold.

## Surgery Theory and 4-manifolds

Posted in
Speaker:
Mark Powell
Affiliation:
Durham/MPIM
Date:
Mon, 2021-04-19 14:00 - 15:00
Parent event:
MPIM Topology Seminar
I will talk about applications of surgery theory to classifications results in 4-manifolds.

This is the second of three talks in the following series.

Series title: Applied surgery
Series abstract: Surgery is the key tool for classifying manifolds, up to homeomorphism or diffeomorphism. This sequence of talks will give an introduction to this tool, and then apply
it to specific questions in four manifold topology.

Meeting ID: 916 5855 1117

## An introduction to surgery

Posted in
Speaker:
Carmen Rovi
Affiliation:
Universität Heidelberg/MPIM
Date:
Mon, 2021-04-12 14:00 - 15:00
Parent event:
MPIM Topology Seminar
The goal of this survey talk is to provide an introduction to surgery theory.  Generally speaking, surgery theory is concerned with the classification of high-dimensional manifolds, where high means greater or equal to 4.  Surgery allows us to study the existence and uniqueness of manifold structures within a prescribed homotopy type, dealing with the following questions:

1) "Can we find a manifold within a homotopy type?"
2) "When is a homotopy equivalence of m-dimensional manifolds homotopic to a homeomorphism?"

## Geometry without spaces: a hyperbolic parable

Posted in
Speaker:
Nicolas Monod
Affiliation:
École Polytechnique Fédérale de Lausanne (EPFL)
Date:
Thu, 2021-04-29 16:30 - 18:00

We revisit old ideas that are shared by functional analysts and logicians alike, in order to do hyperbolic geometry without bothering with practicalities such as spaces or dimension.

Our main interest will be the interplay between (real or complex) hyperbolic geometry and group representations.

## Fibered periods and modularity of conifold fibers

Posted in
Speaker:
Vasily Golyshev
Affiliation:
Moscow
Date:
Wed, 2021-04-07 14:30 - 15:30
Parent event:
Number theory lunch seminar

This is a progress report on my work with Kilian Bönisch and Albrecht Klemm.
We study explicit modular fibrations of rigid Calabi-Yau manifolds occurring as fibers in hypergeometric families similar to the one constructed from the mirror quintic.

Zoom Meeting ID: 919 6497 4060
For password see the email or contact Pieter Moree (moree@mpim...).

## Skein Algebras and Categories

Posted in
Speaker:
Juliet Cooke
Affiliation:
Université Catholique de Louvain/MPIM
Date:
Mon, 2021-03-29 14:30 - 15:00
Parent event:
MPIM Topology Seminar

In this talk I will discuss how to extend skein algebras into skein categories and interpret these skein categories as factorisation homology theories before returning again to algebras.

Meeting ID: 916 5855 1117
Contact: Arunima Ray, Tobias Barthel
Seminar page: https://nextcloud.mpim-bonn.mpg.de/s/Tq9bsCWsAJrRiNk

## Arf invariants in low dimensions

Posted in
Speaker:
Michael Klug
Affiliation:
Berkeley/MPIM
Date:
Mon, 2021-03-29 14:00 - 14:20
Parent event:
MPIM Topology Seminar

I will briefly discuss some work in progress regarding a relationship between several different mod 2 invariants in dimensions 2, 3, and 4. In particular, I will relate the Arf invariant of a knot, the Arf invariant of a characteristic surface, the Rochlin invariant of a homology sphere, and the Kirby-Siebenmann invariant of a 4-manifold.

Meeting ID: 916 5855 1117
Contact: Arunima Ray, Tobias Barthel

## On the negative Pell equation

Posted in
Speaker:
Carlo Pagano
Affiliation:
University of Glasgow/MPIM
Date:
Wed, 2021-03-24 11:00 - 12:00
Parent event:
Number theory lunch seminar

Zoom Meeting ID: 919 6497 4060
For password see the email or contact Pieter Moree (moree@mpim...).

How often does the ring of integers of a real quadratic field have a unit with norm -1? In 1995
Peter Stevenhagen proposed a precise conjectural asymptotic formula describing how many such real quadratic fields should be out there when counted by discriminant. I will discuss a joint upcoming work with Peter Koymans where we establish Stevenhagen's conjecture.

## Exponential sums over primes in short intervals, arithmetic progressions and zeros of the Riemann zeta function

Posted in
Speaker:
Bryce Kerr
Affiliation:
MPIM
Date:
Wed, 2021-03-31 14:30 - 15:30
Parent event:
Number theory lunch seminar

Zoom Meeting ID: 919 6497 4060
For password see the email or contact Pieter Moree (moree@mpim...).

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