## Upcoming conferences & activities

## Geometric Representation Theory

## Twinned conference "Geometric Representation Theory", June 22 - 26, 2020

### Update!

### In light of the current Covid-19 pandemic, we have decided that the conference "Geometric Representation Theory", which was to be held jointly at the Max Planck Institute and the Perimeter Institute, will not be going forward as an in-person event. We are however keen for the event to go ahead remotely, and we are currently investigating how this might be implemented.

## Workshop on "$\infty$-categories and their applications", August 17 - 21, 2020

The quest for solid foundations for $\infty$-categories started several decades ago, but from the mid-2000s there have been spectacular developments which excitingly accelerated the pace of progress. This workshop will focus on these objects, both in their foundations and in the applications to different fields of mathematics. There will be minicourses on $\infty$-categories and on related topics which have benefited substantially from the $\infty$-categorical viewpoint.

## Upcoming Talks

Abstracts of upcoming talks at the MPIM. For an overview see also the calendar.

## Recent developments in Quantum Topology -- Cancelled --

We will review the basics of quantum topology such as the colored Jones polynomial of a knot, its standard conjectures relating to asymptotics, arithmeticity and modularity, as well as the recent quantum hyperbolic invariants of Kashaev et al, their state-integrals and their structural properties. The course is aimed to be accessible by graduate students and young researchers.

## -- CANCELLED -- Specialization of Néron-Severi groups in positive characteristic

Given a family Y------> X of smooth projective varieties over a field k, we study the locus X^{ex} of closed points x in X where the rank of the Neron-Severi group of the fiber of Y------> X at x is bigger then the rank of the generic one. As simple examples show, the properties of X^{ex} depend on the arithmetic of k. We prove that if the characteristic of k is positive and k is infinite finitely generated then this locus is "small", extending previous results in characteristic zero of André and Cadoret-Tamagawa.

## -- CANCELLED -- On the Skolem Problem for parametric families of linear recurrence sequences and some G.C.D. problems

In this talk we discuss a parametric version of the Skolem Problem about decidability of the existence of a zero in a linear recurrence sequence. We show that in some natural parametric families for all but finitely many values of the parameter in the algebraic closure of the rational numbers it can be effectively solved. We then connect this problem to studying the greatest common divisor of two linear recurrence sequences of polynomials. Also, as an application we obtain an explicit version of a result of F. Amoroso, D. Masser and U.

## -- CANCELLED -- Parabolicity conjecture of F-isocrystals

We will present recent developments in the theory of overconvergent F-isocrystals, the p-adic analogue of ell-adic lisse sheaves. For the most part of the talk, we will explain a new result on the algebraic monodromy groups of these objects. At the end, we will mention an application of the theorem to the finiteness of separable p-torsion points of an abelian variety.

## -- CANCELLED --

## -- CANCELLED --

## -- CANCELLED -- Stability of polynomials modulo primes

For a polynomial $f\in\mathbb{K}[X]$ over some field $\mathbb{K}$ we define the sequence of polynomials

$$

f^0(X)=X, \quad \text{and} \quad f^{(n)}(X)=f(f^{(n-1)}(X)), \quad n=1,2,\dots

$$

The polynomial $f$ is said to be *stable* if all iterates $f^{(n)}$ are irreducible.

It is conjectured, that for a quadratic polynomial $f\in\mathbb{Z}[X]$, its reduction $f_p\in\mathbb{F}_p[X]$ modulo $p$ can be stable just for finitely many primes $p$.

## -- CANCELLED --

## Mathematical events in Bonn

##### Bonn Mathematics Calendar

All mathematical events in Bonn are listed in the Bonn Mathematics Calendar. For directions see the map.

##### University Calendar

All lectures and courses at Bonn University can be found in the university calendar.

## Recurring seminars, series and courses

Detailed list of recurring seminars, series of talks, and courses or lectures comprising multiple talks. For an overview see also the calendar.

## Friedrich Hirzebruch Lecture

The annual Friedrich Hirzebruch Lecture is a series of lectures started in 2007 on the occasion of the 80th birthday of Prof. Friedrich Hirzebruch. The lectures address a general audience and aim at illustrating the relation between mathematics and art, society and other fields.

## MPI-Oberseminar

The Oberseminar is a very long running seminar at MPI (‘Ober‘ standing for 'upper'). Its idea is that the guests of the MPI speak in this seminar (hopefully early in their stay) and get the chance to explain their work to the other guests.

## Reading group on "Integer points in polyhedra"

Website: https://sites.google.com/view/integerpointsonpolyhedra/home

We will introduce the algebra of (indicator functions) of polyhedra and study its properties. Linear forms on this algebra produce functions on the set of polytopes (*i.e.* bounded polyhedra), that are compatible with set-theoretic decompositions of polyhedra. For polytopes, the lattice point count or the volume are examples of such linear forms.

## IMPRS seminar on various topics: Hitchin systems

## IMPRS Minicourse

## Representation theory learning seminar

## Extra talk

## Archived Events

To narrow the list of events displayed please select year and event type or fill the search fields, then press *Apply*.

## MPI-Oberseminar

The Oberseminar is a very long running seminar at MPI (‘Ober‘ standing for 'upper'). Its idea is that the guests of the MPI speak in this seminar (hopefully early in their stay) and get the chance to explain their work to the other guests.

## Friedrich Hirzebruch Lecture

The annual Friedrich Hirzebruch Lecture is a series of lectures started in 2007 on the occasion of the 80th birthday of Prof. Friedrich Hirzebruch. The lectures address a general audience and aim at illustrating the relation between mathematics and art, society and other fields.

## Workshop on "$\infty$-categories and their applications", August 17 - 21, 2020

The quest for solid foundations for $\infty$-categories started several decades ago, but from the mid-2000s there have been spectacular developments which excitingly accelerated the pace of progress. This workshop will focus on these objects, both in their foundations and in the applications to different fields of mathematics. There will be minicourses on $\infty$-categories and on related topics which have benefited substantially from the $\infty$-categorical viewpoint.

## Geometric Representation Theory

## Twinned conference "Geometric Representation Theory", June 22 - 26, 2020

### Update!

### In light of the current Covid-19 pandemic, we have decided that the conference "Geometric Representation Theory", which was to be held jointly at the Max Planck Institute and the Perimeter Institute, will not be going forward as an in-person event. We are however keen for the event to go ahead remotely, and we are currently investigating how this might be implemented.

## Lecture series by Prof. Don Zagier

Time: Tuesdays, 4.30 - 6 pm

Place: MPIM Lecture Hall, Vivatsgasse 7

First lecture: on March 3, 2020, end ?

## Lecture series by Prof. Don Zagier

Time: Tuesdays, 4.30 - 6 pm

Place: MPIM Lecture Hall, Vivatsgasse 7

First lecture: on March 3, 2020, end ?

## -- CANCELLED --

## -- CANCELLED -- Stability of polynomials modulo primes

For a polynomial $f\in\mathbb{K}[X]$ over some field $\mathbb{K}$ we define the sequence of polynomials

$$

f^0(X)=X, \quad \text{and} \quad f^{(n)}(X)=f(f^{(n-1)}(X)), \quad n=1,2,\dots

$$

The polynomial $f$ is said to be *stable* if all iterates $f^{(n)}$ are irreducible.

It is conjectured, that for a quadratic polynomial $f\in\mathbb{Z}[X]$, its reduction $f_p\in\mathbb{F}_p[X]$ modulo $p$ can be stable just for finitely many primes $p$.

## Lecture series by Prof. Don Zagier

Time: Tuesdays, 4.30 - 6 pm

Place: MPIM Lecture Hall, Vivatsgasse 7

First lecture: on March 3, 2020, end ?

## -- CANCELLED --

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