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

A dichotomy in dimension four

Posted in
Speaker: 
Inanc Baykur
Zugehörigkeit: 
University of Massachusetts-Amherst
Datum: 
Die, 23/04/2024 - 11:45 - 13:00
Location: 
MPIM Lecture Hall

Does every four-manifold admit either no smooth structure or infinitely many of them? I'll report on recent work, joint with A. Stipsicz and Z. Szabó, addressing this question for four-manifolds with finite cyclic fundamental groups. A bonus discussion may feature fake projective planes in the context of yet another dichotomy.

tba

Posted in
Speaker: 
Stefano Riolo
Zugehörigkeit: 
Università di Bologna
Datum: 
Die, 18/06/2024 - 11:45 - 12:45
Location: 
MPIM Lecture Hall

Group rings and hyperbolic geometry

Posted in
Speaker: 
Grigori Avramidi
Zugehörigkeit: 
MPIM
Datum: 
Mon, 22/04/2024 - 14:00 - 15:00
Location: 
MPIM Lecture Hall
Parent event: 
MPIM Topology Seminar

In the 60's Cohn showed that all ideals in the group algebra of a free group are free. Bass and Wall used this result to show that all two-dimensional complexes with free fundamental groups are standard: they are all homotopy equivalent to wedges of circles and 2-spheres. The goal of this talk is to describe recent results of this type for groups acting on hyperbolic spaces. I will discuss an algorithm showing that in the group algebra of a group acting on a hyperbolic space, ideals generated by ``few'' elements are free (where "few'' is a function of the minimal displacement of the action) and an application to complexity of cell decompositions of hyperbolic manifolds. Joint work with Thomas Delzant.



 

Models for Differentiable Stack Cohomology - A journey via equivariant cohomology and Lie groupoids

Posted in
Speaker: 
Annika Tarnowsky
Zugehörigkeit: 
MPIM/Universität Bonn
Datum: 
Die, 23/04/2024 - 10:00 - 11:30
Location: 
MPIM Lecture Hall

Analytic Rings

Posted in
Speaker: 
Semen Slobodianiuk
Zugehörigkeit: 
Universität Bonn
Datum: 
Die, 23/04/2024 - 14:00 - 16:00
Location: 
MPIM Lecture Hall

Analytic prismatization

Posted in
Speaker: 
Peter Scholze
Zugehörigkeit: 
MPIM
Datum: 
Don, 25/04/2024 - 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

MPI-Oberseminar jointly with  "Arithmetic Geometry, A conference in Honor of Hèléne Esnault on the occasion of Her 70th Birthday" at IHES:
https://indico.math.cnrs.fr/event/11114/
 

Abstract: Prismatic cohomology is a unifying p-adic cohomology of p-adic formal schemes. Motivated by questions on locally analytic representations of p-adic groups and the p-adic Simpson correspondence, an extension of prismatic cohomology to rigid-analytic spaces (over Q_p or over F_p((t))) has been sought. We will explain what form this should take, and our progress on realizing this picture. This includes a degeneration from the analytic Hodge-Tate stack underlying the p-adic Simpson correspondence to a similar (analytic) stack related to the Ogus-Vologodsky correspondence in characteristic p. This is joint work in progress with Johannes Anschütz, Arthur-César le Bras and Juan Esteban Rodriguez Camargo.

 

Hecke eigen-functions for curves over local non-archimedian fields

Posted in
Speaker: 
Alexander Braverman
Zugehörigkeit: 
University of Toronto
Datum: 
Die, 23/04/2024 - 15:00 - 16:00
Location: 
MPIM Seminar Room
Parent event: 
Extra talk

We give a survey of some recent constrictions and results concerning Hecke operators for the moduli space of G-bundles on a smooth projective curve X defined over a local non-archimedian field F (possibly with level structures). These operators are somewhat analogous to the usual Hecke operators in the case when F is a finite field but describing their common eigen-values is a much more difficult task. We'll discuss on what space the Hecke operators act, formulate some general conjectures about eigen-functions and consider some examples. In the end (if time permits) I would like to discuss the example when X is of genus 0, and we study bundles with triviliazation at two points. This example is closely related to  the usual representation theory of G(F). 

The talk is based on joint works (partly in progress) with P.Etingof, D.Kazhdan and A Polishchuk.

Classical real local Langlands for GL_2(R)

Posted in
Speaker: 
Stefan Dawydiak
Zugehörigkeit: 
Universität Bonn
Datum: 
Die, 16/04/2024 - 14:00 - 16:00
Location: 
MPIM Lecture Hall

Computing differentiable stack cohomology via multiplicative Ehresmann connections

Posted in
Speaker: 
Annika Tarnowsky
Zugehörigkeit: 
MPIM
Datum: 
Mit, 17/04/2024 - 10:30 - 12:00
Location: 
MPIM Lecture Hall

tba

Posted in
Speaker: 
Ramesh Sreekantan
Zugehörigkeit: 
Indian Statistical Institute (SMU)
Datum: 
Mit, 08/05/2024 - 14:30 - 15:30
Location: 
MPIM Lecture Hall
Parent event: 
Number theory lunch seminar

Lifting differential equations

Posted in
Speaker: 
Vasily Golyshev
Zugehörigkeit: 
ICTP Trieste
Datum: 
Mit, 24/04/2024 - 14:30 - 15:40
Location: 
MPIM Lecture Hall
Parent event: 
Number theory lunch seminar

I will start by discussing 'frequently occurring congruences' and the related notion of congruence sheaves.  I will then introduce
a method to construct lifts of differential equations by using generalized Taylor's formula in a systematic way.

The talk is based on joint work with Ilia Gaiur.

 

tba *Please note location!*[Bonn symplectic geometry seminar]

Posted in
Speaker: 
Umut Varolgunes
Zugehörigkeit: 
Koç University
Datum: 
Fre, 17/05/2024 - 13:00 - 14:00
Location: 
MPIM Conference Room

Stability problems and differential graded Lie algebras

Posted in
Speaker: 
Karandeep Jandu Singh
Zugehörigkeit: 
MPIM Bonn
Datum: 
Don, 18/04/2024 - 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

Stability problems appear in various forms throughout geometry and algebra. In differential geometry, given a vector field on a manifold that vanishes in a point, one can ask when nearby vector fields also vanish in a point. In algebra, given a Lie algebra and a subalgebra, one can ask when all deformations of the ambient Lie algebra also admit a Lie subalgebra of the same dimension. I will show that both questions are instances of a general question about differential graded Lie algebras. Under a finite-dimensionality assumption which is satisfied in the examples above, I will give a sufficient condition for a positive answer to the general question. I will then discuss some applications.

Proper sheaves on Bun_G

Posted in
Speaker: 
Tim Kuppel
Zugehörigkeit: 
Universität Bonn
Datum: 
Die, 16/04/2024 - 10:00 - 11:30
Location: 
MPIM Lecture Hall

IMPRS seminar on various topics: single talk

Posted in
Datum: 
Die, 16/04/2024 - 10:00 - Die, 06/08/2024 - 11:30
Location: 
MPIM Lecture Hall

On the distribution of supersingular primes for abelian surfaces

Posted in
Speaker: 
Tian Wang
Zugehörigkeit: 
MPIM Bonn
Datum: 
Mit, 17/04/2024 - 14:30 - 15:30
Location: 
MPIM Lecture Hall
Parent event: 
Number theory lunch seminar

In 1976, Lang and Trotter conjectured the asymptotic growth for the number of primes p up to x for which the reduction of a non-CM elliptic curve E/Q at p is supersingular. Though the conjecture is still open, we now have unconditional upper and lower bounds thanks to the work of several mathematicians. However, less has been studied for the distribution of supersingular primes for abelian surfaces (even conjecturally). In this talk, I will present a recent work on unconditional upper bounds for the number of primes p up to x, for which the reduction of a fixed abelian surface at p is supersingular.

 

The equation $c_1x_1^k+...+c_sx_s^k=0$

Posted in
Speaker: 
Doyon Kim
Zugehörigkeit: 
University of Bonn
Datum: 
Mon, 22/04/2024 - 14:00 - 15:00
Location: 
MPIM Seminar Room

tba [OS Differentialgeometrie]

Posted in
Speaker: 
Jean-Marc Schlenker
Zugehörigkeit: 
University of Luxembourg/MPIM
Datum: 
Don, 02/05/2024 - 16:30 - 18:00
Location: 
MPIM Seminar Room

Teleparallel Newton—Cartan Gravity

Posted in
Speaker: 
Philip Schwartz
Zugehörigkeit: 
Universität Hannover
Datum: 
Don, 18/04/2024 - 11:30 - 14:00
Location: 
MPIM Seminar Room
Parent event: 
MPIM Math-Phys Seminar
Newton—Cartan gravity is a differential-geometric reformulation of Newtonian gravity, bringing the latter closer to general relativity (GR): as in GR, gravitational effects are encoded into spacetime geometry, which however is of non-Lorentzian nature.  Newton—Cartan gravity can be shown to be the Newtonian limit of GR in a rigorous sense, hence providing a coordinate-free geometric formulation of this limiting process.
 
In this talk, after giving a brief introduction to standard Newton—Cartan gravity, we are going to discuss a `teleparallelised' version of Newton—Cartan gravity.  We show how this theory arises as a formal large-speed-of-light limit of the so-called teleparallel equivalent of general relativity (TEGR).  Thus, it provides a geometric formulation of the Newtonian limit of TEGR, analogous to the GR case. We show how by a certain gauge-fixing the standard formulation of Newtonian gravity can be recovered.

 

 

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