Upcoming Talks

Abstracts of upcoming talks at the MPIM. For an overview see also the calendar [2].

Oberseminar Arithmetic Geometry and Representation Theory [3]

Posted in

Talk [4]

Organiser(s):

Prof. Dr. J. Fintzen, Prof. Dr. T. Kaletha, Prof. Dr. P. Scholze

Date:

Fri, 11/10/2024 - 14:05 - Fri, 19/12/2025 - 16:00

Location:

MPIM Lecture Hall [5]

Details:

Program [6] and Abstracts [7] of Oberseminar Arithmetic Geometry and Representation Theory

https://people.mpim-bonn.mpg.de/scholze/veranstaltungen.html

Metric ribbon graphs [8]

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Talk [4]

Speaker:

Ivan Yakovlev

Affiliation:

MPIM

Date:

Tue, 15/07/2025 - 11:00 - 12:00

Location:

MPIM Lecture Hall [5]

Parent event:

Low-dimensional topology seminar [9]

Metric ribbon graphs (MRG) are graphs embedded into surfaces equipped with positive edge lengths. Functions counting MRG's with given boundary lengths are a priori piecewise polynomials, but in some cases become honest polynomials.

I will first present one such case -- Kontsevich's polynomials counting trivalent MRG's (from his proof of Witten's conjecture about intersection numbers on the moduli spaces of curves), and explain how they are used to study hyperbolic and flat surfaces.

Read more [8]

Sharp mixed moment bounds for zeta times a Dirichlet L-function [10]

Posted in

Talk [4]

Speaker:

Markus Hagen

Affiliation:

NTNU

Date:

Tue, 15/07/2025 - 16:30 - 17:30

Location:

MPIM Lecture Hall [5]

Parent event:

PLeaSANT (Participative Learning Seminar on Any Number Theory) [11]

A famous theorem of Selberg asserts that $\log|\zeta(\tfrac12+it)|$ is approximately a normal distribution with mean $0$ and variance $\tfrac12\log\log T$, when we sample $t\in [T,2T]$ uniformly.

Read more [10]

Condensable Topological Defects in 4D Dijkgraaf-Witten models—Classification of Fusion 2-Categorical Symmetries [12]

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Talk [4]

Speaker:

Hao Xu

Affiliation:

Göttingen

Date:

Wed, 16/07/2025 - 10:30 - 12:00

Location:

MPIM Lecture Hall [5]

Parent event:

Higher Differential Geometry Seminar [13]

Given a finite group $G$ a 4-cocycle $\pi \in \mathrm{H}^4(G,U(1))$, the 4D Dijkgraaf–Witten model provides an exactly solvable gauge theory with applications in high-energy physics and topological phases of matter. The topological defects in this model form a braided fusion 2-category $\mathscr{Z}(\mathbf{2Vect}^\pi_G)$, the Drinfeld center of $\pi$-twisted $G$-crossed finite semisimple linear categories.

Read more [12]

Hyperbolic Counting and Equidistribution [14]

Posted in

Talk [4]

Speaker:

Marios Voskou

Affiliation:

MPIM

Date:

Wed, 16/07/2025 - 14:30 - 15:30

Location:

MPIM Lecture Hall [5]

Parent event:

Number theory lunch seminar [15]

In Euclidean space, the Gauss Circle Problem concerns estimating the number of lattice points inside a Euclidean circle. In this talk, we examine analogous problems in the hyperbolic plane, approached through the lens of the spectral theory of automorphic forms. We also highlight arithmetic applications, particularly the distribution of ideals in number fields.

Khovanov skein lasagna modules with 1-dimensional inputs [16]

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Talk [4]

Speaker:

Qiuyu Ren

Affiliation:

UC Berkeley

Date:

Thu, 17/07/2025 - 11:00 - 12:00

Location:

MPIM Lecture Hall [5]

Parent event:

Low-dimensional topology seminar [9]

Skein lasagna modules (with 0-dimensional inputs) are 4-manifold invariants introduced by Morrison-Walker-Wedrich. In this context, a skein is a properly embedded surface in a 4-manifold minus a disjoint union of 4-balls, and the lasagna comes from a TQFT for links in S^3 (satisfying mild conditions).

Read more [16]

Non-displaceable Lagrangians in certain Hamiltonian $T$-manifolds [17]

Posted in

Talk [4]

Speaker:

Yao XIao

Affiliation:

MPIM

Date:

Thu, 17/07/2025 - 12:45 - 13:45

Location:

Lipschitz-Saal, Center for Mathematics Bonn [18]

Parent event:

Bonn symplectic geometry seminar [19]

We will discuss how to find Lagrangian submanifolds that are non-displaceable under Hamiltonian diffeomorphisms in certain manifolds with Hamiltonian torus actions, using Lagrangian Floer theory and its equivariant version. The case of compact toric manifolds will be reviewed.

Degeneration of Kähler polarisations associated to imaginary-time flow [20]

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Talk [4]

Speaker:

Dan Wang

Affiliation:

MPIM

Date:

Thu, 17/07/2025 - 15:00 - 16:00

Location:

MPIM Lecture Hall [5]

Parent event:

MPI-Oberseminar [21]

Geometric quantization on symplectic manifolds plays an important role in representation theory and mathematical physics, and is deeply related to symplectic and differential geometry. A crucial problem is to understand the relationships among geometric quantizations associated with different polarizations. In this talk, we will discuss the existence of mixed polarizations and degeneration of Kähler polarizations associated to imaginary-time flow.

Zero entropy on entire Grauert tubes [22]

Posted in

Talk [4]

Speaker:

Pablo Suarez-Serrato

Affiliation:

UNAM/MPIM

Date:

Thu, 17/07/2025 - 16:30 - 17:00

Location:

MPIM Lecture Hall [5]

Parent event:

Summer Geometry Day [23]

On Fixed-Point Sets of $\Z_2$-Tori in Positive Curvature [24]

Posted in

Talk [4]

Speaker:

Catherine Searle

Affiliation:

Wichita State University/MPIM

Date:

Thu, 17/07/2025 - 17:00 - 17:30

Location:

MPIM Lecture Hall [5]

Parent event:

Summer Geometry Day [23]

In recent work of Kennard, Khalili Samani, and the last author, they generalize the Half-Maximal Symmetry Rank result of Wilking for torus actions on positively curved manifolds to $\mathbb{Z}_2$-tori with a fixed point. They show that if the rank is approximately one-fourth of the dimension of the manifold, then fixed point set components of small co-rank subgroups of the $\Z_2$-torus are homotopy equivalent to spheres, real projective spaces, complex projective spaces, or lens spaces.

Read more [24]