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

The Stark conjecture over the field of rational numbers: A new approach

Posted in
Speaker: 
Robert Sczech
Affiliation: 
Rutgers University
Date: 
Wed, 31/05/2023 - 14:30 - 15:30
Location: 
MPIM Lecture Hall
Parent event: 
Number theory lunch seminar

Contact: Pieter Moree (moree @ mpim-bonn.mpg.de)

 

We present a new proof for the algebraicity of the cyclotomic Stark units. These units are defined in a transcendental way, via the derivative at s=0 of a partial zeta function. The proof links these units to the special values of the Riemann zeta function at positive even integers. The rationality of these special values (modulo a power of pi) implies the algebraicity of the cyclotomic Stark units.

 

On the natural stratification of the space of differentiable functions and the space of Morse functions

Posted in
Speaker: 
Julian Brueggemann
Affiliation: 
MPIM/Universität Bonn
Date: 
Tue, 30/05/2023 - 16:30 - 18:00
Location: 
MPIM Lecture Hall
Parent event: 
IMPRS seminar on various topics: Cerf theory

Hybrid. Contact: Christian Kaiser (kaiser @ mpim-bonn.mpg.de)

Margulis Lemma and RCD spaces

Posted in
Speaker: 
Sergio Zamora Barrera
Affiliation: 
Penn State University/MPIM
Date: 
Thu, 01/06/2023 - 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

Contact: Christian Kaiser (kaiser @ mpim-bonn.mpg.de)

The classic Margulis Lemma states that in a hyperbolic manifold, the subgroup of the fundamental group generated by small loops around a certain point is virtually abelian.
I will present some generalizations of this result, includingrecent work (with Qin Deng, Jaime Santos, and Xinrui Zhao) where we include RCD spaces, a non-smooth analogue of manifolds with a lower bound on the Ricci curvature.

 

 

tba

Posted in
Speaker: 
Fan Ye
Date: 
Thu, 15/06/2023 - 12:00 - 13:00
Location: 
MPIM Lecture Hall
Parent event: 
Low-dimensional topology seminar

Contact: Aru Ray (aruray @ mpim-bonn.mpg.de), Steven Sivek (sivek @ mpim-bonn.mpg.de)


 

4-genus bounds from the 10/8+4 theorem

Posted in
Speaker: 
Gordana Matic
Affiliation: 
UGA/MPIM
Date: 
Thu, 01/06/2023 - 12:00 - 13:00
Location: 
MPIM Lecture Hall
Parent event: 
Low-dimensional topology seminar

Contact: Aru Ray (aruray @ mpim-bonn.mpg.de)

Donald and Vafaee described a way to use Furuta’s 10/8 theorem to obstruct sliceness in the 4-ball and Linh Truong used a refinement, the 10/8 +4 theorem of Hopkins-Lin-Shi and Hu, to strengthen this sliceness obstruction. We will show how to expand on this technique to obtain lower bounds for four-ball genus and present some calculations for satellite knots. This is joint work in progress with Sashka Kjuchukova and Linh Truong.

The Nielsen realization for non-spin 4-manifolds

Posted in
Speaker: 
Mihail Arabadji
Affiliation: 
UMass Amherst/MPIM
Date: 
Thu, 01/06/2023 - 10:30 - 11:30
Location: 
MPIM Lecture Hall
Parent event: 
Low-dimensional topology seminar

Contact: Aru Ray (aruray @ mpim-bonn.mpg.de)

We are going to show that there are many families of non-spin 4–manifolds for which the smooth Nielsen realization problem fails; that is, there are (finite) subgroups of their mapping class groups that cannot be realized by a group of diffeomorphisms. This extends and complements the recent results for spin 4–manifolds. This is joint work with Inanc Baykur.


 

 


 

tba

Posted in
Speaker: 
Will Donovan
Affiliation: 
Tsinghua University
Date: 
Mon, 26/06/2023 - 14:00 - 14:50
Location: 
MPIM Lecture Hall
Parent event: 
Mini-workshop in algebraic geometry
Details: 
Program and Abstracts of tba

Contact: Nicolas Addington

tba

Posted in
Speaker: 
Hsueh-Yung Lin
Affiliation: 
National Taiwan University
Date: 
Mon, 26/06/2023 - 11:00 - 12:00
Location: 
MPIM Lecture Hall
Parent event: 
Mini-workshop in algebraic geometry

Contact: Nicolas Addington

tba

Posted in
Speaker: 
Swarnava Mukhopadhyay
Affiliation: 
TIFR/MPIM
Date: 
Mon, 26/06/2023 - 09:30 - 10:30
Location: 
MPIM Lecture Hall
Parent event: 
Mini-workshop in algebraic geometry

Contact: Nicolas Addington

On opers and complex lagrangians

Posted in
Speaker: 
Olivia-Mirela Dumitrescu
Date: 
Thu, 25/05/2023 - 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

Contact: Christian Kaiser

In 2014 Gaiotto conjectured a correspondence between a holomorphic  lagrangian (Hitchin section) in the Dolbeault moduli space of Higgs bundles on a curve ​and the holomorphic lagrangian of opers in the de Rham moduli space of holomorphic connections. This conjecture was established in 2016 for holomorphic opers with an arbitrary complex simple Lie group; the construction is known today as the conformal limit.

Algebraic structures in symplectic geometry I

Posted in
Speaker: 
Nate Bottman
Affiliation: 
MPIM
Date: 
Mon, 22/05/2023 - 12:15 - 13:45
Location: 
MPIM Lecture Hall
Parent event: 
IMPRS Minicourse

Contact: Christian Kaiser

 

Algebraic structures in symplectic geometry II

Posted in
Speaker: 
Nate Bottman
Affiliation: 
MPIM
Date: 
Tue, 23/05/2023 - 16:30 - 18:00
Location: 
MPIM Lecture Hall
Parent event: 
IMPRS Minicourse

Contact: Christian Kaiser

 

On Chowla's non-vanishing conjecture over function fields

Posted in
Speaker: 
Carlo Pagano
Affiliation: 
Concordia University/MPIM
Date: 
Wed, 24/05/2023 - 14:30 - 15:30
Location: 
MPIM Lecture Hall
Parent event: 
Number theory lunch seminar

Chowla's conjecture postulates that the L-function of a quadratic character over Q should never vanish at s=1/2. At present we know that this holds for a positive proportion of characters, thanks to Soundararajan. We also know that over function fields Fq(T) the naive analogue of Chowla's conjecture is false: Li has constructed infinitely many quadratic characters with L-function vanishing at 1/2. The refined form of Chowla's conjecture postulates that the non-vanishing should hold with probability 1.

The Kodaira classification of the moduli of hyperelliptic curves

Posted in
Speaker: 
Ignacio Barros
Affiliation: 
Antwerpen
Date: 
Thu, 25/05/2023 - 10:30 - 11:30
Location: 
MPIM Lecture Hall
Parent event: 
Seminar Algebraic Geometry (SAG)

We study the birational geometry of the moduli spaces of hyperelliptic curves with marked points. We show that these moduli spaces are much worst from the point of view of singularities than the moduli space of pointed stable curves M_{g,n}, but much better from the point of view of birational complexity. We provide a full Kadaira classification with the surprising feature that for n large fixed, the Kodaira dimension decreases as the genus grows. In other words, the space becomes "simpler" as the genus grows. Further, we study the polyhedrality of the effective cone.

Course on slice knots and knot concordance

Posted in
Date: 
Tue, 23/05/2023 - 10:15 - 12:00
Location: 
MPIM Lecture Hall
Parent event: 
Course on slice knots and knot concordance

Contact: Aru Ray (aruray @ mpim-bonn.mpg.de)

Dirichlet eigenvalues of regular polygons

Posted in
Speaker: 
Danylo Radchenko
Affiliation: 
CNRS/MPIM
Date: 
Wed, 17/05/2023 - 14:30 - 15:30
Location: 
MPIM Lecture Hall
Parent event: 
Number theory lunch seminar

Contact: Pieter Moree (moree @ mpim-bonn.mpg.de)

tba

Posted in
Speaker: 
Darrick Lee
Affiliation: 
Oxford
Date: 
Wed, 07/06/2023 - 10:30 - 12:00
Location: 
MPIM Seminar Room
Parent event: 
Higher Differential Geometry Seminar

Course on slice knots and knot concordance

Posted in
Date: 
Tue, 16/05/2023 - 10:15 - 12:00
Location: 
MPIM Lecture Hall
Parent event: 
Course on slice knots and knot concordance

Contact: Aru Ray (aruray @ mpim-bonn.mpg.de)

Strongly quasipositive knots are concordant to infinitely many strongly quasipositive knots

Posted in
Speaker: 
Paula Truöl
Affiliation: 
ETH Zürich
Date: 
Wed, 17/05/2023 - 16:30 - 17:30
Location: 
MPIM Lecture Hall
Parent event: 
Low-dimensional topology seminar

Contact: Aru Ray (aruray @ mpim-bonn.mpg.de)

Differentiation of higher groupoids in tangent categories

Posted in
Speaker: 
Lory Kadiyan
Affiliation: 
MPIM/Universität Bonn
Date: 
Mon, 15/05/2023 - 12:15 - 13:45
Location: 
MPIM Lecture Hall
Parent event: 
IMPRS seminar on various topics: Graded geometry

Hybrid.
Contact: Christian Kaiser

long format
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