# Talk

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

## ONLINE: Semisimple topological quantum field theories and exotic smooth structure

Posted in
Speaker:
David Reutte
Affiliation:
MPIM
Date:
Tue, 2020-06-09 14:00 - 15:00

https://bbb.mpim-bonn.mpg.de/b/gae-a7y-hhd

## Riemann-Hilbert problems from DT theory

Posted in
Speaker:
Gaetan Borot
Affiliation:
MPIM
Date:
Fri, 2020-05-29 18:00 - 19:30

I will start by recalling what are Riemann-Hilbert problems in the usual sense, basic notions attached to them and where they appear. Then, we will describe the notion of (variation of) BPS structure and carefully go through the definition of the corresponding Riemann-Hilbert problem (in a slightly generalized sense), and its explicit solution in the "uncoupled" case (far from being representative, but nevertheless instructive).

## ONLINE: Torsion points of abelian varieties and F-isocyrstals

Posted in
Speaker:
Affiliation:
MPIM
Date:
Tue, 2020-06-02 14:00 - 15:00

https://bbb.mpim-bonn.mpg.de/b/gae-a7y-hhd

## VIRTUAL (Zoom): Higher THH of Thom spectra: an approach via tensors, II

Posted in
Speaker:
Bruno Stonek (MPIM) and Gabriel Valenzuela (MPIM)
Date:
Mon, 2020-05-25 16:15 - 17:00
Parent event:
MPIM Topology Seminar

This talk will be streamed live on this site. We will run a zoom meeting in parallel for people to ask questions; please join if you like to participate:

## VIRTUAL (Zoom): Higher THH of Thom spectra: an approach via tensors, I

Posted in
Speaker:
Bruno Stonek (MPIM) and Gabriel Valenzuela (MPIM)
Date:
Mon, 2020-05-25 15:00 - 15:45
Parent event:
MPIM Topology Seminar

This talk will be streamed live on this site. We will run a zoom meeting in parallel for people to ask questions; please join if you like to participate:

## VIRTUAL (Zoom): Equivariant Khovanov homotopy type

Posted in
Speaker:
Wojciech Politarczyk
Affiliation:
Warsaw University
Date:
Mon, 2020-06-08 15:00 - 16:00
Parent event:
MPIM Topology Seminar

The Khovanov homotopy type is a space level refinement of Khovanov homology in troduced by Lipshitz and Sarkar. The main
goal of the talk will be to show that the Khovanov homotopy type can be effectively used to study periodic links, i.e., links which are invariant under a finite order rotation of the three-sphere. In particular, by applying the classical localization theorem for Borel cohomology and its extension we obtain interesting relations between Khovanov homology of a periodic link and Khovanov homology of the quotient.

## An introduction to refined Donaldson-Thomas theory

Posted in
Speaker:
Matthew Young
Affiliation:
MPIM
Date:
Fri, 2020-05-22 16:00 - 17:30

The subject of this talk is the refined Donaldson-Thomas theory of Konstevich and Soibelman, as further developed by Davison, Efimov, Joyce, Meinhardt, Reineke and many others. The goal of this talk is to motivate the need for a refined (as opposed to numerical) Donaldson-Thomas theory, to state the main structural results of the theory in an accessible way and to illustrate these results in concrete examples. Time permitting, I will also discuss the relationship to the motivic approach to Donaldson-Thomas theory of Joyce and Song.

## VIRTUAL (Zoom): Some applications of Heegaard Floer homology to links in the three-sphere, II

Posted in
Speaker:
Beibei Liu
Affiliation:
MPIM
Date:
Mon, 2020-05-18 16:30 - 17:00
Parent event:
MPIM Topology Seminar

Zoom meeting ID: 919-9946-8404
Password: see email announcement or contact the seminar organisers:
Tobias Barthel (barthel.tobi[at]gmail.com)
David Gay (dgay[at]uga.edu)
Arunima Ray (aruray[at]mpim-bonn.mpg.de)

## Stability conditions from quadratic differentials, Part II: global aspects and wall crossing

Posted in
Speaker:
Campbell Wheeler
Affiliation:
MPIM
Date:
Fri, 2020-05-15 15:00 - 16:30

We will put everything we've done over the last two weeks together to prove the isomorphism between spaces of stability conditions associated to surfaces and spaces of quadratic differentials. We will go through wall crossing in some detail and use this to glue the previous local results together to get the isomorphism.

## VIRTUAL (Zoom): Some applications of Heegaard Floer homology to links in the three-sphere

Posted in
Speaker:
Beibei Liu
Affiliation:
MPIM
Date:
Mon, 2020-05-18 15:00 - 16:00
Parent event:
MPIM Topology Seminar

Zoom meeting ID: 919-9946-8404
Password: see email announcement or contact the seminar organisers:
Tobias Barthel (barthel.tobi[at]gmail.com)
David Gay (dgay[at]uga.edu)
Arunima Ray (aruray[at]mpim-bonn.mpg.de)

## VIRTUAL (Zoom): A homological model for quantum braid representations and colored Jones polynomials, II

Posted in
Speaker:
Jules Martel
Affiliation:
Toulouse
Date:
Mon, 2020-05-11 16:30 - 17:00
Parent event:
MPIM Topology Seminar

Zoom meeting ID: 919-9946-8404
Password: see email announcement or contact the seminar organisers

## VIRTUAL (Zoom): A homological model for quantum braid representations and colored Jones polynomials, I

Posted in
Speaker:
Jules Martel
Affiliation:
Toulouse
Date:
Mon, 2020-05-11 15:00 - 16:00
Parent event:
MPIM Topology Seminar

Zoom meeting ID: 919-9946-8404
Password: see email announcement or contact the seminar organisers

## VIRTUAL (Zoom): Embedded Lagrangian fillings not coming from surgery, II (for experts)

Posted in
Speaker:
Maylis Limouzineau
Affiliation:
Universität zu Köln
Date:
Mon, 2020-05-04 16:30 - 17:00
Parent event:
MPIM Topology Seminar
3-4pm: first part, designed for a general topological audience
4-430pm: virtual tea
430-5pm: second part, designed for experts

Abstract:
Let $\Lambda$ be a Legendrian knot or link in the standard 3-dimensional contact space, and let $\Sigma$ be an immersed Lagrangian filling of $\Lambda$ in the symplectization.

## ONLINE: Stability conditions on quivers with potentials and triangulated surfaces

Posted in
Speaker:
Alessandro Giacchetto
Organiser(s):
Gaetan Borot, Severin Charbonnier, Alessandro Giacchetto, Reinier Kramer and Campbell Wheeler
Affiliation:
MPIM
Date:
Fri, 2020-05-01 16:00 - 17:30

Contact gborot@mpim-bonn.mpg.de to get the access code.

Abstract:

## VIRTUAL (Zoom): Embedded Lagrangian fillings not coming from surgery, I (general topol. audience)

Posted in
Speaker:
Maylis Limouzineau
Affiliation:
Universität zu Köln
Date:
Mon, 2020-05-04 15:00 - 16:00
Parent event:
MPIM Topology Seminar
3-4pm: first part, designed for a general topological audience
4-430pm: virtual tea
430-5pm: second part, designed for experts

Abstract:
Let $\Lambda$ be a Legendrian knot or link in the standard 3-dimensional contact space, and let $\Sigma$ be an immersed Lagrangian filling of $\Lambda$ in the symplectization.

## VIRTUAL (Zoom): Embedding spheres in knot traces

Posted in
Speaker:
Arunima Ray
Affiliation:
MPIM
Date:
Mon, 2020-04-27 15:00 - 16:00
Parent event:
MPIM Topology Seminar
Zoom meeting ID: 919-9946-8404
Password: see email announcement or contact the seminar organisers:
Tobias Barthel (
David Gay (dgay[at]uga.ed

## Hall algebras techniques for DT theory

Posted in
Speaker:
Severin Charbonnier
Organiser(s):
Gaetan Borot, Severin Charbonnier, Alessandro Giacchetto, Reinier Kramer and Campbell Wheeler
Affiliation:
MPIM
Date:
Fri, 2020-04-24 16:00 - 17:30

Contact gborot@mpim-bonn.mpg.de to get the access code.

Abstract:

## ONLINE: Introduction to Bridgeland stability

Posted in
Speaker:
Campbell Wheeler
Organiser(s):
Gaetan Borot, Severin Charbonnier, Alessandro Giacchetto, Reinier Kramer and Campbell Wheeler
Affiliation:
MPIM
Date:
Fri, 2020-04-17 16:00 - 17:30

or via the stream:  https://www.conf.dfn.de/stream/nr57d2v82ptdr

If you plan to join, please give Gaetan Borot (gborot[at]mpim-bonn.mpg.de) notice
in advance, so that we can make sure all people concerned are there before starting the talk.

Abstract:

## VIRTUAL (Zoom): Asymptotic of twisted Alexander polynomials and hyperbolic volume

Posted in
Speaker:
Leo Benard
Affiliation:
Göttingen
Date:
Mon, 2020-04-20 15:00 - 16:00
Parent event:
MPIM Topology Seminar

Given a hyperbolic 3-manifold of finite volume M, we compute the asymptotic of the family of twisted Alexander polynomials on the unit circle. We prove that this family growth asymptotically as the volume times the square of the dimension of the representation. The proof goes through the study of the analytic torsion of some compact hyperbolic manifolds obtained by Dehn surgery on M. Joint work with J. Dubois, M. Heusener and J. Porti.

## ONLINE: Category theory for geometers

Posted in
Speaker:
Reinier Kramer
Organiser(s):
Gaetan Borot, Severin Charbonnier, Alessandro Giacchetto, Reinier Kramer and Campbell Wheeler
Date:
Fri, 2020-04-10 10:00 - 11:30

I will give an informal introduction to categorical notions required for the seminar. This will make the talk somewhat disjointed, as I need to introduce several distinct objects. The main objects are derived categories. My main examples for these will be coherent sheaves on a scheme and quiver representations, and I will briefly recall these notions as well. Furthermore, I will briefly introduce A_\infty categories, giving the examples of path spaces and Fukaya categories.