Joint Seminar on Complex Algebraic Geometry and Complex Analysis
(Bochum - Essen - Köln - Wuppertal)

Photo by Max Greve and Timo Bobert

The Seminar

The "Joint Seminar on Complex Algebraic Geometry and Complex Analysis" is a research seminar, organised by the algebraic and complex geometry research groups in Bochum, Essen, Cologne, and Wuppertal. The seminar meets roughly twice per semester for a full day in Bochum, Essen, Cologne, or Wuppertal. There are three talks per meeting, both by invited guests and by speakers from the organising universities. We aim to leave ample room for discussions.

The talks are open for everyone. Contact one of the organisers if you are interested in attending the meeting. We have some funds that might help to support travel for some junior participants.

Meetings of the seminar are partially supported by the DFG via

• GRK 2553 "Symmetries and Classifying Spaces - analytic, arithmetic, and derived" (Essen)
• SFB/TR 191 "Symplectic structures in geometry, algebra and dynamics" (Bochum-Cologne)

Next Meeting

DATE AND PLACE

The next meeting will take place on Friday, June 18th, 2021 in a virtual format, hosted by Cologne.

TALKS

• Gordon Heier (Houston): Complex analytic and diophantine height inequalities and hyperbolicity
  
  Abstract:
  It has been known for several decades that the area of complex analysis known as Nevanlinna theory (a.k.a. value distribution theory) has many similarities with the theory of diophantine approximation. In his 1983 thesis, Vojta suggested a concrete dictionary relating the two sides. In this spirit, we present our recent generalizations of Cartan's second main theorem in Nevanlinna theory and of the diophantine approximation theorems of Roth and Schmidt. Our approach is to bring modern techniques from algebraic geometry such as Seshadri constants, notions of positivity, and blowing-ups to bear on these types of problems. As applications, we obtain new hyperbolicity theorems generalizing the classical theorems of Picard on entire holomorphic functions and Siegel on integral points. This is joint work with Aaron Levin.



• Louis Ioos (Tel Aviv): Quantization of Kähler-Ricci solitons
  
  Abstract:
  We will show how Kähler-Ricci solitons can be smoothly approximated by relative anticanonically balanced metrics, also called quantized Kähler-Ricci solitons. As a corollary, we recover the classical result of Tian and Zhu on uniqueness of Kähler-Ricci solitons up to automorphisms. Our approach involves a key simplification of a strategy due to Donaldson, via a semiclassical estimate on the quantum noise of Berezin-Toeplitz quantization following joint work with Kaminker, Polterovich and Shmoish.



• Ursula Ludwig (Duisburg-Essen): An Extension of a Theorem by Cheeger and Müller to Spaces with Isolated Conical Singularities
  
  Abstract:
  An important comparison theorem in global analysis is the comparison of analytic and topological torsion for smooth compact manifolds equipped with a unitary flat vector bundle. It has been conjectured by Ray and Singer and has been independently proved by Cheeger and Müller in the ’70s. Bismut and Zhang combined the Witten deformation and local index techniques to generalise the result of Cheeger and Müller to flat vector bundles with arbitrary Hermitian metrics. The aim of this talk is to present an extension of the Cheeger-Müller theorem to spaces with isolated conical singularities by generalising the proof of Bismut and Zhang to the singular setting. In the first part of the talk I will recall the classical Cheeger-Müller theorem on a compact smooth manifold, as well as the main ideas of the approach of Bismut and Zhang to it.

SCHEDULE

11:45 - 12:45 Ioos

13:00 - 14:00 Ludwig

afterwards Lunch break

15:00 - 16:00 Heier

VENUE

Talks will take place using ZOOM. Access data will be distributed via the usual channels. In case you don't have the information and want to participate, please write an eMail to one of the organisers in order to gain access.

Organisers

Valdemar Tsanov
Ruhr-Universität Bochum
Valdemar [dot] Tsanov [at] ruhr-uni-bochum [dot] de

Daniel Greb
Universität Duisburg-Essen
daniel [dot] greb [at] uni-due [dot] de

George Marinescu
Universität zu Köln
gmarines [at] math [dot] uni-koeln [dot] de

Jean Ruppenthal
Bergische Universität Wuppertal
jean [dot] ruppenthal [at] math [dot] uni-wuppertal [dot]de

Past Meetings

26.4.2013, Bochum: Tim Kirschner, Christian Miebach, Henrik Seppänen

28.6.2013, Wuppertal: Rafael Andrist, Immanuel Stampfli, Matei Toma

22.11.2013, Bochum: Sébastien Boucksom, Egmont Porten, Sönke Rollenske

24.1.2014, Wuppertal: Clemens Jörder, Helge Ruddat, Jörg Winkelmann

16.5.2014, Bochum: Alberto Abbondandolo, Judith Brinkschulte, Julius Ross

20.6.2014, Wuppertal: Julie Déserti, Slawomir Dinew, Slawomir Rams

24.10.2014, Bochum: Henri Guenancia, Shulim Kaliman, Adriano Tomassini

15.12.2014, Wuppertal: Richard Lärkäng, Christian Miebach, Marco Spinaci

7.5.2015, Essen: Brent Doran, Erwan Rousseau, Emanuel Scheidegger

15.6.2015, Bochum: Roya Beheshti, Daniel Greb, Hossein Raufi

27.11.2015, Wuppertal: Francesco Bei, Kai Cieliebak, Tyson Ritter

1.2.2016, Essen: Ursula Ludwig, George Marinescu, Wenhao Ou

25.4.2016, Wuppertal: Gian Maria Dall’Ara, Christian Lehn, Luca Tasin

26.6.2016, Cologne: Chin-Yu Hsiao, Stefan Nemirovski, Nikhil Savale

25.11.2016, Bochum: Ana-Maria Brecan, Antonio di Scala, Dan Popovici

27.1.2017, Essen: Tim Kirschner, Viêt Anh Nguyên, Stefan Schreieder

21.4.2017, Wuppertal: Vicente Cortés, Philipp Naumann, Markus Reineke

7.7.2017, Cologne: Roger Bielawski, Dan Coman, Martin Schwald

3.11.2017, Bochum: Junyan Cao, Sönke Rollenske, Robert Szöke

1.2.2018, Essen: Gilberto Bini, Ruadhaí Dervan, Hendrik Herrmann

27.4.2018, Wuppertal: Hugues Auvray, Bernd Stratmann, Michael Lennox Wong

6.7.2018, Cologne: Turgay Bayraktar, Jarek Buczynski, Andrew Dancer

23.11.2018, Bochum: Ben Anthes, Kevin Fritsch, Ariyan Javanpeykar

18.1.2019, Essen: André Belotto, Andreas Höring, Valdemar Tsanov

12.4.2019, Wuppertal: Ya Deng, Christian Miebach, Duc Viet Vu

5.7.2019, Cologne: Tien-Cuong Dinh, Xiaonan Ma, Nessim Sibony

21.11.2019, Bochum: Patrick Graf, Ulrike Rieß, Jonas Stelzig

16.1.2020, Essen: Anda Degeratu, Takeo Ohsawa, Mihai Paun

14.5.2020, Wuppertal (via ZOOM): Lynn Heller, Simone Marchesi, Jan Swoboda

16.7.2020, Cologne (via ZOOM): Shin-ichi Matsumura, Sönke Rollenske, Lars Martin Sektnan

17.11.2020, Bochum (via ZOOM): Rafael Andrist, Nicholas Buchdahl, Eleonora di Nezza

29.1.2021, Essen (via ZOOM): Robert Berman, Simone Diverio, Ilaria Mondello

7.5.2021, Wuppertal (via ZOOM): Siarhei Finski, Laszlo Lempert, Katharina Neusser