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

Photo by Max Greve and Timo Bobert

The Seminar

The "Joint Seminar on Complex Algebraic Geometry and Complex Analysis" is a research seminar, run by the algebraic and complex geometry research groups in Bochum, Essen, Cologne, Münster, and Wuppertal since 2013. The seminar meets roughly twice per semester for a full day at one of the participating departments. 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

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

Next Meeting

DATE AND PLACE

The next meeting will take place on Friday, November 21st, 2025 at Universität zu Köln.

TALKS

• Max Janke (Köln): A class of globally analytic hypoelliptic operators on compact Lie groups
  
  Abstract:
  In this talk, I will discuss global analytic hypoellipticity for a class of differential operators that can be expressed as $P = \sum_{j=1}^\nu X_j^2 + X_0 + a$ with real-analytic coefficients on compact Lie groups. To obtain global analytic hypoellipticity, we assume that the vector fields satisfy Hörmander's finite type condition and that there exists a closed subgroup whose action leaves the vector fields invariant. We further assume the operator is elliptic in directions transversal to the action of the subgroup. This paves the way for further studies on the regularity of sums of squares on principal fiber bundles.



• Roland Púček (RUB): TBA
  
  Abstract:
  TBA



• Shengxuan ZHOU (Toulouse): An Explicit Uniform Bound for Rational Points on Curves
  
  Abstract:
  The celebrated Mordell conjecture, proved by Faltings, asserts that a curve of genus greater than one over a number field has only finitely many rational points. A deep uniform upper bound on the number of rational points follows from Vojta's inequality and the recent works of Dimitrov-Gao-Habegger and Kühne. In this talk, I will introduce an explicit version of this uniform bound. Our approach relies on analyzing Arakelov Kähler forms via localization of Bergman kernels. This is joint work with Jiawei Yu and Xinyi Yuan.

SCHEDULE

10:30 - 11:30 Zhou

11:45 - 12:45 Jahnke

afterwards Lunch

14:30 - 15:30 Púček

VENUE

Talks will take place in the Seminarraum 2 (Raum 204) in the Mathematical Institute, Weyertal 86-90. A campus map can be found here.

Organisers

Stéphanie Cupit-Foutou
Ruhr-Universität Bochum
stephanie [dot] cupit [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

18.6.2021, Cologne (via ZOOM): Gordon Heier, Louis Ioos, Ursula Ludwig

26.11.2021, Bochum: Nikhil Savale, Martin Schwald, Jörg Winkelmann

11.03.2022, Essen: Narasimha Chary Bonala, Matteo Costantini, Josias Reppekus

27.05.2022, Münster: Markus Banagl, Francesco Bei, Nicolina Istrati

20.06.2022, Essen: Workshop organised by JS organisers

25.11.2022, Wuppertal: Masanori Adachi, Laurentiu Maxim, Sara Torelli

20.1.2023, Cologne: Fabrizio Bianchi, Tobias Harz, Susanna Zimmermann

28.4.2023, Bochum: Hans-Joachim Hein, Silvia Sabatini, Richard Wentworth; 10 year celebration

7.7.2023, Essen: Ravjot Kohli, Thomas Kurbach, Niklas Müller

27.10.2023, Münster: Stefan Nemirovski, Shu Shen, Carolina Tamborini

19.2.2024, Wuppertal: Bo Berndtsson, Ana Botero, Jörg Winkelmann

26.4.2024, Cologne: Cécile Gachet, Christian Lehn, Johannes Scheffler

12.7.2024, Bochum: Stéphanie Cupit-Foutou, Bingxiao Liu, Jörg Schürmann

6.12.2024, Essen: Michele Ancona, Siarhei Finski, Alice Garbagnati

25.2.2025, Essen: Judith Brinkschulte, Matteo Costantini

11.4.2025, Wuppertal: Jun-Muk Hwang, Takayuki Koike, Matilde Maccan

18.7.2025, Bochum: Workshop on Transformation Groups, organised by JS organisers