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

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