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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, organised by the algebraic and complex geometry research groups in Bochum, Essen, Cologne, Münster, and Wuppertal. 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 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-Heidelberg)
- ANR-DFG-Projekt QuaSiDy - "Quantization, Singularities, and Holomorphic Dynamics"
Next Meeting
DATE AND PLACE
The next meeting will take place on Friday, January 20th, 2023 at Universität zu Köln (on-site).
TALKS
- Fabrizio Bianchi (Lille) : Holomorphic motions of Julia sets: dynamical stability in one and several
complex variables
Abstract:
We discuss the stability of holomorphic dynamical systems under perturbation. In dimension 1, the theory is now classical and is based on works by Lyubich, Mané-Sad-Sullivan and DeMarco. I will review this theory and present a recent generalisation valid in any dimension. Since classical 1- dimensional techniques no longer apply in higher dimensions, our approach is based on ergodic and pluripotential methods. - Tobias Harz (Wuppertal): On plurisubharmonic defining functions for pseudoconvex domains in $\mathbb{C}^2$
Abstract:
I will present a recent joint work with A.-K. Gallagher. We investigate the question of existence of plurisubharmonic defining functions for smoothly bounded, pseudoconvex domains in $\mathbb{C}^2$. In particular, we construct a family of simple counterexamples to the existence of plurisubharmonic smooth local defining functions. Moreover, we give general criteria equivalent to the existence of plurisubharmonic smooth defining functions on or near the boundary of the domain. These equivalent characterizations are then explored for some classes of domains. - Susanna Zimmermann (Paris): Birational involutions of the real plane
Abstract:
Every birational map of the complex plane is a composition involutions. But who are the birational involutions of the plane, up to conjugation? They were classified by Bayle-Beauville in 2000: they are either conjugate to linear maps or their conjugacy class is determined by their irrational fixed curve. In this talk I present the classification over the real numbers. In particular, I'll show that there are infinitely many non-conjugate real birational involutions fixing the same irrational curve. This is a collaboration with I. Cheltsov, F. Mangolte and E. Yasinsky.
SCHEDULE
10:30 - 11:30 Bianchi
11:45 - 12:45 Zimmermann
afterwards Lunch break
14:30 - 15:30 Harz
VENUE
The talks will take place in Seminarraum 2 at the Mathematical Institute of the University of Cologne. A campus map indicating the location of the Maths Institute can be found here (search for "Mathematik").
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
Ursula Ludwig
WWU Münster
ursula [dot] ludwig [at] uni-muenster [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