# Joint Seminar

# 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, 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, November 25th, 2022** at **Bergische Universität Wuppertal** (on-site).

### TALKS

**Masanori Adachi (Shizuoka/Cologne):**A residue formula for meromorphic connections and applications to stable sets of foliations

Abstract:

We discuss a proof for Brunella’s conjecture: a codimension one holomorphic foliation on a compact complex manifold of dimension > 2 has no exceptional minimal set if its normal bundle is ample. The main idea is the localization of the first Chern class of the normal bundle of the foliation via a holomorphic connection. Although this localization was done via that of the first Atiyah class in our previous proof, we shall explain that this can be shown more directly by a residue formula. This talk is based on joint works with S. Biard and J. Brinkschulte.**Laurentiu Maxim (Madison/MPI Bonn):**On the topology of aspherical complex projective manifolds and related questions

Abstract:

I will report on recent progress on various open problems involving aspherical complex projective manifolds, including the Singer-Hopf conjecture and the Bobadilla-Kollar conjecture. The first part of the talk will be very informal, stating the main problems, historical developments, and some recent results. In the second part I will introduce the main technical tools and sketch proofs of some of the recent results.**Sara Torelli (Hannover):**Holomorphic one forms on moduli of curves

Abstract:

The moduli space $\mathcal{M}_g$ of smooth projective curves of genus $g$ is a quasi-projective variety, singular on loci of dimension at most $2g-1$. Let $\mathcal{M}^0_g$ denote its smooth locus. Not much is known about the cohomology $H^i(\mathcal{M}^0_g, \mathbb{C})$ and even less about the spaces of holomorphic forms $H^i(\Omega^j_{\mathcal{M}^0_g})$. Notice that $\mathcal{M}_g$ is not compact, so in particular it doesn't carry a Hodge decomposition and thus $H^i(\Omega^j_{\mathcal{M}^0_g})$ can't be recovered from $H^i(\mathcal{M}^0_g, \mathbb{C})$ just using Hodge theory. In the talk I will present the result for $i=1,j=0$, namely that $\mathcal{M}^0_g$ does not admit holomorphic 1-forms. The work is joint with F.F. Favale and G.P.Pirola.

### SCHEDULE

**10:30 - 11:30** Adachi

**11:45 - 12:45** Maxim

**afterwards** Lunch break

**14:30 - 15:30** Torelli

### VENUE

Morning talks will take place in

**Hörsaal 10**, afternoon talks in

**Hörsaal 8**. A campus map indication the location of the lecture halls 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

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