This is the third instalment of the THGT conference series. As its predecessors, the conference takes place in Bielefeld in spring, and as before it welcomes researchers studying groups through their interactions with topology and homology, as well as people interested in entering the subject.

If you have questions, please contact the organisers (Kai-Uwe Bux, Dawid Kielak and Stefan Witzel).

This conference is supported by the DFG priority programme 2026 Geometry at Infinity

- Arthur Bartels
- Ursula Hamenstädt
- Tobias Hartnick
- Robert Kropholler
- Clara Löh
- Kim Ruane
- Alain Valette

The talks on Monday and Thursday morning take place in the lecture hall H12 in the main building of the Bielefeld University.

The talks on Tuesday and Thursday afternoon take place in the lecture hall H5.

The talks on Wednesday and Friday take place in the lecture hall H13.

How do I find the university and the lecture hall?For the hike we meet 14:00 in front of the Bielefelder Hof, which directly in front of the main station. The hike will be around 10 km long. There is the possibility to take a short cut (~7km).

The conference dinner will be at the Numa.

Time | Title | Speaker |
---|---|---|

Monday, 28.03 | ||

09:30 - 10:30 | Dimensions for the mapping class group | Ursula Hamenstädt |

10:30 - 11:00 | Coffee break | |

11:00 - 11:30 | A cubical Rips construction | Macarena Arenas |

12:00 - 14:00 | Lunch | |

14:00 - 14:30 | High-dimensional rational cohomology of $SL_n(\mathbb{Z})$ and $Sp_{2n}(\mathbb{Z})$ | Benjamin Brück |

14:30 - 14:45 | Short break | |

14:45 - 15:15 | Fibring of RFRS groups via L2 Betti numbers | Sam Fisher |

15:15 - 15:45 | Coffee break | |

16:00 - 16:30 | Irreducible lattices fibring over the circle | Sam Hughes |

Tuesday, 29.03 | ||

09:30 - 10:30 | Property T for some groups of tame automorphisms of $K[x,y,z]$ | Martin Kassabov |

10:30 - 11:00 | Coffee break | |

11:00 - 12:00 | $K$-theory of Hecke algebras | Arthur Bartels |

12:00 - 14:00 | Lunch | |

14:00 - 14:30 | Compact uniformly recurrent subgroups | Waltraud Lederle |

14:30 - 14:45 | Short break | |

14:45 - 15:15 | Stably free modules and the homotopy type of a finite $2$-complex | John Nicholson |

15:15 - 16:00 | Coffee break | |

16:00 - 16:30 | Stallings-Swan Theorem for unimodular totally disconnected locally compact groups | Ilaria Castellano |

Wednesday, 30.03 | ||

09:30 - 10:30 | Computations in bounded cohomology | Clara Löh |

10:30 - 11:00 | Coffee break | |

11:00 - 12:00 | Explicit Baum-Connes for semi-direct products of $\mathbb{Z}^2$ by some non-amenable subgroups of G | Alain Valette |

12:00 - 14:00 | Lunch | |

14:00 - 18:00 | Hike | |

19:00 - 23:59 | (Conference dinner) | |

Thursday, 31.03 | ||

09:30 - 10:00 | An invitation to coarse groups | Federico Vigolo |

10:30 - 11:00 | Coffee break | |

11:00 - 12:00 | Homological filling functions do not detect solubility of the word problem. | Robert Kropholler |

12:00 - 14:00 | Lunch | |

14:00 - 14:30 | Coarse Embeddings of Symmetric Spaces and Euclidean Buildings | Oussama Bensaid |

14:30 - 14:45 | Short break | |

14:45 - 15:15 | Obstructions to Riemannian smoothing of non-positively curved manifolds | Bakul Sathaye |

15:15 - 16:00 | Coffee break | |

16:00 - 17:00 | CAT(0) Groups; Example and Non-Examples (Kovalevskaya lecture) | Kim Ruane |

Friday, 01.04 | ||

09:30 - 10:30 | Random homotopies and applications to stability of bounded cohomology of arithmetic groups | Tobias Hartnick |

10:30 - 11:00 | Coffee break | |

11:00 - 11:30 | A bootstrapping argument for bounded-cohomological stability in degree three | Carlos De la Cruz Mengual |

Macarena Arenas

Arthur Bartels

Oussama Bensaid

Benjamin Brück

Ilaria Castellano

Carlos De la Cruz Mengual

Sam Fisher

Ursula Hamenstädt

Tobias Hartnick

Sam Hughes

Martin Kassabov

Robert Kropholler

Waltraud Lederle

Clara Löh

John Nicholson

Kim Ruane

Bakul Sathaye

Alain Valette

Federico Vigolo

- Abels, Herbert (
*Universität Bielefeld*) - Andritsch, Konstantin (
*ETH Zürich*) - Arenas, Macarena (
*University of Cambridge*) - Bargagnati , Giuseppe (
*Università di Pisa*) - Baumeister, Barbara (
*University Bielefeld*) - Bensaid, Oussama (
*Université de Paris*) - Bhattacherjee, Sandipan (
*Birla Institute of Technology Mesra, India*) - Blumer, Simone (
*Università degli Studi di Milano-Bicocca*) - Bonn, Laura (
*KIT - Karlsruher Institut für Technoligie*) - Brück, Benjamin (
*ETH Zürich*) - Camacho Cadena, Fernando (
*RKU Heidelberg*) - Capovilla, Pietro (
*SNS Pisa*) - Cassella, Alberto (
*University of Milano - Bicocca / University of Zaragoza*) - Castellano, Ilaria (
*University of Milano Bicocca*) - Chanfi, Dorian (
*Justus-Liebig-Universität Gießen*) - Davies, Isobel (
*Otto-von-Guericke-Universität Magdeburg*) - De la Cruz Mengual, Carlos (
*Weizmann Institute of Science*) - Escalier, Amandine (
*WWU Münster*) - Fisher, Sam (
*University of Oxford*) - Flechsig, Jonas (
*Universität Bielefeld*) - Fournier-Facio, Francesco (
*ETH Zurich*) - Friedl, Stefan (
*Universität Regensburg*) - Fruhling Dutra, Ederson Ricardo (
*University of Regensburg / University of Sao Carlos (Brazil)*) - García Mejía, Jerónimo (
*Karlsruher Institut für Technologie*) - Gardam, Giles (
*University of Münster*) - Gerasimova , Maria (
*WWU Münster*) - Hughes, Sam (
*University of Oxford*) - Incerti-Medici, Merlin (
*IHES*) - Kassabov, Martin (
*Cornell University*) - Kielak, Dawid (
*University of Oxford*) - Kirschner, Lovis (
*Justus-Liebig-Universität Gießen*) - Klinge, Kevin (
*Karlsruhe Intitute for Technology*) - Kudlinska, Monika (
*University of Oxford*) - Le Bars, Corentin (
*Université Paris Saclay*) - Lederle, Waltraud (
*UCLouvain*) - Leoni, Giorgio (
*Università degli Studi Milano-Bicocca*) - Li, Kevin (
*University of Southampton*) - Linton, Marco (
*University of Warwick*) - Lopez de Gamiz Zearra, Jone (
*University of Warwick*) - López Neumann, Antonio (
*Ecole polytechnique*) - Marasco, Domenico (
*University of Pisa*) - Marchionna, Bianca (
*University of Milano-Bicocca*) - Martínez Pérez, Conchita (
*Universidad de Zaragoza*) - Messaci, Mohamed Lamine (
*Université Côte d'Azur*) - Michael, Anna Franziska (
*Otto-von-Guericke Universität Magdeburg*) - Milizia, Francesco (
*SNS Pisa*) - Mineh, Lawk (
*University of Southampton*) - Mizerka, Piotr (
*Institute of Mathematics, Polish Academy of Sciences*) - Munser, Lars (
*Universität Regensburg*) - Nicholson, John (
*Imperial College London*) - Niemeyer, Merik (
*RKU Heidelberg*) - Nitsche, Martin (
*Karlsruhe Institute of Technology*) - Puder, Doron (
*Tel Aviv University*) - Quintanilha, José Pedro (
*Universität Bielefeld*) - Saleh, Nada (
*Justus Liebig Universität*) - Santos Rego, Yuri (
*Otto-von-Guericke Universität Magdeburg*) - Sathaye, Bakul (
*WWU Münster*) - Schesler, Eduard (
*FernUni Hagen*) - Schwer, Petra (
*OVGU Magdeburg*) - Seo, Donggyun (
*Seoul National University*) - Souza, Henrique Augusto (
*Universidad Autónoma de Madrid*) - Sun, Bin (
*University of Oxford*) - Thilmany, François (
*KU Leuven*) - Titz Mite, Thomas (
*JLU Gießen*) - Uschold, Matthias (
*Universität Regensburg*) - Varghese, Olga (
*OVGU Magdeburg*) - Vigolo, Federico (
*Münster University*) - Weigel, Thomas (
*University of Milano-Bicocca*) - Witzel, Stefan (
*JLU Gießen*) - Zumbrunnen, Alexandre (
*Université de Neuchâtel*)