Seminar Geometric Methods in Mathematics
This is the research seminar of Uli (Prof. Dr. Ulrich Krähmer) and his group. The talks cover topics in homological algebra and category theory, noncommutative algebra and geometry, or Hopf algebras and their generalisations. The target audience consists of PhD and MSc students.
Unless otherwise indicated, the seminar takes place in WIL B216 every Friday at 3:00 PM (CEST/CET) and we usually stream them on BigBlueButton: https://bbb.tu-dresden.de/b/ulr-ha4-xul-uoo.
The speakers for the summer term 2026 are:
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17.04.2026 |
Niels Kowalzig (Tor Vergata, Rome) |
| 24.04.2026 | Niels Kowalzig (Tor Vergata, Rome)
Brackets and products from centres in extension categories Building on Retakh’s approach to Ext groups through cate-gories of extensions, Schwede reobtained the well-known Gerstenhaber algebra structure on Ext groups over bimodules of associative algebras both from splicing extensions (leading to the cup product) and from a suitable loop in the cate-gories of extensions (leading to the Lie bracket). We show how Schwede’s construction admits a vast generalisation to general monoidal categories with coefficients of the Ext groups taken in (weak) left and right monoidal (or Drinfel’d) centres. In case of the category of left modules over bialgebroids and coefficients given by commuting pairs of braided (co)commutative (co)monoids in these categorical centres, we provide an explicit description of the algebraic structure obtained this way, and a complete proof that this leads to a Gerstenhaber algebra is then obtained from an operadic approach. This, in particular, considerably generalises the classical construction given by Gerstenhaber himself. Conjecturally, the algebraic structure we describe should produce a Gerstenhaber algebra for an arbitrary monoidal category enriched over abelian groups, but even the bilinearity of the cup product and of the Lie-type bracket defined by the abstract construction in terms of extension categories remain elusive in this general setting. |
The speakers for the winter term 2025/2026 were:
| 21.10.2025 | Marc Stephan |
| 28.10.2025 | Marc Stephan |
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GMM Reading Group on ∞-Categories and ∞-Operads (website)
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The speakers for the summer term 2025 were:
| 15.04.2025 | Andrew Baker | |
| 22.04.2025 | Ulrich Krähmer | |
|
13.05.2025 |
Marcelo Aguiar |
|
| 19.05 + 20.05 |
Symposion on Higher Structures for Hopf Algebras (website)
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|
| 20.05 | Nir Gadish | |
| 03.06 + 17.06 |
Zbigniew Wojciechowski |
|
| 01.07.25 |
Ulrich Krähmer |
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| 15.07.25 |
Ulrich Krähmer |
|
|
19.08.25 |
Florian Warg |
|
| 17.09.25 |
Janis Winter |
The speakers for the winter term 2024/25 were:
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21.10.2024 |
Guy Boyde |
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| 28.10.2024 |
Sarah Brauner |
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| 07.11.2024 |
Réamonn Ó Buachalla |
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| 11.11.2024 |
Hans-Christian Herbig |
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| 13.11.2024 | Jonathan Lindell | |
|
18.11.2024 |
Jonas Nehme |
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| 25.11.2024 | Patricia Commins | |
| 02.12.2024 | Ivan Bartulović | |
| 13.12.2024 | Severin Barmeier | |
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16.12.2024 |
Johannes Flake | |
| 06.01.2025 |
Ulrich Krähmer |
|
| 13.01.2025 | Sylvie Paycha | |
| 20.01.2025 |
Kelly Maggs |
The speakers for the summer term 2024 were:
|
08.04.2024 |
Christian Lomp |
| 15.04.2024 |
Ayelet Lindenstrauss |
| 22.04.2024 |
Zbigniew Wojciechowski |
| 29.04.2024 |
Boris Shoikhet |
| 06.05.2024 |
Adam Rennie |
|
27.05.2024 |
Andre Henriques |
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03.06.2024 |
Niels Kowalzig |
| 10.06.2024 |
Liao Wang |
| 17.06.2024 |
Jean-Simon Pacaud Lemay |
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24.06.2024 |
Justin Barthite |
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01.07.2024 |
Sean Sanford |
|
08.07.2024 |
Mateusz Stroinski |
| 16.07.2024 | Ken Brown |
| 27.08.2024 |
Julius Benner |
The speakers for the winter term 2023/24 were:
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16.10.2023 |
Benjamin Haïoun |
|
18.10.2023 |
John Boiquaye |
| 06.11.2023 |
Oliver Sander |
| 13.11.2023 |
Pedro Tamaroff |
| 20.11.2023 |
Marco De Renzi |
|
11.12.2023 |
Cole Comfort |
| 18.12.2023 | Ehud Meir |
|
08.01.2024 |
Adriana Balan |
| 15.01.2024 |
Daniel Gromada |
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22.01.2024 |
Anna Rodriguez Rasmussen |
|
29.01.2024 |
Manuel Bodirsky |
The speakers for the summer term 2023 were:
| Date | Speaker |
|
31.08.2023 |
Josefin Bernhard |
| 10.07.2023 |
Mateusz Stroinski |
| 03.07.2023 |
Daniel Graves |
| 26.06.2023 |
Anna-Katharina Hirmer |
|
19.06.2023 |
Eamon Quinlan-Gallego |
| 12.06.2023 |
Ján Pulmann |
|
05.06.2023 |
Nima Rasekh |
| 15.05.2023 | Estanislao Herscovich |
|
08.05.2023 |
Ben Elias |
| 24.04.2023 |
Andrew Baker |
| 17.04.2023 | Friedrich Wagemann |
The speakers for the winter term 2023 were:
| Date | Speaker |
|
17.10.2022 |
Daniel Tubbenhauer |
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24.10.2022 |
Richard Garner |
|
07.11.2022 |
John Bourke |
| 14.11.2022 | Julian Holstein |
| 15.11.2022 |
Chris Heunen |
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21.11.2022 |
Misha Feigin |
| 28.11.2022 | Joanna Meinel |
| 05.12.2022 |
Andrea Gagna |
| 12.12.2022 | Vanessa Miemietz |
| 19.12.2022 |
George Balla |
| 16.01.2023 |
Tony Zorman |
| 23.01.2023 |
Zbigniew Wojciechowski |
| 30.01.2023 | Ulrich Krähmer |
The speakers for the summer term 2022 were:
| Date |
Speaker |
|
04.04.2022 11.04.2022 25.04.2022 02.05.2022 09.05.2022 16.05.2022 23.05.2022 30.05.2022 02.06.2022 13.06.2022 20.06.2022 27.06.2022 04.07.2022 11.07.2022 08.08.2022 22.08.2022 |
Robert Laugwitz Gregory Ginot Janez Mrcun Catherine Meussburger Ben Ward Michael Batanin Muriel Livernet Pierre-Louis Curien Ivan Bartulović Bojana Femic Natalia Iyudu Ralph Kaufmann Fosco Loregian Ieke Moerdijk Noemi Combe Hans-Christian Herbig |
The speakers for the winter term 2021/22 were:
| Date |
Speaker |
|
04.10.2021 11.10.2021 18.10.2021 25.10.2021 01.11.2021 08.11.2021 15.11.2021 22.11.2021 29.11.2021 06.12.2021 13.12.2021 20.12.2021 10.01.2022 24.01.2022 31.01.2022 |
Martin Markl Lukas Woike Sebastian Halbig Myriam Mahaman Aryan Ghobadi Laiachi El-Kaoutit Jeff Giansiracusa Jens Kaad Bruce Bartlett Chelsea Walton Michael Cuntz Shahn Majid Tony Zorman Stephanie Feilitzsch (Viva) Myriam Mahaman |
The speakers for the summer term 2021 were:
| Date |
Speaker |
|
19.04.2021 26.04.2021 03.05.2021 10.05.2021 17.05.2021 31.05.2021 07.06.2021 14.06.2021 21.06.2021 28.06.2021 05.07.2021 12.07.2021 26.07.2021 |
Christian Korff Cigdem Yirtici internal presentations Manuel Martins Nicolas Garrel Ingo Runkel Azat Gainutdinov Yorck Sommerhäuser Claudia Scheimbauer Paolo Saracco Tom Leinster Martin Hyland Tony Zorman |
The speakers for the winter term 2020/21 were:
| Date |
Speaker |
|
26.10.2020 02.11.2020 09.11.2020 16.11.2020 23.11.2020 30.11.2020 07.12.2020 14.12.2020 11.01.2021 18.01.2021 25.01.2021 01.02.2021 08.02.2021 15.02.2021 |
Atabey Kaygun Lucia Rotheray Sebastian Halbig Matthias Valvekens Friedrich Wagemann Stephanie Feilitzsch David Jordan Tomasz Brzezinski Anna Kula Ilya Shaprio Yuri Berest Blessing Oni John Boiquaye Ivan Angiono |