Kleine AT

A one-day workshop series for early‑career algebraic topologists in NRW and neighboring regions.

Each edition focuses on a single topic with five talks across the day. All talks are given by participants, and hosts rotate among universities through a democratic voting process.

What is Kleine AT?

Kleine AT (Kleine Algebraische Topologie) is a biannual workshop series designed for Master's and Ph.D. students in algebraic topology from universities across North Rhine-Westphalia and neighboring regions. This one-day intensive workshop focuses on a single, carefully chosen topic within algebraic topology, providing participants with an opportunity to deepen their understanding through a structured series of five one-hour talks given by fellow students.

Kleine AT is a grassroots, community-run initiative where all talks are given by attendees themselves. During each event, attendees propose topics for the next workshop and vote to select the theme. The organizer of the winning proposal then hosts and organizes the next edition at their home institution.

Organisers: Jordi Cardiel, Bhavna Joshi, Qi Zhu

We will study Topological Hochschild Homology and Topological Cyclic Homology. Along the way, we will see many examples such as the THH of Thom Spectra and Bökstedt Periodicity. Along the way, we will practice higher algebra and learn about Thom spectra and Borel-equivariant homotopy theory.

Program and abstracts (PDF)

Schedule

10:00–10:30	Registration
10:30–11:30	Talk 1: Definition of Topological Hochschild Homology
11:30–11:45	Break
11:45–12:45	Talk 2: Thom spectra and THH of spherical group rings
12:45–14:00	Lunch
14:00–14:30	Discussion & Voting
14:30–15:30	Talk 3: Bökstedt periodicity
15:30–16:00	Coffee Break
16:00–17:00	Talk 4: Cyclotomic structure on THH, and Topological Cyclic Homology
17:00–17:15	Break
17:15–18:15	Talk 5: Surprise talk

Registration

Registration is now open and will remain open until the day of the event. The deadline to sign up for a talk is by 1st of March, 2026. We will book lodging for speakers.

Register Now

Past Events

Organisers: Tobias Barthel, David Bowman, Wern Juin Gabriel Ong

Attendance: 39 participants from 12 institutions

Schedule and talks

09:30–10:00	Registration
10:00–11:00	Talk 1: The Filtered Derived Category and the Beilinson t-Structure (Mathieu Wydra)
11:00–11:15	Break
11:15–12:15	Talk 2: Décalage I (Gabriel Ong)
12:15–13:30	Lunch
13:30–14:00	Discussion & Voting
14:00–15:00	Talk 3: Décalage II (Fabio Neugebauer)
15:00–15:30	Coffee Break
15:30–16:30	Talk 4: Evenness I (Qi Zhu)
16:30–16:45	Break
16:45–17:45	Talk 5: Evenness II (Swaminathan Rajagopalan)

Syllabus (PDF)