offices: Endenicher Allee 62 (the building next to the Math department), rooms 1.001-1.002
This is the webpage for the group on formalized mathematics at the mathematical institute of the university of Bonn. We use the Lean Theorem Prover and its mathematical library to prove current mathematical research, see e.g. the Carleson project.
To learn Lean, try out the Natural Number Game, read the online book Mathematics in Lean or work through my course repository. There are also other ways of learning Lean.
Some communication happens within a private channel on Lean’s Zulip Chat. Please send me a message to get access.
Team
Students
Students supervised within the formalized mathematics group or doing a Lean project.
- Hannah Scholz (master)
- Izabela Mandla (master, main supervisor: Christoph Thiele)
- Henri Nikoleit (master, main supervisor: Heiko Röglin)
- Wenrong Zou (master, main supervisor: María Inés de Frutos-Fernández)
- Felix Pernegger (bachelor)
- Johannes Folttmann (bachelor)
Seminar
During the semester break, any seminars are on Friday 14:15-16:00 in room N0.007 (not N0.003 like during the last semester). There are currently no sessions planned
In SuSe 25 the seminar will be Mondays 10-12 in room 0.003.
The Lean hacking session is canceled during the semester break, but will continue in the summer semester.
Courses
- SuSe 25: The Logic of Proof Assistants (Thu 10-12 in room 0.011) (webpage TBD)
Papers/preprints
incomplete
- Sven Manthe A formalization of Borel determinacy in Lean, 2025. arXiv
- Lars Becker, Floris van Doorn, Asgar Jamneshan, Rajula Srivastava, Christoph Thiele, Carleson Operators on Doubling Metric Measure Spaces, 2024. arXiv
Past students
Students supervised within the formalized mathematics group or theses that include a Lean component. Between parentheses is the end date.
Master students:
- Gabin Kolly, Fraïssé limits in Lean (2025); Github
- Kunhong Du, On the Formalization of the Simplicial Model of HoTT (2025); Github, thesis
- Tim Lichtnau†, Stacks in Synthetic Algebraic Geometry (2024; main supervisor: Hugo Moeneclaey); Github
- Óscar Álvarez Sánchez, Demazure operators and Lean (2024; main supervisor: Catharina Stroppel); Github, thesis
- Theofanis Chatzidiamantis Christoforidis, Formalizing Higher Categories (2024; main supervisor: Nima Rasekh); Github, thesis
Bachelor students:
- Ludwig Monnerjahn, Formalisation of constructable numbers (2024); Github , thesis
- Hannah Scholz, Formalisation of CW-complexes (2024); Github, thesis
- Leo Diedering, Contributing to the Formalization of Carleson’s Theorem (2024); Github, thesis
Past seminar sessions
Usual time: Fridays 14:15-16:00 in room N0.003.
- 18.10 Arend Mellendijk on monadic programming in Lean
- 25.10 Floris van Doorn on metaprogramming in Lean
- 01.11 No seminar
- 08.11 Floris van Doorn on metaprogramming in Lean
- 15.11 Floris van Doorn on metaprogramming in Lean and exercises
- 22.11 Jiang Jiedong: Formalizing the Fontaine-Wintenberger theorem
- 29.11 No seminar
- 06.12 No seminar
- 13.12 No seminar
- 20.12 No seminar
- 10.01 No seminar
- 17.01 No seminar
- 24.01 No seminar
- 31.01 Canceled
- 07.02 Kunhong Du: Formalization of type theory
- 14.02 unusual time and place: 12:15 in the CS Building (room 2.050). Henri Nikoleit on FunSearch
- 14.02 (usual time of 14:15 in room N0.003) Kunhong Du master thesis defense: On the Formalization of the Simplicial Model of HoTT
- 18.02 (part of the logic seminar, 11:00 in room N0.003) Gabin Kolly master thesis defense: Fraïssé limits in Lean
Metaprogramming repository
HoTT repository
Past courses