[ The Types Forum (announcements only),
http://lists.seas.upenn.edu/mailman/listinfo/types-announce ]
Dear all,
The next Proof Society Seminar will take place on Monday, 15 December 2025, at
14:00 CET / 13:00 UTC. Our speaker will be Anton Freund, from the University of
Wuerzburg. Details can be found below.
The Proof Society
Seminar<https://urldefense.com/v3/__https://www.proofsociety.org/proof-society-seminar/__;!!IBzWLUs!UcdWFxpH2e7gZnXTEO_3ANKIcs1AKDLAyN-tfOtBPVaCzQ0FE1LF0QkjqTb0KU58LlWh-d7-TEHmOVILgyhRpHMv4AW5pF9FHQ$
> is the official seminar of the Proof Society, and it presents talks by
leading researchers from all areas of proof theory. Everyone who is interested
in the subject is warmly invited to attend! The talks take place online via
Zoom, usually on Mondays, approximately once per month. They start at 13:00 UTC
and may last up to 75 minutes plus questions.
Kind regards,
Lev Beklemishev
Anupam Das
Marianna Girlando
---- Proof Society Seminar, Monday 15.12.2025, 14:00 CET ----
Anton Freund (Wuerzburg University): Approaching Girard's functor Lambda
Abstract: Girard has claimed that Pi^1_1-comprehension corresponds to his
functor Lambda on dilators. He described a plausible proof around 1980, but it
seems that details remain difficult. This talk presents joint work with
Aguilera and Weiermann, in which we give a detailed proof that
Pi^1_1-comprehension corresponds to a variant of Lambda, namely the functor J
of Päppinghaus. No prior knowledge of dilators is assumed.
The seminar takes place via Zoom:
https://bham-ac-uk.zoom.us/j/84261727269
Meeting ID: 842 6172 7269
