The 111th Peripatetic Seminar on Sheaves and Logic (PSSL 111) will take place on Sep 4th and Sep 5th 2025 in Bologna, Italy.

Note that the dates are not on a weekend, but on a Thursday and Friday, unlike the usual PSSL tradition. Since it is outside term time, we expect it will not be a problem for most participants.

PSSL is a long-running series of informal gatherings covering all aspects of category theory and its applications, typically held over a weekend at a university in Europe. The first PSSL was held in Oxford, in May 1976. This is the 111th PSSL, following meetings in Tallinn, Leiden, Terrasini, and Athens.

Registration

To register for PSSL 111, please fill out the following registration form. There are no registration fees, but we kindly ask that you complete the registration form by August 28th at the latest.

When registering, you'll be given the option to submit a talk proposal. We seek proposals for contributed talks on all aspects of category theory and its applications. Talks about work in progress are also warmly welcomed. We especially encourage PhD students and young researchers to submit their work.

Local organizers

The local organizers are Matteo Capucci (Independent) and Vikraman Choudhury (Università di Bologna). Please feel free to contact us if you have questions or suggestions.