Dear colleagues, It is my pleasure to announce: Ultracategories and Stone duality Workshop, 29 June - 1 July 2026, Paris Ultracategories were originally introduced by Michael Makkai in the 1980s to develop a Stone duality for first-order logic. As their theory found a renewed interest in recent years, this workshop aims to gather researchers interested in ultracategories and, more generally, in Stone dualities in the context of predicate logic and topos theory. In addition to a number of invited talks, the workshop will provide ample time for discussion. Anyone interested in the topics is warmly invited to participate, either in person or online. Please register here: https://framaforms.org/ultracategories-and-stone-duality-workshop-registrati... This workshop is funded by ERC Malinca and ANR TopTT. Confirmed speakers: Mathieu Anel, Ivan Di Liberti, Simon Henry, Jérémie Marquès, Elena Pozzan, Giuseppe Rosolini, Gabriel Saadia, Errol Yuksel Organizers: Sam van Gool, Paul-André Melliès, Umberto Tarantino, Joshua Wrigley Date: Monday 29 June — Wednesday 1 July 2026 Place: Room 1001, Sophie Germain building Webpage: https://www.irif.fr/rencontres/pps2026/ultracategories-workshop We hope to see you there! On behalf of the organising committee, Joshua You're receiving this message because you're a member of the Categories mailing list group from Macquarie University. To take part in this conversation, reply all to this message. View group files<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMessage&action=files&smtp=categories%40mq.edu.au&bO=true&GuestId=6bf90c14-94d1-45b7-a0b5-9dd447734d27> | Leave group<https://outlook.office365.com/groups/groupsubscription?source=EscalatedMessage&action=leave&smtp=categories%40mq.edu.au&bO=true&GuestId=6bf90c14-94d1-45b7-a0b5-9dd447734d27> | Learn more about Microsoft 365 Groups<https://aka.ms/o365g>