My anticipation is building for next week’s Nordic Logic Summer School and my class on proof theory. (The fact that I get to visit Reykjavík is to teach is a cool bonus.)
Coming up in less than 18 hours, our two-day Proofs, Rules and Meanings extravaganza. Sophie, Viviane and Francisca have been working hard to organise a productive two days of logic, and our participants get to enjoy the fruits of their hard work very soon.
I think I’m ready for my talk at our two-day proof theory workshop, starting tomorrow: https://consequently.org/presentation/2024/lambda-mu-arche/ — I have a lot to pack in to 25 minutes, so the monster-sized handout contains some of the details I’ll skim over in the talk.
Toshiyasu Arai just put a preprint with a pretty big result in arxiv: "In this paper we give an ordinal analysis of a set theory with (\Pi_N)-Collection."
If right, he found the proof-theoretical ordinal of second-order arithmetic.
Hi! I am a philosopher and logician, and if you would like to understand the kind of work I do, the easiest way to get up to speed is to start with my little slip of a book “Proofs and Models in Philosophical Logic”. https://consequently.org/writing/pmpl-elements/