Using languages of arithmetic, certain classes of formulas correspond to complexity classes. The result that RE sets are precisely those that are Sigma_1 definable is well known. This talk will focus on characterising P and NP is a similar vein.
A set of printed notes will be made available to participants, including a summary of previous week's work.
The theory of negative types is like the simple typed theory of sets except that its types are indexed by the integers not the naturals. A straightforward compactness argument establishes its consistency but beyond that matters are murky, and there are some very natural questions that seem very hard to answer.
This talk aims to bring interested parties up to speed.