AD or AC?

the diagram

A fancy diagram of the consequences of real choice. This was part of a project during my masters' studies at the ILLC concerning the relationship between choice and determinacy. I gave a talk on that project at the Logic Colloquium 2005 in Athens. Later on it may be modified to include RGB colouring according to compatibility with determinacy. Red will mark an incompatible with AD fragment, green a fragment that is also fragment of AD and blue will mark consistency and/or independence from AD. Any comments will be very welcome. References will be given after request.

second order arithmetic talk

GLLC 14½ talk: Topological regularities in second order arithmetic

I am very happy that I was invited at the “Games in Logic, Language and Computation 14½" meeting at the ILLC in Amsterdam (where I finished my masters) to give this talk. The talk is based on work by Peter Koepke and Michael Möllerfeld. It shows that ZFC is equiconsistent with full second order arithmetic (SOA) plus all sets of reals are Lebesgue measurable, have the Baire property and the perfect set property. I helped finish off the forcing side (which admittedly is a bit disappointingly easy). These are the slides.