AustMS 2006 III

The freeway 294 bus route turned out to be just as disastrous as the other options so I was lucky to make Skinner's talk reviewing the Birch-Swinnerton-Dyer conjecture, which started out very simply explaining the genus of a curve and remained clear whilst moving rapidly into some heavy jargon.

In the Mathematical Physics session David Roberts spoke about bundle gerbes and higher Yang-Mills theory, and he was kind enough to translate occasionally for the category theorists who ran off at the end of the talk to hear Dominic Verity on complicial sets. Actually, Verity's title was 'Non-abelian cohomology as the raison d'etre for higher category theory'.

In the afternoon there was another category theory session. Dorette Pronk spoke about strings of adjunctions, an analysis of which involves Temperley-Lieb type diagrams, such as discussed by Baez in week 174. That is, the planar tangles represent 2-morphisms between points labelled by arrows and their duals. Finally today, Mark Weber spoke about one of my favourite topics, namely 2-toposes, in an elementary sense. That doesn't mean elementary as in simple, but as in axiomatic. The tricky thing is to figure out what the subobject classifier should be. It turns out that a good idea for the 2-truth arrow is the functor from pointed sets to sets!