Jouko Mickelsson (Stockholm)
The purpose of this talk is to point out connections between
recent ideas about the gerbes and gerbal actions (as higher categorical extension
of representation theory) and the old discussion in quantum field theory on commutator
anomalies, gauge group extensions, and 3-cocycles. The unifying concept is the
classical obstruction theory for group extensions as explained in the monograph
"Homology" by Saunders Mac Lane.
Arnold Sommerfeld Center