Ronald  Brown


Multiple groupoids: a non abelian tool for local-to-global problems

A 1-fold groupoid is just a groupoid and and n-fold groupoid is a
set with n groupoid structures any two of which satisfy an interchange law.
The aim of the talk is to show the intuitions behind how how types of n-fold
groupoid have been used in homotopy theory and the cohomology of groups to
give new calculations, with a view to encouraging their use in differential
situations.