18 Nov
2005
18 Nov
'05
1:21 p.m.
Ronald Brown wrote:
There is an interesting account of extensions of principal bundles and transitive Lie groupoids by Androulidakis, developing work of Mackenzie, at math.DG/0402007 (not using crossed complexes).
Ronnie Brown www.bangor.ac.uk/r.brown
Ronnie Brown
This brings to mind an interesting (but insufficiently well known) treatment by I htink) Dennis Johnson of extensions A \to E \to G of topological groups which are also principal bundles the classification of such extensions fits into an exact sequence X --> Y --> Z where Z classifies the bundle - forgetting the group structure and X is the appropriate H^2 classifying split topolgocical group extensions i.e. A x G as bundles jim