From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/2881 Path: news.gmane.org!not-for-mail From: jim stasheff Newsgroups: gmane.science.mathematics.categories Subject: Re: Schreier theory Date: Fri, 18 Nov 2005 08:21:39 -0500 Message-ID: References: <437C9478.7010604@ll319dg.fsnet.co.uk> NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1241018960 6202 80.91.229.2 (29 Apr 2009 15:29:20 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 15:29:20 +0000 (UTC) To: categories@mta.ca Original-X-From: rrosebru@mta.ca Fri Nov 18 17:02:56 2005 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 18 Nov 2005 17:02:56 -0400 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1EdDIe-0000ml-SF for categories-list@mta.ca; Fri, 18 Nov 2005 16:57:36 -0400 User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en In-Reply-To: <437C9478.7010604@ll319dg.fsnet.co.uk> X-Scanned-By: MIMEDefang 2.53 on 128.91.55.26 X-Spam-Checker-Version: SpamAssassin 3.0.4 (2005-06-05) on mx1.mta.ca X-Spam-Level: X-Spam-Status: No, score=0.0 required=5.0 tests=none autolearn=disabled version=3.0.4 Original-Sender: cat-dist@mta.ca Precedence: bulk X-Keywords: X-UID: 26 Original-Lines: 38 Xref: news.gmane.org gmane.science.mathematics.categories:2881 Archived-At: 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 > > > > > > > > >