From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/3400 Path: news.gmane.org!not-for-mail From: David Roberts Newsgroups: gmane.science.mathematics.categories Subject: classifying functor and colimits Date: Thu, 24 Aug 2006 15:29:15 +0930 Message-ID: NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1241019282 8581 80.91.229.2 (29 Apr 2009 15:34:42 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 15:34:42 +0000 (UTC) To: categories Original-X-From: rrosebru@mta.ca Sat Aug 26 23:31:04 2006 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sat, 26 Aug 2006 23:31:04 -0300 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1GHAK1-0003PV-Lu for categories-list@mta.ca; Sat, 26 Aug 2006 23:24:25 -0300 Original-Sender: cat-dist@mta.ca Precedence: bulk X-Keywords: X-UID: 33 Original-Lines: 32 Xref: news.gmane.org gmane.science.mathematics.categories:3400 Archived-At: Dear category theorists, I have been plagued by the following question: does the classifying space functor commute with (co)limits? In particular, I have a system of compact topological groups G_i indexed by the natural numbers, and a whole lot of inclusions. Is B colim G_i homotopic to colim BG_i ? I have a hint that this should be so in my particular situation (in a letter of Serre to Grothendieck), but I'd like to know how the general case goes. Cheers, ------------------------------------------------------------------------ -- David Roberts School of Mathematical Sciences University of Adelaide SA 5005 ------------------------------------------------------------------------ -- droberts@maths.adelaide.edu.au www.maths.adelaide.edu.au/~droberts www.trf.org.au