From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/2992 Path: news.gmane.org!not-for-mail From: James Stasheff Newsgroups: gmane.science.mathematics.categories Subject: Re: Partial answer to Jean Benabou Date: Sat, 14 Jan 2006 21:03:20 -0500 (EST) Message-ID: References: NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Trace: ger.gmane.org 1241019028 6797 80.91.229.2 (29 Apr 2009 15:30:28 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 15:30:28 +0000 (UTC) To: Categories Original-X-From: rrosebru@mta.ca Sun Jan 15 10:53:36 2006 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Sun, 15 Jan 2006 10:53:36 -0400 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1Ey97B-0001Lh-AE for categories-list@mta.ca; Sun, 15 Jan 2006 10:44:17 -0400 In-Reply-To: Original-Sender: cat-dist@mta.ca Precedence: bulk X-Keywords: X-UID: 18 Original-Lines: 44 Xref: news.gmane.org gmane.science.mathematics.categories:2992 Archived-At: see also Drinfeld's paper onthe arXiv @2002 on DG categories Jim Stasheff jds@math.upenn.edu Home page: www.math.unc.edu/Faculty/jds As of July 1, 2002, I am Professor Emeritus at UNC and I will be visiting U Penn but for hard copy the relevant address is: 146 Woodland Dr Lansdale PA 19446 (215)822-6707 On Wed, 11 Jan 2006, Andree Ehresmann wrote: > > In answer to the question raised by Jean: > > >if C is a category, what does one need to assume on a subcategory > V of C to be able to construct an analogous C/V and what structure does > it inherit ? > > Charles Ehresmann had studied the problem of the existence of a quotient = > (or at > least 'quasi-quotient') category of a category by a sub-category, which h= > ad led > to the introduction of the notion of a "proper subcategory" (generalizing > distinguished sub-groups). His results, summarized in a Note (CRAS Paris= > 260, > 2116) are developed in the paper on non-abelian cohomology "Cohomologie a > valeurs dans une categorie dominee" (Collloque Topologie Bruxelles, CBRM = > 1866) > . Both papers are reprinted in "Charles Ehresmann: Oeuvres completes et > commentees" Part III-2 (and partially taken back in his book "Categories = > et > structures", Dunod 1965). > With all my best wishes > Andree Ehresmann. > > > >