From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/570 Path: news.gmane.org!not-for-mail From: categories Newsgroups: gmane.science.mathematics.categories Subject: Re: non-Abelian categories Date: Sun, 21 Dec 1997 16:08:15 -0400 (AST) Message-ID: NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Trace: ger.gmane.org 1241017047 26314 80.91.229.2 (29 Apr 2009 14:57:27 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 14:57:27 +0000 (UTC) To: categories Original-X-From: cat-dist Sun Dec 21 16:08:46 1997 Original-Received: (from cat-dist@localhost) by mailserv.mta.ca (8.8.8/8.8.8) id QAA09730; Sun, 21 Dec 1997 16:08:15 -0400 (AST) Original-Lines: 16 Xref: news.gmane.org gmane.science.mathematics.categories:570 Archived-At: Date: Sat, 20 Dec 1997 14:21:35 GMT From: Michael Barr Colin's question, which essentially asks for a solution to the proportion abelian groups:groups :: abelian category:x does not of course have a unique answer. One solution was exact category and that was definitely one of the things I had in mind. In fact, I think I even said so. From my current vantage, I would add the following two properties: pointed and Mal'cev. For an equational category, that is almost enough to force a group structure (associativity is missing). I don't know how to force associativity by categorical properties, but pointed, exact and Mal'cev has to come awfully close to answering the question. Michael