From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/5101 Path: news.gmane.org!not-for-mail From: John Baez Newsgroups: gmane.science.mathematics.categories Subject: Re: Re: The Wikibook on Category Theory Date: Thu, 20 Aug 2009 11:48:35 -0700 Message-ID: Reply-To: John Baez NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1250881626 30373 80.91.229.12 (21 Aug 2009 19:07:06 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 21 Aug 2009 19:07:06 +0000 (UTC) To: categories Original-X-From: categories@mta.ca Fri Aug 21 21:07:00 2009 Return-path: Envelope-to: gsmc-categories@m.gmane.org Original-Received: from mailserv.mta.ca ([138.73.1.1]) by lo.gmane.org with esmtp (Exim 4.50) id 1MeZRz-0004Em-J2 for gsmc-categories@m.gmane.org; Fri, 21 Aug 2009 21:06:59 +0200 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1MeYro-0000Iz-Eq for categories-list@mta.ca; Fri, 21 Aug 2009 15:29:36 -0300 Original-Sender: categories@mta.ca Precedence: bulk Xref: news.gmane.org gmane.science.mathematics.categories:5101 Archived-At: Andrew Salch wrote: I often find that I need to know if certain kinds of limits, or colimits, > or injective envelopes, etc. etc. etc. exist in a particular category, and > having some central database to look at (which would hopefully tell me what > I need to know as well as cite whatever paper the result was proved in) > would be a lot quicker than having to either search the literature for such > a result or try to re-prove the result myself. Does anyone know if there > have been any attempts to compile such a database? > I don't know of any such attempts. I've always wanted such a database! An obvious place to create it is on the nLab. I just started one: http://ncatlab.org/nlab/show/database+of+categories but it will only become interesting after a while. If everyone here contributes an entry or two today, it will be interesting by tomorrow! Best, jb [For admin and other information see: http://www.mta.ca/~cat-dist/ ]