From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/8524 Path: news.gmane.org!not-for-mail From: Uwe Egbert Wolter Newsgroups: gmane.science.mathematics.categories Subject: Category without objects Date: Thu, 05 Mar 2015 12:49:01 +0100 Message-ID: Reply-To: Uwe Egbert Wolter NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1425569029 26955 80.91.229.3 (5 Mar 2015 15:23:49 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 5 Mar 2015 15:23:49 +0000 (UTC) To: categories@mta.ca Original-X-From: majordomo@mlist.mta.ca Thu Mar 05 16:23:43 2015 Return-path: Envelope-to: gsmc-categories@m.gmane.org Original-Received: from smtp3.mta.ca ([138.73.1.127]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YTXck-0002Mz-Qc for gsmc-categories@m.gmane.org; Thu, 05 Mar 2015 16:23:43 +0100 Original-Received: from mlist.mta.ca ([138.73.1.63]:53140) by smtp3.mta.ca with esmtp (Exim 4.80) (envelope-from ) id 1YTXbo-0000fN-0P; Thu, 05 Mar 2015 11:22:44 -0400 Original-Received: from majordomo by mlist.mta.ca with local (Exim 4.71) (envelope-from ) id 1YTXbm-00060C-69 for categories-list@mlist.mta.ca; Thu, 05 Mar 2015 11:22:42 -0400 Precedence: bulk Xref: news.gmane.org gmane.science.mathematics.categories:8524 Archived-At: Some years ago (around 30?) I read a book where it was mentioned that one could define categories without (explicit) objects in the sense that objects are mimicked by identity morphisms. Unfortunately, I can not reconstruct what book it was. I know how this works. I would, however, like to have a reference. Best Uwe Wolter [For admin and other information see: http://www.mta.ca/~cat-dist/ ]