From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/6177 Path: news.gmane.org!not-for-mail From: Vaughan Pratt Newsgroups: gmane.science.mathematics.categories Subject: Is equality evil? Date: Wed, 15 Sep 2010 22:14:19 -0700 Message-ID: References: Reply-To: Vaughan Pratt NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Trace: dough.gmane.org 1284688895 16664 80.91.229.12 (17 Sep 2010 02:01:35 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Fri, 17 Sep 2010 02:01:35 +0000 (UTC) To: categories@mta.ca Original-X-From: majordomo@mlist.mta.ca Fri Sep 17 04:01:31 2010 Return-path: Envelope-to: gsmc-categories@m.gmane.org Original-Received: from smtpy.mta.ca ([138.73.1.139]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1OwQGV-0002Hs-6Z for gsmc-categories@m.gmane.org; Fri, 17 Sep 2010 04:01:27 +0200 Original-Received: from mlist.mta.ca ([138.73.1.63]:60533) by smtpy.mta.ca with esmtp (Exim 4.71) (envelope-from ) id 1OwQF3-0002Xn-7Y; Thu, 16 Sep 2010 22:59:57 -0300 Original-Received: from majordomo by mlist.mta.ca with local (Exim 4.71) (envelope-from ) id 1OwQEy-0002cd-TZ for categories-list@mlist.mta.ca; Thu, 16 Sep 2010 22:59:53 -0300 In-Reply-To: Precedence: bulk Xref: news.gmane.org gmane.science.mathematics.categories:6177 Archived-At: Theorem. Equality if and only if the diagonal. Corollary. P(equality) <--> P(contraction) (where the predicate P may be "Evil", "Nonlinear", "Sophomoric", etc) In this context (as opposed to metric spaces, materials, and maternity wards) contraction is the logical rule predicated on the idea that two things with the same name are actually one. See Kripke and others on the topic of Naming and Necessity. Were Rosa Parks still around she would surely not judge equality evil. [For admin and other information see: http://www.mta.ca/~cat-dist/ ]