From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/9341 Path: news.gmane.org!.POSTED!not-for-mail From: Bob Coecke Newsgroups: gmane.science.mathematics.categories Subject: Re: Fred Date: Tue, 12 Sep 2017 15:44:19 +0100 Message-ID: References: Reply-To: Bob Coecke NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1505398878 20867 195.159.176.226 (14 Sep 2017 14:21:18 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 14 Sep 2017 14:21:18 +0000 (UTC) To: categories Original-X-From: majordomo@mlist.mta.ca Thu Sep 14 16:21:09 2017 Return-path: Envelope-to: gsmc-categories@m.gmane.org Original-Received: from smtp2.mta.ca ([198.164.44.40]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dsV0v-000588-2x for gsmc-categories@m.gmane.org; Thu, 14 Sep 2017 16:21:09 +0200 Original-Received: from mlist.mta.ca ([138.73.1.63]:39589) by smtp2.mta.ca with esmtp (Exim 4.80) (envelope-from ) id 1dsV1I-00026B-1n; Thu, 14 Sep 2017 11:21:32 -0300 Original-Received: from majordomo by mlist.mta.ca with local (Exim 4.71) (envelope-from ) id 1dsUzd-0003wp-4K for categories-list@mlist.mta.ca; Thu, 14 Sep 2017 11:19:49 -0300 In-Reply-To: Precedence: bulk Xref: news.gmane.org gmane.science.mathematics.categories:9341 Archived-At: Dear Andre,=20 Your argument applies equally well beyond mathematics, to other = sciences/practices wherever categorical structure is natural. =20 I met Fred at my first CT, in 99, and immediately he made one feel = welcome. Best wishes, Bob. > On 11 Sep 2017, at 17:19, Joyal, Andr=E9 wrote: >=20 > Dear John, and category theorists, >=20 > The fact that every category has an opposite introduces=20 > a symmetry in mathematics that would not be there otherwise.=20 > The category of sets is not self dual, but a disjoint union of sets=20 > is a coproduct, dual to a product. =20 >=20 > Thurston does not show esteem for logic. > Most mathematicians are taking logic for granted; they just use it=20 > as a part of their natural language.=20 > It is obvious that human understanding depends on the=20 > the laws of thought, on logic.=20 > In a sense, category theory is a branch of mathematical logic, > since it greatly improves mathematical thinking in general. > A category theorist might say (not too loudly) that mathematical logic > is a branch of category theory. >=20 > Best, > andr=E9 >=20 [For admin and other information see: http://www.mta.ca/~cat-dist/ ]