From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/6401 Path: news.gmane.org!not-for-mail From: David Roberts Newsgroups: gmane.science.mathematics.categories Subject: Re: Severe Strict Monoidal Category Naivete Date: Sun, 5 Dec 2010 10:14:08 +1030 Message-ID: References: Reply-To: David Roberts NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 X-Trace: dough.gmane.org 1291507505 31587 80.91.229.12 (5 Dec 2010 00:05:05 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Sun, 5 Dec 2010 00:05:05 +0000 (UTC) To: categories@mta.ca Original-X-From: majordomo@mlist.mta.ca Sun Dec 05 01:05:00 2010 Return-path: Envelope-to: gsmc-categories@m.gmane.org Original-Received: from smtpx.mta.ca ([138.73.1.114]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1PP268-0007bb-82 for gsmc-categories@m.gmane.org; Sun, 05 Dec 2010 01:05:00 +0100 Original-Received: from mlist.mta.ca ([138.73.1.63]:52281) by smtpx.mta.ca with esmtp (Exim 4.71) (envelope-from ) id 1PP25v-0007lB-Qh; Sat, 04 Dec 2010 20:04:47 -0400 Original-Received: from majordomo by mlist.mta.ca with local (Exim 4.71) (envelope-from ) id 1PP25t-0001wJ-6R for categories-list@mlist.mta.ca; Sat, 04 Dec 2010 20:04:45 -0400 In-Reply-To: Precedence: bulk Xref: news.gmane.org gmane.science.mathematics.categories:6401 Archived-At: Hi Ellis, to push the chemical reaction analogy further, tensoring with an identity morphism 1_Y is like having a chemical present that doesn't take part in the reaction: it's there are the beginning and end, but doesn't change. But you can't take it away (and no, it's not like a catalyst, in that your original arrow f was there to begin with), unless perhaps Y has some sort of dual or (weak) tensor inverse, and by now the analogy is stretched beyond breaking point. David [For admin and other information see: http://www.mta.ca/~cat-dist/ ]