From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/4470 Path: news.gmane.org!not-for-mail From: selinger@mathstat.dal.ca (Peter Selinger) Newsgroups: gmane.science.mathematics.categories Subject: Set as a monoidal category Date: Tue, 12 Aug 2008 21:23:59 -0300 (ADT) Message-ID: NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1241019967 13461 80.91.229.2 (29 Apr 2009 15:46:07 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 15:46:07 +0000 (UTC) To: categories@mta.ca (Categories List) Original-X-From: rrosebru@mta.ca Tue Aug 12 21:34:54 2008 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Tue, 12 Aug 2008 21:34:54 -0300 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1KT4Hc-0002TW-1i for categories-list@mta.ca; Tue, 12 Aug 2008 21:32:12 -0300 Original-Sender: cat-dist@mta.ca Precedence: bulk X-Keywords: X-UID: 5 Original-Lines: 12 Xref: news.gmane.org gmane.science.mathematics.categories:4470 Archived-At: Dear Categoreans, I know three monoidal structures on the category of sets, all of them symmetric. Two are the product and coproduct, and I'll leave it to your imagination to figure out the third one. My question is: are these the only three? Proofs, counterexamples, or references appreciated. Thanks, -- Peter