From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/4938 Path: news.gmane.org!not-for-mail From: Hasse Riemann Newsgroups: gmane.science.mathematics.categories Subject: Famous unsolved problems in ordinary category theory Date: Sat, 6 Jun 2009 01:35:11 +0000 Message-ID: Reply-To: Hasse Riemann NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1244326995 17434 80.91.229.12 (6 Jun 2009 22:23:15 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 6 Jun 2009 22:23:15 +0000 (UTC) To: , Original-X-From: categories@mta.ca Sun Jun 07 00:23:13 2009 Return-path: Envelope-to: gsmc-categories@m.gmane.org Original-Received: from mailserv.mta.ca ([138.73.1.1]) by lo.gmane.org with esmtp (Exim 4.50) id 1MD4I9-0005fu-H6 for gsmc-categories@m.gmane.org; Sun, 07 Jun 2009 00:23:09 +0200 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1MD3lg-00038y-SH for categories-list@mta.ca; Sat, 06 Jun 2009 18:49:36 -0300 Original-Sender: categories@mta.ca Precedence: bulk Xref: news.gmane.org gmane.science.mathematics.categories:4938 Archived-At: =20 Hi Paul =20 I still think you are getting me wrong=2C as did Ronnie. But never mind=2C = i am used to it since i don't follow the mainstream science ways to specialize=2C solve pro= blems=2C publish=2C repeat. Yet the problems interest will pass very soon. I now know 19 ordinary categ= ory problems (if you explain this one) vs. at least 23 in higher category theory. This explains why i re= stricted to ordinary categories.=20 =20 >>From the good side i should be thankful that you and Ronnie trie to direct = me towards "true mathematics"=2C but i have already found my "true mathematics". A big part of the process t= o get there was precisely to ask own quastions and finding the answers to them. But some people just got= irritated when i asked them questions (in their field!) they didn't have the answer to. =20 > Another is how to embed the category of locales in a CCC WITHOUT > using illegitimate presheaves (Vickers and Townsend) or the axiom > of collection (Heckmann).=20 =20 I don't follow to the end here. Why should presheaves be illegitimate? Then=2C i suppose the axiom of collection is valid at least in the CCC. But what is so bad about the axiom of collection in this case? Do the embedding get bad? =20 Best regards Rafael Borowiecki [For admin and other information see: http://www.mta.ca/~cat-dist/ ]