From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/5342 Path: news.gmane.org!not-for-mail From: Anders Kock Newsgroups: gmane.science.mathematics.categories Subject: preprint available Date: Thu, 10 Dec 2009 13:14:31 +0100 Message-ID: Reply-To: Anders Kock 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: ger.gmane.org 1260453627 29162 80.91.229.12 (10 Dec 2009 14:00:27 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 10 Dec 2009 14:00:27 +0000 (UTC) To: categories@mta.ca Original-X-From: categories@mta.ca Thu Dec 10 15:00:20 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 1NIjY2-0001zm-SY for gsmc-categories@m.gmane.org; Thu, 10 Dec 2009 14:59:15 +0100 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1NIj0q-0006NT-DL for categories-list@mta.ca; Thu, 10 Dec 2009 09:24:56 -0400 Original-Sender: categories@mta.ca Precedence: bulk Xref: news.gmane.org gmane.science.mathematics.categories:5342 Archived-At: My manuscript "Abstract Projective Lines" is available at arXiv, http://arxiv.org/abs/0912.0822 Abstract: We describe a notion of (abstract) projective line over a field as a set equipped with a certain first order structure, and a projectivity between projective lines as a bijection preserving this structure. The structure in question is that of a groupoid, with certain properties. This leads to a natural notion of bundle of projective lines, forming a stack. Anders Kock [For admin and other information see: http://www.mta.ca/~cat-dist/ ]