From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/5676 Path: news.gmane.org!not-for-mail From: Anders Kock Newsgroups: gmane.science.mathematics.categories Subject: preprint available Date: Mon, 29 Mar 2010 17:44:48 +0200 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: dough.gmane.org 1269886455 25653 80.91.229.12 (29 Mar 2010 18:14:15 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Mon, 29 Mar 2010 18:14:15 +0000 (UTC) To: categories@mta.ca Original-X-From: categories@mta.ca Mon Mar 29 20:14:10 2010 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 4.69) (envelope-from ) id 1NwJTV-0003UN-2m for gsmc-categories@m.gmane.org; Mon, 29 Mar 2010 20:14:09 +0200 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1NwJ11-0004Yi-82 for categories-list@mta.ca; Mon, 29 Mar 2010 14:44:43 -0300 Original-Sender: categories@mta.ca Precedence: bulk Xref: news.gmane.org gmane.science.mathematics.categories:5676 Archived-At: My manuscript "Geometric Algebra of Projective Lines" is available at arXiv, http://arxiv.org/abs/1003.2095 It is a sequel to the preprint on "Abstract Projective Lines" posted in December 2009. Abstract: The projective line over a field carries structure of a groupoid with a certain correspondence between objects and arrows. We discuss to what extent the field can be reconstructed from the groupoid. (The *multiplication* of the field comes from the *composition* of the groupoid; the crux is to reconstruct the *additive* structure.) Anders Kock [For admin and other information see: http://www.mta.ca/~cat-dist/ ]