From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/6594 Path: news.gmane.org!not-for-mail From: Andrej Bauer Newsgroups: gmane.science.mathematics.categories Subject: Re: A conditon on maps between sheaves Date: Sun, 27 Mar 2011 20:27:12 +0200 Message-ID: References: Reply-To: Andrej Bauer NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: dough.gmane.org 1301258766 2547 80.91.229.12 (27 Mar 2011 20:46:06 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Sun, 27 Mar 2011 20:46:06 +0000 (UTC) Cc: zoran skoda , categories list To: Steve Vickers Original-X-From: majordomo@mlist.mta.ca Sun Mar 27 22:46:02 2011 Return-path: Envelope-to: gsmc-categories@m.gmane.org Original-Received: from smtpx.mta.ca ([138.73.1.4]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Q3wqV-0003SN-5B for gsmc-categories@m.gmane.org; Sun, 27 Mar 2011 22:45:59 +0200 Original-Received: from mlist.mta.ca ([138.73.1.63]:53639) by smtpx.mta.ca with esmtp (Exim 4.71) (envelope-from ) id 1Q3wqK-0003wU-Jw; Sun, 27 Mar 2011 17:45:48 -0300 Original-Received: from majordomo by mlist.mta.ca with local (Exim 4.71) (envelope-from ) id 1Q3wqF-000057-Gr for categories-list@mlist.mta.ca; Sun, 27 Mar 2011 17:45:44 -0300 In-Reply-To: Precedence: bulk Xref: news.gmane.org gmane.science.mathematics.categories:6594 Archived-At: Steve Vickers wrote: > For example: take B to be the circle and E' its Moebius double cover, > which has no global sections. Then for every x in B you can take U = B > and your condition holds vacuously for any f whatsoever. > > If E = E'+E' then the codiagonal f has your property but is not mono. I apologize for the noise, I got my conditions all wrong when I tried to "optimize" them for the categories list. As it turns out my condition means that I have a map of etale spaces which is bijective on fibers (and the spaces in question are Hausdorff locally compact). So is there a name for that other than "bijective on fibers"? With kind regards, Andrej [For admin and other information see: http://www.mta.ca/~cat-dist/ ]