From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/4524 Path: news.gmane.org!not-for-mail From: Michael Barr Newsgroups: gmane.science.mathematics.categories Subject: Resolution Date: Mon, 25 Aug 2008 13:27:13 -0400 (EDT) Message-ID: NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Trace: ger.gmane.org 1241020004 13698 80.91.229.2 (29 Apr 2009 15:46:44 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 15:46:44 +0000 (UTC) To: Categories list Original-X-From: rrosebru@mta.ca Mon Aug 25 17:10:27 2008 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Mon, 25 Aug 2008 17:10:27 -0300 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1KXiLu-0005Tv-EY for categories-list@mta.ca; Mon, 25 Aug 2008 17:07:50 -0300 Original-Sender: cat-dist@mta.ca Precedence: bulk X-Keywords: X-UID: 60 Original-Lines: 17 Xref: news.gmane.org gmane.science.mathematics.categories:4524 Archived-At: Thanks to Jonathan Chiche and Johannes Huebschman for the answer to my question. First off, according to the online Encyclopedia of Mathematics, relatively compact means having compact closure (I had called that conditionally compact; neither term is very evocative). Now to denombrable a l'infini, first Johannes wrote that it meant that the one point compactification had a countable basis at the point at infinity. Then Jonathan pointed to a '57 paper of M. Zisman that actually defined it to mean \sigma-compact. In the context of locally compact spaces, the two definitions are easily seen to be equivalent! Since \sigma-compact seems to be widely used, I will go with that. And now let us break off this thread. Michael