From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/3905 Path: news.gmane.org!not-for-mail From: Michael Barr Newsgroups: gmane.science.mathematics.categories Subject: Homomorphisms on Z^n Date: Fri, 14 Sep 2007 08:34:33 -0400 (EDT) Message-ID: NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Trace: ger.gmane.org 1241019596 10811 80.91.229.2 (29 Apr 2009 15:39:56 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 15:39:56 +0000 (UTC) To: Categories list Original-X-From: rrosebru@mta.ca Fri Sep 14 21:02:20 2007 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 14 Sep 2007 21:02:20 -0300 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1IWL3l-00052x-AM for categories-list@mta.ca; Fri, 14 Sep 2007 20:58:53 -0300 Original-Sender: cat-dist@mta.ca Precedence: bulk X-Keywords: X-UID: 29 Original-Lines: 10 Xref: news.gmane.org gmane.science.mathematics.categories:3905 Archived-At: Many years ago (at least 45) Harrison mentioned to me that for any n (including infinite cardinals), Hom(Z^n,Z) = n.Z, in other words the Z-dual of the product is the sum. This is obviously a very special property of Z, almost the negation of injectivity. Has anyone on this list ever seen this before and can give me a reference? Michael