From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/3662 Path: news.gmane.org!not-for-mail From: David Karapetyan Newsgroups: gmane.science.mathematics.categories Subject: monic epics Date: Tue, 06 Mar 2007 17:11:31 -0800 Message-ID: NNTP-Posting-Host: main.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 1241019441 9673 80.91.229.2 (29 Apr 2009 15:37:21 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 15:37:21 +0000 (UTC) To: categories@mta.ca Original-X-From: rrosebru@mta.ca Tue Mar 6 21:39:56 2007 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Tue, 06 Mar 2007 21:39:56 -0400 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HOkzB-0001W0-E6 for categories-list@mta.ca; Tue, 06 Mar 2007 21:30:33 -0400 Original-Sender: cat-dist@mta.ca Precedence: bulk X-Keywords: X-UID: 16 Original-Lines: 12 Xref: news.gmane.org gmane.science.mathematics.categories:3662 Archived-At: Hi, I've been trying to learn some category theory and I came upon the example of a monic, epic in the category of monoids given by the inclusion function of (N,0,+) into (Z,0,+). I know that in monoids every monic arrow is also an injective function but the inclusion function of N into Z provides a counterexample of every epic arrow being a surjective function. I noticed that N is just a "folded" version of Z, where by "folded" I mean take Z and throw away all the inverses of the natural numbers. So does every monic, epic arrow determine such a "folding" or are there monic, epics that can't be characterized in such a way?