From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/3699 Path: news.gmane.org!not-for-mail From: Agnes Boskovitz Newsgroups: gmane.science.mathematics.categories Subject: Re: monic epics Date: Mon, 12 Mar 2007 09:37:12 +1100 Message-ID: NNTP-Posting-Host: main.gmane.org X-Trace: ger.gmane.org 1241019469 9883 80.91.229.2 (29 Apr 2009 15:37:49 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 15:37:49 +0000 (UTC) To: categories@mta.ca Original-X-From: rrosebru@mta.ca Tue Mar 13 21:11:01 2007 -0300 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Tue, 13 Mar 2007 21:11:01 -0300 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1HRH1c-0002gR-6L for categories-list@mta.ca; Tue, 13 Mar 2007 21:07:28 -0300 Original-Sender: cat-dist@mta.ca Precedence: bulk X-Keywords: X-UID: 53 Original-Lines: 32 Xref: news.gmane.org gmane.science.mathematics.categories:3699 Archived-At: Hi You might be interested in the Masters thesis I wrote in 1980 called "Epimorphisms in Algebraic and Some Other Categories", which might have some relevant information in it for you. You can get it from the McGill University library, or from Library and Archives Canada, or I can email you a copy if you wish. Agnes Boskovitz David Karapetyan wrote: > 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? > >