From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/5600 Path: news.gmane.org!not-for-mail From: David Leduc Newsgroups: gmane.science.mathematics.categories Subject: Composing modifications Date: Sat, 27 Feb 2010 14:49:55 +0000 Message-ID: Reply-To: David Leduc NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 X-Trace: dough.gmane.org 1267303613 19145 80.91.229.12 (27 Feb 2010 20:46:53 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Sat, 27 Feb 2010 20:46:53 +0000 (UTC) To: categories@mta.ca Original-X-From: categories@mta.ca Sat Feb 27 21:46:38 2010 Return-path: Envelope-to: gsmc-categories@m.gmane.org Original-Received: from mailserv.mta.ca ([138.73.1.1]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1NlTYX-0007jp-0h for gsmc-categories@m.gmane.org; Sat, 27 Feb 2010 21:46:33 +0100 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.61) (envelope-from ) id 1NlT0U-0004p0-QA for categories-list@mta.ca; Sat, 27 Feb 2010 16:11:22 -0400 Original-Sender: categories@mta.ca Precedence: bulk Xref: news.gmane.org gmane.science.mathematics.categories:5600 Archived-At: Dear all, I am reading Basic Bicategories by Tom Leinster, and I have basic questions about modifications. 1) Suppose that n, n', m and m' are transformations such that m * n and m' * n' are well defined, where * denotes horizontal (= Godement) composition of transformations. >>From given modifications a:m-->m' and b:n-->n' is there a way to derive a modification from m * n to m' * n' ? 2) There are two ways to compose transformations: vertical and horizontal. What are the ways to compose modifications? Thanks for your help, David [For admin and other information see: http://www.mta.ca/~cat-dist/ ]