From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/1921 Path: news.gmane.org!not-for-mail From: Wilkins E B Newsgroups: gmane.science.mathematics.categories Subject: Re: Category Theory and Hereditarily-Finite Sets Date: Thu, 19 Apr 2001 22:19:46 +0100 Organization: University of Essex Message-ID: <3ADF5672.F53C9735@essex.ac.uk> References: <200104191829.TAA04249@koi-pc.dcs.qmw.ac.uk> NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1241018205 1214 80.91.229.2 (29 Apr 2009 15:16:45 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 15:16:45 +0000 (UTC) To: categories@mta.ca Original-X-From: rrosebru@mta.ca Fri Apr 20 12:33:52 2001 -0300 Return-Path: Original-Received: (from Majordom@localhost) by mailserv.mta.ca (8.11.1/8.11.1) id f3KEmXJ26265 for categories-list; Fri, 20 Apr 2001 11:48:33 -0300 (ADT) X-Authentication-Warning: mailserv.mta.ca: Majordom set sender to cat-dist@mta.ca using -f X-Mailer: Mozilla 4.6 [en] (X11; I; Linux 2.2.14 i686) X-Accept-Language: en Original-Sender: cat-dist@mta.ca Precedence: bulk X-Keywords: X-UID: 19 Original-Lines: 22 Xref: news.gmane.org gmane.science.mathematics.categories:1921 Archived-At: Paul Taylor wrote: > > Hereditarily-finite sets are becoming increasingly more popular > > in computer science research. > > Why? Because some ill-advised first year maths lecturer told you that > the element relation was the foundation of mathematics, maybe? Maybe because someone read papers by Friedman (1977) which gave the set theory B which is [Beeson] "the theory of hereditary extensional sets of finite rank" and which is strong enough to model Bishop-style constructive mathematics. This seems to be a good reason. Elwood -- Dr Elwood Wilkins tel: (+44) (0)1206 872771 Senior Research Officer fax: (+44) (0)1206 872788 Department of Computer Science University of Essex, Colchester, Essex, UK