From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/441 Path: news.gmane.org!not-for-mail From: categories Newsgroups: gmane.science.mathematics.categories Subject: Re: functions Omega->Omega Date: Sat, 12 Jul 1997 14:55:00 -0300 (ADT) Message-ID: NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Trace: ger.gmane.org 1241016968 25776 80.91.229.2 (29 Apr 2009 14:56:08 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 14:56:08 +0000 (UTC) To: categories Original-X-From: cat-dist Sat Jul 12 14:55:22 1997 Original-Received: by mailserv.mta.ca; id AA23356; Sat, 12 Jul 1997 14:55:00 -0300 Original-Lines: 17 Xref: news.gmane.org gmane.science.mathematics.categories:441 Archived-At: Date: Fri, 11 Jul 1997 16:56:25 -0400 (EDT) From: Andre Scedrov > f(a) & a = f(true) & a > > I wonder whether anyone has noticed this formula before? Similar formulas and their analogs in intuitionistic second-order propositional calculus are discussed in my paper in the Annals Pure Appl. Logic 27 (1984) 155-164. That paper was motivated by Higgs's observation that every monic Omega -> Omega in a topos is an involution, see Peter Johnstone's paper "Automorphisms of Omega" in Alg. Universalis 9 (1979) 1-7. Andre Scedrov