Re: The seven step-Mathematical preliminaries

2009-06-12 Thread A. Wolf
There, they call arithmetic soundness what me (and many logician) call soundness, when they refer to theories about numbers. Like Mendelson I prefer to use the term logically valid, to what you call soundness. I may have misstated myself, but the wiki article you pointed me to agrees with

Re: The seven step-Mathematical preliminaries

2009-06-12 Thread Bruno Marchal
On 11 Jun 2009, at 21:43, Jesse Mazer wrote: Countably infinite does not mean recursively countably infinite. This is something which I will explain in the seventh step thread. There is theorem by Kleene which links Post-Turing degrees of unsolvability with the shape of arithmetical

Re: The seven step-Mathematical preliminaries

2009-06-12 Thread Bruno Marchal
Le 12-juin-09, à 09:31, Bruno Marchal a écrit : On 11 Jun 2009, at 21:43, Jesse Mazer wrote: Ah, that makes sense--I hadn't thought of combining multiple universal quantifiers in that way, but obviously you can do so and get a meaningful statement about arithmetic that for a

Re: The seven step-Mathematical preliminaries

2009-06-12 Thread Bruno Marchal
Le 12-juin-09, à 08:28, A. Wolf a écrit : There, they call arithmetic soundness what me (and many logician) call soundness, when they refer to theories about numbers. Like Mendelson I prefer to use the term logically valid, to what you call soundness. I may have misstated myself,

Re: The seven step-Mathematical preliminaries

2009-06-12 Thread A. Wolf
Logicians from different fields use terms in different ways. In provability logic and in recursion theory, soundness means often arithmetical soundness. I understand. Part of the reason for my particular viewpoint: there's a group of professors at the college I work at who are working on

Re: The seven step-Mathematical preliminaries

2009-06-12 Thread Torgny Tholerus
Jesse Mazer skrev: Date: Wed, 10 Jun 2009 09:18:10 +0200 From: tor...@dsv.su.se To: everything-list@googlegroups.com Subject: Re: The seven step-Mathematical preliminaries Jesse Mazer skrev: Date: Tue, 9 Jun 2009 18:38:23 +0200 From: tor...@dsv.su.se To:

RE: The seven step-Mathematical preliminaries

2009-06-12 Thread Jesse Mazer
Date: Fri, 12 Jun 2009 18:40:14 +0200 From: tor...@dsv.su.se To: everything-list@googlegroups.com Subject: Re: The seven step-Mathematical preliminaries Jesse Mazer skrev: Date: Wed, 10 Jun 2009 09:18:10 +0200 From: tor...@dsv.su.se To: everything-list@googlegroups.com

RE: The seven step-Mathematical preliminaries

2009-06-12 Thread Jesse Mazer
From: marc...@ulb.ac.be To: everything-list@googlegroups.com Subject: Re: The seven step-Mathematical preliminaries Date: Fri, 12 Jun 2009 09:31:46 +0200 On 11 Jun 2009, at 21:43, Jesse Mazer wrote: Countably infinite does not mean recursively countably infinite. This is something which I