Submitted by Richard Zach on Tue, 11/11/2008 - 5:10pm
Sitting in a talk at CMU by Bill Tait on cut elimnation for predicative systems. His approach, in contrast to Rathjen and Takeuti, is to try to get the cut-elimination proof to be mostly (or even, only) about the proofs, and not about proofs and (mostly) ordinal notation systems. He's using the original Tait calculus, in which formulas are all propositional, but infinitary. His cut-elimination theorem applies in all kinds of cases (essentially up through predicative arithmetic), which I hadn't realized before.
Submitted by Richard Zach on Fri, 11/07/2008 - 2:28pm
David Chalmers and David Bourget are setting up a new online resource for papers in philosophy, for which they're designing a taxonomy of philosophical topics to be used for classifying papers in the database. David asks
Submitted by Richard Zach on Tue, 10/28/2008 - 4:17pm
My former colleague C. B. Martin died last Thursday.
Submitted by Richard Zach on Tue, 10/28/2008 - 4:17pm
My former colleague Charlie Martin died last Thursday. He was a major figure in metaphysics, one of the first to talk about truthmakers.
Obituaries here and here.
Submitted by Richard Zach on Tue, 10/21/2008 - 3:00pm
The venerable Swedish philosophy journal Theoria is published by Blackwell since this past March, and that means it is online, including the back issues. I'm not sure of the exact dates, but in the 70s, when Krister Segerberg was the editor-in-chief of that journal, Theoria was the place to publish modal logic and formal philosophy.
Submitted by Richard Zach on Fri, 10/17/2008 - 4:09pm
One very common informal statement of Gödel's theorem is that it shows that for any (sufficiently strong consistent blah blah) formal system, there are truths that it can't prove. And if you don't formulate Gödel's incompleteness theorem that way, at least you state this as a corollary: Gödel's theorem shows that truth and provability (in any one formal system) come apart. But if you read Gödel''s original paper(s) on incompleteness, you are probably struck by the fact that Gödel doesn't say this.
Submitted by Richard Zach on Fri, 10/17/2008 - 2:47pm
Submitted by Richard Zach on Fri, 10/17/2008 - 2:06am
Submitted by Richard Zach on Thu, 10/16/2008 - 6:35am
If you're going to be in Pittsburgh (at the PSA) in three weeks, please come to the Carnap Reception that Open Court is going to throw on Friday, Nov 7. I think it'll be at 5:30. Vol. 1 of Carnap's Collected Works will be presented. I expect there will be free drinks, too!
Submitted by Richard Zach on Tue, 10/14/2008 - 2:29pm
Submitted by Richard Zach on Mon, 10/13/2008 - 8:17pm
Since I'm hanging out with a bunch of category theorists every Wednesday, web finds with "category theory" in them keep attracting my attention. A couple of weeks ago, I came across this book draft posted on arXiv:
Submitted by Richard Zach on Fri, 10/10/2008 - 3:09pm
Are you sitting in front of the computer, hitting the "reload" button every two seconds to see if the October Jobs for Philosophers is posted on the APA website yet? Why not check out the job that we have right here: Assistant Professor with AOS in Logic?
Submitted by Richard Zach on Wed, 10/08/2008 - 3:16am
Today I taught Ch. 13 of Peter Smith's book. We showed that every Σ1 function can be written as a composition of two Δ0 functions (p. 108). In his proof of this, Peter's following Boolos Burgess & Jeffrey (Lemma 16.12 on p. 206 of the 4th & 5th ed.; it's not in the 3rd so I'm guessing it's due to John Burgess).
Submitted by Richard Zach on Tue, 10/07/2008 - 12:55am
NB: History and philosophy of computation explicitly part of the scope. Note also the philosophers on the program committee and the special session on philosophical and mathematical aspects of hypercomputation.
CiE 2009: COMPUTABILITY IN EUROPE 2009 -
Mathematical Theory and Computational Practice
19 - 24 July 2009
Deadline for submissions: 20 JANUARY, 2009
Submitted by Richard Zach on Sun, 10/05/2008 - 9:15pm
So I got fed up with Bloglines one time too many, and I switched to Google Reader. It maybe it's just that I'm still getting used to it, but I find the user interface of Bloglines a bit more intuitive. And it has served me well for years. Wait--Why do I feel bad about switching feed readers? Anyway.
Submitted by Richard Zach on Fri, 10/03/2008 - 9:25pm
If you're a member of the ASL,* you recently received the September Newsletter. In it--maybe easy to miss--this nice opportunity to acquire some logic books for cheap:
For a limited time, the ASL is making available the following volumes from its book series at an additional discount.
Submitted by Richard Zach on Thu, 10/02/2008 - 4:00pm
Submitted by Richard Zach on Tue, 09/30/2008 - 2:43pm
CUP is giving away copies of Martin Gardner's New Mathematical Library if you can solve a logic puzzle--any reader of this blog should be able to solve this one!
Submitted by Richard Zach on Wed, 09/24/2008 - 5:21pm
My colleague Robin Cockett and I have been running a research group here at Calgary where the various computer scientists, mathematicians, and philosophers interested in logic, theory, foundations, etc. meet and present work. For a long time we've had weekly meetings and everything went great, but then both Robin and I went on leave and almost nothing happened the past year or so. But we're starting up again! We have a fancy new website to prove it!
Submitted by Richard Zach on Wed, 09/24/2008 - 4:01pm
The ASL Newsletter went out today, and it looks like the Winter Meeting will be very exciting:
2008-09 ASL Winter Meeting (with APA) Philadelphia, Pennsylvania
December 27–30, 2008