The University of Calgary is moving its websites to a Content Management System (Drupal, to be specific). My homepage is scheduled to be migrated tonight. Now, I've tried very hard to not break any URLs or links (the IT people probably hate me by now), but there will be some changes. For instance, all the … Continue reading Changes

TYPES Summer School 2007Proofs of Programs and Formalisation of MathematicsAugust 19-31 2007, Bertinoro, Italyhttp://TypesSummerSchool07.cs.unibo.it During the last ten years major achievements have been made in using computers for interactive proof developments to produce secure software and to show interesting mathematical results. Recent major results are, for instance, the complete formalisation of a proof of the … Continue reading TYPES Summer School 2007

Paul Cohen died on Friday of a rare lung disease. This came over FOM today: We are very sorry to tell you that Paul Cohen has suddenly passed away.He has had a rare lung disease for maybe two years now, but symptoms only began to really manifest about a year ago. We did not know … Continue reading Paul Cohen, 1934-2007

Mark Lance posted this insightful message to FOM yesterday, in response to this thread on "progress in philosophy": "The aim of philosophy, abstractly formulated, is to understand how things in the broadest possible sense of the term hang together in the broadest possible sense of the term. Under "things in the broadest possible sense" I … Continue reading Philosophy Spin-offs

Alasdair Urquhart was nice enough to identify the model that's dominating the lounge at BIRS. It's an icosidodecahedral prismatohexacosihecatonicosachoron, and is made of 120 icosidodecahedra, 600 cuboctahedra, 720 pentagonal prisms, its faces are 3600 triangles, 3600 squares, 1440 pentagons, and it has 10,800 edges. I'm sure it's got something to do with E8 (the mapping … Continue reading Icosidodecahedral prismatohexacosihecatonicosachoron

My colleague Marc has updated his SEP entry on Species. Jon Willimason is starting a new online thing called The Reasoner. The Reasoner is a monthly digest highlighting exciting new research on reasoning and interesting new arguments. It is interdisciplinary, covering research in, e.g., philosophy, logic, AI, statistics, cognitive science, law, psychology, mathematics and the … Continue reading Species/the Reasoner

Ok, I wasn't really attacked so much as passed by. Anyway, the slides for my talk at the Annual Meeting are here.

Thanks to Greg for (almost) liveblogging the Banff workshop on Mathematical Methods in Philosophy. So go to Greg's blog to find out what happened!

In his talk this morning, Grisha Mints referred to a paper by Paul Cohen. He didn't have the reference handy, so I tracked it down:Paul J. Cohen, Skolem and pessimism about proof in mathematics. Phil. Trans. R. Soc. A (2005) 363, 2407–2418.The entire issue, on meeting on "The nature of mathmatical proof" organized by Alan … Continue reading The Nature of Mathematical Proof

Just in case you ever need it: \ddots going the other direction: \makeatletter\def\Ddots{\mathinner{\mkern1mu\raise\p@ \vbox{\kern7\p@\hbox{.}}\mkern2mu \raise4\p@\hbox{.}\mkern2mu\raise7\p@\hbox{.}\mkern1mu}}\makeatother Then you can say: \varepsilon_0= \omega^{\omega^{\Ddots}}

For some reason I missed the memo that said that Kenny Easwaran's blog moved from antimeta.org to his Berkeley webspace.

This morning has two talks on modal logic: first up was Marcus Kracht with a survey on the development of modal logic; now Steve Awodey is reporting on joint work with Kishida on topological semantics of first-order modal logic. Marcus talked about some interesting results in the mathematics of modal logic, especially general semantics for … Continue reading Modality Morning

Ok. Brit posted about it. Apparently some people claim that the Faculty Scholarly Productivity Index (FSP) shows something about the rankings produced by the Philosophical Gourmet Report (PGR) (e.g., that they're off). But it doesn't. That is not because the PGR is actually the best possible way to measure program or even faculty quality. It … Continue reading Why the Faculty Scholarly Productivity Index doesn’t mean anything in philosophy

I just had occasion to have to typeset Lewis's strict conditional symbol <img src="http://plato.stanford.edu/archives/win2004/symbols/fishhook.gif" alt="- in LaTeX. It turns out it isn't in the standard AMS fonts. Peter Smith's LaTeX for Logicians to the rescue! There I found: that the strict conditional symbol is in the fonts that are part of the txfonts and pxfonts … Continue reading Strict Conditional in LaTeX

Juliette Kennedy's entry on Kurt Gödel has just been published in in the Stanford Encyclopedia.(It took a long time to get this done because of all the formulas that needed to be converted into HTML. If you find a mistake, please let Juliette or me know.)

I just noticed that Josh Dever's Philosophy Family Tree now comes with a little Java applet that gives you a list of your philosophical ancestors (easier to use than the PDF list).Josh, any plans to make the tree capable of dealing with more than one advisor?

Source

Theoretical Computer Science 160 (1996) 241-270
(with Matthias Baaz and Alexander Leitsch)

Abstract

The first-order temporal logics with □ and ○ of time structures isomorphic to omega (discrete linear time) and trees of omega-segments (linear time with branching gaps) and some of its fragments are compared: The first is not recursively axiomatizable. For the second, a cut-free complete sequent calculus is given, and from this, a resolution system is derived by the method of Maslov.

I'm giving a talk on Friday for a general audience, and I thought it would be cute to claim in the little blurb about me that I am "probably the only person in the world who holds both undergraduate and doctoral degrees in logic." Several people have asked me if that's really true, and now … Continue reading Logic Degree Programs?