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Talk: Computability of Bass-Serre structures in the Grzegorczyk hierarchy

I’m going to abuse this here organ of mine to show off a thing I did yesterday.

My chum the inimitable David Cushing has started a postgrad pure maths seminar at Newcastle. Because there are only a few pure postgrads here, he asked me to give a talk about the stuff I was looking at for the PhD I gave up on last year.

The title of the talk was “Computability of Bass-Serre structures in the Grzegorczyk hierarchy”. It gave an outline of everything needed to show that the fundamental group of a graph of groups is computable in a level of the Grzegorczyk hierarchy at most one higher than its constituent parts, and what that means.

The slides, a recording of the talk, and a link to my presentation template are in a post on my mathem-o-blog: Talk: Computability of Bass-Serre structures in the Grzegorczyk hierarchy

Relatively Prime is done

This is the first Monday in quite a while that I haven’t had a new episode of Relatively Prime to listen to. That’s because all eight episodes have now been released. I meant to put a little post up each week reminding you to listen to the latest episode, but I completely forgot to do that, so here’s a post saying you can now listen to the whole lot. And you should.

Newcastle MathsJam October 2012 Recap

I’ve posted my recollections of what happened at last month’s Newcastle MathsJam over at my mathem-o-blog.

Cardboard SKI calculus

I had a spare day yesterday so, rather than clean my house, I made a model of the SKI combinator calculus out of a pizza box.

[youtube url=http://www.youtube.com/watch?v=fZQMmgElRMI]

Using Computer Modern on the web

Computer Modern is the family of typefaces developed by Donald Knuth for TeX. It’s so good-looking that some scientists do research just so they can write it up in Computer Modern.

I love TeX and everybody knows it, so I was pretty delighted to hear that the cm-unicode project compiles versions of the Computer Modern fonts in a few formats, including TTF. Having the fonts in TTF format means you can use them in non-TeX environments, in particular on the web.

I’ve run the cm-unicode fonts through codeandmore’s @font-face kit generator to get all the weird formats that the various browsers insist on. The result is a set of packages containing everything you need to use the Computer Modern typefaces on the web.

I’ve put up a page containing examples of each face in use and links to the packages. Enjoy!

David’s de Bruijn sequence card trick

A few days ago, my friend David asked me if I could help him with a card trick. I said I could, hence this post. I managed to pin David down in front of my camera long enough for him to demonstrate the trick; a full explanation follows this video:

[youtube url=http://www.youtube.com/watch?v=g71wG6RrTL8]

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