Even a quick half-hour talk is very tiring to prepare, and is not good for the wrists. I think this one was bad because other things continued to happen while I was working on it (why is our email load twice what it was last week?), and the subject matter really is too basic to be interesting. So I was even sillier than usual in my choice of illustrations.
http://www.cus.cam.ac.uk/~fanf2/ http://www.cus.cam.ac.uk/~fanf2/hermes/doc/talks/2004-10-techlinks/ http://www.cus.cam.ac.uk/~fanf2/hermes/doc/talks/2004-10-techlinks/source.html