2006-07-09 [長年日記]
λ. 第十八回圏論勉強会
I attended the seminar of category theory. Although it began at 8:45, I slept in till noon. Actually I had woke up at eight but then I got back to sleep...orz. Anyway I arrived at past 2:00.
Today's first topic was diagonal arguments. Cantor's diagonal arguments were generalized to Lawvere's diagonal theorem which is also called Lawvere's fixpoint theorem. The theorem is related to the works of Russel, Gödel and Tarski. The theorem was very interesting but we couldn't understand Lawvere's arguments about ‘idealization’. The next topic was map objects (expontiation). In exercises we had to prove certain isomorphisms like YT×S≅(YT)S. The calculation was tiresome, but we could prove them by using the uniqueness property of map objects.
After the seminar we went to さくら水産.
λ. 『英語で日記を書いてみる』 石原真弓
という本を最近買ってみたので、日記の一部を英語で書いてみることにした。下手な英語を晒すのは恥ずかしいけど、これで少しは上達するといいなぁ。
λ. Rubyist SNS
参加してみた。OpenPNEってこんな感じなのね。
