Monday, May 25, 2009

Raymond Smullyan's Birthday

CLYDE: I met Raymond Smullyan in the around 1985. He was old then. When did he pass away?

BILL: Lets look it up on Wikipedia. (He does.) OH, he didn't! He is still alive! And his birthday is May 25. He turns 90! (thats not 90 factorial). OH, I can post about it ON his birthday.

CLYDE: What will you say?

BILL: I will say that he wrote many popular books on self-reference which were quite good, but after a while somewhat repetitive. And that he his latest book, Logical Labyrinths came out this year, and claims to bridge the gap between the type of logic in his popular books and serious logic. WOW, looks like he is still active!

CLYDE: Isn't that a short post?

BILL: I'll find other stuff to put around the post to make it a bit longer.

1. "I'll find other stuff to put around the post to make it a bit longer"

lol :)

Happy Birthday

2. I grew up on the puzzle books of Raymond Smullyan-- the earliest one (What is the Name of this Book?) is a perfect present for the mathematically inclined 10 or 12 year old-- AND I (with Ray's permission!) borrow many of his puzzles as hw assignments when I teach Discrete Math.

For those of you unfamiliar, here's an example of his easiest puzzles (they get much harder-- he even manages to teach all of Godel Incompleteness through puzzles like this one :-) , I forget if this one is from What is the Name of this Book? or from The Lady or the Tiger? but here you go:

When Alice entered the Forest of Forgetfulness, she did not forget everything, only certain things. She often forgot her name, and the one thing she was most likely to forget was the day of the week. Now the Lion and the Unicorn were frequent visitors to the forest. The Lion lies on Mondays, Tuesday, and Wednesdays, and tells the truth the other days of the week; the Unicorn, on the other hand, lies on Thursdays, Fridays and Saturdays, but tells the truth on the other days of the week.

One day, Alice met the Lion and the Unicorn resting under a tree. They made the following statements:
(1) Yesterday was one of my lying days.
(2) Yesterday was one of my lying days too.

What day of the week is it?

The only "simple" logic puzzle that I like better than the Smullyan ones is Jim Propp's Self Referential Aptitude Test!