December 6, 2008

They would start about 9 P.M. when Tarski was just getting going. He always smoked, and he kept the door of his study closed so the smoke would stay in the room because he thought that made him concentrate better. “It was awful for me,” Chang said, “because I had asthma, but what could I do? I was his student. I wasn’t really a night person either and after a while it was a struggle to keep my eyes open. Around 2 A.M. he’d ask me if I wanted some coffee and I’d say yes. Sitting at his desk, with the door closed, he’d scream, ‘Mariaahh, Mariaahh,’, as loud as he could. If there was no answer, he’d repeat it, sometimes three or four times until Maria finally opened the door, half asleep, saying ‘Yes, Alfred?’ He’d ask her to bring us two cups of coffee and she trudged into the kitchen to make the coffee and bring it to us. I’ve never seen anything like it before or after.”


One of the many many many amazing stories from the “Alfred Tarski. Life and logic” by Anita and Solomon Feferman

This paper extends interplanetary trade theory to an interstellar setting. It is chiefly concerned with the following question: how should interest rates on goods in transit be computed when the goods travel at close to the speed of light? This is a problem because the time taken in transit will appear less to an observer traveling with the goods than to a stationary observer. A solution is derived from economic theory, and two useless but true theorems are proved.


From an abstract to “The theory of interstellar trade” by Paul Krugman, Nobel prize in economics 2008 winner.

A fair present for all of us in the profession:

Shelah mug


From (they also have sweatshirts, caps, keychains and more). And no, I was not looking for a mug.

I am your good friend

June 18, 2008

On another occasion, Erdos met a mathematician and asked him where he was from. “Vancouver,” the mathematician replied. “Oh, then you must know my good friend Elliot Mendelson,” Erdos said. The mathematician replied, “I am your good friend Elliot Mendelson.”


From “My brain is open ” by Bruce Schechter

“Just take an ultrafilter D”
Saharon Shelah

“God is the Alexandroff compactification of the Universe”
Alexander Grothendieck

“Stone-Cech compactification of the Universe is the paganic polytheism”

Goedel\'s onthological proof of existence of God


Goedel’s formalization of ontological argument using ultrafilters and modal logic, see “Sobel on Goedel’s Ontological Proof” by Robert C. Koons

I started talking with Post regularly. He gave me a batch of his reprints. John Stachel and I asked Post if we could do a reading course with him in mathematical logic. That was in my junior year. We didn’t get very far in the course, because Post had one of his breakdowns after a few weeks. He had just made an important discovery regarding incomparable degrees of unsolvability, and the excitement was too much for him and pitched him over into the manic phase. We didn’t see him again for some months.

Particularly logicians seem to be prone to it! In fact, I had a joke with John Stachel. Post had lost an arm in a childhood accident. Hans Reichenbach, who was sort of a logician and a philosopher, came to City College for a semester to give some courses, and he was essentially stone deaf. Church had vision problems—he had bad cataracts, which in those days was much more of a problem than it is today. So the joke was that, if I’m going to be a logician, maybe I should give up a finger now, instead of something worse!


From the AMS Notices interview with Martin Davis.

Mein Lieblingsfach

March 20, 2008

model theory


“Germany’s Next Topmodel” Barbara Meier, from Germany’s “Jahr der Mathematik” promo-site interview.