**they did not have time to coordinate a strategy in advance**. Each can only assume that the other prisoner is intelligent. Can they always guess correctly? After how many hours?

# Silly

# A Boxes Riddle

**Riddle.**A game takes place where person A and person B are on the same team while person Z is their adversary. There are 100 boxes and 100 notes containing the numbers 1 to 100 (that is, each number is on exactly one note). The game goes as follows:

- First, only Z and A are in the room. Z places one note in each box.
- A sees the actions of Z and may afterwards pick two boxes and switch the notes in them (with each other). He may only perform one such switch.
- Z sees the actions of A and then chooses a number N between 1 and 100.
- A leaves the room while B enters it (they cannot exchange information during this process). Z tells B the number N.
- Finally, B needs to find the box that contains the note with the number N. For this purpose, B may open up to 50 boxes.

*I seem to be getting senile! I just noticed that I wrote the same riddle in a post two years ago…)*

# Quoting Rota

“What can you prove with exterior algebra that you cannot prove without it”? Whenever you hear this question raised about some new piece of mathematics, be assured that you are likely to be in the presence of something important. In my time, I have heard it repeated for random variables, Laurent Schwartz’ theory of distributions, idèles and Grothendieck’s schemes, to mention only a few. A proper retort might be: “You are right. There is nothing in yesterday’s mathematics that could not also be proved without it. Exterior algebra is not meant to prove old facts, it is meant to disclose a new world. Disclosing new worlds is as worthwhile a mathematical enterprise as proving old conjectures.”

One day, in my first year as an assistant professor at MIT, while walking down one of the long corridors, I met professor Z, a respected senior mathematician with a solid international reputation. He stared at me and shouted “Admit it! All lattice theory is trivial!”

# Being a group theorist can be dangerous!

The Maoist movement decided that group theory was a reactionary subject of the old regime, and started protesting at the increasing number of professors in the subject being appointed. Demonstrations erupted outside of the maths department with protesters holding placards demanding ‘No more group theory’. One new appointee in group theory was frightened off and took a job elsewhere. During one demonstration, the students scaled the outside of the building and scrawled `Group Theory Department’ on the wall.

**non-fiction**book Finding Moonshine by Marcus du Sautoy. These events took place in Germany in the early 70’s.

# A Noah’s Ark Joke

Letters to a young mathematician / Ian Stewart.

# Books and quotes

### MY BRAIN IS OPEN: The Mathematical Journeys of Paul Erdős / Bruce Schechter

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

### Mathematical Cranks / Underwood Dudley

Represent heaven, the home of God, as a vector space of infinite dimension over some field known to god but unknown to us, in which the activities of God are quantifiable. Lengths will be measured (Revelation chapter 21 verse 15) in the usual way, as the square roots of the inner self-products of vectors (assuming heaven to be euclidean).

# Was Disney trying to kill mathematicians during the 1930’s?

* A more optimistic Disney-mathematics connection.*

“

Dip the apple in the brew / Let the Sleeping Death seep through.”

Eventually, Turing reenacted the following scene, committing suicide by taking a bite out of a poisoned apple (injected with cyanide).