[Math] The ten martini problem – reason for name

Question

Why is the problem called the ten martini problem? Sounds like an interesting name for people who drink.

Answer 1

The name was coined by Barry Simon in this 1982 article (page 487):

The Ten Martini Problem: The almost Mathieu operator has a Cantor spectrum.

The name comes from the fact that Mark Kac* has offered ten martinis to anyone who solves it. [...] Actually, Kac said "has all its gaps there", so perhaps one should solve instead:

The Ten Martini Problem: (Strong Form, or should it be Dry Form)...

[*] Marc Kac, public communication at 1981 AMS Annual Meeting.