[Fly]

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]

The property that DS mentions about everyone getting a new seat, is a cool probability that Euler discovered while working on what is called the hat problem


[/ QUOTE ]

I've never heard it called the "hat problem". Either "matching problem", "problem of recontre", or for the simplest case, counting derangements.

[/ QUOTE ]

Would make a small bet that its known mainly by the words "Euler's problem of the misaddressed letters"

[/ QUOTE ]

Sure, so long as "mainly" corresponds to what has more (relevant) google hits and/or a wiki entry.

Edit - Spelling Correction

Should be problem of rencontres not recontre