Sunday, August 19, 2012

Hat trick!

Two wise men are brought together to solve the following puzzle. Each is wearing a hat, without being able to see it: they can only see each others hat. Now, our wise men are told at least one of the hats is white. Their challenge is to find out the colour of their own hat, by logical reasoning.

The puzzle is attributed to Martin Gardner who published it as early as in 1961, but is probably much older. It comes in many shapes, ranging from prisoners to be executed (yikes!), to children with muddy faces, with two, three, or even countably infinite (yeeha!) hats, and, of course, all colours of the rainbow. 

The puzzle was also the topic of the first and last paper I wrote, and as such it conveniently marks the start and end of my scientific career. I think it is interesting enough to devote a series of postings to.

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