Of course I've heard. There are different versions of such logical contradictions.Quote:
Originally Posted by Sahir
In a library, there is a book that has a reference to every book in the library that doesn't have a reference to itself.
Question: does the book refer itself?
They are all particularizations of the problem of the set that contains all the subsets that do not contain themselves. And the question is: does the set contain itself?
