This problem was one I was assigned in my math class:
On a certain
island live 1000 persons, all well acquainted with one another, of whom some have
blue eyes and the rest
brown eyes. It is an absolute
taboo on this island to convey any
information on eye color, and
mirrors are unknown. It is furthermore an absolutely accepted rule that any person who is able to
prove that his/her eyes are blue must, at
midnight of the day on which such proof first becomes available, commit
suicide. Finally, there is on the island an
infallible oracle, whose pronouncements are attended every day at noon by all inhabitants of the island. On one fateful day the oracle stated: "There is at least one blue-eyed person on this island." What, if anything, ensues?
Try and figure it out for yourself - it's pretty damn satisfying to do so... like finally getting that damn squirrel out of your birdseed or something.
Answer