for Selmer Bringsjord's Intro to AI Show
Three wise men go before a king who informs them that at least one of them has a white spot upon his forehead. In fact, each of them bears such a spot. The first wise man says: ``I do not know whether or not I have a spot on my forehead." The third wise man -- in the end, the only real wise man -- declares: ``I have a white spot on my forehead. And I can prove it." Give the proof. (Now give a formal version of the proof using AI techniques and formalisms.)