You are on a treasure hunt, wondering where the "Truth Treasure" is buried. You have no idea where it is buried, so you go Truth Town (made up of only Liars and Knights) because it is famous for holding the treasure's secret location.
When you enter the city, you see two twins and they know each other's types, but you don't. One twin says "(Exactly) one of us is a Knight..." and the other twin says "...and (exactly) one of us is a Liar." You can only ask one question and only to one person. You only care about where the treasure is kept, and obviously a liar would give you a wrong answer, so what should you do?
if the first twin is a knight, it means the other is a liar, and as such, he won't admit to being a liar. so the first twin is lying. if the second twin is a kinght it means that the first is a liar. he is already established as a liar, therefore the only conclusion is that they are BOTH liars.
to find the treasure, ask either twin where the treausre ISN'T. as they will lie to you, they will have to say where the treasure actually is, or else they are giving a truthful answer...
Posted by Scott
on 2005-11-23 04:28:03