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?
Because of their comments, they must both be liars. This has been established in previous postings. But then the answer is very simple, and is not what has been previously posted.
If you ask Liar A what Liar B will say, he/she has any number of ways to lie since their are infinite places the treasure is not. To get the location of the treasure, simply ask either one of them "where the treasure is not at?" They will then have to lie about where the treasure is not at. And the only single point on the island where they can answer and still be lying is the true location of the treasure. Then proceed to punch both of them in the face for being so difficult, and go get your treasure.
Do I win a prize?
Posted by todd
on 2005-07-12 21:31:27