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?
(In reply to Solution
"They're both liars so ask either of them where the treasure isn't!"
Not to beat this to death, but the reply could be: "It isn't in the trunk of your car, and if you look there and don't find it, then I'm no Liar." That compound sentence (and + if/then) would be a lie.
(Of course if Liars are allowed to give answers like that, no Knights & Liars puzzle could ever be solved.)
Posted by Penny
on 2005-07-06 03:42:31