In Tripleland, natives always go in trios: a knight, a knave, and a liar.

Once I met such a trio, and I asked one of the natives a simple question ("simple" meaning, "of six words or less"); he answered, and I knew what type he was. Then, I asked another of the natives a different simple question; he answered, and I knew what type he was, and therefore, the type of the third one too.

"Logical" thinking: This cannot be. The natives could be in six possible orders. Two yes-no questions allow four combinations. Thus, you cannot pick one out of six with only two questions; you need one more!

How could this be? What's wrong with the reasoning above?

There is something only a knave could say, but neither a knight or a liar could, so if the first question asked that and you got certain answer, you would know who was the knave. Then, asking any of the other two "Is he the knave?" would show who is the knight and who is the liar.

Posted by Old Original Oskar! on 2006-09-02 16:03:38