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?

(In reply to re(2): Two ways by Charlie)

Good Job, Charlie.

You answered both the "Logical" thinking part of the puzzle, as well as shown how to identify the three natives. 

As the puzzle states that you know the type of the first native from the first question, you are correct that it must be the (lie-first) Knave who answered "Are you a liar." with a "Yes".  Your second question is one of several that could have been asked to ascertain the identity of each of the natives.  With the condition given in the puzzle that you knew the type of the native after the first question, he did not answer "No, I am not a liar" to your question. 

Posted by Dej Mar on 2006-09-02 22:19:28