Alan, Barry and Carl (each either a Knight or a Liar) were rounded up by the cops yesterday, because one of them was suspected of having stolen money from the bank. The three brothers made the following statements under very intensive questioning:

Alan: I'm innocent.

Barry: I'm innocent.

Carl: Barry is the guilty one.

If only one of these men is a Knight, who stole the money?

Barry and Carl directly contradict one another, and so one must be a Knight, and the other a Liar.

Since there are two Liars, Alan is the second liar, and his claim of innocence is false. Alan is the thief.

In addition, now that we know Alan is the thief, we can determine that, since his claim of innocence is true, Barry is the Knight.

Posted by TomM on 2003-02-27 05:40:59