As before, the police have tracked down three suspects for a murder. They know that one of them is guilty and each one of them can be either a knight or a liar. Each one of them wrote two statements, but parts of them are full of coffee stains and they are not sure which one of the words in the brackets should be under each coffee stain:

A: ███ (B/C) is a liar. He is also guilty.

B: A is a ████ (liar/knight). C too.

C: A and B are both ████ (liars/knights). I'm guilty.

From these statements, can you figure out who is guilty?

If A says, "C is a liar and is guilty," then C's statement, "I am guilty," is a contradiction. If A is telling the truth, and C is a guilty liar, then C would claim not to be guilty. If A is lying, and C is an innocent knight, then C also would claim not to be guilty. So A says: "B is a liar. He is also guilty."

Since A claims that B is guilty, and C claims that he himself is guilty, one of them must be lying. However, B claims that A and C are of the same type (which holds true regardless of whether B is a knight or a liar). Therefore, both A and C are liars. Therefore, B is an innocent knight, and C is also innocent, meaning A is guilty.

Since B is a knight, then he must say, "A is a liar."

Since C is a liar, then he can say either, "A and B are both liars," OR "A and B are both knights." Both are false.

Posted by Jyqm on 2007-04-19 15:35:10