Lost in the woods, you finally happen upon a rickety old bridge across a deep ravine. The ravine is too steep to go down and climb back up. You need to know if the bridge is safe. As 'luck' would have it, you recognize that on the other side of the bridge is that dreadful town, "Knight-and-Liarville". Everyone who lives there is a knight (who always tells the truth) or a liar (who always lies). You are tired and you've been lost in Knight-and-Liarville before. You see three men on the other side of the bridge.

You shout out: "Are you a knight?"

The first man says something, but you can't hear what he said.

The second man shouts, "He said he was a knight."

The third man shouts, "No, he didn't. He said he was a liar."

Which man do you ask to find out whether or not the bridge is safe?

Since the second and third men contradict, and there are no knaves, we know that one of them is a knight and one of them is a liar.

This is all we need to know - now we can use the famous "would the other guy tell me the bridge is safe?" logic.

Point being, the first guy is completely irrelevant no matter how you look at it. The second and third guys could be contradicting each other about the color of the grass.

Posted by Gordon on 2004-05-06 17:11:05