My friend told me this complex story. Everyone in it is either a knight, knave, or liar (more than one person can have the same status). Knights always tell truths, liars always lie, and knaves always alternate every statement.

Everyone knew the status of everyone else except for my friend (he knew nothing at first). If anyone lied about what someone said, they didn’t lie about who, when, or whether they said it; they only lied about what the person said. The story goes as follows.

Aaron and Bill were talking to me.
Aaron told me what he was.
At this point, I could tell what Aaron was.
Bill told me one thing that he wasn’t.
Aaron told me that Cassie was a knight.
I then could figure out what Cassie was.
Bill told me that Cassie was a knave.
I thought about this for a minute.
I soon found that the previous thing Bill said allowed me to know for sure what the last of the three people were.

What type is everyone? The puzzle is solvable.

(Haven't read any posts yet.)

Aaron told the friend "I am a liar".  This is the only thing he could say that would reveal what he really was.  Obviously he is a knave who was lying.  The next thing Aaron said was that Cassie was a knight, so this had to be the truth.  Bill said Cassie was a knave, which was a lie, so Bill is either a knave or a liar.  Since Bill's second statement (about Cassie) was a lie, then If he were a knave his first statement would have been the truth, which must have been either "I'm not a liar, or I'm not a knight".  If he were a liar, his first statement could only have been "I'm not a liar."  If that had been his statement, then the friend would not have been able to tell whether he was a liar or a knave.  Since the friend was able to determine what he was, Bill's statement must have been "I'm not a knight".  So the friend was able to determine that he was a knave.

Run down: Aaron and Bill are knaves, Cassie is a knight.

Seems easy.  I'll have to read the comments now.

 

Posted by Galendir on 2004-03-21 06:25:34