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It's unsolvable! (Posted on 2004-02-02) Difficulty: 4 of 5
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.

See The Solution Submitted by Tristan    
Rating: 4.2000 (10 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Question re(5): Pointing out...Tristan?!? | Comment 9 of 24 |
(In reply to re(4): Pointing out... by Brian Wainscott)

I know you said no more hints, but how about some clarification? How much lying is allowed? As I read the problem, you are trying to specifically limit the things that can be lied about.

But when the problem says "Aaron told me Cassie was a knight", if this is a lie, under your description what might have happened is Aaron said "my frog is sick". This is a lie not about who spoke or when, only about what he said. But if this is allowed, then however I slice it there is not enough information. If the storyteller is a liar, all bets are off. If he is a knave, then half the sentences can be rendered meaningless. I've tickled some info out of things even assuming meaningless statements, but not enough. Now, if "Aaron said Cassie was a knight" as a lie can ONLY mean "Aaron said Cassie was not a knight", or possibly "Cassie was a knave/liar" then I think it can be done. But my reading of the problem leaves too much latitude in the lying for me to get anywhere....

  Posted by Brian Wainscott on 2004-02-04 16:19:55

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