Knights always tell the truth,liars always lie,and knaves alternate between truths and lies.

Two people named Jimmy and Johnny make the following claims.

Jimmy:I am a knave.
Johnny:Jimmy is not a knight.
Jimmy:Johnny is a knave.
Johnny:Jimmy is a knave.

What are each?

Jimmy's first and second statements clearly establishes him to be a Liar or Knave.

Johnny's first statement thus implies that he is a Knight.

Accodingly, by Johnny's true second statement, Jimmy is a Knave

Consequently,

Jimmy is a Knave.
Johnny is a Knight. 

Posted by K Sengupta on 2007-07-11 05:46:41