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# Knights and Knaves 2 - Solution

Puzzles -> Logic Puzzles

 The Puzzle: There are three people (Alex, Brook and Cody), one of whom is a knight, one a knave, and one a spy. The knight always tells the truth, the knave always lies, and the spy can either lie or tell the truth. They are brought before a judge who wants to identify the spy.Alex says: "I am not a spy."Brook says: "I am a spy."Now Cody is in fact the spy. The judge asks him: "Is Brook really a spy?"Can Cody give an answer so that he doesn't convict himself as a spy?

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## The Solution . . .

 Cody should answer "No".Brook is either a knave or a spy. If Brook is a spy, then Alex is truthful and is therefore the knight. Alex is a Knight Brook is a Spy Cody is a KnaveOn the other hand, if Brook is the knave, there are two possibilities: Alex is a Spy Brook is a Knave Cody is a Knightor Alex is a Knight Brook is a Knave Cody is a SpyIf Cody is either the knave or the knight, his answer to the question will be "No", and so the judge will not be able to draw a conclusion. On the other hand, Cody can answer "Yes" only if he is the spy.

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