The Collection

Every logic puzzle here is machine-checked by a solver before it is published: one provable solution, no ambiguous clues. Classic imports from the public domain are labeled until they pass review.

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Knights & knaves∎ verified

Knights and Knaves: Frank, Rupert, and Carol

On an island, every inhabitant is either a knight, who always tells the truth, or a knave, who always lies. You meet Frank, Rupert, and Carol. Rupert says: "I am a knave and Frank is a knave." Carol says: "Rupert is a k…

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