Knights and Knaves: Frank, Peggy, Bob, Dave, and Mallory

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knights knaves

On an island, every inhabitant is either a knight, who always tells the truth, or a knave, who always lies. You meet Frank, Peggy, Bob, Dave, and Mallory. Frank says: "Mallory is a knave and I am a knave." Peggy says: "Dave is a knight." Bob says: "Dave is a knight or Peggy is a knave." Mallory says: "Dave is a knave or Bob is a knave." The others say nothing. Who is a knight and who is a knave?

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Solution

Commit an attempt to unseal the proof. Write your answer — right or wrong, thinking it through is the point.

Once you've worked out who is who: how many of the 5 inhabitants are knaves? Answer with the number.

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