[net.puzzle] Liar/Truth-teller/Diplomat puzzle

anderson@uwvax.ARPA (08/28/84)

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Has this puzzle been around yet?

THE LIAR/TRUTH-TELLER/DIPLOMAT PUZZLE

You are confronted with 3 people: one always lies, one always tells
the truth, and the third (the diplomat) gives random yes/no answers.
You don't know which is which, and must figure it out by asking three
yes/no questions.  Each question may be directed to only one of the
three.  Assume all three know which person is which.

Warning: this is pretty hard.

David Anderson (uwvax!anderson)