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 Home > Logic > Liars and Knights These problems are from a very large set of questions about Liars who always lie about everything, and Knights who always tell the truth. Some questions also involve Knaves - people who strictly alternate between lying and telling the truth. (They are of course all indistinguishable from one another by outward appearance, and you must use logic to determine who's who.)
Latest: John, Jack, A, and B Rating: 5.00
A logician named John went to the Land of Knights and Liars. He met two inhabitants, A and B. He asked A two questions.

John:Has B ever said that you are a liar?
A answered, either "Yes" or "No."
John:Is B a liar?
A answered, either "Yes" or "No."

The next day, another logician named Jack went to the Land of Knights and Liars. He met the same two inhabitants, A and B. He also asked A two questions.

Jack:Has B ever said that you are both liars?
A answered, either "Yes" or "No."
Jack:Is B a liar?
A answered, either "Yes" or "No."

One of the two logicians, John and Jack, could figure out what types A and B were, but the other logician could not figure out their types. What are A and B?

 (No Solution Yet, 3 Comments) Submitted on 2024-07-09 by Math Man
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