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Yes/No logic puzzle

  1. Nov 26, 2016 #1
    1. The problem statement, all variables and given/known data
    An explorer is captured by a group of cannibals. There are two types of cannibals--those who always tell the truth and those who always lie. The cannibals will barbecue the explore unless he can determine whether a particular cannibal always lies or always tells the truth. He is allowed to ask the cannibal exactly one question. Find a question that the explorer can use to determine whether the cannibal always lies or always tells the truth.

    2. Relevant equations

    3. The attempt at a solution
    I am not sure where to start. Is there a systematic way to formulate the appropriate question with propositional logic and truth tables, or must one just have divine inspiration?
  2. jcsd
  3. Nov 26, 2016 #2


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    You could always ask the cannibal whether he is a dolphin. If he says he is a dolphin then he's a liar.

    But, I guess that's not the sort of question you are expected to find?
  4. Nov 26, 2016 #3


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    I actually laughed on that one, but it's a correct answer.
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