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Thread: Puzzle cache

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  1. #1
    Johnmelad Guest

    Default Puzzle cache

    A person is standing at the coordinates of the cache. He/she has a choice of opening one of two doors in order to find the cache and sign the log.

    However, each door is guarded by someone - one guard is a liar other one tells the truth.

    This person wants to log the cache. What question does he/she have to pose to either of the guardians so that he knows which door the cache is behind? :coffee:

  2. #2

    Join Date
    Oct 2006
    Posts
    696

    Default

    Ask either guartdian the question "If I ask the other guardian which door is the cache behind, what will he say?" whatever answer you get is the wrong one, so choose the other door.

  3. #3
    keehotee Guest

    Default

    ...assuming the liar always lies.....

  4. #4

    Join Date
    Jan 2006
    Location
    S. E. Wales
    Posts
    1,223

    Default

    I've been trying to visualise this scenario in its various permutations...

    Now my brain hurts.

    Back to bopping that stupid ball on a string...

  5. #5

    Join Date
    Oct 2006
    Posts
    696

    Default

    A always lies, B always tells the truth.

    X is the correct door, Y is the wrong door.

    If you ask A what will B say, he knows that B would tell you the correct door - X, but A will lie and therefore tell you that B would say Y.

    If you ask B what will A say, he knows that X is the correct door but he knows that A will lie to you so B will tell you that A will say Y.

    In either case you will be told the wrong door.

  6. #6
    keehotee Guest

    Default

    Quote Originally Posted by martybartfast View Post
    A always lies, B always tells the truth.

    X is the correct door, Y is the wrong door.

    If you ask A what will B say, he knows that B would tell you the correct door - X, but A will lie and therefore tell you that B would say Y.
    But he's a liar, and not to be trusted.
    What grounds do you have to assume he always lies ....??h34r:

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