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May 17th, 2017, 11:53 AM   #1
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A REALLY confusing logic problem!

If anyone can help me with this problem, that'll be great.
I have my own solution, but I need to check it.

Problem:
There are two doors each labelled A and B respectively.
One door leads to treasure whilst the other leads to certain death.
A doorkeeper stands in your way and you must ask him only one question to know for certain the door with the treasure.
However, the doorkeeper will randomly tell the truth or will randomly lie.
He is only allowed to lie once.
Is there a way to find the correct door?
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May 17th, 2017, 12:22 PM   #2
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Does this involve goats?
Thanks from Joppy and Abidur Rahman
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May 17th, 2017, 01:44 PM   #3
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Quote:
Originally Posted by Abidur Rahman View Post
… you must ask him only one question …
He is only allowed to lie once…
I suspect you've posed the question incorrectly.
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May 17th, 2017, 02:05 PM   #4
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I thought it went: each guard keeper either always lies or always tells the truth, but you don't know which. That one you can figure out. But only allowed to lie once, and randomly?
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May 18th, 2017, 06:02 AM   #5
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Quote:
Originally Posted by Abidur Rahman View Post
If anyone can help me with this problem, that'll be great.
I have my own solution, but I need to check it.

Problem:
There are two doors each labelled A and B respectively.
One door leads to treasure whilst the other leads to certain death.
A doorkeeper stands in your way and you must ask him only one question to know for certain the door with the treasure.
However, the doorkeeper will randomly tell the truth or will randomly lie.
He is only allowed to lie once.
Is there a way to find the correct door?
NOTE: I assure you that I did not write the problem incorrectly, this is an alternate version of the original problem. Good luck.
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May 18th, 2017, 11:15 PM   #6
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The answer is of course, no.
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May 19th, 2017, 01:29 AM   #7
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The answer to what? I would think there is a way. It might require certain minor assumptions, such as that he would answer truthfully if he has previously answered with a lie, and that he understands whatever he is asked, replies in a language that the questioner understands, and replies to questions about what he could reply in hypothetical situations. It might also be necessary to assume that the doorkeeper always uses a direct reply when such a reply is possible.
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May 19th, 2017, 04:21 AM   #8
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Quote:
Originally Posted by Abidur Rahman View Post
A doorkeeper stands in your way and you must ask him only one question to know for certain the door with the treasure.
However, the doorkeeper will randomly tell the truth or will randomly lie.
He is only allowed to lie once.
This makes no sense: "He is only allowed to lie once."
It's automatic that he's also only allowed to tell truth once,
since ONLY one question is asked...
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May 20th, 2017, 01:53 AM   #9
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I guess if you ask him a $2$ part question and force him to lie on the first part , his answer to the second part must be truthfull.

Can you force him to lie? I don't know how

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May 20th, 2017, 11:27 AM   #10
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The question could ask about the replies that would be given to several other questions, or could start with "If you're answering truthfully, what is . . .", etc.
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