The Three Mystery People- An Actual Mystery











up vote
3
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I believe almost everyone has heard this riddle before.




There are three people in front of you. One always tells the truth, one always lies, and one answers randomly between truth and lies. You can ask 3 yes-or-no questions to any of the people. How can you figure out which person tells the truth, which person lies, and which person speaks randomly?




There are several variations on this riddle, including an infamous version where you can't tell if what they are saying means yes or no.



Here's one I came up with.




There are three people in front of you. One always tells the truth, one always lies, and one answers randomly between truth and lies. THE THREE PEOPLE DO NOT KNOW THE IDENTITY OF ANYONE BESIDES THEMSELF. You can ask 3 yes-or-no questions to any of the people. How can you figure out which person tells the truth, which person lies, and which person speaks randomly?




Good luck!










share|improve this question


















  • 1




    Can you clarify how the random person works? If they don't know the answer, will they say "I don't know" or respond with either yes or no randomly?
    – Zimonze
    Nov 16 at 18:29










  • @Zimonze they will say a random thing of yes or no, regardless of they know or not.
    – Excited Raichu
    Nov 16 at 18:32






  • 1




    What about the truthteller and liar? Will they say that they don't know?
    – Zimonze
    Nov 16 at 18:35










  • @Zimonze yes, they will
    – Excited Raichu
    Nov 16 at 18:36










  • Wait, so when you ask a question, can it only be to one person or to the whole group of three? I guess I'm not finding "to any of the people" to be clear enough.
    – Dorrulf
    Nov 16 at 18:44















up vote
3
down vote

favorite
1












I believe almost everyone has heard this riddle before.




There are three people in front of you. One always tells the truth, one always lies, and one answers randomly between truth and lies. You can ask 3 yes-or-no questions to any of the people. How can you figure out which person tells the truth, which person lies, and which person speaks randomly?




There are several variations on this riddle, including an infamous version where you can't tell if what they are saying means yes or no.



Here's one I came up with.




There are three people in front of you. One always tells the truth, one always lies, and one answers randomly between truth and lies. THE THREE PEOPLE DO NOT KNOW THE IDENTITY OF ANYONE BESIDES THEMSELF. You can ask 3 yes-or-no questions to any of the people. How can you figure out which person tells the truth, which person lies, and which person speaks randomly?




Good luck!










share|improve this question


















  • 1




    Can you clarify how the random person works? If they don't know the answer, will they say "I don't know" or respond with either yes or no randomly?
    – Zimonze
    Nov 16 at 18:29










  • @Zimonze they will say a random thing of yes or no, regardless of they know or not.
    – Excited Raichu
    Nov 16 at 18:32






  • 1




    What about the truthteller and liar? Will they say that they don't know?
    – Zimonze
    Nov 16 at 18:35










  • @Zimonze yes, they will
    – Excited Raichu
    Nov 16 at 18:36










  • Wait, so when you ask a question, can it only be to one person or to the whole group of three? I guess I'm not finding "to any of the people" to be clear enough.
    – Dorrulf
    Nov 16 at 18:44













up vote
3
down vote

favorite
1









up vote
3
down vote

favorite
1






1





I believe almost everyone has heard this riddle before.




There are three people in front of you. One always tells the truth, one always lies, and one answers randomly between truth and lies. You can ask 3 yes-or-no questions to any of the people. How can you figure out which person tells the truth, which person lies, and which person speaks randomly?




There are several variations on this riddle, including an infamous version where you can't tell if what they are saying means yes or no.



Here's one I came up with.




There are three people in front of you. One always tells the truth, one always lies, and one answers randomly between truth and lies. THE THREE PEOPLE DO NOT KNOW THE IDENTITY OF ANYONE BESIDES THEMSELF. You can ask 3 yes-or-no questions to any of the people. How can you figure out which person tells the truth, which person lies, and which person speaks randomly?




Good luck!










share|improve this question













I believe almost everyone has heard this riddle before.




There are three people in front of you. One always tells the truth, one always lies, and one answers randomly between truth and lies. You can ask 3 yes-or-no questions to any of the people. How can you figure out which person tells the truth, which person lies, and which person speaks randomly?




There are several variations on this riddle, including an infamous version where you can't tell if what they are saying means yes or no.



Here's one I came up with.




There are three people in front of you. One always tells the truth, one always lies, and one answers randomly between truth and lies. THE THREE PEOPLE DO NOT KNOW THE IDENTITY OF ANYONE BESIDES THEMSELF. You can ask 3 yes-or-no questions to any of the people. How can you figure out which person tells the truth, which person lies, and which person speaks randomly?




Good luck!







logical-deduction liars






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 16 at 18:12









Excited Raichu

4,193752




4,193752








  • 1




    Can you clarify how the random person works? If they don't know the answer, will they say "I don't know" or respond with either yes or no randomly?
    – Zimonze
    Nov 16 at 18:29










  • @Zimonze they will say a random thing of yes or no, regardless of they know or not.
    – Excited Raichu
    Nov 16 at 18:32






  • 1




    What about the truthteller and liar? Will they say that they don't know?
    – Zimonze
    Nov 16 at 18:35










  • @Zimonze yes, they will
    – Excited Raichu
    Nov 16 at 18:36










  • Wait, so when you ask a question, can it only be to one person or to the whole group of three? I guess I'm not finding "to any of the people" to be clear enough.
    – Dorrulf
    Nov 16 at 18:44














  • 1




    Can you clarify how the random person works? If they don't know the answer, will they say "I don't know" or respond with either yes or no randomly?
    – Zimonze
    Nov 16 at 18:29










  • @Zimonze they will say a random thing of yes or no, regardless of they know or not.
    – Excited Raichu
    Nov 16 at 18:32






  • 1




    What about the truthteller and liar? Will they say that they don't know?
    – Zimonze
    Nov 16 at 18:35










  • @Zimonze yes, they will
    – Excited Raichu
    Nov 16 at 18:36










  • Wait, so when you ask a question, can it only be to one person or to the whole group of three? I guess I'm not finding "to any of the people" to be clear enough.
    – Dorrulf
    Nov 16 at 18:44








1




1




Can you clarify how the random person works? If they don't know the answer, will they say "I don't know" or respond with either yes or no randomly?
– Zimonze
Nov 16 at 18:29




Can you clarify how the random person works? If they don't know the answer, will they say "I don't know" or respond with either yes or no randomly?
– Zimonze
Nov 16 at 18:29












@Zimonze they will say a random thing of yes or no, regardless of they know or not.
– Excited Raichu
Nov 16 at 18:32




@Zimonze they will say a random thing of yes or no, regardless of they know or not.
– Excited Raichu
Nov 16 at 18:32




1




1




What about the truthteller and liar? Will they say that they don't know?
– Zimonze
Nov 16 at 18:35




What about the truthteller and liar? Will they say that they don't know?
– Zimonze
Nov 16 at 18:35












@Zimonze yes, they will
– Excited Raichu
Nov 16 at 18:36




@Zimonze yes, they will
– Excited Raichu
Nov 16 at 18:36












Wait, so when you ask a question, can it only be to one person or to the whole group of three? I guess I'm not finding "to any of the people" to be clear enough.
– Dorrulf
Nov 16 at 18:44




Wait, so when you ask a question, can it only be to one person or to the whole group of three? I guess I'm not finding "to any of the people" to be clear enough.
– Dorrulf
Nov 16 at 18:44










4 Answers
4






active

oldest

votes

















up vote
3
down vote



accepted










Alright, let's try this I guess...




I have 2 questions, one I will ask once, and one I will ask twice.

1st question: Ask the person if my underwear is blue (they can't see it). If they answer "I don't know", they're either a truth teller or liar. If they answer yes or no, then we know they are the random one.

2nd question: Ask the person if my eyes are brown (let's say they're actually blue). If they answer no, they are the truth teller or the random, and if they answer yes then they are the liar or the random.

I will ask person 1 the first question. If I find them to be the random, I will ask the 2nd question to each of the next people. If I find them to be either the truth teller or liar, then I will ask the same person the second question and one of the remaining to people the first question again.

Possible outcomes: (in Q-P:A format, 1 - 3)

1-1:Random 2-2:T/F no need for 3rd question, person 3 must be remaining T/F

1-1:T/F 2-1:T/F 3-2:Random remaining 3rd person is remaining T/F

1-1:T/F 2-1:T/F 3-2:T/F remaining 3rd person is Random







share|improve this answer





















  • This gets the check for being the first- my solution used the same exact first question with rot13(Vf gjb cyhf gjb svir?) as the second question.
    – Excited Raichu
    Nov 16 at 19:00










  • Wow, well that really would've been something if they had both been the same.
    – Dorrulf
    Nov 16 at 19:11


















up vote
2
down vote













I can think of one question to start with:




"Do you know whether you tell the truth, lies, or both?"
This question should weed out one of the three rather quickly since the truth-teller will always answer 'yes' and the liar will always answer 'no', but the intermittent answerer will do either and 'pair up' with one of the two people, leaving the other's identity clear without a doubt.

However, I cannot think of a way to weed out the intermittent answerer just yet, since there is a 1/4 chance that they mimic the other person exactly (first answer doesn't matter - either the truth-teller or the liar gets separated from the other two. Then, assuming equal probabilities of either a truth or a lie from this person, there is the one-in-four chance that they answer identically to the one person that they were paired up with initially. Perhaps the same question could be asked again twice and we could rely on the 3-in-4 chance of the intermittent answerer changing their answer.







share|improve this answer




























    up vote
    2
    down vote













    Question 1:




    Ask someone "If I were to flip a coin, will it land on heads?"




    Result:




    If the answer to Question 1 is "yes" or "no", they are the random-teller.


    Skip to Question 3.


    If the answer to Question 1 is "I don't know", they are not the random-teller.


    Ask someone else Question 2.




    Question 2:




    Same as Question 1.




    Result:




    If the answer to Question 2 is "yes" or "no", they are the random-teller.


    If the answer to Question 2 is "I don't know", the person you did not interrogate yet is the random-teller.




    Question 3:




    Ask one non-random-teller "Is 2+2=4?" This identifies the truth teller or liar, and by process of elimination identifies the last person as well.




    Result:




    Success!







    share|improve this answer





















    • rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
      – kanoo
      Nov 16 at 21:15










    • @kanoo look at op's comments on the post.
      – Zimonze
      Nov 16 at 23:03




















    up vote
    1
    down vote













    Approach one of them,




    point to one of the other two, and ask "Does this person tell the truth?"




    Approach a different individual




    point to one of the other two and ask the same question. Since none of them know the others' identities, both the truthteller and the liar will answer that they do not know, while the third person will answer randomly between "yes" and "no"




    Your third question is




    "Do you know your own identity?",




    with the caveat that




    you should ask this question of an individual who has responded "I don't know" to a previous question. "Yes" means this is the truthteller, "no" means this is the liar







    share|improve this answer























    • rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
      – kanoo
      Nov 16 at 21:16











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    4 Answers
    4






    active

    oldest

    votes








    4 Answers
    4






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    3
    down vote



    accepted










    Alright, let's try this I guess...




    I have 2 questions, one I will ask once, and one I will ask twice.

    1st question: Ask the person if my underwear is blue (they can't see it). If they answer "I don't know", they're either a truth teller or liar. If they answer yes or no, then we know they are the random one.

    2nd question: Ask the person if my eyes are brown (let's say they're actually blue). If they answer no, they are the truth teller or the random, and if they answer yes then they are the liar or the random.

    I will ask person 1 the first question. If I find them to be the random, I will ask the 2nd question to each of the next people. If I find them to be either the truth teller or liar, then I will ask the same person the second question and one of the remaining to people the first question again.

    Possible outcomes: (in Q-P:A format, 1 - 3)

    1-1:Random 2-2:T/F no need for 3rd question, person 3 must be remaining T/F

    1-1:T/F 2-1:T/F 3-2:Random remaining 3rd person is remaining T/F

    1-1:T/F 2-1:T/F 3-2:T/F remaining 3rd person is Random







    share|improve this answer





















    • This gets the check for being the first- my solution used the same exact first question with rot13(Vf gjb cyhf gjb svir?) as the second question.
      – Excited Raichu
      Nov 16 at 19:00










    • Wow, well that really would've been something if they had both been the same.
      – Dorrulf
      Nov 16 at 19:11















    up vote
    3
    down vote



    accepted










    Alright, let's try this I guess...




    I have 2 questions, one I will ask once, and one I will ask twice.

    1st question: Ask the person if my underwear is blue (they can't see it). If they answer "I don't know", they're either a truth teller or liar. If they answer yes or no, then we know they are the random one.

    2nd question: Ask the person if my eyes are brown (let's say they're actually blue). If they answer no, they are the truth teller or the random, and if they answer yes then they are the liar or the random.

    I will ask person 1 the first question. If I find them to be the random, I will ask the 2nd question to each of the next people. If I find them to be either the truth teller or liar, then I will ask the same person the second question and one of the remaining to people the first question again.

    Possible outcomes: (in Q-P:A format, 1 - 3)

    1-1:Random 2-2:T/F no need for 3rd question, person 3 must be remaining T/F

    1-1:T/F 2-1:T/F 3-2:Random remaining 3rd person is remaining T/F

    1-1:T/F 2-1:T/F 3-2:T/F remaining 3rd person is Random







    share|improve this answer





















    • This gets the check for being the first- my solution used the same exact first question with rot13(Vf gjb cyhf gjb svir?) as the second question.
      – Excited Raichu
      Nov 16 at 19:00










    • Wow, well that really would've been something if they had both been the same.
      – Dorrulf
      Nov 16 at 19:11













    up vote
    3
    down vote



    accepted







    up vote
    3
    down vote



    accepted






    Alright, let's try this I guess...




    I have 2 questions, one I will ask once, and one I will ask twice.

    1st question: Ask the person if my underwear is blue (they can't see it). If they answer "I don't know", they're either a truth teller or liar. If they answer yes or no, then we know they are the random one.

    2nd question: Ask the person if my eyes are brown (let's say they're actually blue). If they answer no, they are the truth teller or the random, and if they answer yes then they are the liar or the random.

    I will ask person 1 the first question. If I find them to be the random, I will ask the 2nd question to each of the next people. If I find them to be either the truth teller or liar, then I will ask the same person the second question and one of the remaining to people the first question again.

    Possible outcomes: (in Q-P:A format, 1 - 3)

    1-1:Random 2-2:T/F no need for 3rd question, person 3 must be remaining T/F

    1-1:T/F 2-1:T/F 3-2:Random remaining 3rd person is remaining T/F

    1-1:T/F 2-1:T/F 3-2:T/F remaining 3rd person is Random







    share|improve this answer












    Alright, let's try this I guess...




    I have 2 questions, one I will ask once, and one I will ask twice.

    1st question: Ask the person if my underwear is blue (they can't see it). If they answer "I don't know", they're either a truth teller or liar. If they answer yes or no, then we know they are the random one.

    2nd question: Ask the person if my eyes are brown (let's say they're actually blue). If they answer no, they are the truth teller or the random, and if they answer yes then they are the liar or the random.

    I will ask person 1 the first question. If I find them to be the random, I will ask the 2nd question to each of the next people. If I find them to be either the truth teller or liar, then I will ask the same person the second question and one of the remaining to people the first question again.

    Possible outcomes: (in Q-P:A format, 1 - 3)

    1-1:Random 2-2:T/F no need for 3rd question, person 3 must be remaining T/F

    1-1:T/F 2-1:T/F 3-2:Random remaining 3rd person is remaining T/F

    1-1:T/F 2-1:T/F 3-2:T/F remaining 3rd person is Random








    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered Nov 16 at 18:56









    Dorrulf

    1,3527




    1,3527












    • This gets the check for being the first- my solution used the same exact first question with rot13(Vf gjb cyhf gjb svir?) as the second question.
      – Excited Raichu
      Nov 16 at 19:00










    • Wow, well that really would've been something if they had both been the same.
      – Dorrulf
      Nov 16 at 19:11


















    • This gets the check for being the first- my solution used the same exact first question with rot13(Vf gjb cyhf gjb svir?) as the second question.
      – Excited Raichu
      Nov 16 at 19:00










    • Wow, well that really would've been something if they had both been the same.
      – Dorrulf
      Nov 16 at 19:11
















    This gets the check for being the first- my solution used the same exact first question with rot13(Vf gjb cyhf gjb svir?) as the second question.
    – Excited Raichu
    Nov 16 at 19:00




    This gets the check for being the first- my solution used the same exact first question with rot13(Vf gjb cyhf gjb svir?) as the second question.
    – Excited Raichu
    Nov 16 at 19:00












    Wow, well that really would've been something if they had both been the same.
    – Dorrulf
    Nov 16 at 19:11




    Wow, well that really would've been something if they had both been the same.
    – Dorrulf
    Nov 16 at 19:11










    up vote
    2
    down vote













    I can think of one question to start with:




    "Do you know whether you tell the truth, lies, or both?"
    This question should weed out one of the three rather quickly since the truth-teller will always answer 'yes' and the liar will always answer 'no', but the intermittent answerer will do either and 'pair up' with one of the two people, leaving the other's identity clear without a doubt.

    However, I cannot think of a way to weed out the intermittent answerer just yet, since there is a 1/4 chance that they mimic the other person exactly (first answer doesn't matter - either the truth-teller or the liar gets separated from the other two. Then, assuming equal probabilities of either a truth or a lie from this person, there is the one-in-four chance that they answer identically to the one person that they were paired up with initially. Perhaps the same question could be asked again twice and we could rely on the 3-in-4 chance of the intermittent answerer changing their answer.







    share|improve this answer

























      up vote
      2
      down vote













      I can think of one question to start with:




      "Do you know whether you tell the truth, lies, or both?"
      This question should weed out one of the three rather quickly since the truth-teller will always answer 'yes' and the liar will always answer 'no', but the intermittent answerer will do either and 'pair up' with one of the two people, leaving the other's identity clear without a doubt.

      However, I cannot think of a way to weed out the intermittent answerer just yet, since there is a 1/4 chance that they mimic the other person exactly (first answer doesn't matter - either the truth-teller or the liar gets separated from the other two. Then, assuming equal probabilities of either a truth or a lie from this person, there is the one-in-four chance that they answer identically to the one person that they were paired up with initially. Perhaps the same question could be asked again twice and we could rely on the 3-in-4 chance of the intermittent answerer changing their answer.







      share|improve this answer























        up vote
        2
        down vote










        up vote
        2
        down vote









        I can think of one question to start with:




        "Do you know whether you tell the truth, lies, or both?"
        This question should weed out one of the three rather quickly since the truth-teller will always answer 'yes' and the liar will always answer 'no', but the intermittent answerer will do either and 'pair up' with one of the two people, leaving the other's identity clear without a doubt.

        However, I cannot think of a way to weed out the intermittent answerer just yet, since there is a 1/4 chance that they mimic the other person exactly (first answer doesn't matter - either the truth-teller or the liar gets separated from the other two. Then, assuming equal probabilities of either a truth or a lie from this person, there is the one-in-four chance that they answer identically to the one person that they were paired up with initially. Perhaps the same question could be asked again twice and we could rely on the 3-in-4 chance of the intermittent answerer changing their answer.







        share|improve this answer












        I can think of one question to start with:




        "Do you know whether you tell the truth, lies, or both?"
        This question should weed out one of the three rather quickly since the truth-teller will always answer 'yes' and the liar will always answer 'no', but the intermittent answerer will do either and 'pair up' with one of the two people, leaving the other's identity clear without a doubt.

        However, I cannot think of a way to weed out the intermittent answerer just yet, since there is a 1/4 chance that they mimic the other person exactly (first answer doesn't matter - either the truth-teller or the liar gets separated from the other two. Then, assuming equal probabilities of either a truth or a lie from this person, there is the one-in-four chance that they answer identically to the one person that they were paired up with initially. Perhaps the same question could be asked again twice and we could rely on the 3-in-4 chance of the intermittent answerer changing their answer.








        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 16 at 18:22









        kanoo

        1,754224




        1,754224






















            up vote
            2
            down vote













            Question 1:




            Ask someone "If I were to flip a coin, will it land on heads?"




            Result:




            If the answer to Question 1 is "yes" or "no", they are the random-teller.


            Skip to Question 3.


            If the answer to Question 1 is "I don't know", they are not the random-teller.


            Ask someone else Question 2.




            Question 2:




            Same as Question 1.




            Result:




            If the answer to Question 2 is "yes" or "no", they are the random-teller.


            If the answer to Question 2 is "I don't know", the person you did not interrogate yet is the random-teller.




            Question 3:




            Ask one non-random-teller "Is 2+2=4?" This identifies the truth teller or liar, and by process of elimination identifies the last person as well.




            Result:




            Success!







            share|improve this answer





















            • rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
              – kanoo
              Nov 16 at 21:15










            • @kanoo look at op's comments on the post.
              – Zimonze
              Nov 16 at 23:03

















            up vote
            2
            down vote













            Question 1:




            Ask someone "If I were to flip a coin, will it land on heads?"




            Result:




            If the answer to Question 1 is "yes" or "no", they are the random-teller.


            Skip to Question 3.


            If the answer to Question 1 is "I don't know", they are not the random-teller.


            Ask someone else Question 2.




            Question 2:




            Same as Question 1.




            Result:




            If the answer to Question 2 is "yes" or "no", they are the random-teller.


            If the answer to Question 2 is "I don't know", the person you did not interrogate yet is the random-teller.




            Question 3:




            Ask one non-random-teller "Is 2+2=4?" This identifies the truth teller or liar, and by process of elimination identifies the last person as well.




            Result:




            Success!







            share|improve this answer





















            • rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
              – kanoo
              Nov 16 at 21:15










            • @kanoo look at op's comments on the post.
              – Zimonze
              Nov 16 at 23:03















            up vote
            2
            down vote










            up vote
            2
            down vote









            Question 1:




            Ask someone "If I were to flip a coin, will it land on heads?"




            Result:




            If the answer to Question 1 is "yes" or "no", they are the random-teller.


            Skip to Question 3.


            If the answer to Question 1 is "I don't know", they are not the random-teller.


            Ask someone else Question 2.




            Question 2:




            Same as Question 1.




            Result:




            If the answer to Question 2 is "yes" or "no", they are the random-teller.


            If the answer to Question 2 is "I don't know", the person you did not interrogate yet is the random-teller.




            Question 3:




            Ask one non-random-teller "Is 2+2=4?" This identifies the truth teller or liar, and by process of elimination identifies the last person as well.




            Result:




            Success!







            share|improve this answer












            Question 1:




            Ask someone "If I were to flip a coin, will it land on heads?"




            Result:




            If the answer to Question 1 is "yes" or "no", they are the random-teller.


            Skip to Question 3.


            If the answer to Question 1 is "I don't know", they are not the random-teller.


            Ask someone else Question 2.




            Question 2:




            Same as Question 1.




            Result:




            If the answer to Question 2 is "yes" or "no", they are the random-teller.


            If the answer to Question 2 is "I don't know", the person you did not interrogate yet is the random-teller.




            Question 3:




            Ask one non-random-teller "Is 2+2=4?" This identifies the truth teller or liar, and by process of elimination identifies the last person as well.




            Result:




            Success!








            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered Nov 16 at 18:59









            Zimonze

            1,052121




            1,052121












            • rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
              – kanoo
              Nov 16 at 21:15










            • @kanoo look at op's comments on the post.
              – Zimonze
              Nov 16 at 23:03




















            • rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
              – kanoo
              Nov 16 at 21:15










            • @kanoo look at op's comments on the post.
              – Zimonze
              Nov 16 at 23:03


















            rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
            – kanoo
            Nov 16 at 21:15




            rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
            – kanoo
            Nov 16 at 21:15












            @kanoo look at op's comments on the post.
            – Zimonze
            Nov 16 at 23:03






            @kanoo look at op's comments on the post.
            – Zimonze
            Nov 16 at 23:03












            up vote
            1
            down vote













            Approach one of them,




            point to one of the other two, and ask "Does this person tell the truth?"




            Approach a different individual




            point to one of the other two and ask the same question. Since none of them know the others' identities, both the truthteller and the liar will answer that they do not know, while the third person will answer randomly between "yes" and "no"




            Your third question is




            "Do you know your own identity?",




            with the caveat that




            you should ask this question of an individual who has responded "I don't know" to a previous question. "Yes" means this is the truthteller, "no" means this is the liar







            share|improve this answer























            • rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
              – kanoo
              Nov 16 at 21:16















            up vote
            1
            down vote













            Approach one of them,




            point to one of the other two, and ask "Does this person tell the truth?"




            Approach a different individual




            point to one of the other two and ask the same question. Since none of them know the others' identities, both the truthteller and the liar will answer that they do not know, while the third person will answer randomly between "yes" and "no"




            Your third question is




            "Do you know your own identity?",




            with the caveat that




            you should ask this question of an individual who has responded "I don't know" to a previous question. "Yes" means this is the truthteller, "no" means this is the liar







            share|improve this answer























            • rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
              – kanoo
              Nov 16 at 21:16













            up vote
            1
            down vote










            up vote
            1
            down vote









            Approach one of them,




            point to one of the other two, and ask "Does this person tell the truth?"




            Approach a different individual




            point to one of the other two and ask the same question. Since none of them know the others' identities, both the truthteller and the liar will answer that they do not know, while the third person will answer randomly between "yes" and "no"




            Your third question is




            "Do you know your own identity?",




            with the caveat that




            you should ask this question of an individual who has responded "I don't know" to a previous question. "Yes" means this is the truthteller, "no" means this is the liar







            share|improve this answer














            Approach one of them,




            point to one of the other two, and ask "Does this person tell the truth?"




            Approach a different individual




            point to one of the other two and ask the same question. Since none of them know the others' identities, both the truthteller and the liar will answer that they do not know, while the third person will answer randomly between "yes" and "no"




            Your third question is




            "Do you know your own identity?",




            with the caveat that




            you should ask this question of an individual who has responded "I don't know" to a previous question. "Yes" means this is the truthteller, "no" means this is the liar








            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited Nov 16 at 18:57

























            answered Nov 16 at 18:47









            Punintended

            1613




            1613












            • rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
              – kanoo
              Nov 16 at 21:16


















            • rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
              – kanoo
              Nov 16 at 21:16
















            rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
            – kanoo
            Nov 16 at 21:16




            rot13(Jul jbhyq gur enaqbz gryyre fnl lrf be ab? Nyfb, jul jbhyqa'g gur yvne yvr nobhg abg xabjvat naq fnl lrf be ab?)
            – kanoo
            Nov 16 at 21:16


















             

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