bonanova Posted November 2, 2008 Report Share Posted November 2, 2008 I heard this posed [not original with me] and I have not worked out a solution. Yet. A truthful person who is aware of every fact will answer yes/no questions in a certain way. Curiously, a liar who is misinformed about every fact will answer yes/no questions in exactly the same way! If you asked: "Is the sky blue?" both would answer: "Yes." The first, because he knew it to be true and answered truthfully according to his belief. The second, because he believed it to be false and lied according to his belief. The puzzle is this: Can you distinguish between the two by asking a series of yes/no questions? If so [and why would we ask if you couldn't? ] what is the minimum number of questions needed? Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 2, 2008 Report Share Posted November 2, 2008 (edited) I don't know how concrete my answer will be, but I'm willing to give it a shot..... If you ask, "Does the other person tell the truth?", the truth teller would reply no, since he tells the truth and is not misinformed. The liar, misinformed about the truth teller, thinks the truth teller is a liar, but lies and says yes. So we have the two statements, one question (unless you count asking , before we know who is who, that one doesn't tell the truth, and the other does. If we assume the statement that the other is telling the truth is the truth tellers, it can't be because he would be lying and that would make the liar's statement false anyways because he wouldn't be misinformed which doesn't fit the criteria. Therefore, with one question, you should be able to determine which is which. This is assuming that it is fact the truthful person tells the truth and the misinformed liar, lies. After I read over this again, I've confused myself, so it doesn't make sense to me anymore . Anyone care to explain my reasoning? Edited November 2, 2008 by runder_1111 Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 2, 2008 Report Share Posted November 2, 2008 (edited) 'is guy "A" a liar?' both will state the truth (one by knowledge and honesty one by incompetence and lying) and you will know who is who, simple as that. of course if you want to assume the liar knows he is a liar then the one who gets two different answers is the liar and the one who gets two identical answers is the truth teller... Edited November 2, 2008 by bonanova added spoiler Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 2, 2008 Report Share Posted November 2, 2008 yes, one question. Are you my mother? Both are not so the honest one would say no and the dishonest would say yes. Quote Link to comment Share on other sites More sharing options...
0 Prime Posted November 2, 2008 Report Share Posted November 2, 2008 As usually with this type of problems, you ask a question, where the meaning is relative to person's identity. Are you a liar? Informed truth-teller will answer "NO". Misinformed liar, who thinks he is a truth-teller, will answer "YES", since he is compelled to lie. The interesting point is, Liar cannot resolve an apparent disagreement between his own believes and his actions. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 2, 2008 Report Share Posted November 2, 2008 the simple fact that the liar is misinformed in then twists the wrong info, makes his statement true (a double negative), so then you can ask anybody anything and they should both give you the right answer, so I think the puzzle is a bit to easy, since I've heard some variations if this types of riddles and they're usually a bit trickier. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 2, 2008 Report Share Posted November 2, 2008 I heard this posed [not original with me] and I have not worked out a solution. Yet. A truthful person who is aware of every fact will answer yes/no questions in a certain way. Curiously, a liar who is misinformed about every fact will answer yes/no questions in exactly the same way! If you asked: "Is the sky blue?" both would answer: "Yes." The first, because he knew it to be true and answered truthfully according to his belief. The second, because he believed it to be false and lied according to his belief. The puzzle is this: Can you distinguish between the two by asking a series of yes/no questions? If so [and why would we ask if you couldn't? ] what is the minimum number of questions needed? one question lol Quote Link to comment Share on other sites More sharing options...
0 peace*out Posted November 2, 2008 Report Share Posted November 2, 2008 one question lol but what is the question... so far what i have (and heard) is asking if they are my realitive of some sort (sister; brother...). That seems like a good answer (unless the person asking never knew their mother - then you can ask if they are a boy/girl.). Quote Link to comment Share on other sites More sharing options...
0 bonanova Posted November 2, 2008 Author Report Share Posted November 2, 2008 the simple fact that the liar is misinformed in then twists the wrong info, makes his statement true (a double negative), so then you can ask anybody anything and they should both give you the right answer, so I think the puzzle is a bit to easy, since I've heard some variations if this types of riddles and they're usually a bit trickier. I'm not sure I follow your analysis. If they both give the right answer to "anything" that's asked, how does that make distinguishing them a "bit too easy"? Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 2, 2008 Report Share Posted November 2, 2008 but bunches! I know I m such an a** and worse I love it lol ok um oups I was about to do it again i have to insert spoilers Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 2, 2008 Report Share Posted November 2, 2008 it could be are you a liar is he a liar (asking about the other guy) and...um... no the others questions I thought were wrong but bunches! I know I m such an a** and worse I love it lol ok um oups I was about to do it again i have to insert spoilers Quote Link to comment Share on other sites More sharing options...
0 unreality Posted November 2, 2008 Report Share Posted November 2, 2008 Actually this might not work: "Does the other person lie?" The liar will think the truth-teller lies and thus the liar will say "No they're not a liar" What would the truth-teller would then say? The other person may be a wannabe-liar, but their misinformation cancels that out and means they tell the truth. So the liar really is a truth-teller, so in this case both would say "No they're not a liar", right? It depends on what counts as 'being a liar' - is it the intent of wanting to lie (in which case the above question works fine) or is it what actually comes out of their mouth? Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 2, 2008 Report Share Posted November 2, 2008 Actually this might not work: "Does the other person lie?" The liar will think the truth-teller lies and thus the liar will say "No they're not a liar" What would the truth-teller would then say? The other person may be a wannabe-liar, but their misinformation cancels that out and means they tell the truth. So the liar really is a truth-teller, so in this case both would say "No they're not a liar", right? It depends on what counts as 'being a liar' - is it the intent of wanting to lie (in which case the above question works fine) or is it what actually comes out of their mouth? Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 2, 2008 Report Share Posted November 2, 2008 you know if the guy is the liar precisely because he answer that the other guy doesn t lie you know if the guy tells the true because he answers that the other guy lie... anyway you only need one question Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 2, 2008 Report Share Posted November 2, 2008 (edited) you need to ask one question that is ask if one of them is a liar the truthful one will say the other one is and the liar will say the truthful one is assuming you still don't know which is which ( and how should you) pay attention to there body language when they answer the question oor if the liar is "ill informed" then they will think of the other one as the liar and thereselves as not and say the opposite Edited November 2, 2008 by ledger Quote Link to comment Share on other sites More sharing options...
0 Prime Posted November 2, 2008 Report Share Posted November 2, 2008 As I posted, any question, which is interpreted differently by the two persons. That is, the question must carry a variable within it, which is assigned/resolved based on person to whom the question is directed. Examples: Are you a truth-teller? Are you a liar? If both men are present in the room: Is the other guy liar? (or truth-teller) Does the other guy wear hat? (Provided one of them wears hat, and the other does not.) Is your shoelace untied? (Provided one of them has an untied shoelace.) The variable in each question is underlined. To put it simply, since both of them answer the truth, make them answer to a different thing while using the same question. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 2, 2008 Report Share Posted November 2, 2008 Quoting peace*out so far what i have (and heard) is asking if they are my realitive of some sort (sister; brother...). That seems like a good answer (unless the person asking never knew their mother - then you can ask if they are a boy/girl.). THis would not work - If you asked the liar if he was your mother he would think he was and say no. If you asked the truthful man if he was your mother he would say no. Quote Link to comment Share on other sites More sharing options...
0 peace*out Posted November 2, 2008 Report Share Posted November 2, 2008 Quoting peace*out so far what i have (and heard) is asking if they are my realitive of some sort (sister; brother...). That seems like a good answer (unless the person asking never knew their mother - then you can ask if they are a boy/girl.). THis would not work - If you asked the liar if he was your mother he would think he was and say no. If you asked the truthful man if he was your mother he would say no. Thankyou for clearing that up! Then: i dont know! Quote Link to comment Share on other sites More sharing options...
0 unreality Posted November 2, 2008 Report Share Posted November 2, 2008 bn, can we get a definitive response to post 12? What makes someone a liar - the intention of being a liar (in which case there are many answers) or the actual things that the person ends up saying? Quote Link to comment Share on other sites More sharing options...
0 bonanova Posted November 2, 2008 Author Report Share Posted November 2, 2008 bn, can we get a definitive response to post 12? What makes someone a liar - the intention of being a liar (in which case there are many answers) or the actual things that the person ends up saying? For the purposes of this puzzle, a lie is not a statement that is incorrect, rather a statement that is contrary to what you believe is true. The OP says If you asked: "Is the sky blue?" both would answer: "Yes." The first, because he knew it to be true and answered truthfully according to his belief. The second, because he believed it to be false and lied according to his belief. So the second person is a liar because he spoke contrary to the information he believes to be true. The fact he affirms a blue sky does not make him truthful. In this case, what matters is his intention to provide information that he believes to be incorrect. Being ill-informed, or incompetent to make correct observations, does not heal the flaw in his integrity. If that makes sense, you'll see then that his "Yes" answer is a lie, in spite of its correctness. Quote Link to comment Share on other sites More sharing options...
0 unreality Posted November 2, 2008 Report Share Posted November 2, 2008 (edited) Ah okay, thanks... then most of the solutions above will work Edited November 2, 2008 by unreality Quote Link to comment Share on other sites More sharing options...
0 bonanova Posted November 3, 2008 Author Report Share Posted November 3, 2008 Ah okay... then most of the solutions above will work Yes.The question must refer to something that depends on who is asked - like "you". Otherwise the answers cannot be different. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 3, 2008 Report Share Posted November 3, 2008 I heard this posed [not original with me] and I have not worked out a solution. Yet. A truthful person who is aware of every fact will answer yes/no questions in a certain way. Curiously, a liar who is misinformed about every fact will answer yes/no questions in exactly the same way! If you asked: "Is the sky blue?" both would answer: "Yes." The first, because he knew it to be true and answered truthfully according to his belief. The second, because he believed it to be false and lied according to his belief. The puzzle is this: Can you distinguish between the two by asking a series of yes/no questions? If so [and why would we ask if you couldn't? ] what is the minimum number of questions needed? Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 3, 2008 Report Share Posted November 3, 2008 I heard this posed [not original with me] and I have not worked out a solution. Yet. A truthful person who is aware of every fact will answer yes/no questions in a certain way. Curiously, a liar who is misinformed about every fact will answer yes/no questions in exactly the same way! If you asked: "Is the sky blue?" both would answer: "Yes." The first, because he knew it to be true and answered truthfully according to his belief. The second, because he believed it to be false and lied according to his belief. The puzzle is this: Can you distinguish between the two by asking a series of yes/no questions? If so [and why would we ask if you couldn't? ] what is the minimum number of questions needed? you only need one question....approach either one of them and ask, "if i were to ask thee guy who the liar was, what would he tell me?" its complicated to explain but if you think it through it works. im acuprised no one caught the corolation between this teaser and a delima brought up in an episode of, "Dr. Who." (a british sci-fi series in the 80's [no, im not that old (24), and i live in the U.S., i just love knowledge!!]) my answer is correct. YEAH ME!!! Quote Link to comment Share on other sites More sharing options...
0 bonanova Posted November 3, 2008 Author Report Share Posted November 3, 2008 you only need one question....approach either one of them and ask, "if i were to ask thee guy who the liar was, what would he tell me?" its complicated to explain but if you think it through it works. im acuprised no one caught the corolation between this teaser and a delima brought up in an episode of, "Dr. Who." (a british sci-fi series in the 80's [no, im not that old (24), and i live in the U.S., i just love knowledge!!]) my answer is correct. YEAH ME!!! Let's call the them AT and DL. If I were to ask AT who the liar is, he would identify DL as the liar. If I were to ask DL who the liar is, he would identify himself as the liar, believing he wasn't, but then lying. Actually, that question already does the job. If I were to ask AT how DL would answer [assuming AT knows how DL acts] he'd say "he will identify himself as the liar." If I were to ask DL how AT would answer [being deluded about how AT would act, but then lying] he'd say "he will identify me as the liar." And that works, too. Either way, both persons would correctly identify the liar. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted November 3, 2008 Report Share Posted November 3, 2008 Ask both the question? Is the other person a liar? Now if you ask from a liar he is misinformed and he thinks the other one is a liar so he will answer no. If you ask the truthteller he will answer yes. This can easily differentiate. Quote Link to comment Share on other sites More sharing options...
Question
bonanova
I heard this posed [not original with me] and I have not worked out a solution. Yet.
A truthful person who is aware of every fact will answer yes/no questions in a certain way.
Curiously, a liar who is misinformed about every fact will answer yes/no questions in exactly the same way!
If you asked: "Is the sky blue?" both would answer: "Yes."
The first, because he knew it to be true and answered truthfully according to his belief.
The second, because he believed it to be false and lied according to his belief.
The puzzle is this:
Can you distinguish between the two by asking a series of yes/no questions?
If so [and why would we ask if you couldn't?
] what is the minimum number of questions needed?
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