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william wu
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Language Proficiency Verification
« on: Jan 11th, 2003, 3:54am » |
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I'd like to salvage the following interesting puzzle such that it is solvable, but I don't know how to -- or even if the answer is supposed to be that it's not solvable. Exact quote:
"There is a Man A, who claims to know Tamil Language. You dont know Tamil language so you can not test him. You hire another Man B, who knows Tamil Language, to test this. Both A and B knows your language too. Though you dont trust both of these guys still you want to test that A knows B. Also you know that A and B dont know any other language too. How will you test man A knows Tamil ? "
I think it's supposed to be a good puzzle because the page I found it on had it next to sink the sub and single-file hat execution, as examples of problems the webmaster discusses with his CS faculty. Problem is, I don't know what entails not trusting B. Does it mean B will translate our English queries reliably, but won't reliably tell us if A responds in Tamil properly? I e-mailed the author for clarification and his answer was meaningless, and then I e-mailed again and he stopped responding (I think he's sick of me). I won't reprint his e-mail address here. Perhaps we can figure out what is necessary to fix the problem?
One idea I thought of was to grab some obscure English text and first record A's English --> Tamil translation of it, then ask B to translate A's recording back to English and check that against the text. If B's translation of A's recording matches the text, then A knows Tamil for sure. But if there's a false negative, that only tells us that A and/or B is lying.
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| « Last Edit: Jan 11th, 2003, 4:10am by william wu » |
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redPEPPER
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Re: Language Proficiency Verification
« Reply #1 on: Jan 11th, 2003, 8:01am » |
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I found the correct riddle's wording. Here it is:
"There is a Man A who claims to know English language. He's a CS student and likes logic riddles. You like riddles too so you ask him for one. Unfortunately the riddle is worded poorly, which is a problem for a logic riddle where every detail is important. English is obviously not Man A's native language. You can hire another Man B who knows Man A's language and also proper English, to translate the riddle. Though you don't know what is Man A's language. Maybe it's Tamil. You can communicate with Man A in English through e-mail but you can only ask one question, after which any new e-mail will be ignored. How will you gather a correctly worded riddle?"
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prince
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Re: Language Proficiency Verification
« Reply #3 on: Jan 13th, 2003, 11:55am » |
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--"One idea I thought of was to grab some obscure English text and first record A's English --> Tamil translation of it, then ask B to translate A's recording back to English and check that against the text. If B's translation of A's recording matches the text, then A knows Tamil for sure. But if there's a false negative, that only tells us that A and/or B is lying."--
I think that's the right idea. You could add an incentive so B would not lie i.e. add "B, your pay will be doubled if the translations match" to the text to be translated. You could reword the puzzle so that B is not trustworthy, but is greedy.
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Garzahd
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Re: Language Proficiency Verification
« Reply #4 on: Jan 13th, 2003, 2:08pm » |
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I was discussing this with willywutang before, and I tossed that answer out because if A and B are both untrustworthy, then it's possible they may conspire against you.
For instance, say B actually knows Tamil but he also knows the obscure Arctic dialect "Foo". And by a strange coincidence, so does A. You ask them each to write something down, and they deliver identical reports in Foo, which you cannot tell from Tamil.
Then B walks off licking his chops and maybe shares half of his doubled salary with A.
Hence the original comment that we're looking to "salvage" the problem such that it has an interesting solution.
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towr
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Re: Language Proficiency Verification
« Reply #5 on: Jan 13th, 2003, 2:15pm » |
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on Jan 13th, 2003, 2:08pm, Garzahd wrote:| For instance, say B actually knows Tamil but he also knows the obscure Arctic dialect "Foo". And by a strange coincidence, so does A. You ask them each to write something down, and they deliver identical reports in Foo, which you cannot tell from Tamil. |
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But it is stated they don't know any other languages..
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James Fingas
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Re: Language Proficiency Verification
« Reply #6 on: Jan 13th, 2003, 2:16pm » |
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The other way to do a similar thing would be to ask Man A to say something in Tamil, and then get Man B to translate.
Here is another idea. Get Man B to record 1000 sound clips, preferably which all sound a little similar (so that Man A cannot remember all of them). Half are to be meaningful Tamil sentences and half are to be meaningless sounds in the Tamil language. Here are some English examples:
"Brock snooby addleplum" (meaningless ... or is it?)
"Bring me a new chicken" (meaningful ... or is it?)
Now play them to Man A in random order (with replacement), and get Man A to rate each sound clip as "meaningful" or "meaningless".
1) If Man A marks half of them as meaningful, and consistently gives the same rating for each sound clip, then Man A knows Tamil and Man B was trustworthy.
2) If Man A is not consistent in his ratings, then he does not know Tamil.
3) If Man A rates all of them as "meaningful" (or all as "meaningless"), then either Man B was not trustworthy, or Man A does not know Tamil, or both.
There are some other possible outcomes, with similar sorts of conclusions. It is possible for Man B (or Man A) to prevent you from learning whether or not Man A knows Tamil (by not giving you a 50/50 mix of meaninful/meaningless sound clips, or by always answering one way), but you will know if this has happened.
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Icarus
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Re: Language Proficiency Verification
« Reply #7 on: Jan 13th, 2003, 4:45pm » |
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Jame's idea is a lot sounder than the double translation method for another reason: Anyone who has compared an original text to one that has been translated into another language and then back can tell you that even when the translators are really good and honest, the result often varies considerably from the original.
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Garzahd
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Re: Language Proficiency Verification
« Reply #8 on: Jan 13th, 2003, 4:59pm » |
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Alright, my mistake.
So maybe Foo isn't a true language, so maybe they're doing the whole wink-wink-nudge-nudge thing. My point is that if they cooperate to work against you, you're hosed.
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redPEPPER
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Re: Language Proficiency Verification
« Reply #9 on: Jan 14th, 2003, 3:37am » |
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I think the part of the riddle that says they don't know any other language is one of the clearest part of the riddle and is meant to be understood that they can't communicate by any other mean than English or Tamil (if they both know it). No secret code involved. If they want to work against you they'll have to do it in English or Tamil. As you can hear what they would say in English, you have to find a way to know if they conspire in Tamil.
The most cryptic part for me is when the riddle says "you want to test that A knows B". Was that a typo that was supposed to mean we want to test that A know Tamil, as stated at the end of the riddle? Or are we supposed to test both? How is it relevant if A knows B? Would that mean they could prepare a fraud beforehand?
Also, supposing A and B are potential accomplices, what is their goal? Is it to prevent you from verifying A's claim to know Tamil, or is it to make you believe A knows Tamil even if he doesn't? The latter would be too easy to disprove, but the former doesn't really make sense...
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James Fingas
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Re: Language Proficiency Verification
« Reply #10 on: Jan 14th, 2003, 9:55am » |
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I think the problem with this lies in Man B. When we say he is "untrustworthy", what do we mean?
I think it is possible to prove that if Man B wants to screw up your system, then he can prevent you from ever learning whether or not Man A knows Tamil. For instance, he could completely refuse to speak in Tamil, and refuse to properly translate anything spoken in Tamil into English. In this way, he could act as if he doesn't know Tamil, and therefore be completely non-helpful in this problem.
For this reason, the concept that Man B is "not trustworthy" must be clarified for us to propose a foolproof solution.
Here is another thought, based on prince's incentive idea:
1) Tell Man B to go sit in a chair in a room. This chair is located directly underneath an anvil ("big rock" in Tamil) which will fall on Man B in precisely 15 minutes (but Man B does not know this).
2) Tell Man A the situation, and add "To convince me that you actually know the Tamil language, you must speak through an intercom into that room, and convey to Man B the danger that he is in, but without speaking English. When he jumps out of his chair (and looks up at the ceiling, worried), I will consider that proof that you can speak Tamil."
The operative idea is that although Man B may be untrustworthy (he might lie to you about whether or not Man A knows Tamil), he would look out for his own skin if he could.
One more thought: if this is actually a crypto-puzzle in disguise, then we might want to add another prop to the story: a voice-scrambler. The output of the voice scrambler is still recognizeable as speech, and can still be translated, but it is not possible to identify the speaker (even if it is yourself).
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Icarus
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Re: Language Proficiency Verification
« Reply #11 on: Jan 14th, 2003, 6:16pm » |
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James - you have a real mean streak! And what happens if it turns out that A does not speak Tamil? Let's hope you weren't looking for a Tamil speaker to translate for you to the local cops!
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James Fingas
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Re: Language Proficiency Verification
« Reply #12 on: Jan 15th, 2003, 5:30am » |
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But what you don't tell Man A is that it is in fact an inflatable anvil ...
[/backpedal]
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BNC
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Re: Language Proficiency Verification
« Reply #13 on: Jan 15th, 2003, 9:29am » |
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It reminds me of a story by Asimov I read as a child (I can’t remember the name). In that story the hero had to identify a robot with special characteristics (modified 2nd rule for those interested).
One of the methods he tried was similar – exposing the robots to danger. The robot escaped recognition by realizing the investigator won’t kill him unless he was sure.
Similarly, our Man B may think you would not kill him if Man A can’t speak Tamil – thus he would not move!
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James Fingas
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Re: Language Proficiency Verification
« Reply #14 on: Jan 15th, 2003, 9:42am » |
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I guess I'm just a little more ruthless than that ...
Okay, here's another idea that doesn't even use Man B. Originally, I thought of this as a way to make sure Man B was actually speaking Tamil, but then I realized it doesn't matter.
Construct 1000 English sentences, all relatively close in meaning (so that Man A could never remember all 1000 of them). Record Man A speaking the Tamil translation for each of these sentences. After that has been done, play back the Tamil translations, in random order, and get Man A to translate them back to English. If the translations are fairly close to the originals, then Man A does, in fact, know Tamil.
This neatly gets around the fact that you can't trust Man B, because you can trust Man A (to try and prove that he knows Tamil). Furthermore, since it is impossible for Man A to remember all 1000 sentences, never mind trying to remember 1000 phony translations and their correlations to the 1000 sentences, Man A can only correctly give the English sentences back if he encodes the English translation into his "Tamil" translation. It is a given that Man A knows no other languages (than English and possibly Tamil), so if the "Tamil" translations are not in English, then they must be in Tamil.
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towr
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Re: Language Proficiency Verification
« Reply #15 on: Jan 15th, 2003, 10:02am » |
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There are people that can memorize whole telephone books.. So I wouldn't count on him not being able to remember 1000 sentences and their supposed translation..
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James Fingas
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Re: Language Proficiency Verification
« Reply #16 on: Jan 15th, 2003, 11:50am » |
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towr,
That's a good point, but you could just make enough sentences that you're sure he couldn't memorize them all. How many you have to make just depends on how sure you want to be.
Note the the number of possible sentences in a language is infinite, but the storage capacity of the human brain is finite, so there is some sort of limit to his possible memory abilities.
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towr
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Re: Language Proficiency Verification
« Reply #17 on: Jan 15th, 2003, 12:23pm » |
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but you might be dead before that limit is reached..
I would assume you want the test completed in a day, or a week, or at most within a year..
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James Fingas
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Re: Language Proficiency Verification
« Reply #18 on: Jan 15th, 2003, 1:10pm » |
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Now don't get all tied up in the details! What's a couple million years in the grand scheme of things? You're just jealous 'cause I didn't even need to use Man B!
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Johno-G
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Re: Language Proficiency Verification
« Reply #19 on: Jan 15th, 2003, 3:02pm » |
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on Jan 15th, 2003, 10:02am, towr wrote:| There are people that can memorize whole telephone books.. |
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towr: I'm sure memorising phone books is a magic trick! I can't remember how it's done, but I remember being shown by my scout leader! No-one could possibly memorise an entire phone directory!!!
Plus, even if you could, this would have to be done over a LONG period of time - the world record for remembering a number sequence is 100, and that was exceptional! (if my memory serves me correctly, that man is now barred from every casino in Britain!) If it's a stretch for a human to remember 100 integers (that are familiar) in a set order, it's sureley gonna be impossible to memorise, on the spot, 1000 sentences in a languages you've never heard before and their appropriate responses!!
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| « Last Edit: Jan 15th, 2003, 3:07pm by Johno-G » |
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Icarus
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Re: Language Proficiency Verification
« Reply #20 on: Jan 15th, 2003, 8:06pm » |
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on Jan 15th, 2003, 9:29am, BNC wrote:It reminds me of a story by Asimov I read as a child (I can’t remember the name). In that story the hero had to identify a robot with special characteristics (modified 2nd rule for those interested).
One of the methods he tried was similar – exposing the robots to danger. The robot escaped recognition by realizing the investigator won’t kill him unless he was sure.
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The story is "Little Lost Robot", and it can be found most easily in Asimov's "I, Robot" anthology. It was the 1st Law of robotics, "A robot may not injure a human being, or, through inaction, allow a human being to come to harm", that was modified (to drop the "inaction" part). The investigator, Dr. Susan Calvin, the main character of Asimov's Robot novels, pretended to place a person in jeopardy to try and spot which robot would hesitate in rescuing him. The robot escaped recognition by mimicing the behavior of normal robots.
(When you don't have much money to buy books, and don't care for the selections of the local library, you end up reading the ones you like several times.  )
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BNC
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Re: Language Proficiency Verification
« Reply #21 on: Jan 16th, 2003, 1:16am » |
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Icarus: Yes, it was the 1st rule. I remember now. I even remember that solving the problem involved using a seemingly irrelevant talent of the robot (radiation detection). Too bad we can’t use it here.
James: Man A doesn’t need to memorize the sentences. He can just invent a “pseudo-language”. For instance, take the English sentence, and replace each letter with the letter that is 18 places after in the Alpha-Bet (cyclic). Place an “a” as every other letter letter. E.g., the word “hello” would become “zawadadag”. As far as you're concerned, it may be a valid Tamil word. And Man A can easily translate it back.
Note: I used written text, which is simpler to explain in writing, but it may be done just the same (although it may be more difficult) with spoken language.
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| « Last Edit: Jan 16th, 2003, 1:21am by BNC » |
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redPEPPER
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Re: Language Proficiency Verification
« Reply #22 on: Jan 16th, 2003, 3:50am » |
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on Jan 15th, 2003, 8:06pm, Icarus wrote:| The robot escaped recognition by mimicing the behavior of normal robots. |
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I recall at one time it was quite the opposite: the robot escaped recognition by convincing the other robots to mimic its own behavior 
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James Fingas
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Re: Language Proficiency Verification
« Reply #23 on: Jan 16th, 2003, 6:44am » |
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BNC,
That's where I'm relying on the precise definition of the problem. We know that Man A knows no other language, and I would count anything that lets you verbally encode meaning as a language. If we assume that Man A can't invent a language fast enough to encode the sentences properly, then the solution holds.
I know, it's somewhat of a lame answer, but I think it's fundamentally unsolvable if you try to use Man B.
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Icarus
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Re: Language Proficiency Verification
« Reply #24 on: Jan 16th, 2003, 7:35pm » |
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on Jan 16th, 2003, 3:50am, redPEPPER wrote:
I recall at one time it was quite the opposite: the robot escaped recognition by convincing the other robots to mimic its own behavior
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I wasn't trying to give the whole story! Asimov may gone, but his heirs still have lawyers looking for copyright infringement! 
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