'occasional off topic one' Logic Puzzle. - Page 1
Forum section: electronics / general

author: electrolux
author_rank: Regular Contributor
timestamp: May 31, 2015, 01:44:16 pm
content: A couple of logic puzzle which I will watch you shouting your head off, pulling your hairsolving,A group of Tanks are stranded on Island, with assorted coloured paints. They are all perfect logicians - if a conclusion can be logically deduced, they will do it instantly. Each of them can see out of his own muzzle, but cannot see himself. This means each can see the colour paint of everyone else, but does not know the colour of his own tank. Every night at midnight, a ferry stops at the island, to take the tanks to safety. But, there is a catch. Tanks can only leave the island if they know what colour paint they have. Other than sight, they cannot communicate (being tanks of course). There are no mirrors, reflecting surfaces on the island, and everyone knows the rules in this paragraph.On this island, there are 20 white coloured tanks, and 20 black coloured tanks, although the tanks do not know this. So any given white tank can see 19 white tanks and 20 black tanks, but this doesn't tell himself what colour he has. For all he knows, he could have a black paint and there are 21 black tanks in total, or he could have a red, or orange paint.Suddenly, on one day, a booming voice calls from the sky, and shouts:"There is a white tank on the island"Who leaves, and on which following night?Now the next one! (viking and dictator are just tank names.)There are three tanks in front of you: two Vikings and Dictator. However, you are blindfolded, so you cannot see which one is which.You can ask one yes-no question to any one of the three tanks. If you ask the question to a Viking, he will answer your question truthfully. If you ask the question to the Dictator, he will answer randomly (he could answer yes or no).What single question can you ask to identify, with certainty, the location of one of the Vikings?

author: John Coloccia
author_rank: Super Contributor
timestamp: May 31, 2015, 01:54:56 pm
content: **************************SPOILER*************************Well, let's say there's just 1 white tank. In that case, I would only see black tanks, and I know I'm the white tank, so I leave immediately.If there are 2 white tanks, I don't know what to do, but I can see that the other white tank doesn't leave. That means *I* must be a white tank too, so we both leave on the second night.If there are three white tanks, I will see that the other two don't leave on the second night....which means I must be a white tank too. So we all leave on the 3rd night.And for N white tanks, they all leave on the Nth night. The black tanks never leave because they're the N+1 tank (they can see ALL of the white tanks), but all the white tanks leave before it gets to them.Anyhow, I think that makes sense. Personally, if I'm a tank, that ferry's taking me off the island whenever I damn well want to leave.edit:so thinking about it some more, it's more subtle than this, because the black tanks can just as well say "There is a black tank on the island"...duh, they can see them. So the black tanks, in the mean time, have been playing this same game. Turns out they all leave together on the Nth day. I believe that's true even if there's no announcement.

author: electrolux
author_rank: Regular Contributor
timestamp: May 31, 2015, 02:40:28 pm
content: Quote from: John Coloccia on May 31, 2015, 01:54:56 pmSo you're saying white tank No: 20 leaves on the 20th night?

author: John Coloccia
author_rank: Super Contributor
timestamp: May 31, 2015, 04:22:43 pm
content: I think they all leave on the 20th night...black and white both. I'm not so sure about the black ones leaving leaving...but I'm pretty sure all the white ones leave on the 20th night.

author: free_electron
author_rank: Super Contributor
timestamp: May 31, 2015, 05:27:50 pm
content: All tanks start shooting the crap out of the others as fast as possible. .Last tank standing leaves island.There. Where can i cash mt medal ?

author: onlooker
author_rank: Frequent Contributor
timestamp: June 01, 2015, 03:04:52 am
content: This is the same eye color puzzle. I read the solution which relies on the guru/sky anouncement. But, on the other hand, the sky voice seems to provide redundent info to what every tank already know since every tank saw at least 19 white tanks. That is, each tank knows there is at least one white tanks before the anouncement.

author: Rerouter
author_rank: Super Contributor
timestamp: June 01, 2015, 03:19:21 am
content: 2nd night, all the tanks have left, every other tank they have seen is either white or black, it then becomes likely and logical that it will be one of the 2 options,so off the the ferry they all go, and say what they think they are, its a 50/50 chance from the logical progression, and there is no implied punishment other that waiting the next day,so those that guess right go on the ferry the first night, the rest go the next,

author: Delta
author_rank: Super Contributor
timestamp: June 01, 2015, 07:32:48 am
content: you are a total tanker.

author: jadew
author_rank: Frequent Contributor
timestamp: June 01, 2015, 08:00:55 am
content: If I were one of the tanks and see that 19 are of one color and 20 of another, on that night I'd decide to pick a random color between the two, odds are, I'm of one of those colors. If I couldn't count, I'd pick one randomly, but since I can, I'd go for the color of the other 19.Result: everyone leaves the same night.If I'd pick randomly: approximately 50% leave the first night, the rest leave the next night, by saying the other color.Edit:For the second one, you ask the one in the middle if the one on his left is a viking. If it says Yes, it's a viking. If it says no, you pick the one on its right.

author: electrolux
author_rank: Regular Contributor
timestamp: June 01, 2015, 08:52:11 am
content: Quote from: John Coloccia on May 31, 2015, 04:22:43 pmCorrect, all 20 white ones leave on the 20th night cos they are gonna see that no tanks are leaving for 20 nights, they heard the voice so they know there are white tanks on the island, logic tells them they are white.

author: electrolux
author_rank: Regular Contributor
timestamp: June 01, 2015, 08:52:57 am
content: Quote from: free_electron on May 31, 2015, 05:27:50 pmYou've got it Chinese,... Wong!

author: electrolux
author_rank: Regular Contributor
timestamp: June 01, 2015, 08:55:12 am
content: Quote from: jadew on June 01, 2015, 08:00:55 amWrong, for all you know Dictator is in the middle and he is answering you randomly.

author: electrolux
author_rank: Regular Contributor
timestamp: June 01, 2015, 08:55:36 am
content: Quote from: Delta on June 01, 2015, 07:32:48 amAhem

author: jadew
author_rank: Frequent Contributor
timestamp: June 01, 2015, 08:59:28 am
content: Quote from: electrolux on June 01, 2015, 08:55:12 amIf his answer is YES, it is true, because, the other two tanks are vikings. If his answer is NO, because he's lying, the other one has to be a viking anyway. Sothemy answer is Right.Edit:For your first problem, the only solution is the probability game because the problem states that "They are all perfect logicians - if a conclusion can be logically deduced, they will do it instantly". This means that they can't make singular actions based on other tanks, due to concurrency issues. The only solution is to base their actions on probability alone, since they can't work together.

author: John Coloccia
author_rank: Super Contributor
timestamp: June 01, 2015, 09:18:21 am
content: Quote from: jadew on June 01, 2015, 08:59:28 amThat's not true. Read through my post and you'll see exactly how I reasoned it out.

author: jadew
author_rank: Frequent Contributor
timestamp: June 01, 2015, 09:29:07 am
content: Quote from: John Coloccia on June 01, 2015, 09:18:21 amYour approach won't work because when you have more than 2 tanks, everyone knows there's at least two tanks in there, so the shout is useless, since it mentions "at least one white tank".The number of total white tanksisremains unknown so at that point everyone is back to square one and each passing day they won't know what to do, which will bring 0 info to the table.

author: John Coloccia
author_rank: Super Contributor
timestamp: June 01, 2015, 09:37:56 am
content: I reasoned it out for more than two tanks. I'm not going to retype it, but you're welcome to scroll up and read it.

author: jadew
author_rank: Frequent Contributor
timestamp: June 01, 2015, 09:45:26 am
content: Quote from: John Coloccia on June 01, 2015, 09:37:56 amYou said this: "If there are three white tanks, I will see that the other two don't leave on the second night....which means I must be a white tank too. So we all leave on the 3rd night."At this point the other two tanks don't leave because they don't know what colors they are. And they know you don't leave for the same exact same reason. This offers no further information to anyone, so they're stuck as soon as there are more than 2 tanks, shout or no shout.

author: John Coloccia
author_rank: Super Contributor
timestamp: June 01, 2015, 09:50:34 am
content: No, because if I was a black tank, the other two white tanks would have left on the 2nd night....which means I'm a white tank, and we all leave the 3rd night. And 4 tanks leave the 4th night, and so on and so forth.Look, it's pretty obvious to everyone that if there's only 1 white tank, and he looks and sees only black tanks, he immediately knows he's the white tank. That just has to be obvious to begin with.If there are 2 white tanks, they both see each other. They see that the other doesn't leave the 1st night, and they also see that there aren't anymore white tanks, therefore they must be a white tank to...or the other one would have left already. We know this because we reasoned it out a paragraph ago. Therefore, they both leave the 2nd night.If there are 3 white tanks, they all see that the other two didn't leave. Obviously, they would have left if there were ONLY 2 white tanks (we just figured that out), so there must be one more white tank. That must be me. We all leave the 3rd night.etc etc

author: jadew
author_rank: Frequent Contributor
timestamp: June 01, 2015, 11:29:55 am
content: Sorry for the delay, I realized I was wrong about the number as I was leaving home. I was wrong on where your algorithm fails: it's not when there are more than 2, it's when there are more than 3.The situation is clear when there are only 2 tanks and when there are 3 it can be deduced from the lack of action, but my reasoning holds true once the number increases, because it's impossible to tell if you're a white or a black tank.I may be wrong yet again, but can you please explain how things would go if there were 4 white tanks?

author: John Coloccia
author_rank: Super Contributor
timestamp: June 01, 2015, 11:36:08 am
content: They each see 3 other white tanks. When those tanks don't leave on the 3rd night, it can only be because there's a 4th white tank they can all see....ME. Then we all leave on the 4th night. Generally, N tanks leave on Nth night.What I can't figure out is if you absolutely need the announce for more than 2 tanks. For 1 tank and 2 tanks you do, but for 3 or more tanks, EVERYONE can see there is at least one white tank. That's also the case for 2 tanks, but they don't know for sure that the other guy sees a white tank because they don't know their own color. I think for 3+ tanks of the same color, no announcement is necessary since it adds absolutely no information, so I contend that all of the black tanks also leave on the 20th night.

author: Deathwish
author_rank: Unknown
timestamp: June 01, 2015, 11:38:36 am
content: transpose tanks for eyes.http://riddlesforall.com/show_riddle.php?ID=20

author: jadew
author_rank: Frequent Contributor
timestamp: June 01, 2015, 11:49:48 am
content: Quote from: John Coloccia on June 01, 2015, 11:36:08 amYou're right. This works.

author: B.B.Bubby
author_rank: Regular Contributor
timestamp: June 01, 2015, 04:11:08 pm
content: Well, The way I look at it all the white tanks leave the same night on hearing the voice from above. All black tanks never leave the island.There are no reflecting surfaces on the island - so white will look black as will everything else. So all tanks will think they are the sole white one. Which is why all white tanks get RR for the night.The remaining black tanks can only ever guess their colour - so will never leave (unless guessing is allowed??)cheersSimon

author: rolycat
author_rank: Super Contributor
timestamp: June 01, 2015, 05:22:45 pm
content: Quote from: B.B.Bubby on June 01, 2015, 04:11:08 pmThe problem states that each tank can see the colour of every other, so 'no reflecting surfaces' clearly means no mirrorlike surfaces rather than the pathological case of all objects being 100% absorptive.Even if all of the tankswereblack bodies, they could appear to be any colour depending on their temperature.Edit: The prospect of twenty white-hot tanks careering around the island is somewhat alarming

author: rolycat
author_rank: Super Contributor
timestamp: June 01, 2015, 05:30:59 pm
content: In a cruel twist of Fate, after all forty tanks leave on the twentieth night the ferry takes them not to safety but to another island, where the booming voice announces that they are about to face another fiendish test of logic.It informs them that they will be driven in single file into a defile which is too narrow for them to traverse their turrets to the rear. They will thus be able to see all of the tanks ahead of them, but none behind. They will then be miraculously and randomly repainted, although the same two colours will be used. The voice gifts each tank with a radio allowing it to communicate with the others, but cautions them that once in position they may only use it to answer the voice's question: "What colour are you?".The question will be asked of the rearmost tank first, and then each successive tank until it reaches the front. Only tanks which answer correctly will escape the island, the others will be left behind.The voice allows the tanks to discuss the problem before they are driven into the defile, warning them that it can monitor their radio traffic and will leave them all if they attempt to cheat by communicating in any way other than answering "black" or "white" to the question.What is the number of tanks that are guaranteed to escape, and what strategy do they use?

author: B.B.Bubby
author_rank: Regular Contributor
timestamp: June 01, 2015, 05:36:56 pm
content: Quote from: rolycat on June 01, 2015, 05:22:45 pmThe riddle says "So any given white tank can see 19 white tanks and 20 black tanks."A white tank that appears black is still a white tank. A red apple in total darkness is still a red apple.just sayingand yes i'm been a bit silly, but its all i can think of....

author: jadew
author_rank: Frequent Contributor
timestamp: June 01, 2015, 05:38:45 pm
content: @rolycat50% of them are guaranteed to escape.The last tank says the color of the tank in front of it. The next one says the color that the previous tank said, so it gets out.50% make it out for sure, from the remaining ones, about 25% make it out by chance.

author: rolycat
author_rank: Super Contributor
timestamp: June 01, 2015, 05:41:03 pm
content: Quote from: jadew on June 01, 2015, 05:38:45 pmNo, they can do much better than that...

author: suicidaleggroll
author_rank: Super Contributor
timestamp: June 01, 2015, 05:46:44 pm
content: Quote from: John Coloccia on June 01, 2015, 11:36:08 amThe black tanks never leave.Say there are 7 white tanks and 13 black tanks.As a white tank, I see 6 white tanks and 13 black tanks. If nobody leaves on the 6th night, it means there must be 7, and I'm the 7th, so I leave on the 7th night, along with all of the others.As a black tank, I see 7 white tanks and 12 black tanks. Nobody leaves on the 6th night, obviously, and IF nobody left on the 7th night it would mean there were 8, and I was the 8th, so I would leave on the 8th night. But they DO leave on the 7th night, which means there were only 7, and I'm stuck.As a general rule, if there are N white tanks, they will all leave on day N. The black tankswouldleave on day N+1, but since all of the white tanks leave on day N, they don't.

author: John Coloccia
author_rank: Super Contributor
timestamp: June 01, 2015, 06:06:10 pm
content: But the black tanks ALSO know there is a black tank on the island...because they can all see it. So every tank is playing the game of figuring out if he's a black tank or a white tank, IN THIS PARTICULAR case of 20 tanks each. For numbers like 2 and 3, the black tanks are stuck.So on the 20th day, the situation a black tank sees is:1) there are still 20 white tanks on the island2) there are 19 black tanks on the islandAnd I don't know my own color...let's see if we can reason it out....Well, if I'm ANY color tank other than black, the black tanks would have all left on the 19th night, therefore, I MUST be a black tank.Now from a white tank's perspective he sees:- 19 white tanks still on the island- 20 black tanks still on the islandIf I'm ANY color other than white, the white tanks would have all left the day before, therefore I must be white.EVERYONE leaves the island on the 20th day in this particular case.Why? Because saying "There is a white tank on the island" isn't adding any information at all to the puzzle...and neither is saying "There is a black tank on the island". EVERYONE can already see that there is a white tank and a black tank, and there are enough white and black tanks that everyone knows EVERYONE else can see at least one white tank and black tank as well.In the situation with just two white tanks, for example, you must have the voice because although I can clearly see there is a white tank, not knowing my own color means that I don't know if the other guy can see a white tank also...maybe so, maybe not. The voice insures that all tanks have that minimal information. In the OP's case, though, the problem is over specified. Everyone already knows the information the voice is saying, so clearly it's completely unnecessary, AND the same reasoning applies to black tanks as it does white tanks.So it's kind of funny, actually. I went and looked up the original blue eyed one that was mentioned earlier in the thread, and it doesn't seem like anyone's actually caught on to the fact that in the case of lots of blue eyed people, the voice is not giving out additional information AND that brown eyed people can reason just as well to figure out that they're brown eyed. If I actually had any motivation to do it, I might be tempted to mention that and stir the pot a bit!Maybe someone else will do it, and see what happens.

author: John Coloccia
author_rank: Super Contributor
timestamp: June 01, 2015, 06:11:58 pm
content: Quote from: rolycat on June 01, 2015, 05:30:59 pmThis took a while to figure out. Generally, you save N-1, or 39 in this case:***********************spoiler*********************Since you can see everyone in front of you, you know if there is an odd or even number of white and black tanks IN FRONT of you. You all agree that the guy at the back of the line say "White" if there are an even number of white tanks, or "Black" if there are an odd number of white tanks. He has nothing to loose as he still has a 50/50 chance of being right. Everyone else in front simply has to keep track of how many guys behind you are white. When it gets to you, the white behind you, plus the whites in front of you, have to add up the Even or Odd that was specified before. If it doesn't, you're white...if it does, you're black.This one was good! There's no way to reason through it, really...you just have to sit and think about it, and hope something pops into your head.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: June 01, 2015, 06:19:04 pm
content: Quote from: John Coloccia on June 01, 2015, 06:06:10 pmI missed the part in the riddle that any tank can leave when it knows its color, I was thinking it was just white tanks that could leave once they knew they were white.In that case, I'd say the general rule is that the minority color leaves on day N, if there are N of them (and they all know there is at least one of that color in the group), and if there are two colors with equal numbers they all leave on day N.

author: John Coloccia
author_rank: Super Contributor
timestamp: June 01, 2015, 06:23:44 pm
content: Something in my guy tells be that these scenarios have some sort of significance in some obscure branch of mathematics somewhere. It just seems like such a deep question about what's knowable, and what minimum information do you need to know it, that it must belong to some bigger framework that someone's studying. I'll be damned if I could imagine what that is, though

author: rolycat
author_rank: Super Contributor
timestamp: June 01, 2015, 06:32:27 pm
content: Quote from: John Coloccia on June 01, 2015, 06:11:58 pmBrilliant!Technically you randomly save eithernorn-1, but of course the question was how many tanks are guaranteed to escape, which is indeed 39.

author: John Coloccia
author_rank: Super Contributor
timestamp: June 01, 2015, 06:38:42 pm
content: It was pure luck....LOL. On a tangent to end all tangents, I happened to be looking up the various payouts for playing roulette...and I've stepped foot in a casino exactly TWICE, but something else I was looking for just happened to lead me here and I was curious (I was actually checking out a video on some huge pipe organ in Atlantic City that they refurbished). I saw the words "even" and "odd", and the light bulb went on. I doubt I would have figured it out otherwise.Best I could come up with was N/2 using the same method stated earlier, and I figured the problem was impossible and you just stated it wrong.

author: AG6QR
author_rank: Frequent Contributor
timestamp: June 01, 2015, 06:42:03 pm
content: The black tanks will never leave. They must know their own color to leave. How would an individual black tank know he's black, and not blue, orange, purple, or some other color?If the voice from above said that "all tanks are either black or white", then the outcome would be a bit different.

author: John Coloccia
author_rank: Super Contributor
timestamp: June 01, 2015, 07:00:53 pm
content: Quote from: AG6QR on June 01, 2015, 06:42:03 pmThis troubled me too, and it troubled me that the voice was seemingly necessary for the logic to work, but yet the voice was giving redundant information...after all, if there are 20 white and 20 black tanks, then clearly everyone already knows there's a white tank on the island AND a black tank on the island.I think like everyone else, I solved this using induction....start with one white tank...then two...then three. In that case, the voice is absolutely necessary to get it started. But for more tanks, it doesn't seem like it should be required, and yet I couldn't figure out how to do it any other way. Honestly, this has really been bothering me and rattling around in my head.But I just figured it out. Forget about induction. Since these are perfect logicians, they would all be able to figure out an alternate way of doing the problem. They all follow this algorithm:IF you know for sure that there is at least 1 tank of a certain color on the island, AND you know for sure that EVERYONE also knows this same information, simply count the number of each color that you see. On any given day, day N, if there are exactly N-1 tanks of that color on the island, you can leave since that's your color too. Why? Because if you were any other color, the tanks would have already left the day before.But for this to work, there is a minimal number of tanks of a given color you need. If there are only 2 white tanks, for example, even though you see a white tank, you can't be sure that the other guy sees a white tank too. But let's take the case of 4 white tanks, and you'll see why this works.day 1: No one leave...all you know is that there are 3 other white tanks on the islandday 2: no one leaves...you still don't really know any more than you did the day beforeday 3: no one leaves....but now you know EVERYTHING. Why? Because if you were a different color, the other three white tanks would have left today. Since they didn't, now you know you're white too!day 4: everyone leaves.So what keeps this from giving false positives? Let's say you have 4 tanks, but only 3 of them are white. From the perspective of a white tank, you see 2 other white tanks. That fails one of the conditions of the test...everyone must be sure that everyone else knows that there is a white tank. So reasoning it out from the point of view of a white tank, I must assume that I'm black....and then I must assume that when the white tanks are reasoning it out for themselves, THEY must assume that they're black. So even though I can clearly see two white tanks, if I assume I'm black (now there are two black tanks) and if another white tank doing this assumes he's black (now there are 3 black tanks), then the last white tank when he's going through this process will see ZERO white tanks. So the algorithm falls apart and can't be used.But with 20 white tanks...or black tanks...there are ample tanks that everyone can see there are clearly white and black tanks on the island, and the voice is no longer necessary. Anything greater than 3 of a color makes the voice superfluous.Hope that makes sense. It was really bothering me.edit: thinking about it, the minimum number might be 5...I don't think 4 is enough, actually.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: June 01, 2015, 07:18:13 pm
content: Quote from: John Coloccia on June 01, 2015, 06:06:10 pmActually, I'm not so sure it is. The solution relies not only on every tank knowing there's a white tank in the mix, but it also relies on every tank knowing that every other tank knows that there's a white tank in the mix (and that every tank knows that every tank knows that every tank knows...and so on down the line). You hinted on this yourself when you said you still need the voice when there are 2 tanks, so that each of them knows that the other one knows there's a white, but it keeps going. Take the below scenario (I'm numbering the tanks for clarity)Code:Tank 1 2 3 4 5 6 7 8 9Color W W W B B B B B B3 white, 6 blackNow tank 3 knows there are at least 2 white, but as far as tank 3 is concerned, tank 2 only sees 2 whites, and as far as tank 3 is concerned, tank 2 thinks that tank 1 might not see any whites. So when the first night passes and nobody has left, tank 3 knows it's because there is more than 1 white, but tank 3 doesn't know if tank 2 knows that. So when nobody leaves the second night, tank 3 doesn't know if that's because there are 3 whites and it's the third, or if the reason nobody left the second night was because tanks 1 and 2 didn't know if the other knew that there were whites.This keeps on going, all the way back up the line to N tanks. There is no minimum number.The booming voice sets the stage, everybody knows there's a white, and everybody knows that everybody knows (that everybody knows that everybody knows...) that there's a white, so the logic can start without any individuals wondering who knows what.

author: Marco
author_rank: Super Contributor
timestamp: June 01, 2015, 07:40:36 pm
content: Quote from: John Coloccia on May 31, 2015, 01:54:56 pmIt makes sense, but that's not enough ... ultimately puzzles like this can only be proven mathematically. I'm not sure it's doable in this case. The known number of white tanks by any tank can never be less than the number of observed tanks plus or minus one. The only time the voice could ever add information is in the 1 or 2 white tanks, for any more the announcement just serves as a goalpost for an algorithm which kinda feels logical, but also kinda feels ad-hoc.

author: John Coloccia
author_rank: Super Contributor
timestamp: June 01, 2015, 08:17:35 pm
content: Quote from: suicidaleggroll on June 01, 2015, 07:18:13 pmBut there has to be a minimum number. For example, if I can personally see 200 white tanks, it's obvious that THEY can all see at least 199 white tanks, and that they can see all of THOSE can see plenty of white tanks too. It's enough to know that there's at least one white tank, and that everyone knows it. With 200 white tanks, clearly everyone knows it no matter how you arrange things. It's just a matter of what the lower bound is. I think having 5 white tanks is sufficient, but maybe it's higher than that. There must exist a lower bound, though. This is Ramsey theory in action. When you exceed a certain threshold, you're absolutely forced so meet certain conditions, however you try and avoid it.Anyhow, I find this incredibly interesting. I'm a bit frustrated that I can reason it out, but can't formalize why there should be a minimum, and exactly how to calculate it.

author: electrolux
author_rank: Regular Contributor
timestamp: June 02, 2015, 08:30:13 am
content: Quote from: John Coloccia on June 01, 2015, 09:18:21 amQuote from: jadew on June 01, 2015, 08:59:28 amThe first is still wrong the puzzle said ,you have to determine with certainty the location of one of the vikings.

author: jadew
author_rank: Frequent Contributor
timestamp: June 02, 2015, 08:37:58 am
content: Quote from: electrolux on June 02, 2015, 08:30:13 amI don't see how it fails to do that.

author: electrolux
author_rank: Regular Contributor
timestamp: June 02, 2015, 08:38:38 am
content: Theirs been 50 replies to this post and a lot of argument, the answers are: ask a Viking, are you in the middle? If yes then you know he is in the middle. If no then you know he is on the side.All 20 white tanks leave on the 20th night because they see 20 black tanks who don't leave for 20 nights so logically they know they are white.

author: electrolux
author_rank: Regular Contributor
timestamp: June 02, 2015, 08:41:59 am
content: Quote from: jadew on June 02, 2015, 08:37:58 amSee my last post.

author: jadew
author_rank: Frequent Contributor
timestamp: June 02, 2015, 08:43:24 am
content: Quote from: electrolux on June 02, 2015, 08:38:38 amYour answer is wrong. You are blindfolded. You don't knowwhere the viking isif you're talking to a viking or not. My answer is correct regardless if you know you're talking to a Viking or a Dictator.Edit:Also, with your solution, you still don't know where he is. He's on the side, but on which side?Edit 2:If you could ask a particular kind of tank a question, a better one to ask a Viking would be: Is the one in the middle a Dictator? But in this case the twist about the Dictator answering with yes or no randomly makes no sense.

author: John Coloccia
author_rank: Super Contributor
timestamp: June 02, 2015, 09:00:32 am
content: I agree with jadew. His way seems to make sense and works.

author: electrolux
author_rank: Regular Contributor
timestamp: June 10, 2015, 09:30:15 am
content: Quote from: jadew on June 02, 2015, 08:43:24 amYou don't need to know which Viking your asking, all you have to do is determine the location ofoneof the vikings. As for which side you don't need to know there is a Viking on the side & 'side' is a location.

author: LordNobady
author_rank: Contributor
timestamp: June 10, 2015, 10:01:15 am
content: The question is easy.ask one of the tanks ( the middle one for example ) if any other tank ( the right one for example ) is a viking.if it say's yes then it is. if it say's no then the other location ( left in this example ) is a viking.

author: electrolux
author_rank: Regular Contributor
timestamp: June 12, 2015, 05:35:50 pm
content: Quote from: LordNobady on June 10, 2015, 10:01:15 amwhat if the tank you happen to be asking is the Dictator who will answer randomly?

author: kolbep
author_rank: Frequent Contributor
timestamp: June 12, 2015, 06:24:27 pm
content: Maybe i have not understood the question,but i did not see anything in the rules that said you cannot get out of your tank, and look at your colour, as well as the colours of all the other tanks?

author: Ryano
author_rank: Regular Contributor
timestamp: June 12, 2015, 08:15:21 pm
content: Quote from: electrolux on June 12, 2015, 05:35:50 pmIf there were only two tanks that would be a problem. With three it doesn't matter. Look at it this way.....You ask the following question to the tank in the middle."Tank in the middle. Is the tank to your right a Viking?"If the tank in the middle is a Viking;"yes" will mean the tank on the right is a Viking as well."No" will mean the tank on the right is the Dictator.If the tank in the middle is the Dictator.Random "Yes" still makes the tank on the right a Viking because there is only one Dictator.Random "No" means the tank on the right could be, as far as you can tell,theDictator orone ofthe Vikings.Since you can't be sure on a "No" if the tank on the right is a Viking, but only the Dictator can "lie",so the Dictator has to be the middle or the right tank and the left tank has to be a Viking and you choose it.