If you ask the Lie Robot, he will say the True Robot will point to the "Death Door", becuase he is telling a lie. Now if you asked the True Robot, he would say the Lie Robot would point to the death door becuase he always tell's lies. So both ways the death door will be pointed to, take the other door.
The problem says u can ask one question to each robot. So if,as shane said, ask one of robots "Are you a robot?" and it says "Yes", then you know that this is the Truth speaking robot otherwise the Lie Speaking Robot. Once you know this, you can ask the second robot, if its door is the safe door and decide upon it depending upon whether the first robot is Truth Robot or Lie Robot. I think Shane has got it absolutely rite.. hats off Shane for amazing Lateral Thinking...
I don't think the answer given makes sense because if you ask one of the robots what the other robot would say, if he's the lieing one, he'll just tell a lie. You have to be able to ask each robot a question. Unless you just trusted whatever one you picked.
Of Course! (It's confusing at first so read it a few times until you understand)
This is what will happen if you ask either robot the question: "What would the other robot say if I asked it which was the door that would set me free?"
If you told the lying robot; it would say that the truth-telling robot would say that the freedom door would be the death door, without telling you it was the death door, it would tell you it was the freedom door.
If you told the truthful robot; it would say that the lying robot would say that it was the death door, so that means that the freedom door is the one that they didn't say!
The statement says that the robots are guarding the doors, it doesnt say that theres is one robot in front of each door. So Shane's solution doesnt work. The only way then is to ask one robot this question : ''Which door would the other robot choose'' If that robot is the ''TruthRobot'' and says :''He would choose The first door'', then you go to the second door because he is telling the truth about the other robot's choice. Now if that robot is the ''LieRobot'' and says:''He would choose The first door'', well then he is lieing about the other robot's choice, so once again, you go to the second door....simple
restating the question : '' Which door would the other robot say is safe''.... kind of left out important info there. Cause the way your question is stated there's no way to know if the door is safe or leading to your death
K the question is "What would the other robot say if I asked it which was the door that would set me free?" now unless im reading this wrong, but the robot according to the question would not state if the other robot is the lier or the truthful one. The robot would only say that "The other robot would pick this or that door" and not "the truthful robot/lier robot" Therefore there is no way of figuring out which robot is lying or telling the truth..thats what i understand from this..
The answer given in the quiz is the correct one... you might be able to word the question slightly differently but it would be the same answer to the problem
Not seen Labyrinth but this puzzle was used in an Episode of Dr Who back in the glorious days of Tom Baker...
I don't think the Terry pratchett get-out works; The assumption there is a Robot could change its nature to save itself. There is a parable of a scorpian that comes to mind there... I refer the reader to the closing moments of 'The Crying Game'
I think you're wrong. Cause you don't know which is which. So if you asked the lie robot what the lie one would say is the life door, wouldn't the lie robot lie about what it would say.. It would point the the life door. If you asked truth robot what the truth would say, it would point to the life door.
The regular solution I think is correct. Cause if you happen to ask the truth robot what the other would say it would point to the death one. If you happen to ask the lie one what the other would say, it would lie and say the death door. So ask what the other would say and go through the other one.
why do we make assumptions that the robots know which door is safe? and one more thing...why are the robots guarding the doors? It really makes no difference weather the robots truth-telling robot guards the life door or the death door, or which door the lying robot is guarding. or if they are both sitting down in the middle playing scrabble. who cares? The questions should have clarified every possible objection.
ask either robot: does the other robot tell if this is the safe door, if yes, don't go this door, if no, go this door.
if you asked the truth one, then the other lie would not tell a lie, then you know, this is not safe;
(true lie)
if you asked the lie one, eventhough the other true robot tells the truth, but lie one still tells you the lie.
(lie true)
But what if the lying robot decides to say something completely non related to the door question? His only restriction seems to be that he lies, not that he has to answer questions.
For example:
"Which door would the other robot say?
"He'd say the red one." (But both doors are blue)
The problem gets a bit more complicated if there is just one robot, and you just don't know whether it is a truthful one or a lier.
The solution given is as good as it can be, but not perfect. The logical problem remaining is to determine whether a lier robot would accept the conditional part of the question ("if you were a truthful/lier robot... etc"). The solution is good, only if the lier robot makes a point about only lying about the direction, and not about the assumption.
I guess the lier robot would only have to be a "lier" not a mischievous s.o.b. altogether.
This riddle is modified, the robots can only answer by "yes" or "no", this is actually possible, but I forgot the answer, it was a long tricky question though.
Interesting version of the problem is what if the liar is a sinister liar, meaning that he will only tell you an answer that leads you to pick the bad door. Solve that. It has a solution.
if it was me i would turn around and walk out the door i just came through - you must have been able to get into the room in the first place so you know that that door is just an average door with no life or death consequences unlike the other two.
An answer with reasoning for others to see the way it works... if they can't already.
Standing in front of a door, doesn't matter which one, you would ask either robot.
"Would the other robot tell me that this is the door to freedom?"
If the robot you ask answers yes, you would choose and walk through the other door. If the robot you ask answers no, then choose and walk through the door you stand in front of.
Reasoning.
If you are standing in front of the death door and ask;
the 'liar' robot, he would say that the other robot (who tells only truth and would reply no) would say yes. He is of course lying about what the truthful one would say.
the 'truth' robot, he would say that the other robot (who only tells lies and would reply yes) would say yes. He is telling the truth about what the liar would say.
If you are standing in front of the freedom door and ask;
the 'liar' robot, he would say that the other robot (who tells only truth and would reply yes) would say no. He is of course lying about what the truthful one would say.
the 'truth' robot, he would say that the other robot (who only tells lies and would reply no) would say no. He is telling the truth about what the liar would say.
Anyone find that hard to follow?
Sorry Rain but scenario A, the truth answer is wrong.. he would answer NO. Scenario B, the liar answer is wrong, he would answer YES.
a common way to defeat anything or anyone that lies 100% of the time in any problem such as this is to simply ask either liar or truth teller a double negative question "If if were to ask you, is this the door to freedom would you say yes" The truth teller will give you the truth, the liar (by the nature of the question) is also forced to tell you the truth. For instance, if it really were the freedom door you were pointing to, and it really were the liar bot you happen to ask the question to, its reasoning would go like this. "I would in fact say no it is not the freedom door, so i must lie and tell him i would say yes." It works in reverse too. It takes some thinking about.
CASE:1
first ask 1st question to robot1......
r u robot?
if it say "yes" then we can decide robot1 tells true....
now ask second question to robot2.......
which door leads to safe?
select door which is opposite to door told by robot2 becoz robot2 always say lie
CASE2:
first ask 1st question to robot1......
r u robot?
if it say "no" then we can decide robot1 tells lie....
now ask second question to robot2.......
which door leads to safe?
select that door only which is told by robot2 becoz robot2 always say true
STEP 1.ASK ONE ROBOT "WHAT WOULD THE OTHER ROBOT SAY IF I ASK IT WHICH DOOR LEADS TO SAFTY"
(IF YOU ASKED THE LIE ROBOT THEN IT WILL SAY THAT THE TRUTH ROBOT WILL POINT TO THE DEATH DOOR BECAUSE IT ALWAYS TELLS LIES!)
BUT.....
(IF YOU ASKED THE TRUTH ROBOT THEN IT WILL SAY THAT THE LIE ROBOT WILL POINT TO THE DEATH DOOR BECAUSE IT ALWAYS TELLS THE TRUTH!)
STEP 2.THEN YOU KNOW WHICH EVER ROBOT YOU ASKED IT WILL POINT TO THE DEATH DOOR! (LOOK IN ABOVE BACKET IF YOU STILL DONT UNDERSTAND)THEN TAKE THE OPPOSITE DOOR WHICH THE ROBOT IS POINTING TO!
(BY THE WAY IT SAYS YOU CAN ONLY ASK ONE QUETION TO ONE ROBOT AND AFTER THAT YOU CANT ASK ANY MORE QUETIONS TO ETHER ROBOT)
the didnt say the truthful was guarding the freedom door. what to ask to either one
1. what color my hair is.
2. is this the safe door.
if #1 says the wrong color and #2 says yes go through that door.
if #1 says the wrong color and #2 says no go through the other door.
if #1 says the right color and #2 says yes go through the other door.
if #1 says the right color and #2 says no go through that door.
Another possible question that you could ask one robot is "Point to the door that you guard." If the robot pointed to the opposite door then you would know he was a liar. Then you could ask the other robot that tells the truth if his door leads to freedom and death.
or you can say something like, if truth robot is responsible for the freedom door and lying robot is responsible for the death door, take me to ur door.
Both robots will chose the death door so only one needs to be asked.
One question to one robot..one question only to only one robot.
If you ask the truth telling robot what door the other would say is the life door-He will tell you the death door because he knows the other robot is a liar.
If you ask the lying robot what door the truth telling robot would say-He will tell you the death door because he know the other robot would tell the truth.
Therefore both would tell you the death door and you would then chose the other door.
Considering that they will both say the death door only one robot and the one question is needed.
Think this way, asking the truth telling robot which door the liar would say the death door would be the truthful answer. Asking the liar what door the truth telling robot would say the death door would be a lie.
People, the problem clearly states "You can, however, ask one robot one question" which means you only can ask ONE question to ONLY ONE robot not one question to each robot. The problem is that you do not know which robot is that liar and which one isn't. So it doesn't matter what you ask or who you ask you still won't know which door it will be. The example of one of the comments on this page is "you can ask a robot if he is a robot" and depending on the answer you will know who the liar is but you still won't know what door it is.
Also the answer to the problem on the page is incorrect. It says "Ask one robot what the other robot would say, if it was asked which door was safe. Then go through the other door". This still won't tell you that the robot you are asking is telling the truth, it could be the lying robot and it will still not tell you which door is safe. Example
Lets say you ask robot robot # 1 what the other robot will say and he tells you that the other robot # 2 is a liar and that he (robot # 2) will tell you his door is the correct door only if it is the wrong door or that he will tell you not to enter his door if it is the safe door. This would be great the only problem is how do you know for sure that robot # 1 is infact the truthful one???
You can't rely on what the answer robot # 2 will say because if he is infact the liar then you won't know it and you still won't know what door it is.
...about the puzzle is not the answer but the motivations and/or mentality of the people who go on and on and on long after the correct answer is abundantly clear.
Listen guys, this is really too simple. Ask the robot which door they would NOT want you to go through. If it is the truthful robot, then it would point to the "Death Door". If it was the lying robot (evil) then it Wouldn't want you to go to the Life Door, buit since it lies, it would point to the death door as well. Then you just go to the other door.
it should read, you may ask one question and one question only. And you may only ask your question to one of the robots. The other robot will not be able to hear your question. Now, what question do you ask to ensure you will survive?
Clarification on original solution and my thought for the solution.
You can't just go through the other door after asking the question. It could be the door you're standing in front of. Because you will get two seperate answers depending on which robot,liar or truth, is asked. The response determines which door to go through.
The problem is that this riddle is not explained properly, therefore people misinterpret it and think they have found the solution when they haven't. Here is my explanation on how to solve.
In order to solve it, you have to put youself above the problem looking down like this. Here is how to solve this problem, given that the room is layed out like this:
Room Scenario 1 Room Scenario 2
< > < >
F T L D F L T D
< > < >
Where F=Freedom Door, D=Death Door, T=Truth Robot, and L=Liar Robot
These are the only possible combinations that can occur.
Now the solution.
Ask this question to either robot, but only one: "What would the response be if the other robot was asked 'Is your door safe?'"
If that question is asked, the robot will respond with a yes or a no. The answer will tell you which door to go through. You have to test that question 4 times to yourself to figure it out. You will find that a "yes" is always in front of the Freedom Door, and that a "no" is always in front of the Death Door.
Don't know if this helps anybody, but I figured a visual aid would help a little bit.
people confuse robots that lie with robots that want you to die-they are mutually exclusive absolutes.
SOLUTION #2- IF I ASKED YOU FIVE MINUTES AGO WHICH WAS THE DOOR TO FREEDOM WHICH ONE WOULD YOU HAVE POINTED TO?
the truth teller would continue to tell the truth and point to the door to freedom but the liar would have to lie twice thus also (always HAVING to lie)pointing to the door to freemdom
Matt, your logic doesn't work for the lying robot. For example, if you asked the liar "If if were to ask you, is this the door to freedom would you say yes?" and the door was the freedom door, it would say "yes" because that would be a lie. It reality, it would tell you no. The liar would still lie about how it would respond and you'd get nowhere.
I have been reading the possible answers and none are able to give me a definitive solution. The question specifically stated you can only ask ONE question and you Do Not know who the lying robot is and in the remit of the puzzle never will.
However, as a result of only having ONE question, not sure how you would decipher the correct door. Impossible answer
1. Ask the robot which door they would NOT want you to go through.
2. If it is the truthful robot, then it would point to the "Death Door".
3. If it was the lying robot (evil) then it Wouldn't want you to go to the Life Door, buit since it lies, it would point to the death door as well.
4. Then you just go to the other door.
Although there are some wholes in this solution, its the nearest yet to a solution
you would go through the opposite door no matter what, because no matter which robot you ask, their answer will be a lie...
if you were to ask the honest robot what the liar would say, he would be telling, honestly, what the LIAR was saying, which is a lie.
if you asked the liar robot what the honest one would say he would also be lying. he would tell you the wrong door because it is opposite of what the honest robot would actually say is the 'freedom door.'
it doesn't matter what door the robot you are asking is guarding, nor which robot you ask- which comes in handy since you do not know this anyway. you only have to go trough the door that the robot doesn't say that the other one would say is safe.
Pick a robot (doesn't matter which one) Ask the robot "IF I were to ask you which door is safe, what would you answer be?" Now go through that door. Reason: If it is the robot that tells the truth, it tells the truth. If it is the robot that lies you have FORCED it to lie about what lie it would tell.
Are You A Robot?
yes = right door
no = lier
If the Truth robot were asked which was the door to life, it would point towards the life door.
If the lie robot was asked the same he would point to the death door.
So if you asked the lie robot which door the truth robot would say is the door to life, it would point towards the door to death
If you asked the truth robot which door the lie robot would say is the door to life, he could point towards the death door.
So it doesnt matter which robot you ask, or if you ask one or both.
Choose the opposite of the door they point to.
'Tell me which door leads to safety and don't bother lying 'cos you'll be walking through it first, smartarse."
With a gun at the robot's head.
That'll work.
If you told the lying robot; it would say that the truth-telling robot would say that the freedom door would be the death door, without telling you it was the death door, it would tell you it was the freedom door.
If you told the truthful robot; it would say that the lying robot would say that it was the death door, so that means that the freedom door is the one that they didn't say!
This problem was also featured in another movie entitled, ''Arcade''.
Not seen Labyrinth but this puzzle was used in an Episode of Dr Who back in the glorious days of Tom Baker...
I don't think the Terry pratchett get-out works; The assumption there is a Robot could change its nature to save itself. There is a parable of a scorpian that comes to mind there... I refer the reader to the closing moments of 'The Crying Game'
The regular solution I think is correct. Cause if you happen to ask the truth robot what the other would say it would point to the death one. If you happen to ask the lie one what the other would say, it would lie and say the death door. So ask what the other would say and go through the other one.
if you asked the truth one, then the other lie would not tell a lie, then you know, this is not safe;
(true lie)
if you asked the lie one, eventhough the other true robot tells the truth, but lie one still tells you the lie.
(lie true)
This is a pretty standard logic puzzle, I don't know why some people are trying to confuse things.
For example:
"Which door would the other robot say?
"He'd say the red one." (But both doors are blue)
The solution given is as good as it can be, but not perfect. The logical problem remaining is to determine whether a lier robot would accept the conditional part of the question ("if you were a truthful/lier robot... etc"). The solution is good, only if the lier robot makes a point about only lying about the direction, and not about the assumption.
I guess the lier robot would only have to be a "lier" not a mischievous s.o.b. altogether.
and the truth robot guards the door to freedom
ask the robots if THEY ARE a robot
if one says 'yes' go through the door that it guards
if one says 'no' go through the opastite door
simple
scenario A
Liar guards death door
Liar robot would answer: NO --> choose opposite door
Truth Robot would answer: YES --> choose current door
Scenario B
Truth Robot guards death door
Liar Robot would answer: NO --> choose opposite door
Truth Robot would answer: YES --> choose current door
That takes care of all scenarios.
Think this through before further embarassing yourselves.
"Would the other robot tell me that this is the door to freedom?"
If the robot you ask answers yes, you would choose and walk through the other door. If the robot you ask answers no, then choose and walk through the door you stand in front of.
Reasoning.
If you are standing in front of the death door and ask;
the 'liar' robot, he would say that the other robot (who tells only truth and would reply no) would say yes. He is of course lying about what the truthful one would say.
the 'truth' robot, he would say that the other robot (who only tells lies and would reply yes) would say yes. He is telling the truth about what the liar would say.
If you are standing in front of the freedom door and ask;
the 'liar' robot, he would say that the other robot (who tells only truth and would reply yes) would say no. He is of course lying about what the truthful one would say.
the 'truth' robot, he would say that the other robot (who only tells lies and would reply no) would say no. He is telling the truth about what the liar would say.
Anyone find that hard to follow?
Sorry Rain but scenario A, the truth answer is wrong.. he would answer NO. Scenario B, the liar answer is wrong, he would answer YES.
first ask 1st question to robot1......
r u robot?
if it say "yes" then we can decide robot1 tells true....
now ask second question to robot2.......
which door leads to safe?
select door which is opposite to door told by robot2 becoz robot2 always say lie
CASE2:
first ask 1st question to robot1......
r u robot?
if it say "no" then we can decide robot1 tells lie....
now ask second question to robot2.......
which door leads to safe?
select that door only which is told by robot2 becoz robot2 always say true
STEP 1.ASK ONE ROBOT "WHAT WOULD THE OTHER ROBOT SAY IF I ASK IT WHICH DOOR LEADS TO SAFTY"
(IF YOU ASKED THE LIE ROBOT THEN IT WILL SAY THAT THE TRUTH ROBOT WILL POINT TO THE DEATH DOOR BECAUSE IT ALWAYS TELLS LIES!)
BUT.....
(IF YOU ASKED THE TRUTH ROBOT THEN IT WILL SAY THAT THE LIE ROBOT WILL POINT TO THE DEATH DOOR BECAUSE IT ALWAYS TELLS THE TRUTH!)
STEP 2.THEN YOU KNOW WHICH EVER ROBOT YOU ASKED IT WILL POINT TO THE DEATH DOOR! (LOOK IN ABOVE BACKET IF YOU STILL DONT UNDERSTAND)THEN TAKE THE OPPOSITE DOOR WHICH THE ROBOT IS POINTING TO!
(BY THE WAY IT SAYS YOU CAN ONLY ASK ONE QUETION TO ONE ROBOT AND AFTER THAT YOU CANT ASK ANY MORE QUETIONS TO ETHER ROBOT)
READ THIS AGAIN AND AGAIN TILL YOU GET IT! :)
1. what color my hair is.
2. is this the safe door.
if #1 says the wrong color and #2 says yes go through that door.
if #1 says the wrong color and #2 says no go through the other door.
if #1 says the right color and #2 says yes go through the other door.
if #1 says the right color and #2 says no go through that door.
True means (truth robot and death door) or (lying robot and death door)
False means (truth robot and safe door) or (lying robot and safe door)
If you don't know what 'exclusive or' (XOR) means, look it up.
If you ask the truth telling robot what door the other would say is the life door-He will tell you the death door because he knows the other robot is a liar.
If you ask the lying robot what door the truth telling robot would say-He will tell you the death door because he know the other robot would tell the truth.
Therefore both would tell you the death door and you would then chose the other door.
Considering that they will both say the death door only one robot and the one question is needed.
Think this way, asking the truth telling robot which door the liar would say the death door would be the truthful answer. Asking the liar what door the truth telling robot would say the death door would be a lie.
Robot: It would say "wibble!"
Me: Oh damn.
here's how.
case no. 1
you to robot1: what would be the other robot's answer if i asked which door is safe? (liar or not)
definitely the liar robot will tell that the other robot, who tells the truth, will say that the death door is the safe door because he is lying!
but if he asked the other robot the same question,
definitely the robot will say that the liar robot will point the death door is the safe door.
they will tell the same so you should go to the other door which is really the safe door!
Lets say you ask robot robot # 1 what the other robot will say and he tells you that the other robot # 2 is a liar and that he (robot # 2) will tell you his door is the correct door only if it is the wrong door or that he will tell you not to enter his door if it is the safe door. This would be great the only problem is how do you know for sure that robot # 1 is infact the truthful one???
You can't rely on what the answer robot # 2 will say because if he is infact the liar then you won't know it and you still won't know what door it is.
The problem is that this riddle is not explained properly, therefore people misinterpret it and think they have found the solution when they haven't. Here is my explanation on how to solve.
In order to solve it, you have to put youself above the problem looking down like this. Here is how to solve this problem, given that the room is layed out like this:
Room Scenario 1 Room Scenario 2
< > < >
F T L D F L T D
< > < >
Where F=Freedom Door, D=Death Door, T=Truth Robot, and L=Liar Robot
These are the only possible combinations that can occur.
Now the solution.
Ask this question to either robot, but only one: "What would the response be if the other robot was asked 'Is your door safe?'"
If that question is asked, the robot will respond with a yes or a no. The answer will tell you which door to go through. You have to test that question 4 times to yourself to figure it out. You will find that a "yes" is always in front of the Freedom Door, and that a "no" is always in front of the Death Door.
Don't know if this helps anybody, but I figured a visual aid would help a little bit.
WALLWALL WALLWALL
FT LD FL TD
WALLWALL WALLWALL
Hope this works
WA LL = WA LL
FT LD = FL TD
WA LL = WA LL
where WA LL means a wall, haha and the = just means that there are two rooms. haha. Use the above definitions for F,T,L, and D.
SOLUTION #2- IF I ASKED YOU FIVE MINUTES AGO WHICH WAS THE DOOR TO FREEDOM WHICH ONE WOULD YOU HAVE POINTED TO?
the truth teller would continue to tell the truth and point to the door to freedom but the liar would have to lie twice thus also (always HAVING to lie)pointing to the door to freemdom
However, as a result of only having ONE question, not sure how you would decipher the correct door. Impossible answer
Think I need to bring this one to work.
Help
1. Ask the robot which door they would NOT want you to go through.
2. If it is the truthful robot, then it would point to the "Death Door".
3. If it was the lying robot (evil) then it Wouldn't want you to go to the Life Door, buit since it lies, it would point to the death door as well.
4. Then you just go to the other door.
Although there are some wholes in this solution, its the nearest yet to a solution
if you were to ask the honest robot what the liar would say, he would be telling, honestly, what the LIAR was saying, which is a lie.
if you asked the liar robot what the honest one would say he would also be lying. he would tell you the wrong door because it is opposite of what the honest robot would actually say is the 'freedom door.'
it doesn't matter what door the robot you are asking is guarding, nor which robot you ask- which comes in handy since you do not know this anyway. you only have to go trough the door that the robot doesn't say that the other one would say is safe.