the tribe of truth and the tribe of lies

mr tanker
Posers and Puzzles 20 Sep '03 20:48
1. 20 Sep '03 20:481 edit
a traveller is walking to some place from some place and comes to a fork in the road- he has heard of this fork and knows that there is 2 tribes 1 that tells the truth all the time and one that tells lies all the time. he doesnt know which way to go and cant take the risk of going the wrong way (either coz he'll a horrible death or coz hes lazy) and he also knows that he'll only be allowed to ask one question (the same question to both tribes) which question will he ask to be sure of going the correct way?

sorry mr moderator i clicked alert instead of edit. sorry for any inconvienienceicneicne or however that word is spelt_the worst thing is i now cant remeber what i wanted to edit
2. 20 Sep '03 21:03
Originally posted by mr tanker
a traveller is walking to some place from some place and comes to a fork in the road- he has heard of this fork and knows that there is 2 tribes 1 that tells the truth all the time and one that tells lies all the time. he doesnt know which way to go and cant take the risk of going the wrong way (either coz he'll a horrible death or coz hes lazy) and he al ...[text shortened]... he same question to both tribes) which question will he ask to be sure of going the correct way?

He's only allowed one question to a certain person.
He does not know to which tribe this person belongs.
So he does not know wether this person speaks the truth yes or no.
Still he's only allowed one question to ask whether he should go to the left or to the right. To place A or to place B.

Am I correct ?
3. 20 Sep '03 21:05
nearly he gets to only ask one question but to both tribes (the same question)
4. 20 Sep '03 21:15
Originally posted by mr tanker
nearly he gets to only ask one question but to both tribes (the same question)

In any case let's suppose the traveller has to go to place B , because that's the safest way to get to his final destination. Place A is the most dangerous way to go to his final destination.He does not know to go left or right because he does not know where A or B is situated.

Agreed ?
5. 20 Sep '03 21:17
Originally posted by mr tanker
nearly he gets to only ask one question but to both tribes (the same question)
I think only one question to one indeterminate tribesman is required:

Would another person of your tribe tell me the left-hand fork was safe?

The answer reliably tells him whether the left hand fork is safe or not.
6. 20 Sep '03 21:303 edits
Originally posted by iamatiger
I think only one question to one indeterminate tribesman is required:

Would another person of your tribe tell me the left-hand fork was safe?

The answer reliably tells him whether the left hand fork is safe or not.
Well I hope MrTanker will clarify this, because I think I know a solution to the problem, when the traveller is only allowed one question to only one repesentative of one of the tribes, the traveller not knowing to what tribe this representative belongs. I thought this was the very tricky and difficult ingredient of this riddle.

I will however not post my solution to give others a chance to dive into this one. MrTanker, I'll send you a PM with my solution to the problem.

It's a very good riddle MrTanker !
7. 20 Sep '03 21:55
Originally posted by iamatiger
I think only one question to one indeterminate tribesman is required:

Would another person of your tribe tell me the left-hand fork was safe?

The answer reliably tells him whether the left hand fork is safe or not.

Suppose the answer is &quot;yes&quot;. In what direction would you continue your journey ?Let's suppose you're the traveller. To the left or to the right ?
8. 20 Sep '03 22:001 edit
Originally posted by mr tanker
nearly he gets to only ask one question but to both tribes (the same question)
In my solution to the problem it's not necessary to ask both tribes. the traveller only asks one question to one person, of whom he does not know to which tribe he belongs, and then he knows which direction he has to go Left or Right !

9. 21 Sep '03 10:101 edit
Originally posted by ivanhoe

Suppose the answer is "yes". In what direction would you continue your journey ?Let's suppose you're the traveller. To the left or to the right ?
Left, it's guaranteed to be safe. Here's a table of possible situations

Truthful...Left...........Yes
Truthful...Right.........No
Liars.......Left...........Yes
Liars.......Right.........No

By asking what another person of the tribe would say the traveller cleverly makes sure that the tribesman must answer truthfully.
10. 21 Sep '03 12:295 edits
Originally posted by iamatiger
Left, it's guaranteed to be safe. Here's a table of possible situations

[b]Tribe
Truthful...Left...........Yes
Truthful...Right.........No
Liars.......Left...........Yes
Liars.......Righ ...[text shortened]... er cleverly makes sure that the tribesman must answer truthfully. [/b]
Ho ho bro iamatiger,

All right, (you're the traveller not knowing were to go)

Suppose the answer is yes. What direction would you take. You must make a decision based on the information you received. You have to continue your journey. So do you go left or do you go right ? You answered to the left.

There is something rotten in the tribe of liars or non liars. How do you know beforehand (you are the traveller) that the safe route is to the left if you get the answer &quot;yes&quot;. Well ,of course you would say: because I've asked the question.
If you know that before you ask the question then what is the point in asking.You assume that if the answer is &quot;yes&quot; the safe route to go is to the left and when the answer is &quot;no&quot; the safe route is on the right. But that's exactly the question. You don't know where the safe route is.

I'm wondering what's wrong. Can somebody help me pléééase ?

iamatiger, can you please write down the exact (!) question you would ask if you were the traveller ? Thanks.

11. 21 Sep '03 13:071 edit
Originally posted by ivanhoe
Ho ho bro iamatiger,

All right, (you're the traveller not knowing were to go)

Suppose the answer is yes. What directi ...[text shortened]... (!) question you would ask if you were the traveller ? Thanks.

Ho Ho Ivan, ho.

The exactamundo question is just so:

If I asked another member of your tribe whether the left hand fork was safe, would they say yes?
12. 21 Sep '03 13:101 edit
Originally posted by mr tanker
nearly he gets to only ask one question but to both tribes (the same question)
I have contacted MrTanker about that and I've understood that the traveller is only allowed one question to one person and after that he knows which way to go.
13. 24 Sep '03 17:33
Originally posted by iamatiger
Ho Ho Ivan, ho.

The exactamundo question is just so:

If I asked another member of your tribe whether the left hand fork was safe, would they say yes?

I hope Mr.Tanker will react to your solution.
Mr.Tanker ?
14. 24 Sep '03 21:04
oh yeah sorry i forgot about this one. the question that i had in mind would be &quot;if u were in the other tribe which way would u tell me to go&quot; then whatever the answer was u would walk in the other direction. u have to ask both tribes this question as if u only asked 1 tribe and it was the tribe of liars u may get the response of &quot;monkeys&quot; or some such nonsense🙄
15. 24 Sep '03 22:19
Originally posted by mr tanker
u have to ask both tribes this question as if u only asked 1 tribe and it was the tribe of liars u may get the response of "monkeys" or some such nonsense🙄
Unfortuntely, if the liars are that smart, then the truth-tellers know it, so they answer &quot;I have no idea&quot; or maybe &quot;Monkeys&quot; and no single question will help.

In a book that discusssed this type of puzzle, I saw this question suggested &quot;Did you know that my friend has opened a bar on the safe road and is giving away free beer today?&quot;. The truth-tellers say &quot;no&quot;, the liars say &quot;yes&quot; or &quot;monkeys&quot; or &quot;I hate beer&quot;, but, in any case, you just follow them. 😵