# Islander problem

• Feb 18th 2009, 04:10 AM
zhupolongjoe
Islander problem
You are on an island with three tribes. One always tells the truth, one always lies, and one gives an answer randomly (like a flip of a coin, truth or lie)..

What are TWO (if possible) yes or no questions that you can direct to two different tribe members or to the same tribe member to determine which way to go..
• Feb 18th 2009, 07:19 AM
HallsofIvy
Quote:

Originally Posted by zhupolongjoe
You are on an island with three tribes. One always tells the truth, one always lies, and one gives an answer randomly (like a flip of a coin, truth or lie)..

What are TWO (if possible) yes or no questions that you can direct to two different tribe members or to the same tribe member to determine which way to go..

?? Wouldn't that depend on which way you want to go?
• Feb 18th 2009, 07:50 AM
heathrowjohnny
It would depend who you asked right? If you asked the tribe that always told the truth, then you would get a reasonable answer (e.g. suppose you want to get North). So you could ask the same question twice.
• Feb 18th 2009, 07:59 AM
zhupolongjoe
Maybe it wasn't clear. One road leads to heaven, one to hell. You want heaven.

The three tribes are indistinguishable. What are two questions to ask?
• Feb 18th 2009, 08:16 AM
heathrowjohnny
Quote:

Originally Posted by zhupolongjoe
Maybe it wasn't clear. One road leads to heaven, one to hell. You want heaven.

The three tribes are indistinguishable. What are two questions to ask?

1. Are you a liar for saying that road A leads to heaven?

2. Are you telling the truth for saying that road B leads to hell?
• Feb 18th 2009, 08:52 AM
zhupolongjoe
Can you explain that? What if the random guy is answering that, how will you know. Doesn't sound correct to me, but maybe with some explanation,
• Mar 16th 2009, 06:28 AM
oqd
an interesting point
to make it simple, you've got a, b and c. They live on an island, therefore they know each other.
If there were just a liar and a truth talker you could ask what the other guy would say.
• Mar 17th 2009, 01:35 AM
oqd
not there yet, but
we are talking about three tribes