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        riddles >> hard >> Fork in the road 
        
(Message started by: Karishma on Nov 12^th, 2005, 9:27am)

Title: Fork in the road
Post by Karishma on Nov 12^th, 2005, 9:27am

You are travelling to a town and you get lost, and you come to a fork on the road you are walking on, and a person standing at the fork, you know that green men always tell the truth and red men always lie, however it is now too dark to see what colour they are. You only have time to ask them one question, what question do you ask them to know what path to take to the town you are looking for?

There's no second person like in the more commonly told version of this riddle.

I don't know the answer as well, but its for a little game type thing on my blog so I'd be grateful if anybody could figure it out and tell me.

Title: Re: Fork in the road
Post by Icarus on Nov 12^th, 2005, 10:18am

They probably want something like "If I asked someone of the opposite color from you which is the right road, which one would they say?" or the more direct "If I were to ask you which is the right road, what would you say?"

If a liar were constrained to answer with one of the two forks, either of these would be sufficient. This is just a small variation of the two person answer - you pretend the other person is there even if they aren't.

The other works by being a metaquestion: The liar must lie about the lie he would tell if asked the direct question, and so gives the true answer.

But there is a problem: the conditions of the puzzle actually allow the liar to make other responses. If you were to ask either question, the red guy is liable to answer "It sure is dark out!" (revelling at this unusual opportunity to make a truthful statement while still lying). Since in fact both he and any greenie would have answered with a road, this is still a lie.

Without tighter constraints on the possible answers, there is no question that is guaranteed to give the right answer.

Title: Re: Fork in the road
Post by 123HI on Dec 22^nd, 2005, 3:34pm

there has to be... i thought the 2nd quote you said was right "Which way would the other guy say is the right way" if you get the liar, then he will lie about the truth, if you get the truthful guy he will tell the truth about the lie. this means that whichever answer they give you go the opposite direction! SEE THERE IS AN ANSWER

Title: Re: Fork in the road
Post by BNC on Dec 22^nd, 2005, 5:40pm

on 12/22/05 at 15:34:53, 123HI wrote:

You: "Which way would the other guy say is the right way?"
Liar: "He would say there isn't one!" (a blunt lie, see...)