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        riddles >> hard >> Fork In the Road II
        
(Message started by: Macduff472y on Dec 25^th, 2002, 5:31pm)

Title: Fork In the Road II
Post by Macduff472y on Dec 25^th, 2002, 5:31pm

The question you should ask them both is,
"What would your brother say if I asked him in which direction Village A was?" The one who tells the truth will point in the direction of Village B (because that's what his brother the liar would say) and the liar would point in the direction of Village B
(because his brother would point in the direction of Village A.)

Title: Re: Fork In the Road II
Post by Mike Thomas G on Feb 16^th, 2004, 7:22pm

You can only ask ONE of them a question. Not both

Title: Re: Fork In the Road II
Post by towr on Feb 17^th, 2004, 12:35am

It still works if you replace 'both' with 'either', which was probably what was intended in the first place..

Title: Re: Fork In the Road II
Post by R. on Feb 26^th, 2004, 12:00pm

I think the following question works.

Ask one of them while pointing to one fork:

"Of theses two statements: 'You are a liar' and 'I'm pointing to way to the city of safety', is one and only one of them true?"

If yes take the road, if no take the other.

R.

Title: Re: Fork In the Road II
Post by Speaker on Feb 29^th, 2004, 10:16pm

There is another way, similar to asking what your brother would have answered. That is: "What direction would you have told me travel to reach village A, if I had asked you yesterday?"

Then, go in the direction they point. The honest brother will tell you truthfully that he would have directed you to A. The prevaricating brother will have to lie about how he would have answered the previous day.

Title: Re: Fork In the Road II
Post by R. on Mar 1^st, 2004, 9:34am

That is a superb ans.

Title: Re: Fork In the Road II
Post by grimbal on Apr 28^th, 2004, 2:06pm

Why don't you ask just one person:
"If I would ask you whether this path leads to A, would you reply positively?"
You will get the right answer whether or not the guy is lying or not. You don't need to know whether exactly one of them lies, whether each knows whether the other guy lies, or anything. You just ask one question to one person.

By the way, if you ask: "What would you say if I would ask you whether this path leads to A?", there still is the risk that the guy, being a liar would answer "yes", which would be a lie, because he actually would answer "absolutely".

Title: Re: Fork In the Road II
Post by Cerberus on Apr 1^st, 2009, 11:36am

How is this different from Fork In The Road I?

Title: Re: Fork In the Road II
Post by towr on Apr 1^st, 2009, 11:52am

on 04/01/09 at 11:36:43, Cerberus wrote:

How is this different from Fork In The Road I?

Here, there isn't a link between where they are from and their disposition for telling truths/lies.

Title: Re: Fork In the Road II
Post by Cerberus on Apr 2^nd, 2009, 5:05am

But the same question ("Which road would he tell me is the right one") is the solution to both, is it not?

Title: Re: Fork In the Road II
Post by towr on Apr 2^nd, 2009, 6:10am

on 04/02/09 at 05:05:48, Cerberus wrote:

But the same question ("Which road would he tell me is the right one") is the solution to both, is it not?

It's a solution to both. But for FitR I, you can also ask "Which road leads to your city?", which doesn't work for FitR II.
A simpler question to solve a simpler problem.

There is an even simpler version of the riddle, usually one with doors. The liar stands in front of the door leading to hell, and the truth-teller in front of the door leading to Heaven. There you only need to know who tells the truth, so you can suffice by asking "Am I a pizza?" (or any other question you are quite positive of knowing the answer to)

Title: Re: Fork In the Road II
Post by Cerberus on Apr 2^nd, 2009, 6:22am

But I am a pizza :o

Title: Re: Fork In the Road II
Post by rmsgrey on Apr 2^nd, 2009, 4:37pm

on 04/02/09 at 06:22:38, Cerberus wrote:

But I am a pizza :o

Then if the guy answers "yes" you know he's standing in front of the door to pizza-heaven...