Oh boy, never mind, after a good night sleep the solution is super obvious... Grrr what a waste of time ;-) The solution is in the sentence "the logician has then enough information to solve the problem", which I yesterday read like "the problem can now be solved", which is not the same. So the second answer must have been "Yes" otherwise the logician did not have enough information to solve the problem (because two cases still remain). Gee. But it was good Haskell practice ;-)

...

("John is a knave ","Bill is a knight","Yes","Yes")

----- Oorspronkelijk bericht ----- Van: Peter Verswyvelen [mailto:bf3@telenet.be] Verzonden: donderdag, augustus 9, 2007 11:35 PM Aan: steve@fenestra.com, haskell-cafe@haskell.org Onderwerp: RE: [Haskell-cafe] Problem with question 3 about knights and knaves onw ikipedia

Indeed, I missed that. This rules out the first answer is "no"

But I still keep the 3 other solutions then :(

...

("John is a knight","Bill is a knight","Yes","No ") ("John is a knave ","Bill is a knight","Yes","Yes") ("John is a knave ","Bill is a knave ","Yes","No ")

Any more help (or just the solution, I give up) is very welcome to help this poor man in logic hell ;-)

Oh well, it seems I'm getting too old for this stuff ;)

-----Original Message----- From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Steve Schafer Sent: Thursday, August 09, 2007 8:22 PM To: haskell-cafe@haskell.org Subject: Re: [Haskell-cafe] Problem with question 3 about knights and knaves onw ikipedia

On Thu, 9 Aug 2007 20:07:02 +0200, you wrote:

...

("John is a knight","Bill is a knight","Yes","No ") ("John is a knave ","Bill is a knight","Yes","Yes") ("John is a knave ","Bill is a knave ","Yes","No ")

Anyone has an idea what I missed here?

You're missing a key element of the problem: After John answers the first question, the Logician doesn't have enough information to solve the problem. Think about that for a second, and you will see the light.

Steve Schafer Fenestra Technologies Corp. http://www.fenestra.com/ _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

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