Talk:Knights and knaves

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I'm not certain that Smullyan first did these, but he certainly does many of them. To my mind, the ancestor of these puzzles is the old story about the two guards on two doors, one with treasuer, one with a tiger, and one guard lies, one tells the truth, and you only have one question to ask. Does this old one have a specific name? Where does it originate? (it has a 1001 nights feel?) -- Tarquin 21:48 19 Jul 2003 (UTC)

Regarding Question 2 - Without using any formal boolean algebra, a different solution came to me immediately - it appears to me that it could also be that both Bill and John are knaves (in this case, both Bill and John's statements are false, which is consistent with them both being knaves). Any problem with that solution? It seems a much simpler reasoning than the solution presented in section 1.5... Zoopee 09:09, 26 August 2006 (UTC)

I believe that's correct, they're both knaves, since they can't both be knights because of Bill's statement, they can't be a knave and a knight because then John's statement wouldn't be false, and they can't be a knight and a knave because then Bill's statement would be true. Which leaves us with two knaves. The solution to the puzzle isn't given in the article though, I think it was just meant as an example.--BigCow 21:18, 21 November 2006 (UTC)

yes, both of you are right, they are both knaves. I wrote the solution in the italian version but I can't write it in good english --Arirossa 20:55, 19 January 2007 (UTC)

On the other hand, if Bill is a knight and John is a knave, it works: Bill's statement that they are different is truthful, and, seeing as the requirements for John's statement to have meaning are unfulfilled, it could well be that he is lying and Bill's position has no bearing on John. The 2-knaves answer obviously works as well, so this has more than one answer.--68.100.78.205 20:06, 24 March 2007 (UTC)

Answer to 3, in case someone can put it in boolean: John answers yes to the first question (if he answered no, he would have to be a knight and the logician would figure it out immediately) and yes to the second (if he answered no, the answer would remain unclear). He is a knave and Bill is a knight; allowing him to say no yes both times (since John and Bill are different, both yeses are untrue).--68.100.78.205 20:15, 24 March 2007 (UTC)

For 4: The answer is "Are you the sort of person who would say that Someplaceorother is to the left?" Nobody would claim to be a knave, so if they say yes, it is to the left, and if no, it is to the right. The second problem posed has nothing to do with the question: "Does 2+2=4?" would do, or any obvious equivalent. --68.100.78.205 20:19, 24 March 2007 (UTC)