Even in the unsociable interpretation, A is still the correct box to tick. In particular, there is a directed path: Paul --> Linda --> John such that Paul is married and John is unmarried. Hence, there must be a pair of adjacent nodes X --> Y such that X is married and Y is not married. -- APG.
Sent: Friday, May 05, 2017 at 12:05 PM From: "Fred Lunnon" <fred.lunnon@gmail.com> To: math-fun <math-fun@mailman.xmission.com> Subject: Re: [math-fun] Brain teaser
Huh? The explanation is much more likely to be that the question is subtly ambiguous. The unsociable interpret "is looking at" literally as an asymmetrical relation, so tick C; the sociable (apparently!) assume that the phrase implies both parties are "looking at" one another, so tick A.
As to option B, I am unable to arrive at any conclusion which does not reflect unflatteringly on the neurological apparatus of the responder ...
WFL
On 5/5/17, Gareth McCaughan <gareth.mccaughan@pobox.com> wrote:
On 05/05/2017 09:36, Victor Miller wrote:
Is there some trick? If Linda is married, then the Linda-John pair is the married/not married pair. If Linda isn't married then the Paul/lLinda pair is the one.
The only trick is that a surprising number of people, even rather clever people, get only as far as figuring out that they can't tell whether L&J are married nor whether P&L are married, and conclude that the answer to the question is no.
I think it likely that training in mathematics correlates strongly with answering this correctly. I am not sure how the explanation for this, if I'm right, should be divided between the effect of learning about logic and the effect of being the sort of person who is willing to spend time learning about logic.
-- g
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