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Comment by zck | Hacker News Reader

It seems like 2 is improperly specified:

>2. Jane went to visit Jill. Jill is Jane's only husband's mother-in-law's only husband's only daughter's only daughter. What relation is Jill to Jane?

Here's the reasoning I think they want:

Jane's only husband's mother-in-law is Jane's mother.

Jane's mother's only husband is Jane's father.

Jane's father's only daughter is Jane.

Jane's only daughter is Jane's daughter.

But wait! Just because Jane's mother has only been married once doesn't make Jane's mother's husband Jane's father! Children can be born out of wedlock. So Jane's mother's husband could have had a daughter who isn't Jane. What does that make Jane and that person's daughter? Absolutely nothing.

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If and only if you make the obvious assumptions, there is a really nice answer, easy to explain in a newspaper article. Otherwise, you'd need to spend three pages clarifying a three sentence question.

Some people have two wives. Sometimes it's legal, and sometimes it's not; either way, it happens. Maybe Jane's only husband divorced her and remarried, and his new mother-in-law is in the same boat with respect to her husband. Also, one or more of the daughters may have been adopted. Also, there are multiple definitions of "relation" and of "husband" that you might use. And, it all depends on what the definition of "is" is.

Ha, when first formulating the argument, I realized that the husband could have been married multiple times, but forgot that when I wrote my post. Excellent point.

But it seems to me that if the whole reason for your group existing is that you're smarter than most people, you shouldn't have flaws in your exam like this.

The question itself is an implicit test of logical deduction to determine the most likely assumptions given the restraints imposed by the question.

Just because random things are possible (the husband had two wives!), does not make them the most likely assumptions given the nature of the question. If the answer was "Unrelated - Jane's dad had a harem of several women", the question wouldn't make much sense on any type of quiz designed to determine intelligence.

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