Criteria for closing questions as duplicates

Question

I recently came across this question which was closed as being a duplicate. When I read the linked source question, it was not a literal or even particularly specifically close duplicate, but in all fairness did present a discussion of principles which could be used to solve OP's question. However, the OP of the closed question is a new user, and as such might be expected not possess the mathematical savvy to both (a) abstract the relevant principles from the cited question, and (b) apply them to his specific case. The very language of OP's question seems to confirm such a view.

It further seems to me that if the criterion for closing a question as a duplicate is simply that the relevant principles have been laid out in previous questions, then almost all questions will be duplicates, or all answers can simply refer the OP to a relevant textbook. This seems to me to be an awfully ungenerous criterion, especially for novice question posers.

What is the community consensus on when a question is sufficiently addressed in prior posts to be deemed a duplicate? Further to that query, how much expertise ought the OP be credited with when the linked duplicate is written at a somewhat higher level of mathematical language and achievement than is evidenced in the posed question?

Answer 1

It is important to understand that "closing as a duplicate" can be done in different ways. For example, a thing that can be done in such a case is to explain how the duplicate applies. Note the comment by the user that closed it:

"See the linked dupe for how to find all roots of $\,n^2\equiv n\pmod{1000}\ \ $"

This comment translates the question as asked in the phrasing of the duplicate target, where the case $900$ instead of $1000$ was asked about.

What's more the answers there basically treat the general case.

Thus I think the particular closure is justified, because on the one hand it was explained how the duplicate applies and the duplicate actually is rather directly applicable.

That said, it is possible that the duplicate will not help the poster. Yet then they could for example ask the user that closed as a duplicate or edit theit post and explain what specifically they do not understand.

Put differently, likely we would not object to an answer to the new question that uses congruences because the user might not know about it.

It is hard to answer such question in abstract which is why I focus on the particular post. That said, a key point here is the comment. It serves two purposes:

• It explains how the other thread applies.
• It gives a natural hook for the poster to ask for clarification.

I think to leave such comments is a good practice. Conversely if it is possible to explain in a few words how the target applies that usually should be alright.