One could answer " when they are the same" but what if a question is answered by combination of more than one old post?

So, let's say a question ask how to show a statement C from a statement A but previously two questions were asked " show statement B from statement A" and " show statement C from statement B". How would one close then?

Honestly I feel it should be closed but its unclear on what basis it should be closed. It seems so the criteria for its closure is in some sense beyond the SE system.

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    $\begingroup$ Perhaps an example or two would be a good idea, Generally...well, every mathematical argument can be broken down into a combination of other arguments, so your notion of "duplicate" would cover a lot of ground. $\endgroup$
    – lulu
    Aug 14, 2022 at 12:10
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    $\begingroup$ Maybe we should cross this bridge when we come to it. $\endgroup$ Aug 14, 2022 at 12:15
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    $\begingroup$ @GerryMyerson I suspect that this question is directly related to this answer, and my comments below that answer. $\endgroup$
    – Xander Henderson Mod
    Aug 14, 2022 at 12:24
  • $\begingroup$ Conclusion: If the set of duplicate forms a space having dimension $2$ or more , then the question can't be closed. ( two duplicate posts are independent if both can be proved independently). For an example consider the following question : Does there exist any function $f:\Bbb{R}\to\Bbb{R}$ which is continuous only on rational? $\\$ First duplicate : The set of continuity forms a $G_{\delta}$ set. $\\$ Second duplicate: $\Bbb{Q}$ is not a $G_{\delta}$ set. $\\$ This question can't be closed as both the duplicate target have independent proof. Am I right @XanderHenderson ? $\endgroup$ Aug 14, 2022 at 13:19
  • $\begingroup$ ... If yes then it should be clearly mentioned in the EoQS page. $\endgroup$ Aug 14, 2022 at 13:23
  • $\begingroup$ Hmm, I mean, if each fine point was mentioned, then the page would be very long. The goal should be to quickly convey the general idea. Exceptional issues can probably given their own threads (like here for instance) $\endgroup$ Aug 14, 2022 at 13:25

1 Answer 1


A post which genuinely asks two (or more) questions should be closed as being "too broad".

A post which asks one question which can be answered by linking together or combining the answers to two or more other questions should not be closed as a duplicate.

A post which can be answered by a single answer to another question should be closed as a duplicate of that question. If there are multiple questions, all of which have answers which will, on their own, answer the post, the question can be closed as a duplicate of all of those questions by either a moderator or a gold badge holder in one of the original tags on the question.

In the pseudo-example you give, "How do I prove A using C?" is likely not answered by an answer to the question "How do I prove A from B?" nor by an answer to the question "How do I prove B from C?" As such, it is a new question, and should not be closed as a duplicate. That said, a reasonable answer would include links to the earlier questions.


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