I'm a second year physics and second year mathematics student, who does lots of self-studying. I'm mostly very strict about the rigour of the mathematics that I'm doing, and this means I can spend hours just to clarify a single point in a single proof, and this generally leads me to write very clear and understandable (in my opinion) proofs at the end, and I can even stand to throw those proofs, for this keep them until the end of the semester :)

Since this is Q&A site, even thought for some theorems, there are really good answer, and complete proof, for most of the theorem that I'm looking, there is not much rigorous, clear and understandable proofs, (I mean sometimes even the notation is confusion although the theorem is quite basic).

Hence, I was thinking to post some questions (for example asking for a proof of a theorem) and then answer them with the proof that I have written, but is this an acceptable behaviour in this site ? is it in the rules of the site ? If so, do you have any suggestions for me to pay attention while doing that ?

Note: Of course the question is already has been asked, I can post my own proofs to those questions, but of course, sometimes, OP might ask for a specific thing in the proof or the answer that I would write might not a direct answer to that question.

Plus, sometimes I specifically want to know why is something not true, which for in the first take it looks to be true, so in those answer, I would clarify why something is not the case.

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    $\begingroup$ Also, since you will be posting answers to your own questions, and probably to old ones, be sure that your answers are in as best possible state as possible. That means sitting on them another week, searching for typos or $\rm\LaTeX$ errors, etc. There is nothing more infuriating than people posting self-answers or answering old questions with crap that has to be edited six or seven times before giving up on it. $\endgroup$ – Asaf Karagila Nov 13 '17 at 19:04
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    $\begingroup$ I would also say, if someone has already posted essentially the same proof with a reasonable level of rigor, you probably shouldn't post yours as well. $\endgroup$ – Qudit Nov 13 '17 at 20:03
  • $\begingroup$ If the question already exists, answer there. (i.e., do not post a duplicate question). I'm personally wary of someone who posts a question and immediately posts an answer, because they, as the "asker" can award themselves ("as the answerer") with accept votes, and there are almost always questions currently existing to which you can answer with as much rigor as you want, without creating an altogether new post for self-satisfaction. $\endgroup$ – amWhy Nov 13 '17 at 20:09
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    $\begingroup$ Worse, you're suggesting you'd be merely posting a question in order to write your proof as an answer. But that means it is not a question to you. I don't like make believe questions, or having to determine if a question is fake or not. If you have a mathematical question, by all means, ask it here (and ask it well). That doesn't make it okay to post a "question" you know the answer to, (Hence a dishonest question) so you can have a platform (answer field) to showcase your proofs. $\endgroup$ – amWhy Nov 13 '17 at 20:53
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    $\begingroup$ If you do this, be sure to indicate in your question that you intend to post an answer, so no one wastes any time writing up stuff that you already know. $\endgroup$ – Gerry Myerson Nov 13 '17 at 21:38
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    $\begingroup$ When you ask a question, there's a checkbox that allows you to post an answer at the same time. You should use that if you choose to do this. $\endgroup$ – Qudit Nov 13 '17 at 23:42
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    $\begingroup$ The purpose of this site is to post questions that you do not know the answer to. If you want a forum to post things you already know, consider a personal webpage or blog instead. $\endgroup$ – Carl Mummert Nov 14 '17 at 2:12
  • $\begingroup$ @GerryMyerson Good thought. $\endgroup$ – Our Nov 14 '17 at 5:18
  • $\begingroup$ @Qudit Thanks for pointing out,I didn't thought that. $\endgroup$ – Our Nov 14 '17 at 5:19

Stack exchange in general welcomes self-answered questions. However, there are instances which self-answered question did annoy other users (IMO for good reasons). See here and here.

And you should be careful about the quality of your questions, which are judged by other users just like any other question. Some might even suggest that we should judge self-answered questions with a higher standard since, like answering question to old posts, these posts in general are less visible.

So as a general rule, please provide sufficient context to your question even though you have an answer already.

Second, if your question are exact duplicate of others, your question will be closed and indeed you should just post the answer to the existing question. If it is not an exact duplicate, state that explicitly in your question why. But be prepared that some users will disagree and close your questions. That the existing answers are not rigorous enough is not a valid reason for posting a new question.

For your specific purpose: Note that what you find "non-rigorous" might look very rigorous from others. If you are going too far, some users might find your answer too long and not useful. Your answers might get downvoted or even deleted.

(As an example, I once had a student in the real analysis class who insisted to prove everything from nothing for every assignments he handed in. His HW is on average 20 times longer than other students. I will never think that his work is better than other students just because his works is more "rigorous")

You may just go ahead to post one or two questions and see how the community reacts.

  • $\begingroup$ As an example, I was talking about such answers, math.stackexchange.com/a/2518701/279869 $\endgroup$ – Our Nov 13 '17 at 18:43
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    $\begingroup$ For your linked question and answers @onurcanbektas, IMO both the question and the existing answer are well-written, and the answer answered the questions nicely. Your answer proves (i)-(iv), but the questioner states explicitly that they have no difficulties proving (i), (iii) and (iv) (Yes, the title of the question is not the best). So strictly speaking your answer are not answering the question. I am fine if someone wants to write a complete solution to that question. May be you should state that clearly in your answer. $\endgroup$ – user99914 Nov 13 '17 at 19:14
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    $\begingroup$ Such posts are not welcomed on the site in all cases in which they occur. So don't start with a misleading statement. $\endgroup$ – amWhy Nov 13 '17 at 20:04
  • $\begingroup$ @amwhy: By "such posts" do you mean self-answered post? $\endgroup$ – user99914 Nov 13 '17 at 20:59
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    $\begingroup$ @JohnMa I mean that yes, it is not the case that all self-answered question/answer posts are always welcome on this site. I never said any thing to indicate they are never welcome. I simply stated, equivalently, that there are some self-asked-answers which have not, and may not be welcome. They may, in some, even many case, be unwelcome. But I have not claimed, nor do I believe, that "such questions" are automatically never welcomed. But I do not believe that they are automatically always welcome. $\endgroup$ – amWhy Nov 13 '17 at 21:04
  • $\begingroup$ Btw, I support the rest of your answer! $\endgroup$ – amWhy Nov 13 '17 at 21:07
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    $\begingroup$ "The site welcomes self-answered questions." The way I see it, what the site welcomes is self-answered questions by people who didn't know the answer when they posted the question, but were helped to see how to answer by comments. $\endgroup$ – Gerry Myerson Nov 13 '17 at 21:36
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    $\begingroup$ @amwhy: Yes I think I did took that too literally. Please see the edit. $\endgroup$ – user99914 Nov 13 '17 at 21:37
  • $\begingroup$ @GerryMyerson That's the way I pretty much see it, too. $\endgroup$ – amWhy Nov 13 '17 at 21:41
  • $\begingroup$ It seems that how the community reacts depend more on the quality and quantity of those self-answered questions @GerryMyerson, but less on whether they know the answers. $\endgroup$ – user99914 Nov 13 '17 at 21:45
  • $\begingroup$ Did you read my first comment (or second) below the question, @JohnMa ? I think it matters a lot to many users that a question actually be a question for the user posting it. It's not just about it's quality or lack thereof, but also of motives: When a question is asked by a user who knows how to answer it, and what the answer is, it ceases to become an honest question, but rather, the user/"asker" is simply manipulating the situation in order to answer their question, which was never a question, to start with. $\endgroup$ – amWhy Nov 13 '17 at 21:49
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    $\begingroup$ @amwhy I think your comment is to point out that self-answered question are not always welcomed? I am aware of that many users care about the motive. But I am also aware that many users do not care and I am one of them. (I guess you know very well that the discussion, if continued, will lead to the discussion of the goal of this site....) $\endgroup$ – user99914 Nov 13 '17 at 22:32
  • $\begingroup$ My goal is to indicate that you, yourself, nor you answer, suffices to speak to the reception of fake questions/answers to what was never a question, all by one and the same user, nor do you speak for SE when you say "Stack exchange in general welcomes self-answered questions." You aren't privileged to divine the intent or representation of "MSE policies, conventions, etc." Speak for yourself, not for SE, MSE, and not "in general" (to support a tenuous position). $\endgroup$ – amWhy Nov 13 '17 at 22:38
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    $\begingroup$ I am quoting SE, I do not speak for them. Read the link, please. @amwhy. Saying that "SE in general welcomes self-answered questions" is already an understatement. $\endgroup$ – user99914 Nov 13 '17 at 23:36
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    $\begingroup$ @JohnMa As a reply to your first comment: As I have stated in my question, the answers that I'm giving might not a direct answers to the question, and that is why I was mainly considering asking question for those answers. $\endgroup$ – Our Nov 14 '17 at 5:22

The main criterion to keep in mind here is:

If your question is something you might have searched math.stackexchange.com for prior to working things out for yourself, then it is probably reasonable to post the question-answer pair.

The point being that someone else may well have your question and search math.stackexchange.com for the answer, and then they'll find your post!

To be clear, I mean that your question goes into a (well-written) question posted to the site, and your answer is posted as an answer to the question. Don't put your answer in the body of your question!


One way to do it is like this one. Say that you have a proof, but invite others to provide their own proofs. Then (after an appropriate delay, I waited 3 weeks in that case) post your own proof if it has something more to say.


Here is a data point/anecdote that might be of interest:

I posted this question, entirely with the intention of posting an answer to it that summarizes the contents of a paper that was not very easily accessible when I had written the question. (The paper has been made available online since then, and I have then edited the question.)

I eventually did get around to answering it myself, but a different user posted his (very good!) answer in the meantime, and it garnered a lot of votes.


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