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The purpose of this thread is to help focus the attention of the community on posts that may require exceptional handling. This includes requests for reopen and undeletion votes. A request should be posted as an answer below.

Please do not use this thread to engage in debates on contentious matters (e.g. reasons for closure). That should be done in a separate linked thread. The goal is to keep this meta thread free of tension, so that everyone feels comfortable posting here. Please be polite, and respect the many different viewpoints in our diverse community.

To inform readers of the current (and past) states of the targeted post, please prepend tags such as:

Reopened, reclosed or

Undeleted

at the start of the answer when a change of status occurs. (This also makes it easier to browse through the list by creating a visual difference for posts that still require action.)

Beware that "short" requests such as "request reopening of " may be automatically converted to comments by the SE software, so you may need to write more (e.g. why you think that the question should be reopened or undeleted).

Notice that the first edit after the question was put on-hold pushes the question into reopen review queue, if the edit was done withing 5 days of closure. So does a reopen vote. It is reasonable to wait until the review is finished before posting here. (If the review has already been finished, it is shown on the timeline of the question.)


(description copied from the old thread)

As has been proposed in chat (and seconded by a couple of users), it seems that it is time to create a new thread for reopen and undeletion requests. The old thread (as of now) has over $200$ answers, and it is really hard to scroll through the mass of old and/or possibly outdated answers--voting is a mess, too. (It's especially problematic for 10k users who can see the deleted posts.)

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Reopened, closed as duplicate

This question was closed as opinion based (although two votes were to close as a duplicate). It should be reopened and re-closed properly as a duplicate, since this topic has been discussed before. Two immediate duplicates:

  1. Is $0$ a natural number?
  2. Should $\mathbb{N}$ contain $0$?

There might be more out there.

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  • $\begingroup$ No, since the links are in the comments below, whereas a duplicate banner is on the top of the post and the first thing you see. Moreover the question is in fact a duplicate. "Closed is closed" is not true, there are different kinds of closure for questions, it can be closed since it's off topic, or since it's missing details (which is under off topic, but not really off topic), or it can be opinion based, or it can be a duplicate. Different closures mean different things. This question is a duplicate and should be closed as such. $\endgroup$
    – Asaf Karagila Mod
    Jan 7, 2015 at 23:32
  • $\begingroup$ So... "why is there such a conflict in conventions?" automatically make bad questions for the site? I disagree. $\endgroup$
    – Asaf Karagila Mod
    Jan 7, 2015 at 23:34
  • $\begingroup$ @Daniel: Thanks. It's a shame the dupe-hammer cannot be applied to link to multiple questions at the same time. $\endgroup$
    – Asaf Karagila Mod
    Jan 8, 2015 at 0:01
  • $\begingroup$ Indeed, that would be a nice feature. $\endgroup$ Jan 8, 2015 at 0:04
  • $\begingroup$ @Daniel: Although unlikely to be implemented (since if something is a duplicate of several questions it "means" that either it contains multiple questions or those questions are duplicates; of course this is not at all true in reality, but philosophically it seems to be the guiding idea). $\endgroup$
    – Asaf Karagila Mod
    Jan 8, 2015 at 0:07
  • $\begingroup$ @Asaf: I think on MSE it is sometimes done. Shog9 can even close a closed question or something like that. $\endgroup$
    – quid Mod
    Jan 8, 2015 at 1:11
  • $\begingroup$ @quid: Yes, but he's using godmode cheats. :-) $\endgroup$
    – Asaf Karagila Mod
    Jan 8, 2015 at 7:14
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Reopened

I'd like this question reopened. The confusion in the question is perfectly clear - the OP does not have a clear distinction between the terms 'sequence' and 'number' - but this could be easily remedied by an answer that explicitly points this out, explains the distinction between sequences and numbers, and then goes on to explain that sequences can have limits. The sequence $n \in \mathbb{N} \mapsto (9/10)^n k$ does not literally equal the number $0$, but it has a limit, and that limit does indeed equal $0$. On the other hand, the number $0.9999\ldots$ literally equals $1$.

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Reopened

This question was put on hold as being unclear about what is being asked but as can be seen on comments there had hints on how to improve. Everything who was suggested was adopted to improve the question and no new comments came in about why is it unclear. I therefore request the question to be reopen as I really need answers to it.

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  • $\begingroup$ The question just had a major revision. $\endgroup$
    – AlexR
    Feb 5, 2015 at 22:15
  • $\begingroup$ @Gerry For consistency, please note all the other answers (except for one....) use a new format for status update. $\endgroup$ Feb 6, 2015 at 8:23
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    $\begingroup$ @Najib, any system strong enough to be complete will be inconsistent. $\endgroup$ Feb 6, 2015 at 23:07
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Reopened

The author of Probability of going into an absorbing state seems to have an idea of an approach, but there are better approaches to suggest. Good hints will be useful to the author and to future readers. The methods of attack will be useful to general absorption problems. I believe that the question should be reopened so that hints can be provided.

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Closed, Reopened, Closed as duplicate

This question should have been closed as a duplicate of

I can't re-close right now due to system constraints.

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  • $\begingroup$ +1 It is also too broad - explaining "every little detail" would require a book (and there are already many books that discuss induction in great detail, to which the OP should be directed). $\endgroup$ Feb 21, 2015 at 22:39
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Reopened

I wish to appeal for the reopening of one of my questions: Evaluating $\int e^{\Gamma(x)} dx $ and $\int \pi^{\Gamma(x)} dx $

I have almost nothing more to say; question was even bolded in the original post, and still was marked as unclear. I do not know why; nevertheless I've done what I can in editing it, and see absolutely no grave mistakes/issues with my question. Lot of interesting insights and answers have been lost due to the fact people are not able to answer/give hints. Please help me reopen this.

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  • $\begingroup$ Why did you edit @Najib? It was there in every answer, hence I did that... $\endgroup$ Mar 1, 2015 at 9:44
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    $\begingroup$ Only the change in status is recorded, not the original status. It makes it easier to browse through the list by creating a visual difference between requests for which nothing has changed (and thus still require action), and those for which something has changed (usually the issue has been resolved). Moreover, the format you used was different from the format of all the other requests... $\endgroup$ Mar 1, 2015 at 9:46
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    $\begingroup$ As for your question... I suggest that you edit the title. "The most complex integral you've encountered" is not very descriptive, it could be pretty much anything depending on who you are... I also think that putting the actual question before the background would be a good idea: people read from top to bottom, and having to scan the text for the question might be off-putting. Other than that your question isn't really unclear (though I'm not sure why you expect a nice form for these integrals). $\endgroup$ Mar 1, 2015 at 9:54
  • $\begingroup$ I did that believing I'd remove some ambiguity about the status that way, but I understand now. Ty for the edit. Will incorporate your suggestions. $\endgroup$ Mar 1, 2015 at 9:54
  • $\begingroup$ @NajibIdrissi Done. $\endgroup$ Mar 1, 2015 at 10:01
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[RE-OPENED]

I would like for this question to be reopened. It was only closed in the first place because of a minor typo in the title of the question; the OP has since fixed the typo in question.

There are three answers to the question one of which has been accepted.

The stated reason for putting the question on hold is not valid.

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  • $\begingroup$ Your answer appear to be false. As the typo apparently was in the post not the title. Perhaps you could fix this. $\endgroup$
    – quid Mod
    Mar 7, 2015 at 11:33
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    $\begingroup$ I give up.${}{}$ $\endgroup$ Mar 7, 2015 at 12:16
  • $\begingroup$ @quid, good point. I don't think that my answer loses any utility by not being exactly the one the OP meant to ask. In fact I'll often given an answer to a similar question which is not identical to the OP's in order to discourage cheating. That is the OP should at least have to apply the method himself. I'll just add a note at the beginning of my answer mentioning the discrepancy. $\endgroup$
    – Spencer
    Mar 7, 2015 at 19:54
  • $\begingroup$ This seems a reasonbale solution given the situation at hand. $\endgroup$
    – quid Mod
    Mar 7, 2015 at 19:58
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Duplicate redirected

This question has been marked a duplicate of How come the number $N!$ can terminate in exactly $1,2,3,4,$ or $6$ zeroes but never $5$ zeroes? which on its turn is marked a duplicate of Highest power of a prime $p$ dividing $N!$. It would be better to link the first question directly to that last one.

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Reopened, Reclosed, Rereopened

I would like this feature request to be re-opened.

It was closed as a duplicate, not of a feature request, but of a question from someone who was curious to know why missing details make a question off-topic. I am not curious to know why this is done. I posted a feature request, not a request to be told why that is done. I no longer care why it is done because I am satisfied that it is wrong and I don't want to study the reasons why rude people are rude. I'm sure the study of why people do things that are wrong is fascinating, but it's off topic in my feature request.

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[Re-opened]

I think that Is the axiom of choice really all that important? should be reopened.

I can cast a unilateral vote to reopen, but I feel that since I wrote answers both to this one and the duplicate, I shouldn't be hasty to use my powers here.

In any case, the two questions (the question, and the voted duplicate) are different in their presentation and therefore the answers are somewhat different in their essence. Sufficient, I feel, for not having them as duplicates.

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[Reopened]

This question was closed because it is said to be a duplicate of this question.

This is absurd. The content of the newly closed question is:

Why the word "error" was chosen as the name of the function $$ x\mapsto\operatorname{erf}(x)=\frac 2{\sqrt{\pi}} \int_{-\infty}^x e^{-t^2}\,dt\text{ ?} \tag 1 $$

The content of the earlier question, of which that was alleged to be a duplicate, is:

Why is it normalized in that way, rather than using the function $$ x\mapsto \frac 1 2 + \operatorname{erf}\left(\frac x {\sqrt 2} \right) = \frac 1 {\sqrt{2\pi}} \int_{-\infty}^x e^{-t^2/2}\,dt, $$ which arises naturally in the theory of probability?

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    $\begingroup$ You have a point there and I voted to reopen, while dupe closure seems not "absurd" either. However, could you please try to internalize that one cannot notify users that voted to close, so that you writing several near-identical comments is completely pointless and pure noise. $\endgroup$
    – quid Mod
    Apr 30, 2015 at 22:20
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    $\begingroup$ @quid : Are you saying nothing appears in their notifications? If so, I'd say that's a bug. But I also wonder how you would know that. ${}\qquad{}$ $\endgroup$ Apr 30, 2015 at 22:21
  • $\begingroup$ Yes, this is what I am saying. I know because I read the documentation of the feature (and I assume the documentation is in-line with the behavior on the site). Here the relevant bit (my emphasis), it is even made explicit there (not just inferable as it is not mentioned as possible): "For questions: The moderator who closed the question. Users who have closed or reopened a question without a binding close vote (i.e. without a gold tag badge or a moderator vote) cannot be notified." $\endgroup$
    – quid Mod
    Apr 30, 2015 at 22:27
  • $\begingroup$ I have no idea what a "gold tag badge" is and I can only surmise what the term "moderator vote" means. How to tell whether a question has been closed without those things is something I've never given a second's thought to. $\endgroup$ Apr 30, 2015 at 22:38
  • $\begingroup$ As a rule you can assume it was closed without this and you cannot notify. You can notify only a closer marked with a diamond (mod) or a yellow circle (gold badge in tag on question, ie, 1000 score in 200 non CW answer). The point is these can close a question alone (binding vote, one vote suffices). In this case it makes some sense to allow to notify this one user. However, it is not desirable that numerous users are notified especially not via numerous comments (as you tried), which is a rational behind the design. $\endgroup$
    – quid Mod
    Apr 30, 2015 at 22:48
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    $\begingroup$ @quid : Why is it undesirable? To me responsibility appears desirable. ${}\qquad{}$ $\endgroup$ Apr 30, 2015 at 23:52
  • $\begingroup$ @MichaelHardy You are right. I erred in voting to close here. $\endgroup$
    – Potato
    Apr 30, 2015 at 23:54
  • $\begingroup$ Because it adds too much noise. Anyway, this was not really my point. The point is it does not work, and it is by design it does not work. (I will not recommend you file a feature-request if you want it changed as I am pretty sure it was filed already frequently.) $\endgroup$
    – quid Mod
    Apr 30, 2015 at 23:56
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    $\begingroup$ @quid : What makes you think it was filed frequently? And is that really a reason not to request it again? One might think that if the number of people requesting something is large, that in itself might be a cogent reason to think it should be done. $\endgroup$ Apr 30, 2015 at 23:59
  • $\begingroup$ It is just an educated guess. See this and that and third for related but not identical ideas. Yet, do as you please. And, I just said "I will not recommend" not "I will recommend not." (Abstractly, upvoting existing requests is common, not reposting.) $\endgroup$
    – quid Mod
    May 1, 2015 at 0:14
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Re-opened.

This question is about a chapter epigraph in Wilfred Hodges, A Shorter Model Theory. Please reopen it. It has been closed for being off topic.

That claim is false, as the text under the musical notation shows. Hodges states that the epigraph is intended as a heuristic illustration("with allowances for artistry") of an important concept, "an indiscernible sequence", theorems about which are central to the chapter.

The question asking about the epigraph is a question about indiscernible sequences, and is on topic.

Further, closing the question is unfair to the asker. It shows genuine research effort, highlighting a non-obvious point in an advanced textbook. I had not previously noticed that this epigraph needs more attention to understand it than other chapter headings of the book. The answer I wrote is certainly not definitive, but the question has motivated me to return to the book and I have a better understanding of the chapter as a result. To that extent the question is helpful to other readers of the book. It is really of much higher quality than most of what is asked on this site!

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  • $\begingroup$ Thanks, Martin. $\endgroup$
    – HTFB
    Jun 16, 2015 at 8:52
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    $\begingroup$ As is usual with this kind of request, editing this kind of information into the question would make things easier for everyone. $\endgroup$ Jun 16, 2015 at 19:44
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Undeleted

Please vote for undelete the following question: Projective dimension of all principal ideals is finite. Is R an integral domain?. This is not trivial, has an upvoted answer, and moreover it's linked to this question: If $R$ is a noetherian local ring, then every 2-generated ideal has finite projective dimension iff $R$ is a UFD

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Reopened

What is the minimum cardinality for a set intersecting each member of a configurations of pairwise intersecting disks of the same radius? was closed as unclear. I had moderate success in guiding OP to clarify; I think the question can be understood now [and it certainly can, if you are also willing to dive into the comments]. Last time I looked, it had stalled at 4 votes to reopen. Is there a fifth?

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    $\begingroup$ Is it possible that it stalled at four votes to reopen because you need to read a dozen comments to fully understand the question...? $\endgroup$ Feb 18, 2016 at 7:10
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    $\begingroup$ I rewrote it now. Hoping to match the intent. $\endgroup$
    – quid Mod
    Feb 18, 2016 at 14:15
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Reopened and dupe-closed (with different target)

The question is closed as a duplicate of a question that is not at all a good target.

Show that the group $G$ is abelian if $G/Z(G)$ is cyclic

I would like it to be reopened. It then could be closed as a duplicated of the many better targets (see comment there) or also treated as a "proof verification" (but I think just closing it again would make sense).

(The problem is that the target literally asks something very different, commutator instead of center, and only then proceeds to give a proof as if the commutator where the center. What's worse the answer picks up the literal version of the question, so one cannot even edit the target to improve it.)

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Reopened, waiting for a reclose

Reclosed as appropriate duplicate

Request to reopen and then reclose this question:

Rational points on circles centered at the origin

This closing reason of this question as an extra duplicate of Does $a^2+b^2=1$ have infinitely many solutions for $a,b\in\mathbb{Q}$? is mathematically wrong. Knowing there are infinitely many rational solution $x^2+y^2 = 1$ doesn't help to determine whether $x^2+y^2 = z$ has rational $x,y$ as solutions for a generic rational number $z$.

Please reopen and then reclose above question as a duplicate of Which rationals can be written as the sum of two rational squares? which contains answers appropriate to above question.

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Reopened

Please consider reopening this question. It was closed as unclear. The confusion (I guess) is probably that the statement is very closed to the statement concerning diagonalization of symmetric matrices.

However, the question as stated is quite clear (and is not the same as the theorem on diagonalization) and should stay on the site, since this is a legitimate confusion that a student would have when they first learn diagonalization and other students would benefit from this question (and of course the answers).

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  • $\begingroup$ It is not clear to me that the asker really understood the question they wrote, or intended the quantifiers to be the way they are implied by their phrasing. The only response they have given to the feedback they received is accepting egreg's answer, which doesn't clearly address this point. So while I agree that what the asker literally wrote is a question worth having, I'm not sure it's the question they meant to ask... $\endgroup$ Oct 22, 2017 at 3:39
  • $\begingroup$ @EricWofsey: Yes, I agree it's not clear that they understand. But that seems to be orthogonal to whether the question should be closed? $\endgroup$
    – user99914
    Oct 22, 2017 at 3:53
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Reopened

This question got closed as off-topic. However in the comments OP showed that they have tried to solve the problem and put some efforts in it. Furthermore, the question has context. They edited the question and I tried to improve a bit the formatting.

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Reopened.

Please reopen Changing the values of a function $f:[a,b] \to \mathbb R$ of bounded variation for countably infinitely many points not a dense subset of $[a,b]$

It was closed as a duplicate of Changing the values of an integrable function $f:[a,b] \to \mathbb R$ countably infinitely many points not a dense subset of $[a,b]$, but voters apparently missed the distinction that the original question is about bounded variation while the alleged duplicate is about integrability.

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    $\begingroup$ Agreed on the distinction. Remains the lack of personal input. $\endgroup$
    – Did
    Aug 22, 2015 at 10:58
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    $\begingroup$ It is reopened now. Should it be closed again, this time for lack of context, @Did? (There is at least some context - the OP says what happens for finitely many points.) $\endgroup$ Aug 23, 2015 at 11:42
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Closed, Reopened, Closed, Deleted, Undeleted, Deleted, Undeleted, Deleted, Undeleted, Deleted

I would like my question to be undeleted and reopened: https://math.stackexchange.com/questions/1353475/nice-combinatorics-puzzle

My question was initially closed for missing context. After I provided the requested context, it was reopened. Then it was closed for the second time, now for being off-topic. Apparently some members of the community are of the opinion that mathematical puzzles have no place at this site. Yet there are countless examples of well-received puzzles at this site that prove otherwise.

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Update, september 2018. After three years I return to this website, only to see that my question has not been reopened or undeleted (in contrast to many others). Strange. If I click on the link, I am lead to my old question. In the column on the right I see a whole list of similar puzzle-type of questions which have been approved and awarded points. Bizarre.

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    $\begingroup$ You might be interested in this. $\endgroup$ Aug 2, 2015 at 7:52
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    $\begingroup$ I voted to undelete, for two reasons: a) A comment under the question (which received $4$ upvotes and thus played a significant role in the discussion) says: "We're here to help people, and you don't need help with this." I disagree; in fact it's quite normal for questions to be posted for reasons other than needing help, and most such questions are not closed or deleted. $\endgroup$
    – joriki
    Aug 13, 2015 at 11:46
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    $\begingroup$ b) The partial answer given by Emisor demonstrates that thinking about prime factorizations is required to solve the puzzle. This is not "elementary, using only every day ideas and notions" (as described in the question Najib linked to above). There are many more trivial questions about divisibility and prime factorizations, and they're generally considered mathematical and not closed or deleted. $\endgroup$
    – joriki
    Aug 13, 2015 at 11:46
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    $\begingroup$ FWIW I cast a vote to undelete this. Memories. $\endgroup$ Sep 23, 2018 at 5:24
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Reopened

It's about this question: The multiplicative group of all complex $2^n$-th roots of unity, where $n = 0 , 1, 2 , \ldots$.

In my opinion, from the very beginning the OP showed enough effort and determination to solve the problem by himself, so I think it was unfair to close it. I've voted for reopening, and maybe others want to do the same.

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Reopened.

I would like to request that this question be re-opened. In its original form, it was closed as being primarily opinion-based -- a decision I don't disagree with. But I have edited it so that it now asks a fact-based question, one to which I am prepared to provide an objective, researched answer.

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Reopened

Please I would like to request to remove the "put on hold" of: If a n-manifold exists, then is it the boundary of an existing (n+1)-manifold? [on hold]

I have rewritten the question to clarify it. I have read carefully the comments and simplified it. Indeed it is already answered, and the user that answered understood what I wanted to express, and I already accepted the answer. So if possible I would appreciate very much if could be removed the on-hold with the changes I did. If still the new formatting of the question is unclear please let me know, sometimes it is hard to express things for a non native English speaker :) Thanks in advance!

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Reopened.

Polynomial equations of degree larger than 4 was put on hold as "unclear". OP has now edited the question so that it is clear (the introductory part is still a little rough, but the boldface part is quite clear, I think). Please consider voting to reopen.

[It's quite possible that the question is a duplicate of some earlier question, although no one has nominated a candidate. In any event, there is the option to reopen, then close as a duplicate, if warranted.]

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Hi I want to reopen my question, can you give me a tip on how I can improve it so it will qualify for this site.

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    $\begingroup$ Everything up the "Question" part is fine. It talks about some algorithm about factoring. However, the last few lines in the question section is problematic. It seems you are asking how to implement a function for that. If that is indeed the case, then it is about programming and not math, that will be off-topic for math.SE. If that is not the case, then you haven't told us the real "math" question. $\endgroup$ Jan 22, 2016 at 16:13
  • $\begingroup$ @achillehui Tnx, I edited the question to make it more clear. Please take a look in it now. $\endgroup$ Jan 23, 2016 at 10:46
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    $\begingroup$ This is better now, you get at least one reopen vote from me. $\endgroup$ Jan 23, 2016 at 11:43
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Undeleted, re-deleted, undeleted, reopened

This question from 2012 (!) was recently closed (and deleted) with the explanation, "Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it." I guess that those who voted to close it didn't notice that the user who posted it had not only included his thoughts on the problem and any attempts he made to solve it – he had actually posted a solution to the problem, based on some hints he was given. This kind of outcome should be celebrated, not closed and deleted over three years after the fact. Please consider voting to undelete.

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    $\begingroup$ The message does say "Please improve the question". The question is, indeed, not any good right now: bad grammar and spelling, not even a question, and, yes, no context. If I went through the question sheet on integrals my students have and asked and answered each and every single one of them with no explanation or motivation, would that be a good thing for the site? I don't think so. But if the question included some motivation, explanation about problems encountered and so on, now maybe that would be interesting... $\endgroup$ Feb 4, 2016 at 10:34
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    $\begingroup$ The reason it says "please improve the question" is that we don't want people using the site to get their work done for them without their putting in any of their own effort. OP has manifestly put considerable effort into answering the question, so the reason – the reason behind the reason, if you will – does not apply. $\endgroup$ Feb 4, 2016 at 10:38
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    $\begingroup$ Context is also required to make the question useful for future visitors. I hope that we can agree that a question without context is not (at least less) useful for future visitors? What I would like to understand is: if use to future visitors is not a concern... Then what's the point of keeping the question? OP got their answer. And if it is a concern, then the question clearly doesn't meet standards relative to context (which directly impacts its use for future visitors) and keeping it 1/ sends a bad signal ("it's okay to post subpar questions") and 2/ dilutes the good content of the site. $\endgroup$ Feb 4, 2016 at 11:13
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    $\begingroup$ (Due to a glitch my earlier comment didn't get posted apparently, but I also wanted to make the point that the age of the question is completely irrelevant. This ties into my previous point: OP got their answer 3 years ago. Now the only possible reason to keep this Q&A is for future visitors, and the age of the question has no impact whatsoever on that.) $\endgroup$ Feb 4, 2016 at 11:16
  • $\begingroup$ I voted to undelete it. I think Gerry has a point here. I will refrain from voting again, if the disagreement continues, because I don't think that's right. Nevertheless, the question does not look like your average HW question. It probably was a HW question, and we can all surely see that there should be solutions.But explicit examples are apparently not easy to come up with. None of the close-voters made suggestions to the OP what to try. $\endgroup$ Feb 4, 2016 at 16:11
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    $\begingroup$ I have edited the post, so that the information that OP's attempt is posted as an answer is more visible. (I suppose this can be a factor if somebody sees the question and deliberates whether the question should be deleted or should stay.) I was tempted to user first person (and simply copy the beginning of the answer), but since we already had some disagreement about this in the past, I chose to use more neutral language. If there are some other improvements which can be made, go ahead and edit the question further. $\endgroup$ Feb 4, 2016 at 16:28
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    $\begingroup$ You (everyone) know, my question wasn't rhetorical. I'm genuinely interested: why do you (everyone) want to keep this question? For what purpose? (FWIW, I don't think the added sentence makes the question better... @Jyrki says explicit examples are not easy to come by: why not include that information instead? Maybe showing that naive guesses don't work. This would show to everyone that the question is actually interesting, and not another iteration on "solve this system for me".) $\endgroup$ Feb 4, 2016 at 16:38
  • $\begingroup$ Four days later, and nobody has been able to answer my question. So I'm voting to delete again. Since a moderator undeleted the question when there was only one undelete vote, I think it's fair that only two users (plus me who had already voted) are enough to re-delete the question :) $\endgroup$ Feb 8, 2016 at 8:56
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    $\begingroup$ I vehemently disagree with your first comment. The reason it says "please improve the question" is so that we then have better (written) questions on the site, not to make an OP jump through hoops to earn the privilege to get an answer. $\endgroup$
    – quid Mod
    Feb 8, 2016 at 12:11
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    $\begingroup$ I removed the "meta" content from the post, and cast the last vote to reopen. $\endgroup$
    – quid Mod
    Feb 8, 2016 at 17:24
  • $\begingroup$ I think the reason we need to require context before questions are answered is because, after someone gets an answer, there is much less incentive to edit the question. In this case, the OP has been inactive since 2013, so asking for them to edit the question seems futile. We can and should look for more quality in questions than "here is a seemingly arbitrary list of requirements, can you cook up a function that meets them". $\endgroup$ Feb 9, 2016 at 15:22
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Reopened

I think If $f:[0,\infty)\to [0,\infty)$ and $f(x+y)=f(x)+f(y)$ then prove that $f(x)=ax$ should be reopened. It was closed as duplicate of a question about Cauchy's functional equation, but it is subtly different, and in my opinion both interesting and a little surprising. (No assumption on regularity, but instead demanding $f$ mapping positive reals to positive reals.)

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    $\begingroup$ It took 40 minutes to reopen this question... Maybe next time wait a few hours for the review queue to do its thing before posting here? :) $\endgroup$ Feb 15, 2016 at 15:26
  • $\begingroup$ @NajibIdrissi It wouldn't have hit the review queue. (The edit was made before the final vote to close.) $\endgroup$
    – mrf
    Feb 15, 2016 at 15:30
  • $\begingroup$ Your reopen vote put it in the review queue: math.stackexchange.com/review/reopen/577459 and three of the votes to reopen came from there... Anyway, what's done is done. $\endgroup$ Feb 15, 2016 at 15:32
  • $\begingroup$ Additionally, incorrect close votes were also discussed in chat. So users of that chatroom might have noticed it as well. (In fact, I planned to post reopen request there if the question is not reopened from the review.) $\endgroup$ Feb 15, 2016 at 15:42
  • $\begingroup$ But I should also say that I am glad that the question was reopened. (Just in case the comments sounded too negative.) $\endgroup$ Feb 16, 2016 at 6:55
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Reopened

I think How do I prove something without premises in a Fitch system? should be reopened.

The OP has been edited to provide the necessary information. Proofs without premises are hard to figure out in the Fitch system, and the answer to this quesiton would likely help later users.

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Undeleted

I'd like to see Volume enclosed by $(x^2+y^2+z^2)^2=x$ undeleted.

The question was deleted very soon after a comment by myself and a reasonable answer by Christian Blatter - though, that answer did offer a solution using an alternative approach. It certainly appears to be a frustrating case where an experienced user creates a temporary account to ask a question only to delete it as soon as they feel they understand it. The comments lead me to think that they don't actually understand it and I'd like to add an answer illustrating the correct approach.

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  • $\begingroup$ @DanielFischer Thank you! $\endgroup$ May 28, 2016 at 23:23
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Reopened

Please reopen

Prove that there are not two matrices 2x2 such that: $AB-BA=I_2$

The question was closed as a duplicate of the more general question:

$AB-BA=I$ having no solutions

The point is that for the $2\times 2$ one can simply write two general matrices $A$ and $B$ with entries and show that there are no solution to this. This method wouldn't work (at least not very well) for the general case. As such there is value in having the $2\times 2$ case as a separate question.

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    $\begingroup$ I believe the etiquette is to hold back on posting here until the post went through the queue. But other than that I can see the point in this case more than in some other recent examples. It's at least not impossible somebody would be asked the former without knowing about the trace. $\endgroup$
    – quid Mod
    Jun 23, 2016 at 20:09
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