# Requests for Reopen & Undeletion Votes (volume 07/2018 - today)

The purpose of this thread is to help focus the attention of the community on posts that may require reopen and undeletion votes. A request should be posted as an answer below (one request per answer).

Some guidelines:

• Please be polite, and respect the many different viewpoints in our diverse community. This goes for the person making the request as well as those commenting on it.

• There is a reopen queue. Please wait until a post has gone through this queue, before posting here. Notice that the first edit after the question was put on-hold pushes the question into reopen review queue, if the edit was done within 5 days of closure. So does a reopen vote. (If the review has already been finished, it is shown on the timeline of the question.) In doubt, wait 24 hours after the last substantive action.

• To inform readers of the current (and past) states of the targeted post, please add once the request resulted in some action the information Reopened or Undeleted at the start. (If it the action is undone, add this too, like Reopened, reclosed.)

• Do not only post a request, like "request reopening of ". Instead make a case for your concern. Yet keep in mind that it can be easier to get your request handled if you try to frame in a away that takes the feedback the post received into account in a positive way rather then seeking confrontation. Also, try to improve the post before posting here.

• In case of "small" requests, like one missing vote, it can make sense to ask in chat instead of posting here. The room CRUDE is a reasonable place for such requests. The same guidelines apply there.

Earlier versions of this thread that served as a model:

Undeleted, reopened

Please undelete and reopen this post: Evaluate this limit: $$\lim_{n \rightarrow \infty} \frac{n\sin n}{2n^2 - 1}$$

This post is by no means missing context. OP clearly stated at the beginning what he/she tried and where he/she got stuck. This post has also a detailed answer by a 50K+ user.

• It might be worth noting that unfortunately that so-called detailed answer completely ignores the provided context, in that sense it's a rather poor answer, but arguably that's tangential. I'd tend to agree that this question does show reasonable context. If we take the context into account, likely it's a dupe. – quid Sep 23 '19 at 15:52
• Instead of saying "what goes wrong with my thoughts" or "how can I go on with my original approach", OP explicitly stated that "Any help will be appreciated". And @Clement C. helped this user by directly giving an argument. Not a poor answer, and there have four people considering it good. This post is an extremely poor choice for deletion. – Jack Sep 23 '19 at 15:58
• quid does make a fair point that an answer showing how OP could go on with the original approach may be more useful for the asker. One could add such an answer after this post is reopened. – Jack Sep 23 '19 at 16:06

Undeleted, reopened

Please undelete and reopen this post:

How can one use the direct comparison test for $$S=\sum_{k=1}^{\infty}{\frac{1}{\sqrt{k}+10k}}$$?

Even in the very first version of the post, OP states his/her thoughts and difficulties he/she has. This post is NOT missing context. And it is NOT a duplicate of any other question.

• Because we already have many questions where divergence of a series is deduced from a comparison with the harmonic series, this is bound to be a duplicate dozens of times over. Therefore the question should also be closed as too localized (not adding anything new to the site, and only helping the asker do their homework). Missing context is the best proxy we currently have, so if reopened I will vote to reclose and redelete. – Jyrki Lahtonen Sep 30 '19 at 4:53
• @JyrkiLahtonen Maybe I should have trie to search a bit more, but by a quick search I only found this: Calculus II: Comparison Test for Divergence $\sum\limits_{n=1}^{\infty}\frac{1}{n+\sqrt{n}}$. (All I am saying that I am unable to confirm that there are dozens of posts which are close to duplicates. Although I agree that when I saw the question, I expected that there should be many similar questions.) – Martin Sleziak Sep 30 '19 at 8:09
• @MartinSleziak It is one of the standard series to use a comparison test with :-) Anyway, when the question is a (near-) duplicate IMO showing effort/thoughts is NOT SUFFICIENT to stop closure/deletion. The questions should have wider interest, and the context should demonstrate that. – Jyrki Lahtonen Sep 30 '19 at 9:59
• Mathematics Stack Exchange is a question and answer site for people studying math at ANY level and professionals in related fields. How many questions a student asks are not supposed to be "standard"?! And is any one of the four mentioned in the first comment not standard? – Jack Sep 30 '19 at 11:59
• @Jack Your comment about MSE being for questions at any level is a red herring---the question was not closed because of its level. The question is a standard question which occurs (in one form or another) in many elementary texts on calculus. Moreover, it is a question which already has an answer on MSE. What new, valuable information does this particular question add to MSE which isn't already on the site? – Xander Henderson Sep 30 '19 at 20:18
• How many questions a student asks are not supposed to be "standard"?! @Jack, not very many. The same applies to StackOverflow. Which is exactly why Jeff Atwood wrote that a new asker should spend 98% of their time on StackExchange searching. Getting more and more questions does not improve the site, and is not necessary for its success any longer. On occasion it is quite the opposite. – Jyrki Lahtonen Oct 1 '19 at 14:06

Undeleted, deleted, undeleted, reopened, closed as duplicate, deleted, undeleted, deleted, undeleted

Please consider to undelete this question.

The OP brings some background about the problem and is just trying to find an easy solution. The one provided by me looks quite unknown (as it seems from the comments and the answers) thus I think it can be of future help if the question is undeleted.

• It's good form to disclose that one has an answer on the post oneself. – quid Aug 15 '19 at 21:00
• This question is a duplicate of many other questions on MSE. While I don't think that it is worth keeping (it brings nothing new to the table), if it is going to be kept, it should be closed as a duplicate. I left comments indicating a couple of potential dupe targets. – Xander Henderson Aug 17 '19 at 15:05
• On the contrary I believe it brings something new to the table. My solution is different than any other from all the linked posts. – Zacky Aug 19 '19 at 20:24
• @Zacky In that case your answer will stand its ground as an answer to the duplicate target as well, and you might consider relocating it there! Just by posting a new answer, the thread of your choice will be bumped to the front page, meaning that many viewers will see it and be able to vote it. <- This could be my template reply to all the users who are sad about a deletion of a duplicate. They can easily save their work this way! – Jyrki Lahtonen Aug 30 '19 at 18:19
• "Partial fraction without defraction for an integral" What the heck does that mean? Is defraction really a word? Why has no one edited that title to something intelligible? – Gerry Myerson Aug 30 '19 at 23:00
• @GerryMyerson I think that no one had edited the title into something intelligible because no one actually knows what the asker intended. That is part of the problem with the question (aside from the fact that it is a duplicate). – Xander Henderson Aug 31 '19 at 14:17
• @Zacky Honestly, I think that Jyrki's advice is good advice. Indeed, I think that your answer would be a better fit for one of the other questions, if for no other reason than the current question specifically asks about partial fraction decomposition, while the others don't. Your answer would be a better fit for a different question. – Xander Henderson Aug 31 '19 at 14:18
• @XanderHenderson something looks off. You said that it brings nothing new to the table and it's not worth to be kept, you even ranted on how my answer isn't a "pedagogical". Are you sure that you honestly believe that is a good advice? – Zacky Sep 1 '19 at 8:52
• I also wrote in my pre-edit for OP: "Since this is just for your training, here's a more different approach for it. If it doesn't fit for you, I will delete it (it doesn't use any partial fractions)", when OP commented I think I received a positive feedback about it from OP.// Indeed it doesn't answer the exact question, but another answer (which got accepted by OP) shows a way with partial fractions. I only posted my answer after I saw it, and after the comments (from some high-rep users) who encouraged OP to not look for a better way? – Zacky Sep 1 '19 at 8:58

Reopened, undeleted, closed, reopened

Please consider undeleting this question where I also provided an answer: Integrating $$\int_0^1\frac{x\ln (1+x)}{1+x^2}dx$$ with restricted techniques.

The OP from clearly provides background on how the integral appeared, although it was some kind of homework now it can be useful for others too.

• It's good form to disclose that one has an answer on the post oneself. – quid Aug 15 '19 at 20:59
• Hope I don't sound rude, but I don't understand what you wrote even with translate. Did you meant: It's a good thing to mention that I posted an answer to the linked question? – Zacky Aug 15 '19 at 21:07
• Yes. You should mention this. It makes clear that you are not a neutral third party. You have a personal interest in the undeletion. This does not disqualify you from making the proposal. But it is good form to be upfront about it. – quid Aug 15 '19 at 21:12

I believe A paper in English? should be reopened (despite the bad title). It asks how to locate a a mathematical paper but was closed as “not about mathematics”. Reference requests are allowed – this is not a reference request, but the intention behind seeking a reference and seeking to locate a known reference is essentially the same; I see no reason why one should have its own tag () and the other should be off topic.

• The question is though is the question to locate the reference or is the question to get the document delivered. The former is maybe borderline on-topic, the later is off-topic, and indeed not about mathematics. – quid Apr 26 at 10:01
• It is also not clear from the question whether the OP looks for the original or they want to know about existence of English translation. The tags (reference-request) and (translation-request) might be suitable there. – Martin Sleziak Apr 26 at 10:02
• @quid: How do you mean, "delivered"? Do you mean the question could be interpreted as asking for someone to send them the paper? I would take "seeking" to mean that they would like someone to point them to where to find it (in an archive, in a collection, ...). – joriki Apr 26 at 10:05
• Yes, that's what I mean. (If "send" includes provide a link to a download.) Having looked at the edit history I agree with @MartinSleziak that the intent of the question is rather unclear. Maybe it could be on-topic but as is it's unclear what even is asked. – quid Apr 26 at 10:10
• @quid: But what's off-topic about seeking a link where one could download a paper? How is a link different from a reference? They're both resource locators. Where else would a person be on-topic asking where to find a math paper if not here? – joriki Apr 26 at 10:12
• @quid: I posted that before seeing the edit to your comment. If it's unclear, it should be clarified, or at most closed as unclear; then the OP can clarify it and get it reopened. Currently the close reason is telling the OP that questions about locating papers (or translations thereof) are not welcome here, which would be news to me. – joriki Apr 26 at 10:17
• The question is what does "locating" mean in your comment. Typically with an exact reference it is trivial to locate a version of the document. Yet to access them might cost time and/or money, and helping with the last step is not about mathematics. – quid Apr 26 at 10:24
• @quid: What are you basing this on? I can't find any related policies. You're dividing locating resources into steps and defining some of the steps as off topic and others not. But finding a way to download a paper somewhere is just as much or little about mathematics as finding a classical reference to it. Being trivial is different from being off-topic. Lots of uncontroversially on-topic mathematical questions on the site are trivial. – joriki Apr 26 at 10:30
• Common sense. But actually it also did come up I think. And to elaborate on the "common sense" providing service to access documents given a reference is a service that is provided. The people that provide it are, eg, librarians, often without any particular competence in the subject of the paper but instead in well providing access to the literature. – quid Apr 26 at 10:35
• @quid: OK, that's a criterion that makes sense to me. So the question would be off-topic if it asks for a service that doesn't benefit from mathematical expertise (and could in fact perhaps be performed better by a librarian than a mathematician), but would be on-topic if if benefits from mathematical expertise? That distinction would not always be clear-cut (mathematicians probably know their way around some online math resources better than librarians), but it would be a sensible explication of what it means for a reference request to be "about mathematics". – joriki Apr 26 at 10:39
• Yes it is not always clear cut. Regarding the distinction it is relevant to know what do you mean by "finding a classical reference"? The word "finding" specifically. If I have a mathematical result and I want to find a reference for it, that is, I want to learn about a book or paper that contains it, then this is on-topic. If I want to read chapter 3 of Hardy and Wright "Introduction to the theory of numbers" and I ask where to find it, then this is off-topic. – quid Apr 26 at 10:42
• @quid: That last case is clear-cut because it clearly doesn't require mathematical expertise to locate that book. But with a little-known article in a little-known journal, it's less obvious whether mathematicians might have a better chance of knowing how to find it than others. – joriki Apr 26 at 10:50
• With exact bibliographic data I don't really see that Where it starts to become interesting is when the bib data is incomplete or unclear and one basically needs to be able to infer what it should be. Anyway, the question as is, seems at least unclear and therefore should be closed; if it is clarified it possibly could be reopened. If you care, you can guide the user in revising their post. (No it is not necessary to undo the closure to close as "unclear " instead.) – quid Apr 26 at 11:04
• @quid: What are you basing the last sentence on? – joriki Apr 26 at 11:05
• Since you care about the old days, certainly you still recall "too localized". – quid Apr 26 at 11:41

REOPENED

I request to reopen Why does $f(z) = z^n$ have no antiderivative only for $n=-1$? It was closed as a duplicate of Antiderivative 1/z on C.

I disagree that it is a duplicate. The first question was a soft question and the second was a hard question. OP wasn't literally asking for a proof that $$1/z$$ doesn't have an antiderivative. He was asking what makes $$n=-1$$ "special". This is a different question. One question is soft and the other is hard.

Please consider undeleting and reopening the post (question & answer both): Why integral of $$dx$$ is not $$∫dxdx$$.

This is a basic question came to OP's mind on the subject. There are a lot of people who have the same doubt about the fact. It will be very much helpful for those. Also my answer was accepted by OP and also being appreciated by the other members on this site. I think those question and answer are suitable for the site. I strongly recommend to undelete the post.

Undeleted, deleted, undeleted, deleted, undeleted, reopened, closed, locked, unlocked, deleted, undeleted, locked (for historical significance).

I think this question should be reopened. Thank you!

The original poster looked for the possibility to use the substitution $$t=\tan\frac{x}{2}$$ and he got a number of solutions.

By the way, the first comment of Lord Shark the Unknown is nothing. At the least, it gives a very complicated solution which the topic starter tried to apply but without success.

• Quote from the question: "I tried tangent half-angle substitution but it became too complicated." First comment on main: "Try half-angle substitution, but with a little more determination. – Lord Shark the Unknown Aug 9 at 9:54" Answer by the OP: [DNE]. – Did Sep 8 '18 at 22:17
• "By the way, the first comment of Lord Shark the Unknown it's nothing" Pfff... – Did Sep 8 '18 at 22:44
• And now there's a rollback war. – Gerry Myerson Oct 1 '18 at 12:35
• This question feels like a joke that everyone gets but me. (1) Why is this question particularly bad? The OP said they tried the obvious thing but to no avail. Presumably they made a mistake, but so what? That doesn't invalidate the question. (2) Why is there such a fierce edit/close/delete war? The question is 2 months old - let it rest!!! – user1729 Oct 12 '18 at 17:11
• Rollback to Revision 9 by Alex Francisco, rollback to revision 10 by Michael Rozenberg, rollback to 9 by Alex, back to 12 by Michael, to 9 by Alex, to 14 by Michael, to 9 by Alex, to 16 by Michael. Crazy! – Gerry Myerson Oct 15 '18 at 22:44
• This is just sorta embarrassing to watch at this point. And it's already back to 2 undelete votes, so I expect another full cycle in the next day. – user296602 Nov 27 '18 at 18:28

Undeleted, reopened

I humbly request undeletion and reopening of this question, if you see fit to do so, because

a) reasons for closing should be derived from the question itself and not from speculation about the skills of the asker.

b) the given reasons for closing are incorrect - while the question sails close to an open problem, it asks a different but related question - it asks if the open problem (which relates to a series of polynomials) can be extended to its limit point.

c) the time from entering the reopen queue to deletion was less than two hours, denying any who might have been interested in its reopening the opportunity to declare the same.

d) moreover, I think others will find the question and any prospective answers of interest and value.

• The time from entering the reopen queue to deletion may have been short, but the question had been on hold for five days already. As for the close reasons, I'll note that 2 of the close voters did not use "not math". I think that personnally I would have probably voted to close as unclear what you're asking, because on a first reading I honestly had no idea what you were talking about. – Arnaud D. Dec 1 '18 at 12:43
• @ArnaudD. Yes, but the reopen request followed an edit which increased focus on the actual question and removed the motivation for it, when I believe the question's motivation was almost certainly the cause for the down votes and closure in the first place, rather than the question itself which stands alone. – samerivertwice Dec 1 '18 at 12:47
• By the way, I think the most recent edit on your question (post-deletion) already makes the question more interesting. It only consists of adding a Wikipedia link, but that link already explains some of the context better than your question (for example, I hadn't realized that you were talking about polynomial bijections $\mathbb{N}^k \to\mathbb{N}$, but maybe that's just me). – Arnaud D. Dec 1 '18 at 12:57
• For what it's worth, the reopen review was completed before the deletion, as one can see here. – Arnaud D. Dec 1 '18 at 13:15
• @ArnaudD. good point, although predominantly the same users. Is there a better review link that shows timings etc.? I thought I saw one before but can never re-find it. – samerivertwice Dec 1 '18 at 13:39
• There's the timeline, but I don't know if it is as detailed as you'd want. (By the way, there's another question about how to find it). – Arnaud D. Dec 1 '18 at 13:44
• Setting aside all other issues, there are some obvious (and, I think, easily correctible) errors in your question's key equation, stating the F-P conjecture: the right hand side has no $y$ in it, and the index of summation $n$ appears nowhere in the expression being summed. I'm pretty sure you want the summation to go from $k=1$ to $n$, not $n=1$ to $k$, with $f_n(x_1,\ldots,x_n)$ on the left hand side, not $f_k(y)$. – Barry Cipra Dec 1 '18 at 15:28
• @BarryCipra thank-you. I think I intended $y$ to be the set $\{x_1,x_2,\ldots x_k\}$ and yes, I agree I appear to have exchanged an $n$ with a $k$ but alas no edits are allowed on a deleted post so I can't correct it :( – samerivertwice Dec 1 '18 at 18:17
• @RobertFrost That's surprising. In any case, I've just done the correction. – Arnaud D. Dec 1 '18 at 18:57
• @ArnaudD. Thanks and you even got the $f_n$ I thought might get missed. – samerivertwice Dec 1 '18 at 19:00
• What do you mean by "timings"? The time of the review is there exactly. As usual, hover over the time stamp to get a resolution to the second. – quid Dec 1 '18 at 23:44
• @quid thank-you. That probably covers it although I can only see a deleted post on desktop so I'll have to check later – samerivertwice Dec 2 '18 at 4:07
• @ArnaudD. Thank-you for the edit. A reopen vote would be greatly appreciated (only if you think it appropriate). Else the deleters will reverse the undeleters! – samerivertwice Dec 3 '18 at 10:39

Can this answer (on permutation groups) be undeleted:

https://math.stackexchange.com/a/3197094/10513

It was deleted for not providing an answer to the question. However, it gives a decent hint which leads to a solution. The hint is essentially "consider odd vs. even numbers". This was made formal in the accepted answer, which used mod 2.

• I think it's a bit of a stretch from that hint to the accepted answer. The hint ought to be a comment (in my opinion). – Gerry Myerson Apr 29 '19 at 12:50
• @GerryMyerson Hints are a grey area. But I don't think deleting them because they are "a bit of a stretch" is the right thing to do. – user1729 Apr 29 '19 at 12:55
• It would have been better, had a moderator converted the "answer" to a comment. You could try flagging the question for moderator attention, and making that suggestion. – Gerry Myerson Apr 29 '19 at 12:59
• I flagged it beforehand, and was told to post my request here (admittedly i didn't suggest making it into a comment) – user1729 Apr 29 '19 at 13:19
• OK, now you know what to do. – Gerry Myerson Apr 29 '19 at 13:22

Undeleted, Merged and then deleted

Please reopen https://math.stackexchange.com/q/3208119/290189 since OP has self-deleted his/her own post after getting an answer. The community should have been given enough time to vote.

• You can't reopen a question that isn't closed, GNU. Now it has been closed, as a duplicate, but I don't see how $x^y+y^x=(xy)^2-19$ is a duplicate of $x^y-y^x=xy^2-19$. So, I'm flagging for moderator attention. – Gerry Myerson Apr 30 '19 at 13:47
• @GerryMyerson By the moment I posted this answer, I did voted to close this question as missing context. I did notice the difference between the two. Thanks for reminding me. – GNUSupporter 8964民主女神 地下教會 Apr 30 '19 at 13:52
• @GerryMyerson a problem is that the original version of the question was incorrect. A third party edited it to this version, while main OP had re-asked a different version. – quid Apr 30 '19 at 15:32
• I deleted it after the merge now. This did not work out ideally, but it's near impossible to fix. If somebody wants that version of the question on the site I recommend to ask it anew. – quid May 2 '19 at 18:17

Please unmark the duplicate of this question. I have clearly said that my question has nothing to do with duplicate one. I am asking totally different thing and the duplicate question's answer does not help me at all. It is also an unique question which follows m previous question.

• I don't believe the relationship between the Questions is quite so simple as one "has nothing to do with" the other. Both involve intersections between two spherical caps, although you might not have visualized your problem in this way. There might still be a further problem in stating the area in terms of how you parameterized the spherical region, I grant, but it would be worth understanding the solution of the proposed duplicate to try restating the area given there in your terms. – hardmath Jun 6 '19 at 17:11

Undeleted, closed, deleted, undeleted, redeleted

I nominate Solve the recurrence $$\sqrt {x_n} − 5 \sqrt {x _{n−1} }+ 6\sqrt {x_{n−2}} = 0$$ for undeletion because OP has self-deleted his post shortly after receiving an answer. That's rude to the answerer.

• I agree that the question should not have been deleted by the original asker, and would have voted to undelete had I seen this before the question was undeleted. That being said, it is a pretty low quality question, and would like to now nominate it for closure and (if it is not improved) eventual deletion. – Xander Henderson Nov 12 '18 at 23:26
• @XanderHenderson Agreed and updated the status of my answer. – GNUSupporter 8964民主女神 地下教會 Nov 13 '18 at 1:27
• It is inconceivable this question is undeleted. Even the answer is pretty low-quality. – YuiTo Cheng Jun 26 '19 at 4:53
• I find that revision history really surprising : one (now removed) user voted to undelete and then close the question, OP initially self-deleted the question but 5 days later voted to undelete after the second deletion, and now you've voted to undelete and then redelete the day after. Pardon my French, but WTF? – Arnaud D. Jun 27 '19 at 9:31

Undeleted, reopened

Please consider undeleting and reopening this post:

where OP gave his/her thoughts:

Honestly I have no idea about how to approach this problem. I tried the expansion of $$\sin x$$ on the left hand side and then expand $$\cos x$$ on the right but end up with a mess. Then again $$\cos x=(\sin x)'$$, but by converting each term on the right hand side into derivative of sine does not give any sensible identity to draw out something. Really out of ideas on this one. Is there any way to do this? Please give me some hints. Thanks for your time.

Undeleted, deleted, undeleted, reopened, closed as duplicate (mod)

Please consider undeleting this post: 2011 IMC Section A Problem 3

This is not an ongoing contest problem. The answer is known online. @Aqua's answer (with 14 net upvotes) is a useful one.

• Poorly explained answer. Had downvoted it back then. – quid Jul 6 '19 at 19:53
• That was a really bad excuse for deletion. – Jack Jul 6 '19 at 21:09
• Since I did not delete it, I don't need any excuse (and I doubt the delete-voters where aware of my voting back then). Please do not write comments that might suggest otherwise as not everybody can check it easily. – quid Jul 6 '19 at 22:20

Undeleted, deleted, undeleted, deleted, undeleted, reopened

Please consider casting the final undelete vote and reopening this post:
Evaluate $$1+2-3-4+5+6-7-8+\cdots+50.$$

This question is well written and with effort. It has very well written answers, one of which gives a generalization of the problem.

Deleted, undeleted, deleted.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

The close notice for How to prove that the permanent of a doubly stochastic matrix is positive? says, "Add details and clarify the problem being solved. This will help others answer the question."

The problem being solved is perfectly clear (to anyone who knows what a doubly stochastic matrix is, and what the permanent of a matrix is), and others have not needed any help answering the question, so the close notice strikes me as invalid. Please consider voting to reopen this question.

• Possibly you did not get the memo: math.meta.stackexchange.com/questions/31147/… – quid Mar 5 at 15:31
• @quid if a user is going to vote to close a question, and if none of the currently available close reasons applies, I reckon the user really ought to leave a comment explaining how the question doesn't measure up. What was done for this question, even if OP clicked to see the further information on "add details and clarify," gives OP no clue as to what to do. Heck, it gives me no idea as to what the close-voters actually had in mind. Let's reopen the question, and give the close-voters the chance to make their case. – Gerry Myerson Mar 5 at 21:30
• Maybe that would have been better but there is only so much time and it fits well enough. As for you, it is hard to believe that you actually had not understood what the matter was (as opposed to disagreeing). Either way, I hope you keep the information obtained here in mind going forward. – quid Mar 6 at 4:36

Reopened

Please consider reopening Indian Mathematicians. The question was closed as off-topic, apparently because of the existence of the History of Science and Mathematics site.

As I pointed out in a comment, first, questions about history of mathematics are on-topic here. The tag has almost two thousand questions and a decent amount of recent activity.

Second, the quality of many interactions at the HSM site is sadly rather poor (I was very enthusiastic about it when it started, so this poor quality quite bothers me), and it may end up being a disservice to send this question there.

(I would actually love to see the quality at that site to raise uniformly, and hope it happens relatively soon. But that is another matter.)

• I think at least the formulation of the question should be clarified a bit before it is reopened. The first answerer already misunderstood it. – quid Aug 30 '18 at 21:11
• Fair enough. I'll do a slight edit. – Andrés E. Caicedo Aug 30 '18 at 21:16
• I had decided to do an edit myself. Sorry for the confusion. I'll check back in one or two hours. If it's still closed then I'll give the final vote(s). This allows also for further editing. – quid Aug 30 '18 at 21:19
• No problem. I gave the edit a second pass. (And thank you.) – Andrés E. Caicedo Aug 30 '18 at 21:22

Undeleted, deleted, undeleted, reopened

Please undelete On a colon ideal in the polynomial ring $\mathbb R[x,y]$ because this question has got a score of 2 after OP included his/her own thoughts on the problem. This algebraic geometry question might add value to the main site.

• Selfdeleted without answer. No need to undelete. – quid Feb 25 '19 at 9:16

Undeleted, redeleted, re-undeleted, redeleted, undeleted

Please consider undeleting the question: The asymptotic behavior of $$n\ln n -n$$

• Well, I'd consider something in the spirit of the comment as the best answer there. Anyway given the complete lack of context it's hard to know which type of answer would be useful, whence the voluminous list. Also all standard likely on the site in similar form tens if not hundreds of times. At least one answerer made the effort to link it to related posts. – quid Jun 6 '19 at 22:37
• Redeleted (6/17/19) by a same group of users. One initiated three times the delete votes and one voted three times to delete this post. – Jack Jun 17 '19 at 22:01
• Probably I should have refrained of posting an answer there - however at the time when I posted there were some answers already and they seemed (to me) more complicated than needed. I have also included links to some other questions - you can see that similar questions are on the site (and they have similar answers). I will also say that when posting the answer I was fully aware that the question is likely to be closed/deleted. – Martin Sleziak Jun 18 '19 at 17:35
• @MartinSleziak: I believe "closing" is enough for this particular post. I strongly disagree with the deletion considering the high qualities of answers. Such good contents will be useful for future readers (this is closed post is not some stupid trivial textbook exercise) and should be preserved on the site. – Jack Jun 28 '19 at 12:22
• @Jack Well, several discussions here on meta suggest that when deciding about closing (and probably also deleting), most users take into account mainly quality of the question (and do not look at answers). Since you have mentioned that you care about preserving context, I should specifically point out that my answer contains some links to other posts which use Stol-Cesaro. Will Jagy reposted his answer in another thread. (For obvious reasons, I might be a bit biased in this particular case.) – Martin Sleziak Jul 6 '19 at 17:55

Please consider undeleting this post: Integral $$\int_{0}^{2\pi} \ln (2\sin(\frac{x}{2}))dx$$

Whether the asker should articulate more details in "I've tried some substitutions" could be debatable for reopening the post; I do not think it should be deleted. There have been two answers, one of which has 11 upvotes.

• The question was on hold for a week without modification before it was deleted. The answers are fine, but standard, and don't rise to the level of exceptional. I see no reason to undelete this question. The asker clearly got what they wanted, and I don't see that question providing any lasting value to the site. – Xander Henderson Jul 2 '19 at 0:46
• The lasting value to the site, like many other posts, is that there are two good answers to a tricky calculus question, which is not only useful for the asker but also future readers. – Jack Jul 2 '19 at 1:48
• The first part of your reply to me does not contradict what I said: you say that there are two good answers, I said that there are no exceptional answers. As to use to future readers: I disagree. This is a specific integral which can be analyzed using relatively standard techniques. The question itself is not terribly searchable (it is only going to come up if someone wants to deal with that specific integral (e.g. they are assigned the same problem as a homework exercise, and are trying to cheat), and the answers are not of any general interest (they are standard, but not general). – Xander Henderson Jul 2 '19 at 1:53
• Disagree. "This is a specific integral which can be analyzed using relatively standard techniques. ... the answers are not of any general interest " does not justify the deletion. MSE is not MO: most, if not all, of questions here "can be analyzed using relatively standard techniques". For instance, this recent question that has two good answers, the accepted one written in detail nicely by you, is a rather "standard" one. I would certainly not vote to delete such posts. (In case of any possible confusion: this is NOT sarcasm.) – Jack Jul 2 '19 at 2:48
• It is funny that you pick that example. I downvoted that question, and voted to close it. It was not closed, and the other answers were, in my opinion poor answers (as they failed to address the key point, which is that an induction proof is needed somewhere). If the question is not going to be closed and deleted, it should at least have a correct answer. I would still be happy to see that question closed, and would not object to its deletion---my answer is nothing special, and doesn't (IMO) rise to the level of exceptional. – Xander Henderson Jul 2 '19 at 2:56
• Moreover, applying standard results to a specific problem is very different from demonstrating the correctness of standard results then leaving it to the reader to apply that result to their specific problem. – Xander Henderson Jul 2 '19 at 3:01
• Well, (1) I have done my proposal for undeletion. Readers can make their own decisions. (2) I will object strongly the post I just mentioned being deleted, considering the quality of your exposition and egreg's good answer. (How do you find the review history by the way?) (3) ... have to leave now. – Jack Jul 2 '19 at 3:13
• Probably a duplicate of one or more of math.stackexchange.com/questions/815762/… and math.stackexchange.com/questions/889902/… and math.stackexchange.com/questions/679233/… and math.stackexchange.com/questions/2656431/… and also comes up in any question containing the name "Clausen". – Gerry Myerson Jul 2 '19 at 3:20
• @Jack To find the review history I go to the timeline of the post and then click on the link to the review event there. I don't know if there's a quicker way. – Brahadeesh Jul 2 '19 at 6:41
• @GerryMyerson: having read your links one by one, I would probably not called the post a duplicate of those, although they are related to the Clausen function. (Never known this before, thanks for mentioning it.) – Jack Jul 2 '19 at 11:47
• @Brahadeesh: Thanks for that. One can indeed use math.stackexchange.com/posts/3143084/timeline – Jack Jul 2 '19 at 11:56
• It's funny how those who voted to close/ delete are here on this site for a while, and even claim to know that the question is easily searchable. Yet, instead of trying to mark it as duplicate, they simply delete it. Also it's quite bold for a single group of people (CRUDE users) to decide that it has no value for this site. – Zacky Jul 22 '19 at 8:50
• @XanderHenderson I wrote above in the third person since you're not the only one who believes that, but since you commented it here, can you please tell me why haven't you tried to mark it as duplicate (if it's easily searchable) and simply decided to remove the content? (maybe there's a reason that I'm missing). – Zacky Jul 22 '19 at 8:58
• -> Before voting to delete, please check whether there are any good answers; if so, then the question should be flagged for moderator attention as a potential merge candidate. We don't like to lose great answers!. And the answers provided there are definetly good. Thus those who deleted it violated the "rule" that I copy-pasted. // A little off-topic, but I hope that you are aware that who asked the question couldn't care less if the question is deleted since he/she already took the informatio needed. Thus by deleting the question, it even helps that user instead of penalizing them. – Zacky Jul 22 '19 at 14:00
• -> Of course, the posts around here aren't only for those who asked, but for the whole community. I fail to see why there ins't a way to penalize the users (for example a "question ban" if the questions previously posted are bad), but instead the decision that CRUDE users took is to penalize the whole community by erasing good content. Anyway, it's pointless if I type here in the comments, soon I will try to make a meta post about something related to this. Thanks for your time and have a nice day! – Zacky Jul 22 '19 at 14:12

Undeleted

Please undeleting this post: How to prove that $$\frac{e-1}{2e} \le \int_0^1 \frac{e^{-x}}{1+x}dx \le \ln 2$$

OP did have his/her own attempt. This is not a zero-effort trivial question, which should not be deleted.

Please undelete this post: $$n^4 + 4^n$$ is a not a prime

OP clearly states context for his/her question:

This question appeared in the undergrad entrance exam of the Indian Statistical institute.

When $$n$$ is even the proof is simple. For $$𝑛=2𝑚+1$$ I am utterly stuck.

True that this is a duplicate of some previous posts, but duplicate can be useful. Moreover, it is not necessarily easy at all to identify this question as a duplicate:

• The useful searching engine Approach0 is NOT well known, neither it is mentioned on the page of help center of MSE.
• A quick search of the expression $$n^4+4^n$$ on the MSE searching box returns something irrelevant:
• If one posts this as a new question: the "similar questions" box does not show any one of the duplicate:

"Questions that are extremely off topic, or of very low quality, may be removed at the discretion of the community and moderators." This 5 upvoted one with three answers is not.

• At some point, every math student really ought to be shown the factorization of $x^4+4$. – Gerry Myerson Sep 26 '19 at 7:47
• This is an umpteenth reincarnation. Even in 2013 when André Nicolas answered it we had already covered it many times. Also, while duplicates were seen as somewhat useful back in 2013 (when Jeff Atwood's strangedupe comment was often cited), the site has moved on since. The most recent word from above (don't remember for sure whether it is from JA or the current CEO Joel Spolsky) reads: Over time duplicates become vast landmine fields. – Jyrki Lahtonen Sep 26 '19 at 16:24
• The sentence ("... landmine fields") Jyrki mentioned is from this article by Jeff Atwood. That one is specifically talk about StackOverflow, which is sort of the counterpart of MathOverflow. (cont.) – Jack Sep 26 '19 at 17:18
• Jeff explicitly writes in that article the following : But I will point out that there is plenty of precedent on the Stack Exchange network for splitting sites into "expert" and "beginner" areas with slightly different rulesets. We've seen this for Math vs. MathOverflow, English vs. English Learners, Unix vs. Ubuntu... perhaps it's time for a more beginner focused Stack Overflow where duplicates are less frowned upon, and conversational rules are a bit more lenient? – Jack Sep 26 '19 at 17:18
• I am not following SO much at all, but what little I have seen of it it is nowhere near the level of sophistication of MathOverflow (admittedly my observations are likely biased). But I would support walling off lower level math (like freshman and below) to a Math Learner site. – Jyrki Lahtonen Sep 26 '19 at 21:49
• I don't get what's the contradiction even. Certainly duplicates will happen, some will be caught other won't be caught. Of those that do get caught we'll keep some that seems relevant as "sign posts" and we remove the rest without much ado (either way). Why would we want to keep them? – quid Sep 26 '19 at 22:26
• On search, searching n^4 + 4^n for works like a charm Why would one use strange spacing, or in any case just check one version, and include the completely irrelevant dollars? – quid Sep 26 '19 at 22:34
• @quid: your linked search of n^4 + 4^n , which does return a duplicate result, uses "strange spacing". If one searches n^4+4^n without the spacing before and after the plus sign, one would not see the charm. – Jack Sep 27 '19 at 0:04
• The answers are all dupes of answers given many times in the past. This FAQ occurs many times every year. There is no need to keep adding duplicate answers every time it reoccurs. Doing so makes it difficult if not impossible for users to locate the most enlightening answers. – Gone Sep 27 '19 at 0:45
• @Jack I forgot to add that Theoretical Computer Science is the StackOverflow analogue of MathOverflow. Don't get mislead by the inclusion of the word Overflow. If SO walls off a learners' site, we should do the same. – Jyrki Lahtonen Sep 27 '19 at 3:42
• And also, the voting already gives low level math an unhealthy advantage in the gamification aspects of the site. Simply because users are obviously not going to (and should not) vote on material over their head. You wanting to be more lenient about low level duplicates would exacerbate an already serious problem. – Jyrki Lahtonen Sep 27 '19 at 3:45
• Well, let's forget about which spacing is strange or not. One might learn the lesson that one should search for both variations. I'd still maintain that the spacing there is the more natural way to type it. But I am glad that you seem to agree now that the dollars are useless. // And even if it was completely unnatural it is the very spacing that was used in that post that you want undel too. Thus at least that user likely would have used the same spacing if they had searched and keeping this as a dupe would not even help future searches (except maybe via answer, but then merge could do). – quid Sep 27 '19 at 8:44

Reopened

I propose reopening Has Gödel’s second incompleteness theorem been formalized?

The question simply asks whether there is a computer-verified version of the proof of the theorem. This strikes me as a perfectly reasonable mathematical question, and I can't see why anyone would vote to close it, much less delete it (there are currently two votes to delete).

Full disclosure: I posted an answer (the only answer) to the question, which OP has accepted. The answer attracted a downvote – I'm guessing that was done to make it easier to close and delete the question, since I can't see what objection anyone could have to the answer.

I nominate https://math.meta.stackexchange.com/q/29570/290189 to be undeleted because this meta question contains moderator's feedback to deal with serial downvotes.

• What information is in that post that is not in the FAQ? Also as it was auto-delered it'd be redeleted. – quid Feb 9 '19 at 12:46
• @quid That post provides real examples of questions being serial downvoted. – GNUSupporter 8964民主女神 地下教會 Feb 9 '19 at 12:48
• How is that useful? – quid Feb 9 '19 at 13:14

Deleted, undeleted, redeleted and merged with another question

I request the undeletion of this question (on denesting $$\sqrt{a-b\sqrt{c}}\,)$$

Reason: I asked this question, and it turned out to be a duplicate. However, this doesn't deserve deletion as this question contains a crucial formula that is a very useful one. It is very useful to me, and it is sad for me to see that the community is not able to access it anymore. Please undelete this question.

• The answers there are dupes of the answers in the linked dupe thread (and many others - this is a FAQ). I see no reason to further such rampant duplication. – Gone Mar 1 '19 at 1:03
• @BillDubuque there is a useful formula. Perhaps if you can transfer the answer to the other question?? I find it really useful. – Max0815 Mar 1 '19 at 1:04
• That well-known formula is already in Frank's answer in the dupe (and many, many other answers here). Moreover, he derives if instead of pulling it out of a hat as in the answer in your thread. – Gone Mar 1 '19 at 1:06
• @BillDubuque how is it derived? even if so, the other answer on my question has a basic method that is not included in the other question. – Max0815 Mar 1 '19 at 1:08
• @BillDubuque oh, right. – Max0815 Mar 1 '19 at 1:11
• I don't understand why this question was deleted. It seems to me that the only reason is that it is a duplicate. I do not believe that this is a reason to delete duplicated (and this was discussed recently here). – user1729 Mar 7 '19 at 13:10

I would like to see this question undeleted and mark as duplicate but keep it alive on the network.

Also, I object to the deletion since although the questions are looking for the same thing, I must mention that they are not word by word duplicates and the context also seems a bit different. Also, the answers are not duplicates (except one which coincidentally was answered by the respective OPs of both questions).

• This question was deleted by a moderator, which means that only a moderator can undelete it. As such, there is pretty much nothing that anyone here can do for you. – Xander Henderson Apr 5 '19 at 17:50
• @XanderHenderson I posted this on meta. Someone asked me to post here (just to be shot with 3 odd downvotes here ) – tatan Apr 5 '19 at 18:54
• Votes on meta do not mean the same thing that they mean on the main site. A downvote means "I do not agree with this statement." I would interpret the downvotes here as an indication that the community does not want to reopen / undelete your question. – Xander Henderson Apr 5 '19 at 20:50
• @Aloizio Macedo can you please give some reasons on why you single-handedly deleted the question? (as it stands it looks like an abuse of power, but maybe there'a reason that I'm missing) – Zacky Jul 22 '19 at 9:16

Undeleted,reopened

+6 question with thousands of views and with two, +18 answers. Created in 2016, deleted last week.

Found by the SEDE query Suspicious question deletions from the last week.

• Standard solve-my-problem-without-me post, and nothing spectacular about the answers. I oppose undeletion. – user296602 Jun 3 '19 at 10:29
• @T.Bongers To me, it is absolutely non-trivial, if the sum of a singular and a nonsingular matrix is always nonsingular. The example in the accepted answer was catartic to me. Your attitude would be probably acceptable on the MO, but that is another site. Here sub-phd, maybe even pre-grad level questions are allowed, and you should view the quality and usefulness of a question on the level for which it is written, and not on yours. – peterh - Reinstate Monica Jun 3 '19 at 10:38
• I have no idea at what level the question was written (and neither do you), because the asker never bothered to say anything at all beyond the statement of the problem. This is not a do-my-homework site, regardless of how little quality control some users want. – user296602 Jun 3 '19 at 10:44
• @T.Bongers Maybe the user 1) is enough educated to be able to think about, is the sum singular and nonsingular matrix always nonsingular 2) But he is not enough well educated to know its answer? Is it enough narrow to know, who is he? Hm? Or should he have attached his CV to his question as well? – peterh - Reinstate Monica Jun 3 '19 at 10:47
• This isn't a case for some hyperbolic slippery slope argument, and you know that. If the question had context, it could be appropriate for the site. – user296602 Jun 3 '19 at 10:51
• @T.Bongers The required "context" what you would want so strongly, is clearly visible in the post. And you know that. This is a typical case of the dark direction what you made from this once so friendly and open site. – peterh - Reinstate Monica Jun 3 '19 at 10:54
• I disagree with T.Bongers's comment: "Standard solve-my-problem-without-me post..." In what "standard", if exists at all, for a site "that is for people studying math at any level and professionals in related fields"? I disagree with the deletion in a way that I would strongly disagree with (possible in the future) deletion of this and this "standard" exercises (created 2016 and 2018) T.Bongers answered (nicely!). – Jack Jun 3 '19 at 11:55
• @Jack Thanks for bringing those posts to my attention; I agree with your judgement of the first one (but not the second), and have started a close vote. I would delete my answer if I could, but it was accepted. Of course, it's clear that your comment is a disingenuous off-topic attempt to poison the well by calling me a hypocrite. So it goes. – user296602 Jun 3 '19 at 12:15
• @T.Bongers: Thank you for your message. "it's clear that your comment is a disingenuous off-topic attempt to poison the well by calling me a hypocrite." Please don't put any word into my mouth that I did not say at all. I am sorry that you think it in that way. I do mean what I said and I do NOT mean to be sarcastic at all. Since we are talking about "deletion", I don't think my previous comment is off-topic. And yes, if you or others were going to vote to delete the linked posts that you answered, I would disagree and vote to undelete. – Jack Jun 3 '19 at 12:48
• I'd like to remind everyone to keep it civil. – Asaf Karagila Jun 3 '19 at 15:17

Undeleted, closed, re-deleted (not by question-asker this time)

Please reopen https://math.stackexchange.com/q/3129981/290189 because the question asker has self-deleted his/her own post after getting an answer. The communnity has not got enough time to judge its value.

Please undelete https://math.stackexchange.com/q/2192864/290189 because OP has self-deleted his question one minute after receiving an answer from me. This is an abuse of the system.

• OP shouldn't have deleted it, but what a miserable excuse for a question! With all due respect, I don't think you should have answered it, not without first getting OP to bring it up to standards. – Gerry Myerson May 24 '19 at 2:47
• The question was deleted one minute after receiving an answer, but this request was posted more than two years later. If the asker deleted the question to cover up the fact that they got help, then they already succeeded. I don't really see a reason to undelete this, because it would just get closed and deleted again. – user296602 May 24 '19 at 6:42