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

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. – user334732 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. – user334732 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 :( – user334732 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. – user334732 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 – user334732 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! – user334732 Dec 3 '18 at 10:39

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 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 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 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 at 18:17

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. – T. Bongers Nov 27 '18 at 18:28

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 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 at 12:48
• How is that useful? – quid Feb 9 at 13:14

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 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 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 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 at 13:19
• OK, now you know what to do. – Gerry Myerson Apr 29 at 13:22

This question was closed and deleted with the reason given "This question is missing context or other detail". However the author of the question explained both his educational background (he is an undergraduate) and his motivation for the question (it was information that wasn't covered in his degree).

This information is sufficient context to give an answer, indeed I can't think of any further context that a person asking the question could add that would result in a better answer.

• The body does not even contain the question. That question-post is poor, and the thread of very limited value overall. The answers being pretty terse and not giving enough detail. // Added: Given the comment below I'll add that it was not I that deleted it. – quid May 9 at 6:59
• As far as I can tell, if a post was deleted by a moderator - like in this case - the deletion cannot be reversed by regular users. (Of course, voting your posts still can show to which extent users support undeletion - and if there is some support, perhaps moderators might have a look at the the question again.) – Martin Sleziak May 9 at 6:59
• @quid can you explain what is poor about the question? Broadly speaking pen and paper methods of factoring numbers is a subject that the site should have coverage of. – Q the Platypus May 9 at 23:32
• I already mentioned one shortcoming. Further and more drastically, the question does not contain any relevant thought of the OP or even just explanation what they want that information for. For example, do they realize that one can easily recognize that some number are not prime? How would they approach the problem for two digit numbers? Or something else, would all make the question better. That said, the question would arguably be saveable. But what for? The answers are low quality. I'd prefer somebody, say my students, won't find any information here rather than those answers. – quid May 10 at 9:55
• Fortunately similar information is available in other and better threads. In my opinion, the site is quite simply better without this thread. – quid May 10 at 9:57

Undeleted, and deleted again

Please undelete https://math.stackexchange.com/q/3110919/290189 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 at 9:16

What OP wrote under the problem statement clearly show his/her thoughts:

How can I do this if I don't know how $$a_n$$ is defined? I can use the given limit to get the range of $$a_n$$ in terms of $$L$$, but I lack the direction to complete the proof.

This is not a zero effort question. Please consider undeleting this post:

Given positive sequence $$a_n$$ where $$\lim _{n\to \infty} a_n = L, L >0$$, prove that $$\lim_{n \to \infty} 1/a_n = 1/L$$

• Did you check if it's a duplicate? It's a very standard question. – quid Apr 26 at 14:32
• @quid, it probably is a duplicate (although I had no luck finding an example), but then shouldn't it be closed as a duplicate rather than as off-topic? – Gerry Myerson Apr 27 at 0:34
• @GerryMyerson a question might be eligible for closure for multiple reasons. It's maybe not a PSQ in it's purest form, but it's still not a good question. I'd say if somebody wants to restore a question it's on them to make sure no reason applies not just the one that was chosen. Further, it would have been on the asker to make some good faith effort to find a dupe before answering (and then complaining that their answer was removed). If a dupe of this question is not findable what does this tell about the level of organization in those tags. The priorities are not good. – quid Apr 27 at 7:12
• @quid, I see Jack complaining that the question was deleted, not that his/her answer was removed. As to whether Jack made a good faith effort to find a dupe, I have no way to know for sure. The tags seem reasonable, and I wouldn't expect a duplicate to use all three of them, and just searching among questions with, say, the tag "limits" seems pretty hopeless, considering how many questions have that tag. All I can really go by is the difficulty I had in finding a duplicate, using approach0. – Gerry Myerson Apr 27 at 7:20
• @GerryMyerson here math.stackexchange.com/questions/1171733/… it was pretty trivial to find. – quid Apr 27 at 7:22
• Well, in any case they complain. We can replace the "that" by "after". On the rest, again the onus is on them. They ought to explain that there is no dupe (supposedly). Further, it is generally considered as good form to mention if one has answered oneself. Especially if it is the only answer. @GerryMyerson – quid Apr 27 at 7:26
• @quid, well done – you're clearly better at searching than I am. – Gerry Myerson Apr 27 at 7:29
• @GerryMyerson not sure about that. I might have had the luck to use the better strategy for that example, searching for words via Google on this site not for formulas for example 'convergence of inverse of convergent sequence' works well. – quid Apr 27 at 7:31
• @GerryMyerson (and quid) I did try to find a duplicate and I indeed noticed that limit of reciprocal of a sequence away from zero should be a rather standard exercise in calculus/analysis and should have been asked before. However, I think "context" counts as an integral part of a post, and that is why we insist on "contexts", don't we? [cont.] – Jack Apr 27 at 13:14
• [cont.] I am not able to find any same/similar confusion ("How can I do this if I don't know how $a_n$ is defined?") in any known post, for instance in the linked post in one of quid's previous comments and thus I do not think this post should be considered as an "absolute" duplicate that one should delete it. – Jack Apr 27 at 13:14
• I agree with Jack's comments above, I don't think this post should be closed if a duplicate is not found where the same confusion is addressed. To the best of my knowledge, this confusion has not been addressed before, so this post should be undeleted and reopened. – Brahadeesh Apr 28 at 5:43
• @GerryMyerson Basically a duplicate, except it doesn't require $a_n$ to be a positive sequence, was asked fairly recently at Sequence Limit Reciprocal Law Proof, where I provided an accepted answer. As for finding it, note it originally only used the tag "elementary-number-theory", but I changed it later to "limits", so searching for it initially might not have turned it up. However, I can't see the original deleted question content, but the page it brings up shows $2$ other somewhat related ... – John Omielan May 2 at 8:08
• (cont) questions: Given: $\lim\limits_{n\to\infty}a_n=0$ prove $\lim\limits_{n\to\infty}\frac{1}{a_n}=\infty$ and How to formally prove that if $\lim \limits_{n \to \infty}a_n=\infty$, then $\lim \limits_{n \to \infty}\frac{1}{a_n}=0$.. Although they're somewhat different, and I haven't checked them carefully, I suspect their techniques are transferable. – John Omielan May 2 at 8:09

Deleted, undeleted

Please reopen Calculating the summation$\sum_{n=1}^{\infty}\frac{H_{n+1}}{n(n+1)}$ because it's not an elementary question and OP has tried checking the proposition using Wolfram Alpha.

• In my opinion it's very poor style to reignite this after month without mentioning any of the earlier activity in which you even were involved. Thus, I locked the post for now. – quid Apr 30 at 11:43
• I'm puzzled. A "content dispute" notice was lifted in March 2018. The content has not been altered since then. So it seems strange to lock it for "content dispute" now, @quid. [I guess I should mention that I was involved in earlier activity.] – Gerry Myerson Apr 30 at 13:56
• @GerryMyerson Are your really puzzled or are you just searching an argument? First, the content of the post was also not changed between the first locking and the first unlocking. Second, the lock was not lifted in the sense of somebody lifting it, it simply expired. It was not reinstated as there seemed no need back then about a year ago. Then half a year ago, there was one more round of undelete-delete but it fizzled out quickly. Now somebody wants to go back to this again, indeed without any further changes, simply picking up the del-undel again. To prevent this, I locked it. – quid Apr 30 at 14:36
• Third, it might be relevant to note that the lock was "lifted" while the post was deleted. Thus, if consistency is the concern of course I should lock it again now. I could also have it become undeleted and then personally delete it again. Last time around some where keen on locks being used. So, there you go. Of course that's not fine for you now either, presumably because it does not cater to your personal preferences. – quid Apr 30 at 14:43
• To sum up, I locked it to prevent the delete-undelete cycle being restarted. By now the question was deleted four times. Plus it is an odd situation, in that it first got siginificantly improved by a third party only for this then being undone If anything should happen likely a completely new version should be posted. This would be a reasonable thing to do if preserving content is the actual goal. Of course if playing un-del games should be the goal... thus locked. @GerryMyerson – quid Apr 30 at 14:48
• @quid, when I write that I am puzzled, please do me the courtesy of accepting that I really am puzzled. I'm puzzled not so much by the locking but by the phrase, "Content dispute", when there was no change in content. Had the locking notice said "Prevent delete/undelete cycle" I don't know that I would have made any comment. Does a moderator have the option of inserting custom-made locking notices, or is "Content dispute" the only phrase available? Also, I always assumed that when a moderator locked a question, the question stayed locked until a moderator decided it was time to unlock it.... – Gerry Myerson Apr 30 at 22:46
• ....I didn't know that locks expired of their own accord after a week. I've been here almost a decade, and I'm still learning how the place works. – Gerry Myerson Apr 30 at 22:47
• @GerryMyerson the list of reasons is fixed (we can ask for additions in principle but not spontaneously) "content dispute" is the one commonly used in this case, others are "off topic comments", "contest question", "cw answer", "historical significance". We can lock for an hour, for a day, for a week, or permanently. Usually one tries to avoid permanent locks. – quid Apr 30 at 23:58
• Probably it's worth mentioning that there already is one answer in this thread about the same question. – Martin Sleziak May 15 at 7:34

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.

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 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 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 at 20:50

unfortunately the question i asked https://math.stackexchange.com/questions/3056520/why-is-the-zero-polynomial-the-only-one-to-have-infinite-roots was put on hold as off-topic first then closed and then deleted . i edited it much for it to be reopened but it wasn't opened. i apologise if it was off- topic to you, but i edited it. If it being off topic yet, kindly suggest improvement or undelete it please.

• Have you finally made up your mind between "Wikipedia" and "wikipedia"? – Did Feb 3 at 21:37

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. – Bill Dubuque Mar 1 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 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. – Bill Dubuque Mar 1 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 at 1:08
• @BillDubuque oh, right. – Max0815 Mar 1 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 at 13:10

I think we need to open the following Mike Lyons's answer: The smallest value of $$x^2 + 5y^2 + 8z^2$$ such that $$yz+zx+xy=-1$$

I think it's a beautiful and right answer. We need to redact it only.

It was my mistake to delete this answer.

• Note that the question has since been deleted. – Gerry Myerson Oct 9 '18 at 22:27

protected by Community♦Oct 1 '18 at 14:49

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