Requests for Reopen & Undeletion Votes (volume 01/2022 - today)

The purpose of this thread is to 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. Please do not use this thread to engage in debates on site policy or other contentious matters. 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.

• 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 may push the question into the reopen review queue if the edit is done within 5 days of closure The question will only be added to the queue if you check the box to indicate that the question's original close reason has been addressed. And one can also use a reopen vote. (If the review has already been finished, it is shown on the timeline of the question.) When 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 the information Reopened or Undeleted at the start once the request has resulted in some action. (If the action is undone, add this too, like Reopened, Reclosed.)

• Do not only post a request, like "request reopening of link". 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 it in a way that takes the feedback the post received into account positively 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 CURED is a reasonable place for such requests. The same guidelines apply there.

Earlier versions of the thread that served as a model:

• Creating a new thread is unnecessary and bad idea, e.g. see here and its links Jan 6 at 10:42
• I applaud annual lists, lest the lists of "answers" becomes difficult to navigate. Also, @Paramanand, thanks for including the links to other "volumes", previously! Jan 6 at 20:31
• I'm sorry to be nitpicky about this, but the second bullet point may need some further tweaking. Rather than saying, "Notice that the first edit after the question may push the question into the reopen review queue if the edit is done within 5 days of closure...", it might be better to just say "Any question with significant edits that address the close reason(s) are automatically put into a review queue to be considered for reopening", which is the text in the corresponding Help Center article. Jan 22 at 9:57
• @BillDubuque My answer here that you said should not be deleted, was just deleted. math.meta.stackexchange.com/questions/34447/… Jun 20 at 22:41
• @Nick Flag it for moderator attention. Jun 21 at 2:01
• @Bill, the answer on meta has now been deleted and locked by "Community" so it can no longer be flagged. Jun 26 at 0:16
• @Gerry the deleted answer is still flaggable for me. In any case one can raise the flag anywhere (e.g. on this question), and Nick has already done so (cf. Math Mods' Office chat). Jun 26 at 3:11

Reopened

How do you find the center of a cake with just a knife? was closed as a duplicate of Determine the centre of a circle but it is not a duplicate. Cutting a cake with a knife is not the same thing as drawing lines with an unmarked straightedge; there are things you can do with the one that you can't do with the other. This was not made clear in the original posting of the problem, but it has been made abundantly clear with an edit. Please consider voting to reopen.

• @amWhy, I will stand by my statement that you can do things with a knife and a cake that you can't do with an unmarked straightedge and a circle (and I'm not referring to eating). Did you look at the edit to the question? Did you understand the diagram there? Mar 13 at 23:07
• This is not small stuff, it's not splitting hairs, and it's not being contrarian. You can't find the center of a circle using just an unmarked straightedge, but you can find the center of a circular cake using just a knife. If you don't see how to do it, @amWhy, just take my word for it, it can be done. Mar 13 at 23:29

Undeleted

Please vote for undeleting this question: Bounds involving number of invariant factors and elementary divisors. The question is interesting, and I provided the OP enough hints in order to solve it, so they could post an answer, or maybe someone else. This way other students will benefit from it.

Reopened

Why does $$\Psi(n)=H_{n-1}-\gamma$$ has been closed as a duplicate of Did I derive a new form of the gamma function?. It is stated in my answer to the latter question that $$\psi(n)=-\gamma+H_{n-1}$$, but nowhere on that page is this equation proven.

I have written an answer to the question that was closed.

I really don't see how the former question is a duplicate of the latter. I think that "Why does $$\Psi(n)=H_{n-1}-\gamma$$" should be reopened.

• Agree that it should be reopened.
– Paramanand Singh Mod
Feb 16 at 10:36

Consider undeleting and reopening the question

The question was sloppily written, but interesting. It was closed; later it was deleted by the system bot. For the record: I wrote an answer to the question, recording what I found in the literature. I also rewrote the question to make it more precise.

Edit: The original question was closed, due to lack of clarity. My edit aimed to improve clarity was rolled back to the original post, as written by OP.

• @amWhy: The essence of question is the same, the difference is the added background and a better formulation. But if the question does not get reopened, I will ask a new question myself. Jan 12 at 20:15
• The new question is here (for those who are <10k). Not sure why there is an edit war on this post.... Jan 24 at 21:45
• I did not intend to participate, and will not continue to edit this answer. I just wanted to make the update use the correct terminology and be more convenient to look at in the future with links. I apologise for any wrongdoings. For Math.SE users who do not know: Here is a link to meta.SE explaining what a merged question is, and here are the guidelines for context rewrites. Feb 1 at 3:13

Seven line segments, with lengths no greater than 10 inches, and no shorter than 1 inch, are given asks a clear and straightforward mathematical question. It was posted in 2015, and soon attracted several answers with net upvotes. But recently it was closed and deleted for "lacking context".

The argument for requiring context is “by providing a context you help the potential responders to your question give you the best help you need.” This argument is inapplicable to a seven-year-old question that already has several good-quality answers.

One of the stated purposes of the site is to be a permanent repository of mathematical questions and answers. Deletion of old posts with good-quality answers is contrary to that purpose. Deletion of this post makes the site less useful.

I suggest this post be undeleted.

• Thanks for reminding me. Aug 21 at 12:10

Reopened

Request to reopen my question post "What is the name of the symbol = in English?". It has been closed as a "Needs details or clarity" post. I clarified my question's distinction and submitted to review but not accepted as "Original close reason(s) were not resolved". I cannot understand or grasp the reviews' opinion or idea that they thought what is not clear.

Reopened

Was a PSQ, but the OP provided quite some context in the comment and also in the answer they later posted.

Undeleted, reopened

I asked about the cardinality of the space of functionals on square integrable functions, Cardinality of the space of functionals on $$L^2$$ functions

I believe the question is a good on-topic question very similar to other questions about the cardinality of spaces of functions but new since it is about the cardinality of a space of functionals.

I believe the question was closed due to an initial error on my part in not including what I meant with $$L^2$$ functions. I have since clarified that I mean square integrable functions and have provided a link to its definition on wikipedia. A further comment asked $$L^2$$ functions on what space and I clarified I am interested in the cases $$L^2(R^n)$$ i.e. functions from $$R^n \to R$$.

I have tried reopening through editing and the undelete progress before but it somehow failed. (I don't believe I received any further comment explaining whether there was still an issue with the question). I still have the same question again months later and was about to write a similar question again when I remembered having asked this question before. So unfortunately for me etiquette requires I do not re-ask but instead try to get my question reopened.

Reopened

This question has been closed on the grounds that if one read and understood a definition and some results from a wikipedia page, then one could construct an answer which uses the result proven in the answers to the associated question.

The question itself only involves basic ring theory, and the OP has made clear that they find the terminology in the wiki page and associated answer intimidating and prefer my direct answer.

I feel both answers have their merits, and it is not too hard to see that they essentially do the same thing, once you get past the terminology. However the existence of an answer which uses another another answer, does not make a question a duplicate.

• +1. OP explicitly states in a comment that "I have done only 1 course course in commutative algebra and you expect me to learn Von Neumann (regular) and regular rings. I am sorry these terms had nothing to do with my course. "
– user1046533
Jul 10 at 20:40
• Such close is in the idea of this very old meta post: Coping with abstract duplicate questions. Nevertheless, Arturo's comment (emphasize mine) has yet to be addressed: "It would require the 'survivor variant' to have answers that address both the general strategy (so as to be useful for future minor variants) and specific application to the question at hand (which shows how the general strategy applies to a specific problem)."
– user1046533
Jul 10 at 20:44
• The claims in the post above grossly misrepresent the matter. Please read all the comments on the question before voting. In fact tkf's use of ultrafilters is surely more foreign to most comm. algebra beginners than is deriving the trivial needed consequences from the simple definition of von neumman regular rings. I fully support user26857's original dupe closure. That the OP strangely does not want to read a simple one-line elementary definition does not mean that the question is not a dupe. Jul 10 at 21:07
• @BillDubuque Yes I agree the term 'ultrafilter' is as intimidating as 'Von Neumann (regular)'. That is why I only mentioned the terminology incidentally, not as a core part of my answer. I think you should give your solution as an answer, only mentioning the terminology 'Von Neumann (regular)' and the associated question incidentally, and repeating the argument from the associated post so your argument is self contained. I would upvote such an answer and believe that it would have value complimentary to mine. But the fact another answer could be given, is no reason to close the question.
– tkf
Jul 10 at 21:22
• That answer is already given in the linked dupe. It would be ridiculous to duplicate an answer simply because the OP refuses to read a simple definition - viz. a ring R is v.n. regular if for every element a in R there is an x in R with a = axa (true for fields: let x = 1/a for nonzero a), and this property is clearly preserved in products of fields. That's all that one needs to know about v.n. regular rings to use the short simple proof in the dupe (which uses only basic comm. algebra and -further - gives simple characterizations of rings having the property studied by the OP). Jul 10 at 21:32
• I will have deleted the "Closed Reopened Closed" from the top of this post because that space is reserved for actions taken after the post is made here, not for the history of the question before the post here. Jul 10 at 23:00

Re-opened

Proving Wolstenholme's Theorem has been closed as a duplicate of Proof of Wolstenholme's theorem. However, the supposed duplicate asks not for a proof, but what is wrong with their proof.

The mistakes made in the proof seem easy enough to make, and would be instructive to others, in my opinion.

• Perhaps this should be re-titled, e.g. "What's the mistake in my proof of Wolstenholme's Theorem?" Apr 2 at 12:49

Undeleted

Undeleted

Please vote for undeleting this answer: https://math.stackexchange.com/a/1933337/121097. It is correct, and for some reason that I don't know it was downvoted twice, and this probably determined the answerer to delete it.

You can also upvote it, since it is way simpler than the accepted answer.

Reopened

I would like to ask for this question to be reopened: Polyhedron with only π/4 dihedral angles. I think there has been plenty context provided; the OP is responsive in comments and has clearly given it a fair shake; the question has been received well (6 votes). At the very least, it would be nice to understand why some think it should be closed. It has already failed to pass the reopen queue once.

• I found it somewhat difficult to visualize the angles (e.g. how the "bowtie" is an example of what is described) but I put that down to my own poor geometric positioning rather than a lack of explanation. I voted to reopen (and voted the question up). Jul 12 at 9:19
• @SarveshRavichandranIyer its this bowtie with the same vertices as a square (hence a 'square bowtie') Jul 12 at 10:49
• (After breaking my head trying to understand that diagram for about $5$ minutes and then finally getting it) AHA! NOW I SEE IT! This question is just difficult to visualize, really, it's not lacking context or anything. If anything, feel free to add the diagram as a context edit. It cleared everything up for me. (Actually, perhaps I could get it from the older image as well, so this is just a "me" problem). Jul 12 at 11:00
• I did not vote to close the question, but I do not understand how interior angles are defined in the case of non-embedded polyhedra (OP did not respond). For instance, consider the case of a polyhedral Klein bottle in $R^3$.... Jul 12 at 11:35
• I added the image. @MoisheKohan yes, though what you said wasn't phrased as a question, and your implication to not consider such shapes seems obvious. (also, is that from a conversation that is partially removed?) Jul 12 at 11:56
• @CalvinKhor: I do not understand what you are saying. Do you understand the definition of an interior angle for non-embedded polyhedra? An image (whatever it may be) is not a definition. Jul 12 at 14:18
• @MoisheKohan sorry, the image is unrelated to you, but I didn't want to litter the comments section with two comments. I am essentially agreeing with you Jul 12 at 14:25

Closed as duplicate

I don't know if I can use this thread for closing a question as a duplicate, but let me try.

Please vote for closing this question Intersection of Cyclotomic Extensions - gcd as a duplicate. Link for the dupe can be found under the question.

• Why the need to post here, will it not be closed via the normal pathway of reviews? Feb 3 at 10:56
• I guess not.... Feb 3 at 11:01
• I know, else you wouldn't have posted here, but "why" still remains? I filtered the close queue by dupes and yours was the third post to be reviewed for me. (I would rather not vote because I have no idea what the topic is) Feb 3 at 11:08
• I had other experiences with similar dupes that never closed as such. Feb 3 at 11:09
• Well this arguably doesn't belong here, but I think you might find support in the CURED room chat.stackexchange.com/rooms/2165/cured Feb 3 at 11:11
• @CalvinKhor fyi: As I stated when I created the original thread 10 years ago: "The purpose of this thread is to help focus the attention of the community on posts that may require exceptional handling". Some dupe closures may indeed require exceptional handling, since many (queue) reviewers have neither the time nor expertise to properly judge them. Feb 3 at 14:05
• I have voted to close as duplicate, and I agree with the direction of closing. However I think it would be good to disclose in such cases that you bring to the attention of Meta Math.SE that you have edited the Q being closed to more closely resemble the older Q. I agree with your edit (some domain knowledge is useful to appreciate the issues). Feb 3 at 15:27
• There's a duplicate thread that you might use Feb 3 at 15:30
• @Bill I did think of you as I recall you pointing that out in last year’s thread. But I don’t think user26857 has made a case for why it requires such handling. Perhaps this is instead obvious to you from the content. In addition, just as we ask for posts to make it through the reopen queue before posting here, I think it would have been better if user was more patient. All this to say well. I don’t really have any horse in the race and I didn’t vote on this answer. Feb 3 at 16:08
• @ArcticChar There shouldn't be a separate dupe thread. Those requests belong here, cf. my prior comment. The (original) purpose of the thread is to handle all such exceptional requests - which localizes front page resources to one slot, minimizes bumping, etc, cf, my prior comment. Feb 6 at 9:15
• @Calvin One can argue, why post a reopen request: "will it not be [reopened] via the normal pathway of reviews?" There are avenues for reopening via queues. Just like there are for closure. If you think a separate thread is needed for reopening, for which there is a devoted queue, then it only makes sense that this thread should allow for close votes. Undeletion requestions are a separate issue, and belong here. What's good for the gander is good for the goose, wrt Reopen/close votes. Feb 11 at 20:56
• @amWhy my point is not that the answer should never have been posted. But the answer was posted at soon after their first close vote (I forget the timing now, this was last week.) certainly we do not want every reopen vote to be posted here. So if it requires ‘exceptional handling’ perhaps a brief explanation why would be good? In addition I’d like to ask, do you agree that the post could have also been closed via CURED? Feb 12 at 1:19
• Calvin One could respond to your first post "Why the need to post here, in this thread, when the moderator tools can accomplish the same?" May 25 at 17:53

Reopened

The question Are there any usages for growth rate that are relatively easy to show? was closed for not providing context. The context is brief but clear, including mention of growth rates and Gromov's polynomial growth theorem, and a request for some simple implications of growth rates. It's a unique question for this site and there could be some valuable answers (I made such a comment already, in lieu of being able to make an answer).

• As noted in the comments below that question, the text being used is not mentioned, nor are their links to the mentioned Wikipedia pages. Moreover, one of the comments seems make it clear that the question itself is not as clear as you suggest: "Well, Gromov's result is rather concrete - see wikipedia. You can talk about it without giving a proof. Certainly you should ask your adviser for the seminar for more details on your topic. It seems that you need to present some of the basics on geometric group theory, too"
– Xander Henderson Mod
May 6 at 21:28
• I am also concerned that the question is looking for "trivial" and "intuitive" examples, which is rather a matter of opinion (again, see the comment I quoted above). Personally, I do not believe that this question is a very strong candidate for reopening in its current form.
– Xander Henderson Mod
May 6 at 21:29

Undeleted and reopened.

Please consider reopening the following question:

In what sense is $$\Bbb R(x)$$ an "instantiation" of the hyperreals?

It seems to have been closed simply because $$\Bbb R(x)$$ is not an "instantiation" of hyperreal numbers in the strict sense of the word, rather than there being an issue with the question itself.

It was deleted by a bot.

It has, in the past, been undeleted and reopened; I made a case for it that goes something like this:

• The question has been answered in error by a well-established & respected user, only to have that answer deleted as incorrect. Surely, then, there is enough of a misunderstanding about hyperreal numbers for there to be a need for the question.

• The proposed duplicate doesn't mention $$\Bbb R(x)$$. Since the video in question makes the analogy between $$\Bbb R(x)$$ and hyperreal numbers, there must be some sense in the analogy, right? This needs addressing and the duplicate does not do so.

• It has context. I put a lot of effort into the question and I believe it shows.

In the comments on the question, there is a link to a valuable chat discussion on hyperreals.

A particular user has agreed to answer the question if it is reopened again.

• Posts containing advertising for bad made up videos do not belong on this site. Instead of complaining why do you not just improve the question so that it deserves an undeletion ? Jun 25 at 12:05
• Yes the given dupe is a very poor choice. You may find helpful the links I give here. Jun 25 at 12:10
• As I said here, @Peter, it is not an advertisement; I don't see how you can make that claim. How am I to ask what is meant by the terminology without referencing where I encountered it? Jun 25 at 12:17

Reopened

I posted this question: Optimal path on the surface of cuboid doesn't visit the same face twice. It was a simple one and someone answered it as a comment. I was planning to expand on the comment and post an answer. This would have been useful for my future reference. However, the question was closed. I'd like to appeal this. Just because its a simple question doesn't mean it can't be useful. The reason says "it doesn't have context". But I feel its completely self-contained and additional context is unnecessary. In any case, I have added it in an edit.

• "Just because its a simple question doesn't mean it can't be useful" and just because it's useful (no evidence given for that) doesn't mean it should be open. Reviewers (and commenters in this case) attempted to ask for some kind of information or elicit some effort out of you , likely because they felt the need to do so instead of answer directly. The link provided is good enough ,in my eyes, for context. Note that "structured optimization" (optimal controls having specific properties) is a big deal in research, and this is a toy example. Jun 12 at 23:42

Undeleted (but still closed), Deleted, Undeleted (after 3 months!), Reopened

“Does it make sense to try to extend the concept of a raised set to a real number?” asks an easily intelligible question: can one can make sense of the notation $$\Bbb R^x$$ even when $$x$$ is a non-integer. It was closed, without comment, as “off-topic”, and then deleted.

I considered the question on-topic and contributed an answer. My answer included some elementary remarks and then citations to pertinent mathematical research, published in the American Mathematical Monthly. In my mind, this should be sufficient to show that the issue is neither “off-topic” or “not about mathematics”.

• FYI: two of the five close votes were for "lacking context". For what it is worth, I agree with those voters. As I read the question it is "Does $\mathbb{R}^t$ make sense for arbitrary $t$ and can I publish it?" (I am guessing that the second part of that question is the bit that the remaining three voters felt was off-topic). That being said, your answer is nice---you might consider rewriting the question.
– Xander Henderson Mod
Mar 2 at 21:05
• Why did you answer a question lacking any and all context, @MJD, and why now, five months after the post's appropriate deletion, does this concern you? Mar 2 at 21:48
• @Delete-voters. Requests ("answers") in this thread should not be deleted, e.g. see this moderator comment. This is a longstanding policy. Mar 2 at 23:39
• @XanderHenderson The question doesn't say anything about publishing the result. It says “is it possible to make a paper out of it?” I took this to mean something like a high school term paper. We don't know what the questioner did mean. I wish people here would be a little more charitable and a little less hasty when judging the intentions of strangers who might be children, might not be writing in their first language, and might be from places where the exact nuances of English are different from those of their own dialect.
– MJD
Mar 3 at 22:16
• @MJD I did not interpret the sentence in the same way you did, which I think lends credence to the argument that the question is unclear. And if your interpretation is correct, the question is still off-topic, as that particular question is a matter of opinion, and is best posed to an advisor or instructor who might ultimately have to grade that paper.
– Xander Henderson Mod
Mar 3 at 23:06

Reopened (yay)

My Question is ostensibly similar to this Question as they refer to and are illustrated by the same mathematical exercise.

However, they do not duplicate each other, because

• my Question queries about the derivation of the upper bound of a particular detail used to algorithmically obtain the solutions, while the other Question queries about the number of solutions.

To better focus my Question (and to clarify the misunderstanding), I've boldfaced its thesis “But why the upper bound $$\frac r2$$ for $$n\,?$$” Again: this issue is neither raised nor directly nor indirectly addressed in the other Question.

Hopefully, this explanation is sufficiently persuasive.

Update: This Question has been undeleted and reopened.

1. A newcomer, unschooled in Mathematical English, posts this reasonable and natural Question:

• Since there is actually exactly one dog, why do we still say that there is "some" (i.e., at least one) dog?

In general, how do I know when "some" means at least one, and when it means exactly one?

My Answer explains that even when we know that there's exactly one dog, it is not wrong to state that there is "some" (i.e., at least one) dog, and that, in many contexts (for example, existence proofs), not only is the latter formulation sufficiently precise, it even makes our work easier.

2. The Question was closed for lacking details/clarity, and subsequently deleted.

I am requesting undeletion on the grounds that the Question is legitimate, feels so natural that it is likely useful to future readers in the same shoes, and certainly not an incoherent rubbishy piece of site clutter.

(And while it is short and inherently reflects the fuzziness of the OP's crystallisation process, it clearly encapsulates the OP's points of confusion; expanding it to give the semblance of fuller context would just be pointless verbiage.)

• This seems to be a duplicate of a more general question. "Reasonable" and "natural" are not, in-and-of-themselves, sufficient reasons to retain a question. "Novel" is also required.
– Xander Henderson Mod
Jul 19 at 20:38
• If it's a duplicate, I'd suggest it should be closed (and deleted) as a duplicate, rather than with the notice "This question needs details or clarity." Jul 19 at 23:00
• "A newcomer, unschooled in mathematical vocabulary and arguments ... " Obviously, this "context" you mentioned is either being ignored or regarded as useless by the second comment above.
– user1046533
Jul 20 at 1:15
• @XanderHenderson My undelete request's thesis question is regarding the confusion over multiple interpretations of For Some, whereas your linked question is asking about the difference between For All and For Any, so both questions (each is a good FAQ) in fact cleanly complement each other. Jul 20 at 2:52
• Your misunderstanding was due to the latter's inaccurate title and irrelevant cursory side-mention of For Some, and the former's similar irrelevant cursory side-mention of For All & Any. (Yes, neither author is a particularly good writer, and I've just edited the latter, for clarity.) $\quad$ Also, note that the two post's Answers do not at all cross-address each other's Questions. $\quad$ (ping @GerryMyerson for reference) Jul 20 at 2:53
• @GerryMyerson I don't disagree, but the question is currently deleted. It seems like a waste of time to undelete it, reopen it, close it as a duplicate, and then delete it again.
– Xander Henderson Mod
Jul 20 at 2:56
• @ryang I very much appreciate you mathsplaining to me what it is that I misunderstand. However, I see both questions as fundamentally being about what quantifiers mean. Neither is a very good question (in my opinion), but an answer to one could easily be an answer to the other with very little editing. For example, you could make some very small edits to your answer and post it to the older question. The goal of the site is to create a repository of question and answers---lumping together closely related questions improves the overall quality of that respository.
– Xander Henderson Mod
Jul 20 at 2:58
• There are other related questions: math.stackexchange.com/q/1593297, math.stackexchange.com/q/4207093, math.stackexchange.com/q/4308984. There are probably others. This seems like a good candidate for a nicely written FAQ post.
– Xander Henderson Mod
Jul 20 at 3:13
• Have looked through all 4 suggested links: the 5 posts collectively are at best cousins. Distilling such Questions into a bigass FAQ is as reasonable/realistic and fair as doing likewise for Questions related to parabolic curves. Jul 20 at 13:00

Reopened.

Please consider reopening $p$-cycle in $S_p$ lies in certain subgroup., a question about how to prove a nontrivial result mentioned without proof in a paper. It is not clear to me what additional context anyone would want for this question beyond the linked paper, or how the site would be better off without this question and others like it.

Reopened.

This question was just closed as opinion based. It is not opinion based (what are the opinions on which it is based?) and should be reopened. The question asks about connections between PDE and representation theory. A similar, if not the same, question exists on Mathoverflow since 2019. It is upvoted many times and has several answers.

• I made some comments regarding this in the main thread itself. The "opinion" on which it is based seems to be whether the theory of automorphic forms falls under DE or not. Nevertheless, the MO thread seems to be a fairly objective/fact-based answer to the question. While the author revealed themselves to be beginning their Masters, a few close and down votes have come before this comment : that information is essential for deciphering the level of the student, and without it someone would have had to opine about the author's preference/aptitude for a certain subject. Jan 11 at 6:26

Reopened

I think that this question should not have been closed as a duplicate. It is tagged - the asker does not want to know how the proposition is proved, but to know if their own proof is valid.

• From the main thread, "Further, leaving it open almost always results in users posting many duplicate answers, which leads to rampant duplication - making it difficult if not impossible to locate "best" answers." strikes at the heart of the debate. This question is tagged solution-verification, yet there is very little confidence that the next answerer will respect this. Jul 5 at 10:04

Reopened

Please consider reopening Show that the $l_p$ norm of $x$ as $p\to 0$ is the support of $x$

The post is edited and the context is quite clear as OP mentioned in a comment.

• I actually don't agree that the OP's mention of a page in a linked preview (of a $$60+ book) is proper or clear context. The proposition itself seems relatively easy to demonstrate (as it follows from solving the case n=1). Before banging our heads over trying to get the OP to provide context, perhaps we should check for potential duplicates? Aug 14 at 3:14 • See my comments under that post, and also : this book is open-source, see here. It is not the demonstration that one must focus on here : given that the author is coming from the point of view of compressed sensing, answering this question requires one to also understand how and why this question relates to CS : the answer being that as an identity, it is used for l_0 norm minimization problems, which form a large part of sparse matrix linear algebra. This question is relevant beyond the mere identity via context Aug 14 at 4:50 • @hardmath: I do not think that "the OP's mention of a page" alone is context. "Context" means a lot of things. To me, the very definition of the l_p norm and the \textrm{supp} are all context. // If it were to be closed as a duplicate, it should be reopened first I suppose. What is a "$$60+ book"?
– user1046533
Aug 14 at 11:24

Undeleted and Reopened

Please vote for undeleting this question.

This question was closed 11 days ago and deleted 8 days ago. I'm still confused by the deletion. In my opinion, this question didn't miss any contexts. He knows the limit of $$f_n$$, but he just didn’t know how to prove the uniform convergence, so he asked in MSE. It is a very good question, in my opinion, so I would like to take some time writting an answer for it.

What's more, the question owns 3 upvotes and 1 bookmark; my answer was accepted by OP and owns 4 upvotes.

Reopened, reclosed, deleted

I edited my post. Can you reopen it? I accept the answer.

@banana told me to do it

Reopened after moderator intervention

While reading an an answer to What should I do if I find the answer to an old question of mine that was automatically deleted as abandoned? over at the main StackExchange Meta site, I came across the following comments:

This topic math.stackexchange.com/questions/2706956 with beautiful problem and my nice answer was deleted. How can we undelete this topic? Thank you! – Michael Rozenberg Aug 16, 2018

@MichaelRozenberg I'm afraid I probably wouldn't know enough to be able to comment on that Q&A even if I could see it. If you can tell what the problem with the question is and can fix it, edit and ask the community to undelete. Or raise the question on your site's meta. I don't know how things work on Math, but I've seen the community fix and undelete questions on other sites, if the problem is fixable. – Monica Cellio Aug 16, 2018 at 17:08

To justify a variance from the fourth guideline above...

While Michael Rozenberg appears to still be active on Mathematics 'proper', he does not seem to have an account at all here on Maths Meta.

As I don't know if anyone (e.g. the original question author) has followed up on why that answered question about triangle inequalities was deleted (and I can't view the deleted question to evaluate it myself, of course), I am posting it here in case there is anything promising within the referenced question and/or answer!

- Jim

• Hi Jim, I give credit to MR for the answer (and his many answers over the years) , and this question looks rescuable, because it isn't a duplicate, and apart from lacking context has no other problem. For example, I believe that if we can edit the Euler and Gerritsen inequalities into the post, we can call for undeletion. Guidelines for context edits and rewrites will ensure that I can insert the required definitions, so I will do it myself. In hindsight, there is an answer that uses Gerritsen's inequality, so it is useful eventually. Therefore, I will edit the post shortly. Jul 16 at 3:22
• The post has been deleted by a moderator, so cannot be undeleted by users. I have still edited the post, and will probably flag for undeletion. Jul 16 at 3:31
• Reopened now, enjoy Aug 3 at 5:59
• Thank you for improving the question. Aug 4 at 3:28
• You are welcome! Aug 4 at 3:42

Please consider reopening Proving that $\langle x, y \rangle$ is a not principal ideal of $\mathbb{Q}[x, y]$

Although related, the current linked question, which is closed too, asking for an example, is not a duplicate. Moreover, the post is linked to a chain of questions that are all closed.

If this question is to be closed, there is supposed to be a better "duplicate" target: in the all closed chain of questions, NONE new answer is allowed to added.

• This proof in the linked dupe does exactly what the OP seeks (put $c = y\in\Bbb Q[y]$) so it is not clear what you mean by "better dupe target". There are many possible dupe targets (chase the links) for this common exercise, and nothing at all novel in the (duplicate) answers posted. [Your profile shows zero activity in abstract algebra. Experience in a field is usually necessary in order to properly assess duplicates]. Aug 24 at 1:38
• It seems that you have a very different definition of "dupe" from mine, whatever it is. Experience in a field $\Large{\neq}$ activities in your mathSE profile. "better dupe" means one does not need to "chase the links", not to mention that it is linked to a closed question that may be voted to be deleted by users.
– user1046533
Aug 24 at 1:41
• In my experience it is - esp. for most users whose tags don't go much beyond calculus. Please explain what you mean by a "better dupe target". We can easily add more dupe links. Aug 24 at 1:43
• Yes, usually, maybe.
– user1046533
Aug 24 at 1:47
• Your recent comments (and votes) on main made it clear that you are strongly against abstract dupes. But this is only a very slight abstraction - viz. specializing the nonzero nonunit $c$ to $y\in \Bbb Q[y]\,$ in the Lemma in the dupe. It would be greatly obfuscatory to have separate questions for various choices of nonunits $c$ in motley domains. A primary goal of abstract algebra is to prove theorems at their natural level of abstraction - so they apply as widely as possible. Aug 24 at 2:02
• "Your recent comments (and votes) on main made it clear that you are strongly against abstract dupes." Please don't put labels on me Bill. I do not want to discuss anything in general under this thread.// Comments are not supposed to be answers in main; one should address the issue Arturo mentioned in meta if one wants to handle abstract dupe: (cont.)
– user1046533
Aug 24 at 2:27
• (cont.) *It would require the "survivor variant" to have answers that address both the general strategy (so as to be useful for future minor variants) and specific application to the question at hand (which shows how the general strategy applies to a specific problem). *
– user1046533
Aug 24 at 2:30
• This is probably a more exact dupe target (containing the "survivor variant"). Aug 24 at 10:08
• @Sarves But that is already true for the existing linked dupe (case $K = \Bbb Q$; the simple proof works for coefficient field $K$ and no simplification arises when $K = \Bbb Q$) Aug 24 at 15:35
• @BillDubuque You're right, the same proof works with $K$ replaced by $\mathbb Q$, but I think you should leave a comment mentioning this , however obvious it might seem. Heck, I'll do it. Aug 24 at 15:51
• @Sarvesh Any student studying ideal theory in rings that doesn't see immediately how to specialize a theorem on fields to the field $\Bbb Q$ has seriously put the cart before the horse. This goes back to my original comment - it is crucial for those assessing dupes to have significant experience in the topic in order to understand which inferences can be assumed trivial and left to the reader. Aug 24 at 16:25

Please consider reopening this post: For any $k \ge 2$ so $k^3 + 27$ can never be a prime.

which is not a duplicate of the currently linked one:

Show that $\frac{(3^{77}-1)}{2}$ is odd and composite

• I agree that the last duplicate target in the list is dubious. But to claim that the question is not a duplicate of the other two (an many others) is just silly. It may have been that the dupehammerer wanted to add a relevant target they had not answered themself. That is something I fully support and strive to do whenever feasible. Aug 26 at 11:56
• @JyrkiLahtonen "But to claim that the question is not a duplicate of the other two (an many others) is just silly." Well, I suggest you check the timeline of the dupe list history and that of my answer.
– user1046533
Aug 26 at 13:08
• I see. Anyway, when I see an obvious duplicate like that, the first instinct is to close it as a duplicate of something. If somebody else had already found a good enough target, I, too, would use a dupehammer (if I have one). You see, after the feature to edit duplicate targets was made available to gold badge holders, the list of targets can be polished afterwards. With the main objective accomplished by the closure. Aug 26 at 13:22
• There is potential for abuse by the dupehammerers to either try and force their opinions over the others (seen plenty of that for example two dupehammerers sequentially overruling the other), or to only use threads they themselves have answered as targets. Neither of those objections fully applies here. I also concede that, the way the site is organized, finding a good dupe target you have answered yourself is faster than searching for other targets. Nevertheless, I think gold badge holders should strive to use threads they are themselves not invested in. Sometimes it is difficult. Aug 26 at 13:27
• You see, I really hate it when rep farmers answer dupes like this. That's why speed of closure has become a high priority (at least for me). I do feel bad that relative newbies such as you are disadvantaged by this. We need to find other ways for you to get to show off and collect the points to earn all the privileges. There are many six digit rep holders who consider it their right to answer anything they can. EoQS and other measures are, in my opinion, really targeting those users. Aug 26 at 13:52
• I am not against closing duplicates as Bill thought I am. But I do think "dupes" should be closed properly with good target(s). But that's a broader issue that one may post another meta question.
– user1046533
Aug 26 at 14:39

Undeleted, closed, deleted by regular users

Please vote for reopening this question: https://math.stackexchange.com/questions/4410226. See the edit history at https://math.stackexchange.com/posts/4410226/revisions. The post was closed. Then I substantially changed the question and then the question was reopened. However, the current version of the question was deleted and then undeleted. Then a user's comments was finally made an answer. Then, I accepted the answer. However, the question has again been closed. Two people have already voted to delete this and with one more delete vote, it will be deleted again. So, I am requesting for the question to be reopened.

• It is a bad question, so why should it be undeleted? May 20 at 20:59
• @user21820 The old version was a bad question. I substantially changed the question. The new version should be accepted. May 20 at 21:16
• You clearly did not read the linked post. May 20 at 21:49
• @user21820 Of course I read the linked post. The post says "Provide context, include the source and motivation for your question.". My question does have context. And same thing applies with all the rules given in the post. May 20 at 22:37
• First, you were asked in the comments to write out your substitution, but you didn't do it. Second, you say you want to get an answer, but an answer was handed to you on a silver platter in one of the comments, and you ignored it. m.se helps those who help themselves. May 20 at 22:56
• @GerryMyerson I gain two points of reputation by accepting an answer. So, I am waiting for that opportunity. May 22 at 16:20
• That doesn't excuse your refusal to engage with the comments. You could have posted a comment, pinging the user who posted the hint, asking that user to please post that comment as an answer, so you could accept it. Or, you could have used that hint to work out a solution yourself, and then you could have posted your solution as an answer, and then you could have accepted it. You have to interact with the users who are trying to help you, not just sit back and wait for an answer to appear out of nowhere. May 22 at 23:57
• Anyway, the question is undeleted and reopened now, so you can still take these actions I have suggested. May 22 at 23:58
• Please do not vote to delete the question again. May 24 at 4:58
• I really don't understand the idea behind voting to delete this post. Not the one on main – this post right here. If you can't ask for something to be reopened or undeleted here, what alternative do you have left? Vote this post down, if you think it deserves it, but please don't delete it. May 24 at 13:04
• @GerryMyerson that could have been because of the dupe request (which is now deleted, so this one hopefully stays) May 24 at 14:05