@ParamanandSingh Yes, and in particular you can see in his "Set Theory" introductory text a completely consistent framework with precise definitions of "function" and "surjection" that cohere with my statement. Of course, there are some (unconventional) foundational systems that force you to declare the output type of a function and also force you to type-cast when types do not match exactly, but this actually makes things worse because you will have a whole heap of annoying type-casts.

Anyway we can discuss more about this in another chat-room.

4 questions in 1, also see comments.

@supinf Have you flagged for moderator attention? If so, then maybe you could mention it so that other people don't duplicate-flag. =)

@XanderHenderson Weird idea to solve a quadratic without square roots

@user21820 not this question, but one of the linked questions.

@supinf Ok thanks!

@XanderHenderson No, because the asker should have googled for "compute square-root" and at least tried what the top results yield, and because the asker is only interested in an uninteresting instance of the quadratic equation which is of no use to others.

I suggest to close Zeros of periodic function – it is a repost of math.stackexchange.com/q/4251327/42969 (now deleted) where I helped to clarify the question. But context has not been added despite multiple requests.

C/D

This PSQ asks 100 questions in less than 100 words!! (And it got a full answer to all of them!!!)

C/D

C

@MartinR It is closed now.

D1, D2, D3, D4

D5, D6, D7, D8

D9, D10

one more delete vote needed

I don't know what is happening here, but the identical question has today been posted four times, from different accounts: math.stackexchange.com/q/4251780/42969, math.stackexchange.com/q/4251856/42969, math.stackexchange.com/q/4251881/42969, math.stackexchange.com/q/4251969/42969.

All of them are deleted shortly after the duplication is mentioned in the comments.

@MartinR I can't see those (not enough rep) but are they related to this one at all? math.stackexchange.com/questions/4251596/…

That's been closed, refused a re-opening, and another re-opening is being attempted. Possibly because a high-rep user has answered it (with some caveats about not wanting any rep from it, but given the question is clearly not up to site standards that seems more hand-wringing than sincere)

@postmortes No, this is a different one, it is titled “How to determine Taylor Polynomial of third degree by solving IVP?” and similar.

@MartinR Ah ok, thanks :) It seems like there's quite bit of odd behaviour on the site at the moment then

I have just answered this question in order to resolve the asker's issue, but I think that the question probably does not belong on Math SE in the long term. I don't want to close the question unilaterally, because I fear that would give the impression that I am trying answer the question, earn XP, and lock anyone else out from earning that same XP.

However, if others agree that it is off-topic, I have no objection to the question being closed and deleted.

@XanderHenderson Just because the answer is a nonmathematical one does not make the question off topic.

Would it be on topic if the symbol in question were a mathematical symbol?

OP appears to be approaching the text with the assumption that this is a mathematical expression with which they are unfamiliar. This is perfectly well on topic.

@ThomasMarkov I don't think that this hypothetical is relevant. The answer to the question is "You got a bad copy of the text. Please get a proper copy." If every person with an 8th generation photocopy of some book came to Math SE to ask about notation, how useful would the site be?

At the end of the day, the question is not about notation---it is about a badly copied version of a bit of source material.

Seems to me like requiring that you already know the answer to your question to know if it is on topic is a pretty poor measuring stick for on-topicness.

Shouldnt we generally expect askers to know that their question is on topic before they post it?

@ThomasMarkov You miss the point. Math SE is supposed to be a repository of questions about mathematics. This question, it turns out, is not about mathematics. The original asker didn't know that, but the original asker has now had their question answered. The question is now of little use, and can be deleted.

I have not suggested that the question should never have been posted. I have only suggested that we now know that the question is not mathematical, and it can therefore be cleaned up.

There are a lot of questions which get posted because someone was sloppy in their reading, or has a bad set of notes, or is otherwise confused by some non-mathematical issue. I think that it is entirely reasonable to try to help those people, but to then clean up the site after that has been done.

Seems odd to me to intentionally make a space for questions that you intend to delete later.

@XanderHenderson Seems like duplicate closure is the way to go here.

@ThomasMarkov I can't quite figure out what you are trying to argue, here. We can't expect users to know, 100% of the time, whether or not a question is on-topic. The question gets posted, and we can make a determination.

If the question is off-topic, we can delete it.

Otherwise, keep it around.

However, I have no objection to trying to help the asker as best I can in the iterim.

This serves two goals (1) keep the database clean (a long term goal) and (2) help folk who need it.

@XanderHenderson The only aspect I do not understand , why you did not mention this typo (or is there anything else that is important to point out ?) just in a comment. I agree that it was not bad that this question was posted , but that it is reasonable to delete it after everything has been clarified , since it is only useful for readers of this version of this particular book.

@Peter Per my answer, images don't fit in comments.

@XanderHenderson Why not post it as CW?

@amWhy Oh, derp!

I should have done that. Thanks, @amWhy.

@XanderHenderson I don't mean to imply you shouldn't have answered, nor that you should have used CW, just that one nice think about it is one can assure others one is not seeking rep.

Low quality? Or are the evaluations made for small $n$ (no details provided) enough hint to provide a general pattern?

(Note : I've closed for now, I will retract if it's too harsh)

Not an answer? seems to miss the main point i.e. the simplification of the $\delta$s.

@TeresaLisbon I think it's nothing more than PSQ. No source or motivation or an attempt at a proof. Verifying a formula for $n=1,2$ is not a serious attempt.

Low quality question

@ParamanandSingh Done, thanks, I will keep my vote on.

Low quality question Likely duplicate as well.

Low quality question This is more of an opinion than the others, but I expect it to be correct.

Low quality question

Low quality question

Offensive content (at least towards site)

Another low quality question Same author as above. Interestingly enough , their first question was so good that at least one member here praised it.

@TeresaLisbon An excellent demonstration that this site does not work at all. One comment told the complete story , nevertheless two answers, one with several upvotes.

@TeresaLisbon Flagged as "rude/abusive"

@Peter Agreed, good to see it closed.

C

@ArcticChar done

Needs a lot of work before it gets an answer: math.stackexchange.com/q/4252277/29335

Has anyone else been noticing unusually upvoted poor quests, even in cases in which there are no answerers? I'm getting the impression we have the return of users who make a point of upvoting questions they know are downvote/closure material. @Xander? Any thoughts?

@amWhy Really impossible to say.

@XanderHenderson I imagine so. I expect upvotes on questions, no matter how poor, when there are many answers, But I'm noticing what looks like random upvotes on the questions under the "NEW" question tab, prior to many of them even making it to the "first questions queue", or immediately after a downvote. I encountered, via review about at least 18 such questions, no answers, but upvoted PSQs.

I ask in part because there was a person a while back who had several accounts. I was working with quid at the time, where, as soon as an account was deleted, they created another, anew. He/she would answer in comments, even after closure, and used all their votes to upvote poor posts. This all preceded your election. But I presume there are a few, not many, users dedicated to such mischief.

He loved to flaunt his "you can't catch me", which made it easy to identify them, despite the many accounts.

@XanderHenderson I ask in part because I don't flag very poor posts with unexplainable upvotes (again, often without answers). But when patterns emerge, I'm not sure what to do.

I have flagged questions in which the asker seems to have asked many poor questions, but whose posts mostly have two or more upvotes. So I guess it needs to be a case by case call.

@XanderHenderson Sorry, did not mean to be so long winded :/

@Xander Example of answering in comments: math.stackexchange.com/questions/4244464/…. If you find it impossible to do anything, then say so, or give me direction about how can I address the issues above in a way or manner that might see results. "Really impossible to say" is not at all informative. Please add constructive comments regarding alternatives available to me.

Now, I've linked a specific post with on ongoing back and forth dialogue in comments between an asker and someone essentially answering the asker's questions. You have a lot of experience in cutting off threads like that, and sending to a chatroom. In any case, I still hope to this day, that I don't always have to bring mods up to speed, in order for them to have a clue about ongoing antics of some users. I get that your last comment to me was a "walk away" dismissal, Too bad.

I have very mixed feelings about answers in comments. Better to answer a bad question in the comments than to post a new answer. I'm also reasonably content to let a comment thread go for 5-10 comments of back and forth (since ChatJax is not everywhere).

But I'll keep an eye on that one.