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12:00 AM
@amWhy Yeah, I thought about that.
But the notation could also be used to think of a group $G$ acting on some kind of Cartesian product.
I mean, it is a little awkward to discuss rigorously, but if $(x,y,z)$ is a tuple and $k$ is a thing which reasonably acts on each of $x$, $y$, and $z$, then the notation $k(x,y,z)$ ought to be clear.
Also, I hate HATE that so many elementary calculus texts confuse points and vectors.
It is nice that the tangent space of $\mathbb{R}^n$ over a point is isomorphic to $\mathbb{R}^n$, but points live in the base space, and vectors live in the tangent space. Different animals. :\
12:18 AM
@XanderHenderson I saw that :/
I mean, at some level, most of modern mathematics come from physics. But I would say that the formalism of vectors come from mathematics---physicists have used and abused vectors for ages, but it is the mathematical formalism which makes them work.
@XanderHenderson I very much agree.
4 hours later…
4:02 AM
4:55 AM
I'm the only one here , took action on everything above.
5:43 AM
Q: A = B= {1,2,3,...10} find no. Of functions A to B such that f(f(x) = x

Bsusoa jsiwPlease explain how to solve this. f(X) = X or f(X) = 1 - X ...or 10-x. Or f(X) = 1/x I think these are the only functions to count but how?

need one more dupe vote
I found the duplicate in the review queue because the OP of the above question put a non-answer answer on the duplicate
6:09 AM
Q: A= B= {1,2,3,...10} find all functions such that f(f(X)) = x

Bsusoa jsiwPlease explain how to solve this. f(X) = X or f(X) = 1 - X ...or 11-x Or f(X) = 1/x I think these are the only functions to count but how?

at it again
6:41 AM
@amWhy Template text is easy enough. Make the following a bookmark after editing the sample text to what you want:
> javascript:document.execCommand("insertText",false,"This is a sample text.");void(0);
Note that if you want to use a double-quote or backslash inside the text, you need to add a backslash in front of each of them (this is called escaping).
Wait a minute, such javascript is not allowed to run in bookmarks. Gah. You'll need GreaseMonkey or TamperMonkey then. Sigh..
7:00 AM
@ParclyTaxel This one is gone, the previous one has been closed. OP is determined to show that the answer is 10126, apparently!
7:11 AM
To delete this, we must be fast since there are already 4 reopening votes
@amWhy @TeresaLisbon @XanderHenderson @ParamanandSingh: I realized I was using the wrong function (for editable textareas instead of textboxes)... Try this bookmark:
> javascript:text="This is a sample text.";active=document.activeElement;v=active.value;p=active.selectionStart;q=active.selectionEnd; r=p+text.length; active.value=v.substr(0,p)+text+v.substring(q); active.setSelectionRange(r,r);void(0);
@ParamanandSingh @user21820 Still one more delete-vote needed
now gone , but I expect undelete-votes.
1 hour later…
8:36 AM
Q: Irreducibility of a specific polynomial

EurekaQuestion: Check whether the polynomial $x^4 - 20 x^2 + 16$ is irreducible over the rationals. Eisenstein's criterion cannot be applied here and I couldn't come up with any other method to check whether this is irreducible or not. Any help in getting this done is much appreciated.

Bill Dubuque incorrectly marked this as duplicate
There is no mention of the fact that the root of the quartic is a sum of two square roots. The only thing needed here is irreducibility
I get the feeling he's too trigger-happy with that gold tag badge
(and yes, I am inching ever closer to my own one)
Voted to reopen because the question substances are different
8:57 AM
Trying to argue with him to no avail
The connection between the two questions is too tenuous to justify closing as duplicate
1 hour later…
10:12 AM
math.stackexchange.com/questions/4133747/… is this good enough to answer?
1 hour later…
11:20 AM
@ParclyTaxel: that irreducibilty question has many dupe targets specified. One of them deals with a similar question and the answer by Jyrki uses same technique.
1 hour later…
@ParclyTaxel Yes, it's not suitable for the site, a similar question was discussed here recently.
It is a good question, but not a good question for MSE , as a great mod (more than) once said.
Funnily enough the post has 3 delete votes. I thought it should have gone by now?
From history : a migration to puzzling.stackexchange was rejected for this question.
@TeresaLisbon No. More upvotes require more delete votes.
12:38 PM
@ParclyTaxel As for this question, I mean, the attempt is literally just one step ahead although the factorization 37*41 is super useful. There's a couple of answers, if you wish to illustrate something beyond what the others have done then maybe go for it, although it feels to me like that's difficult.
@XanderHenderson How many more? Five?
It has 12 upvotes as of writing.
Don't rermember. And I am workking on grading right now,so not rraeally onlinie
I think kit is somethiing likek one extra voe ffor everyr net 10 scorre
to a max of 10 dellete votes.
Ok great. I'll put it out more affirmatively : DELETE THIS!
1:16 PM
@XanderHenderson Coincidence : I was working on grades as well.
1:27 PM
@Euler2 I mean, these are fun questions but NOT here! For example, 478994326880221257733489964321 is a semi-prime, the product of a ten digit and a twenty digit prime, both of whose last three digits are 389. If you typed that randomly, you should join some crypto firm!
2:18 PM
6 messages moved to ­Trash
@XanderHenderson err rally (anagram)
@XanderHenderson you r wakking? What, exactly, are you cooking in a wok? ;P
@ParclyTaxel Please be careful about accusations against others you name in this chatroom. It seems you're mainly upset because you answered it and want it to remain open?
2:35 PM
Please close
@ParclyTaxel There are three dupes linked, and your answer duplicated an answer given by another user.
2:52 PM
Hello! I want to ask if this is a low-quality question?
@soupless Regarddless of quallity, I wouulld say iiit is off-topiic, as it asks about how to iniput answers into WA.
Maybe off-topic (what I'll say), but why does the OP have to use WA to solve for the geometric series when it is quite elementary?
@soupless That is a complletely orthogonal issue. Before you even get to the "why" or ""how", the questioni is funddamentally about ising WA. It is off-ttopic, even if it were asekd wwell.
Yes, I understand that.
There iis no rerason to even cconssiiiderr rthe quality, as iit isn't ansswerable wiithin the sccope of Math SE.
3:04 PM
No offense, but is there a problem with the way you type right now? It seems as if some characters are repeated, like cconssiiiderr
My goodd keyboard dis pllugged into my worrkk computer.
So I am stucky wth the terrrible on-board Apple butterfly keyboardd, which is errible.
Sometimes, the keys regiistter multiplel hiiits, otherrtimes, not at alll.
Oh. I don't know what to say. I am sorry. I still understand what you say though
^^^ In part, this sort of question would require a "conversation" with a potential helpful user, but is not answerable in an answer field.
3:19 PM
I agree that iit is too broad for rMath SE, but don't ccurrently ahve a functiional keyboard with wwhicch tto respondd to the asker, and d am ini cclass fo the next three horus (startiinig in 10 minutes). II will close t he questoin for beinig too broad, bu iit woudl be ccooll if someone eellse took some time to interact witht he askker.
If not, I'lll lbe bacck later.
@XanderHenderson Nooooo PProbbblemmm! ;)
@amWhy :::)))
Andd now II am gone.
smoke bomb
@vitamind I voted to close as "off topic: seeks personal advice". Yes, "opinion based" is appropriate as well.
@amWhy This is better.
3:31 PM
@XanderHenderson Warning, warning!!!! @Xander has turned into a six-eyed monster with three mouths!!! ;D
close? reasoning: answer is a one liner, already answered in the comments -> closing prevents rep hungry users to answer and the answer can be found with 10 if not 5 seconds of online research
@vitamind YES!
4:08 PM
In fact, the "infinity minus divergent series" nonsense got an undelete-vote. We have to prepare for a recovery :(
4:25 PM
two undelete-votes :(
@Peter Can you link me?
It is this question
Thanks. I've got it open in a tab!
That is insane. I can count on one hand the possible culprits responsible for reopen votes and/or undelete votes.
4:40 PM
By the way, I just noticed the change in font.
@vitamind And again "Reimann" instead of "Riemann"
@Peter Oh yes!! Wir Deutsche sind nicht gewappnet für die Verstümmelung mathematisch-deutscher Namen ;)...
Also with Euler, pronounciation I have heard were weeler, youler etc.
@vitamind Isn't it like the English "oiler"?
@amWhy Yes exactly
@TeresaLisbon Any new factors ?
4:49 PM
@amWhy Yes
Regarding the structure of duplicate question links: is it better to have the dupe tree shallow or deep? (Shallow means there are a few big questions which have many duplicates)
I prefer shallower trees
@ParclyTaxel That would make a better Meta question. And you don't really articulate how you distinguish "shallow, vs. deep." E.g., the question, What are the roots of $x^2 -1$, is a dupe of the more abstract question "What are the roots of $x^2 - a^2$? In the first case, a = 1. which means $x^2 - 1^2$. Ahaa! difference of squares, which means it can be factored into $(x+a)(x-a)$, so when a=1, we have $(x+1)(x-1)$. The roots being $\pm a$, or in the original case, the roots being $\pm 1$.
@vitamind Habe noch nie diese Schreibweise des Schweizers gesehen. "Reimann" dagegen sehr oft.
Imagine the questions as vertices, and there is a directed edge from a question to its duplicate (there may be more than one). If we take a question that is not a duplicate as the root, then shallow means I only have to click at most once to get to the root, while deep means two or more
5:09 PM
@Peter Meinte nicht die Schreibweise sondern die Aussprache. Oft hört man "uuler", seltener "wieler". (Aber das eher bei "Einsteiger"-Mathematikern.)
My mind is not large enough to make all the correct generalisations to identify a duplicate, even after searching. As mentioned on my profile, I do My Little Pony art as well, and I'm only a week out from this semester's final exams in maths and computer science
@vitamind Wollte dich einladen für den Raum "Martin Hopf's prime numbers" , aber irgendwie funktioniert das nicht.
@Peter Das muss ich übersehen haben. Bitte lad mich nochmal ein.
I just feel so weak against the 100K+ users of this site because they have more time on here than me. (Right now I'm watching MSI 2021, and I have a commission to do)
@vitamind Habe das Projekt in diesem Raum gepostet.
5:19 PM
@ParclyTaxel How is rep relevant to how much time a user has or how intimidating they are? Also you're not so far away from 100k yourself. (I genuinely can't understand what you mean.)
@Peter Aber das war schon Ewigkeiten her... Werde selber reingehen :)
(MSI is League of Legends's Mid-Season Invitational.) I am actually just jealous. They answer questions I can't, but the questions I do answer, sometimes one of the following happens: (1) I'm not fast enough, (2) it gets closed as duplicate by a gold tag badge user (and I get scolded for making a duplicate answer)
@ParclyTaxel For the first point I can relate. It often happens that if I want to write a long and clear answer another user writes a one-liner and the answer immediatly get's many upvotes. (This is of course not against the mse policy, it's just a little bit frustrating.) And for the second point, just try to search duplicates in MSE, google, Approach0 etc. If the rare case happens where you cannot find a dupe but it actually is, it's not a problem.
5:47 PM
@Peter Same old, same old, but the curves are moving faster. Next time, I should consider combining smaller numbers (~C500) with bigger numbers (~C5000).
That will give me some optimism when I need it!
The same applies to quadradics in general: $ax^2 + bx + c =0$. We don't want a flood of "how to factor this one particular quadratic with specific a, b, and c. In all such questions we have $x= \frac{-b \pm\sqrt{b^2 - 4ac
@TeresaLisbon You can also search for other factors, if you have a free window (see Martin Hopf's room)
@Peter I wish I had a free window, but that's what I'm missing. I'm thinking of aborting one of the searches, but then I'm thinking I'm already 20 days in , nothing to lose and so on. Just praying for a miracle, then.
PSQ (I informed user of EoQS some time ago : flag if needed)
(by user, I meant answerer above)
6:02 PM
@RRL Voted on all of these.
Downvote and delete perhaps the answer as well.
@Peter, @vitamind: is that German?
@Peter and @vitamind Let's all stick with English in this chat room. It's a tad rude to have ongoing exchanges in a chatroom in a language in which other users cannot participate.
Feel free to make your own chat: Chatroom for Peter and vitamind, e.g.?
@amWhy I agree, sorry. Our last messages were however about going to another room and that I did not receive an invite even though peter send one etc.
6:10 PM
@vitamind No problem.
@vitamind: you should help me with the translation work mentioned here
Hello, @KReiser!
6:25 PM
@ParamanandSingh Looking at the comments and answers, it seems that there is no translation. I'll try to find one and I'll notify you but I'm not very optimistic. But if you have the book (Not sure if it's free) and there are some parts which are not clear, please ask me whenever you like.
@ParamanandSingh Rewarding to learn new languages occasionally, I picked up some Russian terminology and stuff to read Matiyasevich's paper on completely enumerable sets being diophantine.
Let's keep stars to more of a minimum. I.e., save stars for use on posts that have lasting value, rather than treating them like comment upvotes.
Question : The delete button for an answer is visible from a mobile device, right? A user is having trouble deleting answers from their mobile device, perhaps it will be good to at least give directions.
6:51 PM
@TeresaLisbon : I use the site on mobile device, but I use the "full site" version which gives all the features. There is also a mobile site which is with less features. Maybe that is the problem with that user.
@ParamanandSingh Exactly, that seems to be the problem. Can you suggest how the "full site" version can be displayed?
@TeresaLisbon: at the bottom of each page of this website there is link "full site". One needs to search for it and click on it.
This needs to be done once for each site like mathse physics se and whatever se and the setting is stored via some cookie for a long time (few months or so).
@amWhy Gone
@ParamanandSingh Thanks, shared it with the user.
6:57 PM
Let's hope they can enjoy all the features even on mobile device.
@TeresaLisbon One more delete vote needed on the answer.
@amWhy Thanks, that had to be mine!
@TeresaLisbon It's a terrible question. Some answerers are getting more desperate (the higher rep users), while other answerers are beginning to steer a bit from answering VLQ questions.
@TeresaLisbon Awesome!!
@amWhy OOOOf, this level of desperation is , I mean, what do I even say?
Besides, the question is also a PSQ as it stands, so bring it on!
7:12 PM
Look at just the profile written here, @Teresa. I think one problem on this site is that some retired users get a second wind on this site, earning rep, and they have little else to do.
I'm not condoning that any way whatsoever. They could easily choose to guide new users, all users, and contribute to site quality, rather than indulge themselves only in self-glorification, at the cost to this site.
last psq has context but no attempt
Close. Op complains of a downvote.
@amWhy Correct, that's the attitude I'd like them to have : the shining guiding lights. They still are guiding lights, but not in the way one'd imagine.
@TeresaLisbon Indeed!
@vitamind HOW is that question for a seventh grader? Having said that , I have no clue what goes on in some of those countries, in Romania it'd probably be fourth grade.
7:46 PM
Let me remind everyone, particularly newer users here, that we try to set a limit of twelve close requests per user and 12 delete vote requests per user; otherwise we risk not having sufficient votes to go around. So everyone posting close vote or delete post requests, please limit the number to 12 each per close/per delete in any given day. Since we have more contributers than when we set it at a dozen of each, we may to curtail that to ten of each per day, per user.
But for now, I trust each user to keep this limit in mind, and abide by it. We want to allow everyone here the to suggest posts for closure and/or deletion, and when a few eat up others votes with too many requests, we risk letting some users requests getting lost. Thanks!!!
@amWhy To be sure: 12close and 12delete together so max=12 or 12close and 12delete seperately so max=24? In any case, I posted 8 comments with a link to PSQ questions so I'll stop for now. Thanks for notifying, I wasn't aware of a limit.
8:01 PM
@vitamind 12 of each, but a request to close, then delete, counts as one of each. I'm just suggesting that we allow everyone the opportunity to suggest, and have some success. If we all had unlimited close votes, down votes, and delete posts, I'd say: The more suggestions, the merrier! Since users are most active at various times of the day, we don't want to burn up a lot of users votes, leaving them unable to assist a user's request. This was not directed at anyone, really! ;-)
@amWhy Ok, I understand.
@vitamind You have not overdone anything... Think of my message as a PSA: Public Service Announcement, regularly scheduled ;D
8:37 PM
math.stackexchange.com/questions/4134382/… I think I remember this person as the one who asked a question and erased context while arguing with me
Style is much the same, I recall
math.stackexchange.com/questions/4130324/… this question: I remember OP's name as Kiawe there
Even got the "I will give you a Check Mark" comment I got blasted with repeatedly on the old question. What to do?
@ParclyTaxel The user seemed to have deleted the account. There is nothing you can do.
I am talking about the OP of the first question, not the second. It's deja vu for me
@ParclyTaxel What are you asking here?
It seems to me that the OPs in the first question and the second question are the same. The second question, TheSimpliFire said that the (second question) OP had a history of editing questions after they got answers, and the account was deleted
@ParclyTaxel Their attitude is obnoxious, asking a commenter to answer a previous question. I have voted to close that question, and flagged as low quality.
Please flag the answer with the information you've shared with me, both posts. Seriously! Mods can find the deleted account, and see any previous patterns.
8:50 PM
You mean the questions?
OK I flagged the first question. I put a flag on the second question soms days ago, when my argument with that OP was finished
@ParclyTaxel Yes (oops sorry, I meant flag the question). Something seems fishy there, with that user. The mods may not know whether it's the same user since then (second post), but they can see more than you or I.
@ParclyTaxel Thanks for your alert. We can use all the help we can get, and you've made it clear you want to do right, and you're also bringing to attention possibly nefarious OP's! We couldn't ask for anything more!
9:23 PM
@ParclyTaxel I flagged the post posted as Kia, with a link to the previous user id of the account that was deleted, as well. Mods usually say, the more flags the better, but there is something really fishy going on with that user.
Are you baaaack, @Xander? Nothing urgent. Just checkin' ;D
10:11 PM
@amWhy hello
@Snoop I was afraid my hello scared you off, so I deleted it! Hello!!!
@amWhy my notifications lag significantly
@Snoop Yes, I've noticed that, too, with my own notifications :(

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