Wikipedia talk:WikiProject Mathematics/Archive/2021/Dec

Spatial complexity edit

What is Spatial complexity? The article, completely unhelpfully, describes it as "the complexity of a spatial entity". The rest of the article is just as bad. If the references didn't include a Springer book entitled "Spatial Complexity" I would have AFD'd it, but presumably somebody with access to the book can fix the article. User:力 (powera, π, ν) 21:30, 30 November 2021 (UTC)Reply

I was able to download the pdf of the book and found it to be as vague and pseudo-scientific as the article. It surveys a variety of disconnected mathematical ideas that could be construed as spatial complexity (Kolmogorov complexity, genus, entropy), defines a couple new notions of spatial complexity, and then talks about aesthetic, psychological, and philosophical aspects of spatial complexity. A generous reading would be that the book is an examination of what a definition of spatial complexity could consist of, but it doesn't appear that "spatial complexity" is a formal mathematical or scientific notion. Fawly (talk) 23:08, 30 November 2021 (UTC)Reply
An aspect of computational complexity, DSPACE. The minimum amount of storage space (in bits, for example) required to perform the specified computation as a function of the characteristic size of the problem. JRSpriggs (talk) 01:24, 1 December 2021 (UTC)Reply
Yes, I agree that space complexity is an actual formal field of study. Whatever's being referred to as spatial complexity in this article is definitely different, though. For what it's worth, I don't see any reference to space complexity in this book about spatial complexity, since it's moreso focused about the "complexity" of an object in space rather than describing the complexity of a problem in terms of the amount of space necessary for that task. Fawly (talk) 02:11, 1 December 2021 (UTC)Reply
I've AFD-ed it: this is clearly not a well-defined term, but a bunch of people using it to mean different things. User:力 (powera, π, ν) 03:27, 1 December 2021 (UTC)Reply

Hopf maximum principle vs. Maximum principle edit

It seems to me that the page Hopf maximum principle is encompassed by the page Maximum principle and so should be deleted, unless the latter is changed to be specifically about the weak maximum principle. Even if not, maybe the title "Hopf maximum principle" should be changed to "strong maximum principle," since that is the more common name. Any thoughts? Gumshoe2 (talk) 04:16, 1 December 2021 (UTC)Reply

about complex analytic variety edit

I would like some advice on redirects and article names. see Talk:Complex analytic variety#Create a redirect to this article. thanks ! --SilverMatsu (talk) 01:17, 22 December 2021 (UTC)Reply

More uniformization articles? edit

We have an article titled Simultaneous uniformization theorem, which begins as follows:

In mathematics, the simultaneous uniformization theorem, proved by Bers (1960), states that it is possible to simultaneously uniformize two different Riemann surfaces of the same genus using a quasi-Fuchsian group of the first kind.

One of the links was put there by me today: [[uniformization theorem|uniformize]]. At Uniformization theorem we see this:

In mathematics, the uniformization theorem says that every simply connected Riemann surface is conformally equivalent to one of three Riemann surfaces: the open unit disk, the complex plane, or the Riemann sphere.

The first quote above says "of the same genus", meaning this isn't only about simply connected surfaces, and yet the second quote deals only with simply connected surfaces. Thus the story of "uniformization" in this sense of the word is incomplete in this set of articles. Is there another article that deals with uniformization of surfaces that are not simply connected? If not, should we create one? Michael Hardy (talk) 20:42, 22 December 2021 (UTC)Reply

There are several generalisations of the uniformization theorem, mostly dating back to Paul Koebe. The article planar Riemann surfaces surveys some of these generalisations (including circle packing). The Riemann mapping theorem also covers this material from a slightly different point of view using normal families. (Jänich wrote a pocket-sized Springer-Lehrbuch on it.) Mathsci (talk) 21:13, 22 December 2021 (UTC)Reply
These (uniformisation and simultaneous uniformisation) are two completely different theorems; if anything, the classical uniformisation theorem is a pre-requisite for Bers' simultaneous uniformisation theorem. The latter is a parametrisation of a certain family of representations of surface groups into the group of isometries of hyperbolic 3-space; the statement amounts as saying that given a surface of genus at least 2, and any pair of points in its Teichmüller space, there exists an action of its fundamental group on hyperbolic 3-space whose domain of discontnuity on its boundary (the Riemann sphere) is a pair of discs, with actions corresponding to the points in Teichmüller space. This takes for granted the fact that Riemann surfaces of genus at least 2 are quotients of the disc, which is essentially the content of the classical uniformisation theorem. jraimbau (talk) 23:06, 22 December 2021 (UTC)Reply

Difference equation edit

See Wikipedia:Requests_for_undeletion#Difference_equation. The redirect pages Difference equation and Difference equations were deleted although something like a couple of dozen articles link to them. Michael Hardy (talk) 00:46, 30 December 2021 (UTC)Reply

Analytic number theory expert needed edit

https://en.wikipedia.org/w/index.php?title=Prime-counting_function&oldid=1033755551

On July 30th, 2021, Vitamindeth misunderstood the derivation of the explicit formula for the prime-counting function and made some major edits. In particular, he wrote that the equality

 

does not hold (see the article for the details about Riemann's R-function), while it actually follows from Riesel&Göhl.

On December 23rd I noticed that flaw and made the corresponding fixes, but A1E6 completely reverted them. To avoid WP:WAR I started discussion on the Talk page, but A1E6 turned out to be intractable. I found the source with the expansion for   directly leading to the equality questioned, but A1E6 decided that's not WP:CALC but WP:OR. In my opinion, article presupposes the reader's sufficient competence to understand how that equality follows from the sources cited. I would like to revert A1E6's recent edits to this version: https://en.wikipedia.org/w/index.php?title=Prime-counting_function&oldid=1062149402

Please take a look and help us to resolve this dispute. Droog Andrey (talk) 09:05, 28 December 2021 (UTC)Reply

Please cite the page and line in which the equality was proven in Riesel and Göhl. vitamindeth
The equality
 
comes straightly from the expression (32) in paper by Riesel & Göhl.
Note that the sum   does not converge because
  for  , where   is Euler's constant.
Nevertheless, we still write
 
in analytical sense since
 
and actually converging sum is
 .
Summarizing this, we have
 
Droog Andrey (talk) 17:53, 28 December 2021 (UTC)Reply
@Droog Andrey: So, you did not cite the page and line in which the equality was proven in Riesel and Göhl. By the way, (32) in Riesel and Göhl is the following:
 
where   as  . A1E6 (talk) 18:56, 28 December 2021 (UTC)Reply
Another way to write it is
 
and since   and   as  ,
 
immediately follows. Droog Andrey (talk) 20:55, 28 December 2021 (UTC)Reply
@Droog Andrey: Yes, but here
 
your   was used. And   is nowhere in Riesel and Göhl. There's not even any mention of zeta regularization in Riesel and Göhl. A1E6 (talk) 21:10, 28 December 2021 (UTC)Reply
Good for you to agree about arctan. Now let's switch to  .
Prime-counting_function states that   by Möbius inversion.
Is it clear for you? Droog Andrey (talk) 21:25, 28 December 2021 (UTC)Reply
The following equalities are in the prime-counting function article:
 
 
 
Your
 
is not in the article. And you're trying to prove
 
Notice the   term. This leads you to use   when you want to write
  A1E6 (talk) 21:36, 28 December 2021 (UTC)Reply
Are you sure that   is the correct way of applying Möbius inversion?
If you dig up the details, you will find   inside, because
  diverges, while
  converges.
Droog Andrey (talk) 22:20, 28 December 2021 (UTC)Reply
The convergence of
 
does not prove  . Neither does the convergence of
 
prove
  A1E6 (talk) 22:29, 28 December 2021 (UTC)Reply
The convergence of
 
actually proves that
 
because generalized sum matches regular sum inside the convergence region. Droog Andrey (talk) 00:19, 29 December 2021 (UTC)Reply
Two major mistakes: (1) The Möbius inversion of the oscillatory term converges. (2) The relation   only holds for s>1 if proven by the Euler product. You apply it for s=0. Vitamindeth (talk) 14:29, 29 December 2021 (UTC)Reply
Vitamindeth, please sign your edits. (1) What is "oscillatory term"? (2) We are in the field of analytic, not arithmetic number theory. Droog Andrey (talk) 07:44, 29 December 2021 (UTC)Reply
Your comments show how little you know about this topic. This discussion site is not a place to lecture someone in mathematics. Maybe someone with more time on their hands can explain it to you step by step, even though A1E6 has already tried. Vitamindeth (talk) 14:29, 29 December 2021 (UTC)Reply
You know, my knowledge extends a bit beyond classic Titchmarsh's textbook which I studied 20 years ago. Note that you've just violated WP:PA.
My question about the oscillatory term was a hint for you, since   actually diverges (the reason was stated before). So let's wait and see what others have to say. Droog Andrey (talk) 21:40, 29 December 2021 (UTC)Reply
This is obviously well beyond the sort of basic arithmetic covered by WP:CALC. You should follow the sources closely. If you are covering ground the sources don't It doesn't really matter if you are correct or incorrect, what matters is matching the best available sources. MrOllie (talk) 22:21, 29 December 2021 (UTC)Reply

Wow. I hate to wade into such a mess, but it appears to me that Droog Andrey is correct. From the conversation above, it appears that A1E6 is confused about how conditional convergence works, and how analytic continuation works, and thus is getting tangled up in details that are conventionally "well-understood". 67.198.37.16 (talk) 18:32, 30 December 2021 (UTC)Reply

I agree with MrOllie. --JBL (talk) 19:33, 30 December 2021 (UTC)Reply
@67.198.37.16: Under the standard interpretation of infinite summation,   doesn't sum up to any real number. We can't have Droog Andrey's contribution in the article, since there's no mention of   in Riesel and Göhl, nor of any generalized summation methods. Droog Andrey's work is not covered by WP:CALC in any way. A1E6 (talk) 19:34, 30 December 2021 (UTC)Reply
This is a total mess. If we start with the first statement: The oscillatory term doesn't converge. I'm sure we are all familiar with the formula for the Riemann prime counting function J(x), consisting of 5 finite terms. If we apply Möbius inversion, we can see that all terms are finite, which implies that the series in question is finite too. This is very easy to see and only requires one well-known(!) prerequsite we all agree on. Your argument relies on the big-O expression. Do you have a reference? Droog AndreyVitamindeth (talk) 00:03, 31 December 2021 (UTC)Reply
I just want to mention that I removed the link http://www.primefan.ru/stuff/primes/table.html from the article (per WP:RSSELF). It was self-published by Andrey V. Kulsha. On that page, you can also find a reasoning very similar to Droog Andrey's. All this is pretty suspicious.
I've also found https://arxiv.org/abs/1806.06969, authored by Andrey V. Kulsha, reflecting his interest in chemistry. And compare this with [1] (Droog Andrey's edit history) prior to 23 December 2021 – but this is rather a sidenote.
Self-promotion is not allowed on Wikipedia, and this is just one of the many problems with Droog Andrey. Also see WP:REDFLAG. A1E6 (talk) 16:28, 31 December 2021 (UTC)Reply
Quoting my first edit on this page (30 July 2021)‎: "There is a clear misinterpretation of the paper of Riesel and Göhl. The arctan-log terms *are not* equivalent to the integral term. They are only an approximation. A cited site gives good numerical tables but has a major mistake implemented when calculating the exact form." I was talking about the same article you A1E6 have mentioned. Vitamindeth (talk) 16:51, 31 December 2021 (UTC)Reply
Even if the numerical tables are "good", they can't be mentioned in the article, for the reasons above. A1E6 (talk) 16:58, 31 December 2021 (UTC)Reply
The approximations can be mentioned in the article because of something which actually follows from Riesel and Göhl. The reason is however totally different from the derivation on the site. Vitamindeth (talk) 17:10, 31 December 2021 (UTC)Reply
@Vitamindeth: The approximation is already mentioned in the "History" section. The only thing missing is "  comes from an approximation to   due to Riesel and Göhl." This is rather just a rewording of the stuff from the "History" section, but you can of course add it to the article if you wish. A1E6 (talk) 17:16, 31 December 2021 (UTC)Reply
@A1E6: I know that it's already in the article (I put it there). With my last reply I wanted to say that the calculations are in a way useful. Vitamindeth (talk) 17:45, 31 December 2021 (UTC)Reply
Alright, then. And please sign your edits. A1E6 (talk) 17:39, 31 December 2021 (UTC)Reply

Articles on "differential calculus" and "integral calculus" edit

For whatever probably silly reason, I happened to be looking at old discussions in talk:calculus and I came across one in which the querent asks why we have an article called differential calculus but none called integral calculus (the latter is a redirect to integral).

D.Lazard asserted that "differential calculus" was much more used than "integral calculus", which seems unlikely to me. (D., do you want to elaborate on this claim?)

As I see it, "differential calculus" and "integral calculus" are not so much areas of mathematics, as they are units in a course of study. In the former, you teach students what a derivative is, how to compute it, and what it's used for/how to use it. In the latter, you do the same thing for integrals. There might be a case for writing about these separate portions of a course, from a math-education point of view. Otherwise it would make sense to me to merge "differential calculus" into derivative.

Thoughts? --Trovatore (talk) 19:07, 27 December 2021 (UTC)Reply

My assertion (summarized by Trovatore) was a feeling. It results probably from my French culture. In fact, the French equivalent to "calculus" is "calcul différentiel et intégral". This long phrase is generally abbreviated into "calcul différentiel", and this is probably the origin of my feeling.
The strong relation between these two subjects makes artificial to distinguish them. For example, the fundamental theorem of calculus belongs to both calculi and says essentially that they are equivalent.
So, without reading again the articles, my first suggestion would be to merge Differential calculus partly to Calculus and partly to Differentiable function and/or Derivative, to redirect both Differential calculus and Integral calculus to Calculus, and editing Calculus for making clear that calculus is an abbreviation of "differential and integral calculus", or is an abbreviation of both "differential calculus" and "integral calculus" (the choice depends on sources that can be found). D.Lazard (talk) 20:06, 27 December 2021 (UTC)Reply
Hmm, if we're going to get historical, I think "calculus" is an abbreviation of "the infinitesimal calculus".
As a practical matter, differential calculus has quite a bit of content, and may be useful to a certain contingent of readers as a separate article. I would just like to figure out its aboutness and make it clear, and probably avoid giving the implication that it's a separate area of study. I don't see any reason a parallel integral calculus article wouldn't be just as useful and for the same reasons, but I have no enthusiasm for working on it myself. --Trovatore (talk) 20:56, 27 December 2021 (UTC)Reply
Well spotted by Trovatore. I’m still thinking about it. The problem isn’t confined to the two articles about differentiation because the process of integration is also covered by two similar articles: Integral and Antiderivative. Some merging is looking attractive. Dolphin (t) 06:58, 28 December 2021 (UTC)Reply
To be fair, there is an articulable difference between integrals and antiderivatives, though it isn't one you'd explain to a first-semester calculus student. It might be reasonable to pitch antiderivative at a slightly higher level rather than merging it, perhaps comparable to Riemann integral (I haven't checked that article to see how it's written). --Trovatore (talk) 07:39, 28 December 2021 (UTC)Reply
though it isn't one you'd explain to a first-semester calculus student !!! Understanding the ideas of integration and antidifferentation separately is an essential part of a good first course in calculus. --JBL (talk) 01:13, 29 December 2021 (UTC)Reply
OK, this is a bit of a tangent, but let me at least say what I mean. I wouldn't be too disappointed in a first-semester student who thought they were the same, in the sense that you get "the same answer". Of course you don't always, because the integrand doesn't have to be continuous. But that's a point I wouldn't linger over in a low-level course. --Trovatore (talk) 20:58, 29 December 2021 (UTC) Reply
Sure, fair enough. --JBL (talk) 22:17, 29 December 2021 (UTC)Reply

I'm glad to see someone explicitly distinguishing between topics in mathematics and units in a course of study. I've encountered actual mathematicians who, in some contexts at least, are somewhat challenge on that point. Michael Hardy (talk) 19:40, 28 December 2021 (UTC)Reply

Yes: as a non-academic, I get worried when I see Wikipedia discussions that allude to course content. To illustrate why, I think that although the Riemann integral article inevitably contains technical detail, other chunks there could be understood by a non-mathematician interested enough to look up the topic. (That said, the final section has an interesting paragraph on the place of different theories of integration in educational settings, which I'd be disappointed to see removed.)
There seems to be different emphasis in Differential calculus versus Derivative. The latter involves definitions, calculation methods and generalisations beyond real-valued functions of a real variable. The former is more of a hotch-potch: it includes applications and major results such as the Mean value theorem that probably fit quite well; but the first two sections on the Derivative and History has a lot of detail that I think might be better incorporated into the main Derivative article. To my mind there's little redundancy in the content of Calculus compared to Differential calculus, so I'd agree that Differential calculus does have a place if it can be a bit more sure about what it contains.
Integral calculus redirects to Integral. I'd find it hard to define what would go into an Integral calculus article that isn't in the current Integral one, or why it should go in one and not the other. NeilOnWiki (talk) 21:15, 29 December 2021 (UTC)Reply
I don't think anyone was suggesting that "Riemann integral" was not a natural name for an article on a mathematical topic. It describes a particular mathematical construction; it's not in any way specific to course content.
The concern about specificity to course content is more about "differential calculus" and "integral calculus", which are not really separate mathematical areas of study (anytime you're doing one of them you're likely doing the other as well). These phrases do mainly come up in reference to courses. --Trovatore (talk) 06:47, 30 December 2021 (UTC)Reply

Since the topic of Fundamental theorem of calculus came up in this discussion, I added Fundamental theorem for complex line integrals to article of Cauchy's integral theorem, which is better to add to article of Fundamental theorem of calculus ? Also, I noticed that Complex calculus is a red link. --SilverMatsu (talk) 02:31, 31 December 2021 (UTC)Reply

As to the second point, I think I would prefer that complex calculus remain a redlink. I don't know that term as being used with any fixed meaning. I suppose if someone wanted to redirect it to complex analysis, I wouldn't be disturbed enough to try to have it deleted, but I also don't see any great value in it. --Trovatore (talk) 03:38, 31 December 2021 (UTC)Reply
Thank you for your reply. I agree with your comment. After reading your comment, I thinking about adding Cauchy's integral theorem to the list of see also, instead of creating a new section in the Fundamental theorem of calculus. --SilverMatsu (talk) 22:02, 31 December 2021 (UTC)Reply