Wikipedia talk:WikiProject Mathematics/Archive/2020/May

Edit war at Unknown

There's a disagreement that could use some more eyes at Unknown (dab page)). See also Talk:Unknown#Ordering of sections. D.Lazard (talk) 14:56, 3 May 2020 (UTC)

Auxiliary normed space

The entire initial section of the new article with this title is as follows:

Two methods of constructing normed spaces were systematically employed by Alexander Grothendieck to define nuclear operators and nuclear spaces.

Could someone who know something about the topic and about Wikipedia usages change this to something appropriate? Michael Hardy (talk) 19:48, 28 April 2020 (UTC)

Hi! I added some introductory sentences giving a quick overview of the two methods of constructing auxiliary normed spaces. Best wishes.Mgkrupa (talk) 00:07, 4 May 2020 (UTC)

Hyperoperations, User:Ferctus

Ferctus (talk · contribs · deleted contribs · logs · filter log · block user · block log) They've just recreated some pointless redirects (octation, heptation) that have recently been deleted, are adding pointless cruft to articles like tetration and pentation, etc. Some more eyes would be welcome. --JBL (talk) 21:19, 7 May 2020 (UTC)

I tried to prune the cruft back and was reverted minutes later without explanation [1][2]. XOR'easter (talk) 23:00, 7 May 2020 (UTC)

Seems to have sorted itself out. --JBL (talk) 00:59, 8 May 2020 (UTC)

System of differential equations

As we can see, "system of differential equations" is a red link. Is this topic really missing or should it be redirected? (In contrast, system of polynomial equations does exist, unsurprisingly I suppose). —- Taku (talk) 08:02, 5 May 2020 (UTC)

The topic seems distributed. We have ordinary_differential_equation#System_of_ODEs, matrix differential equation and partial_differential_equation#Systems_of_first-order_equations_and_characteristic_surfaces. Perhaps a disambiguation page or broad concept article/stub would be appropriate? --{{u|Mark viking}} {Talk} 10:59, 5 May 2020 (UTC)

System of equations is already such a stub/broad-concept article. system of differential equations could redirect there. D.Lazard (talk) 11:49, 5 May 2020 (UTC)

A redirect seems like a subpar solution; the readers interested in this topic will surely be unhappy with system of equations (as there are some many specific aspects in the differential case). I also noticed differential system redirects, which seems also problematic. I have therefore started System of differential equations. -- Taku (talk) 23:54, 5 May 2020 (UTC)

A related question: is the article "Matrix differential equation" redundant? I mean, should it be merged with ordinary differential equation? -- Taku (talk) 00:18, 6 May 2020 (UTC)

As one might expect, a matrix differential equation is just a way to represent a system of differential equations. It might be worth merging it to system of differential equations. — MarkH₂₁^talk 15:21, 6 May 2020 (UTC)

I get what you mean but, despite the article title, the bulk of the article is simply about linear ODE; especially how to solve it using linear algebra (which is important and should be discussed in the ODE article, in my opinion). It ignores PDE entirely; in fact this article seems an instance where (matrix) "differential equation" means linear system of ODEs, similar to the case when a undergraduate course named "introduction to diff equ" refers to linear system of ODE. -- Taku (talk) 04:01, 8 May 2020 (UTC)

Yeah, I think the content can be merged to both System of differential equations and Ordinary differential equation#System of ODEs since the existing content is pertinent in both places, but the title should redirect to System of differential equations in the end since the title refers to systems of PDEs as well. — MarkH₂₁^talk 04:06, 8 May 2020 (UTC)

Help at Carrying capacity (K)

Not really my field (population dynamics), but what was written earlier was total bunk. I deleted almost all the polemics about human overpopulation, and am trying to rewrite the article in the way I was taught this stuff decades ago. Which involved a lot of math...

I'm wondering if the main two equations (or at least one) I copied into the text could be rewritten so that K= yaddayadda. Is that even kosher (with regards to sourcing)?

After the introductory maths, I'd then like an example with a graph, the same I had back in the day, population of bacteria in a petridish, where the pop. reaches K in a sigmoid curve and then falls in the same curve (what's that called, bell-shaped?).

Could someone also vet what I've done so far? Outside of the standard application, environmentalists claim K is not actually a constant, but a variable which is determined by N. I spent all night thinking how that could work mathematically ... is this just patent nonsense? Cheers, Leo Breman (talk) 09:25, 9 May 2020 (UTC)

About the last point: In mathematics the distinction between variable and constant is essentially context dependent. As far as I understand what you have written in the article, K is a "model constant" or empirical constant, that is a quantity that cannot be measured, but is chosen for a best fit between a model and the reality. That is in this sense that K depends on N and its variation.

About "K= yaddayadda": The definition of K can be viewed as a generalized implicit equation. In general, an implicit equation cannot be explicitly solved. I suspect that it is the case here. In any case, if it is not solved in the literature, providing a solution would be WP:OR, and could not be given here. D.Lazard (talk) 10:37, 9 May 2020 (UTC)

Thanks, that actually makes a lot of sense. You're saying K is approximated from the change in N, not actually measured. But that is not exactly what was being said earlier, which was that K decreases as a function of when N nears K... but it turned out that the reference used did not say that at all (didn't even mention the subject matter), so I deleted all that. About "K= yaddayadda": Okay, too bad. Now you mention it, with the bacteria stuff we derived K and r from the experiment. Hey, useful, thanks, Leo Breman (talk) 11:34, 9 May 2020 (UTC)

Redirects for discussion

There are three mathematics-related redirects for discussion: ⋾, V* and 4-sphere. XOR'easter (talk) 18:11, 9 May 2020 (UTC)

Bottema's theorem: article draft

Dear WikiProject Mathematics, I just wrote an article draft for Bottema's theorem: Bottema's theorem. Could please have a look at it and inform me if it is acceptable? Any improvement is of course very much appreciated. A last question: can I join the WikiProject Mathematics? Is there an official way to join the project? Best Regards; Count Von Aubel (talk) 18:32, 9 May 2020 (UTC)

@Count Von Aubel: There’s no formal process for joining the WikiProject! Just chime in whenever you want :)

You can also add the user box {{User WikiProject Mathematics}} to your user page if you want. — MarkH₂₁^talk 18:38, 9 May 2020 (UTC)

You can also add yourself to Wikipedia:WikiProject Mathematics/Participants. —David Eppstein (talk) 18:43, 9 May 2020 (UTC)

Many Thanks! Count Von Aubel (talk) 18:52, 9 May 2020 (UTC)

Magic this and that

If someone wants to clean out some exceptionally crufty recreational mathematics articles, have a look at Magic hypercube, Magic hyperbeam, and Nasik magic hypercube. Between the three of them, there are enough good sources for one decent encyclopedia article, but it won't look anything like the first two articles I've linked. (Nasik magic hypercube is in better shape.) I started on Magic hypercube, then got discouraged by the magnitude of the cruft. --JBL (talk) 16:08, 17 May 2020 (UTC)

Associate Legendre Functions with meaningful learning expansions

I did many mathematical equations and formulas they are still not perfect as I use them much [move to various places]but I can retype them [ i may have them in eletronic version as well]and improve [especially meaningul expansions of particular letter. Preferably they would be in meaningful pair of [noun+verb] which would be easier to remember and implement. Here2,3 is associated legendre function and here meaningful expansions. 2 Fermiparadox97 (talk) 15:50, 14 May 2020 (UTC)

I am sorry. But these appear to be original research (see WP:OR) which is not allowed in articles and usually not even tolerated on talk pages. You could put it into your WP:Sandbox and thus have it in a more readable form. JRSpriggs (talk) 20:24, 14 May 2020 (UTC)

"Not even tolerated on talk pages"? I hadn't heard of that. Michael Hardy (talk) 18:43, 16 May 2020 (UTC)

Probably WP:NOTFORUM is the relevant thing. --JBL (talk) 16:09, 17 May 2020 (UTC)

"Not even tolerated" is perhaps slightly too strong; "usually frowned upon" might be closer. As JBL points out, talk pages are supposed to be for discussing how to improve the articles they're attached to, not for more wide-ranging discussion of the subject matter. Of course, there's going to be some gray area between those. XOR'easter (talk) 16:18, 17 May 2020 (UTC)

Old Noether photo

If anyone has useful knowledge about the early publication history of the main photo in our Emmy Noether article, File:Noether.jpg, it would be a useful contribution to the discussion at Commons:Commons:Deletion requests/File:Noether.jpg. Without suitable information about its provenance, the file seems headed for deletion on commons as it may not be public domain under German law (it may be possible to save a copy locally on en.Wikipedia.com, though, as it is likely to be public domain under US law and if I remember correctly that's the one that's considered controlling for en). —David Eppstein (talk) 01:24, 19 May 2020 (UTC)

Not directly related, but this reminds me of when a book about Emmy Noether had accidentally used a photo of a different woman for the cover. — MarkH₂₁^talk 04:49, 19 May 2020 (UTC)

Fascinating! —David Eppstein (talk) 05:02, 19 May 2020 (UTC)

Draft:Centromerick numbers

Can someone please take a look at this draft and see if they can explain what centromerick numbers are?

I have forgotten all of the mathematics that I learned in college, but I have not forgotten the mathematics that I learned in high school, through introductory calculus, and I have not forgotten the mathematics that I learned in middle school, and this appears to be number theory, which is advanced arithmetic. I don't understand this draft, and I think that this draft is not capable of being understood in English. Maybe the Russian is capable of being understood if one can read Russian. Robert McClenon (talk) 23:29, 22 May 2020 (UTC)

Has all the signs of pure crankery. --JBL (talk) 23:47, 22 May 2020 (UTC)

Thank you, User:Joel B. Lewis. Robert McClenon (talk) 20:03, 25 May 2020 (UTC)

I've rejected the paper because it is incomprehensible. Robert McClenon (talk) 20:08, 25 May 2020 (UTC)

People reverting my edits

Hi, probably because I put Möbius_function instead of From someone reverted my edits. Then the same user became nuts and other users came too.

There is a huge problem with users reverting other's edits.

Those people clearly don't understand anything about the edit itself. This is not acceptable to be insulted in such a way for several days when just adding a formula on an article. https://en.wikipedia.org/w/index.php?title=Euler%27s_totient_function&action=history

This is of course not about me, I don't care at all, I'm just upset because I am a wikipedia user and a good mathematician/student/teacher and obviously I want to be allowed to do a few edits by year without having any interaction with those harmful people.

You should detect the number of revertions made by each user and block, for a month, anyone who is doing too many such harmful reversions.

Reuns (talk) 02:05, 27 May 2020 (UTC)

@Reuns: The primary issue is that you are edit warring. Repeatedly reverting to add your edit back because you think others don’t understand is not allowed. Go to the talk page and discuss if you think someone doesn’t understand your edits.

The underlying issue is not the formula. It’s the bad piped link. Read WP:SUBMARINE as others have directed you to. Also read WP:SURPRISE. They’re commonly accepted standards of writing. — MarkH₂₁^talk 02:16, 27 May 2020 (UTC)

@Reuns: I acknowledge that you have removed the link from your last edits. It remains that beginning the statement of a theorem by a proof of it consisting in two huge formulas is a very bad idea, which is confusing for most readers (most will not read the sentence until the statement of interest). I agree that the current statement lacks of some explanations, but two formulas are not an explanation. So, as Wikipedia is a collective work, a discussion on the talk page is needed for finding collectively the best formulation. Before getting a consensus, the disputed section must not be changed. See WP:BRD for details about this standard process of Wikipedia. D.Lazard (talk) 08:12, 27 May 2020 (UTC)

Redirect for deletion: Steriruncitruncated 6-demicube

Can anyone explain why Steriruncitruncated_6-demicube is a redirect to Pentic 6-cubes? Vote in the discussion here: Wikipedia:Redirects for discussion/Log/2020 May 28#Steriruncitruncated 6-demicube. —Naddruf (talk ~ contribs) 02:51, 29 May 2020 (UTC)

@Naddruf: Probably because there is a section Pentic 6-cubes#Pentisteriruncicantic 6-cube, and this would be a 6-demicube kind of analogue? Just a guess. — MarkH₂₁^talk 08:19, 29 May 2020 (UTC)

Generalized minimal residual method

I was alerted to this edit offwiki (someone trying to program the algorithm). Was the edit correct generally, and specifically, is r_0 = b correct if x_0 = 0 (rather than r_0 = -b)? --Izno (talk) 20:40, 28 May 2020 (UTC)

Formally it should be -b but it does not seem to change anything regarding the algorithm as the only thing that counts is the subspace generated by $r_{0}$. Anyway in Saad's book he seems to take $r_{0}=b-Ax_{0}$ so I put this convention in the article's text. This should probably be rewritten more in depth by somebody who is more familar with the subject or has more time than I do to get a better presentation. jraimbau (talk) 11:19, 29 May 2020 (UTC)