Wikipedia talk:WikiProject Mathematics/Archive/2023/Apr

Dirichlet's theorem on arithmetic progressions

Looks like the beginnings of an edit war at Dirichlet's theorem on arithmetic progressions.—Myasuda (talk) 14:42, 1 April 2023 (UTC)

The excitement seems to be over: the editor on one side of the issue thought it would be a persuasive tactic to start insulting and hounding other editors, and creating sockpuppets to push their view. They got indef-blocked for their efforts. —David Eppstein (talk) 21:32, 1 April 2023 (UTC)

Mathematics Genealogy Project

I have asked whether Mathematics Genealogy Project can be considered a reliable source Wikipedia:Reliable_sources/Noticeboard#Mathematics_Genealogy_Project. Any comments from member of this project? 76.14.122.5 (talk) 19:55, 2 April 2023 (UTC)

Coxeter-Dynkin representations of polytopes

About families of polytopes, I keep seeing the phrase "represented by permutations of rings of the Coxeter-Dynkin diagram." The word permutations looks wrong to me: the number of rings is not constant, and two rings are not distinguishable. Why not combinations? Looking for the sense of the community on this. —Tamfang (talk) 03:24, 5 April 2023 (UTC)

The right question to ask about our polytope cruft is usually: is any of this covered by reliable sources? If so what terminology do they use? If not it should just be removed. It certainly needs disambiguation concerning whether "rings" here means some kind of algebraic structure, the ringed nodes of a Coxeter-Dynkin diagram, or something else. —David Eppstein (talk) 05:54, 5 April 2023 (UTC)

GCD matrix

I have fixed the references in the article GCD matrix, and I have changed some headings as well. The only problem is that the lead section because it was too short and did not entirely summarize the whole article; maybe someone can help to rewrite it. Regards, Dedhert.Jr (talk) 12:57, 5 April 2023 (UTC)

Requested move at Talk:Ex Falso (tag editor)#Requested move 7 April 2023

There is a requested move discussion at Talk:Ex Falso (tag editor)#Requested move 7 April 2023 that may be of interest to members of this WikiProject. ASUKITE 19:48, 7 April 2023 (UTC)

Project-independent quality assessments

Quality assessments by Wikipedia editors rate articles in terms of completeness, organization, prose quality, sourcing, etc. Most wikiprojects follow the general guidelines at Wikipedia:Content assessment, but some have specialized assessment guidelines. A recent Village pump proposal was approved and has been implemented to add a |class= parameter to {{WikiProject banner shell}}, which can display a general quality assessment for an article, and to let project banner templates "inherit" this assessment.

No action is required if your wikiproject follows the standard assessment approach. Over time, quality assessments will be migrated up to {{WikiProject banner shell}}, and your project banner will automatically "inherit" any changes to the general assessments for the purpose of assigning categories.

However, if your project has decided to "opt out" and follow a non-standard quality assessment approach, all you have to do is modify your wikiproject banner template to pass {{WPBannerMeta}} a new |QUALITY_CRITERIA=custom parameter. If this is done, changes to the general quality assessment will be ignored, and your project-level assessment will be displayed and used to create categories, as at present. Aymatth2 (talk) 14:19, 12 April 2023 (UTC)

Good article reassessment for Albert Einstein

Albert Einstein has been nominated for a good article reassessment. If you are interested in the discussion, please participate by adding your comments to the reassessment page. If concerns are not addressed during the review period, the good article status may be removed from the article. ~~ AirshipJungleman29 (talk) 23:03, 17 April 2023 (UTC)

Wikipedia:Articles for deletion/Connes connection

Hello everyone,

There is an AfD that can use some inputs from the members of the project: Wikipedia:Articles for deletion/Connes connection. The article which the afd is about was started by me. There are suggestions in the AfD that the topic may be too niche for there to be a standalone article on it. Perhaps. But I can't find good merger _targets; for example, the article noncommutative geometry seems to be a poor choice since having some technical materials damages the tone and the balance of the article (i.e., it should be general in tone and not too technical). -- Taku (talk) 16:32, 18 April 2023 (UTC)

Request for comment on draft

I'm reviewing Draft:Divisibility for all divisors relative prime to 10 at AfC, and wanted to ask those more familiar with the subject matter whether this looks like a typical (or even viable) maths article? The first thing that caught my attention, apart from the copious 'maths script', is the referencing, which is few and far between, suggesting there could be some OR included among it. But again, if that's how these things are routinely done on en.wiki, then who am I to criticise? Any comments appreciated – thanks! -- DoubleGrazing (talk) 09:33, 7 April 2023 (UTC)

The draft is implicitly alleged as WP:OR, since it presents a method without providing the name of its author or a citation that describes the method. The presentation is very confusing, and this makes difficult to see whether the method was previously known. The citations that are not general texts on number theory are either unpublished or published in journals for college students. So, no reliable sources. In short, definitively not suitable for Wikipedia. D.Lazard (talk) 15:35, 7 April 2023 (UTC)

Thank you @D.Lazard, much appreciated! -- DoubleGrazing (talk) 15:40, 7 April 2023 (UTC)

It now has some citations, but still fails as to OR: it reads like an extended homework essay of "everything I've learned about divisors". It would be acceptable as an essay for school credit, but it is not how one organizes knowledge in an encyclopedia. 67.198.37.16 (talk) 21:36, 21 April 2023 (UTC)

Order of operations

A minor skirmish at Order of operations has been reported at ANI. Perhaps people here could contribute to the article to provide other views. Johnuniq (talk) 04:53, 22 April 2023 (UTC)

The most recent change to the article was made by an editor who signed himself 2601:18f:107f:e2a0:7142:367:472:ca68 and who restored Mr. Swordfish's version of the article. Rick Norwood (talk) 09:37, 22 April 2023 (UTC)

Ergodicity

This page has been edited recently by an editor who insists on restoring an overly vague and broad introductory sub-section on ergodicity in geometry (https://en.wikipedia.org/wiki/Ergodicity#In_classical_mechanics_and_geometry). I strongly believe these edits are, at best, misled. They started taunting about 3RR so i'm bringing this to a larger audience here. More generally i think this page could use the help of more mathematically competent editors (not necessarily on this issue alone).

To be more precise: some time ago the section about "Ergodicity in physics and geometry" was added (among others), with the noble purpose of making the article less dry and more palatable to people with no mathematical background. Reading the geometry section i found it extremely badly (though very enthusiastically) written, mentioning in a too precise (for an introductory section) the geodesic flow (with far too much emphasis put on the symplectic aspects which are not germane to the article, at least not in an introductory section with no mention of their relevance), and mentions on some topics in ergodic theory which, again, should not appear in the introductory section (if i'm generous the last paragraph seems to refer, without ever mentioning it explicitely, to the link between the geodesic flow and symbolic dynamics, and the measure classification of shifts---once again, not a topic directly related to the subject of the article).

I edited this section down to the geodesic flow on flat tori, the simplest example for the theory of flows in Riemannian geometry, with an additional mention of negatively curved surfaces and Riemannian manifolds without giving details (note that these topics are referred to again in the more technical body of the article, with links to more detailed specific articles about them). You can see this version here : https://en.wikipedia.org/w/index.php?title=Ergodicity&oldid=1150858382#In_geometry.

To sum up: i replaced an overly broad and confused/confusing introductory paragraph (in my view as a mathematician) with a more to-the-point and precise paragraph, somebody's taken issue with it and seems to enjoy taunting an unproductive edit war about it.

Finally, if there are interested people i'd suggest them to take a look at the parts on physics to see if a similar mess of the topic is not made in them (i lack the expertise, inclination and time to do this myself). Cheers,jraimbau (talk) 07:40, 21 April 2023 (UTC)

The person that jraimbau is complaining about is me. Many of you might know who I am, as I've been posting here at WP:M for 18+ years. You probably also know that I prefer to remain anonymous, precisely because I'm easily exhausted by character attacks, such as the above.

I posted the following reply to him, on Talk:Ergodicity, which I copy here:

We live in the age of search engines. College professors post class notes on ergodicity on-line. There are dozens of PDF's out there. Download them. Read them. Educate yourself. Once you find some evidence that I'm wrong about something, and are able to articulate what it is, then sure ... there's plenty of subtlety and fine points that are hard to capture in such a short article.

As to encyclopedic content, well ... there's a way to understand that, too. Go out and talk, face-to-face, with actual people who are actually trying to learn mathematics from Wikipedia. I have. The consistent complaint that I hear is that they are frustrated with the wall of formulas, lacking in any sort of explanation or intuitive insight into what is "actually happening" with those formulas. What I am trying to do here, as with all the other edits I've made, is to explain complex mathematical topics to non-experts, using plain and simple sentences, plain and simple verbal explanations. Now, of course, if someone wants the actual precise and exact definition of something, then yes, they'd have to stare at the formulas and ponder what they actually mean. But for those who only want a general survey, an overview, then a more informal introduction is exactly what is needed. This is what we should strive for: an encyclopedia that non-experts find informative, and experts find useful. 67.198.37.16 (talk) 20:35, 21 April 2023 (UTC)

The issue i have with your edits is not informality, and you do not address the problems with the "geometry" paragraph that i mention above. Why should there be a long discussion of the relation of geodesic flow with symplectic geometry in an introductory paragraph in this article? This is not justified anywhere, not in your version of the article nor in you talk page comments. I'm inferring that you are enthusiastic about the subject but have no real grasp on the topic as you learned it haphazardly from "PDF's out there" (which you don't cite in the article), and the result is a mess that would do nothing but confuse a serious beginner. If you construe these observations as a "character attack" so be it, but as far as i can see i've been less insulting, if more direct, in this conversation than you have.

In any case, and whatever our very divergent opinions, it would be helpful if you could provide actual, pointed criticisms instead of the general issues you allude to in your reply above. To corner an issue, exactly do you think is wrong with this : https://en.wikipedia.org/w/index.php?title=Ergodicity&oldid=1150858382#In_geometry as compared to the current version, as an informal short introduction to the ergodicity (not ergodic theory) of geodesic flows on Riemannian manifolds? This version is certainly not a "wall of formulas". jraimbau (talk) 06:10, 22 April 2023 (UTC)

Earlier versions of the article said, "the case of classical mechanics is handled in the subsection titled 'geometry', below." Two or three issues became apparent. One editor noted that "below" no longer makes sense with the new cell-phone navigation system. Another was that your edit removed all references to classical mechanics (flat tori are not classical mechanics, and also, they're trivial.) Third, there was some squirrely statement about how one cannot know how to move in a straight lines on a curved surface, or something equally weird. Looking at the edit history, I saw that it was you who added that remark. I concluded that you did not know Riemannian geometry, and so I used the word "geodesic" more than once, hoping it would set off a light-bulb. I also got the impression that you were unaware that classical mechanics is "just" symplectic geometry. So I tried to emphasize that, too. The motion of mechanical systems, as studied in classical mechanics, is given by solutions to the Hamilton-Jacobi equations. This is standard undergraduate college physics. So, here's the kicker: geodesics on Riemannian manifolds are given by solutions to the Hamilton-Jacobi equations on the tangent bundle. In this sense, motion on Reimannian manifolds is a special case of classical mechanics. This is because the tangent bundle is always a symplectic manifold.

Proving ergodicity is hard, so one always looks for simpler cases. The first case where ergodicity was proved in the non-trivial case is the Bolza surface, I think in the 1930's, which kind of launched the whole project of ergodicity in geometry. The next interesting results on "flat space" were Yakov Sinai's work in the 1960's(??) on a model, intended to approximate the atoms of a physical gas with hard elastic spheres. (Gasses are one of the classical topics in physics, and are used to illustrate all the basic thermodynamic relationships. Thus, being able to rigorously prove that a gas actually is ergodic is a big deal.) Sinai's system is now known as "Sinai's billiards" or (rarely?) the "hard-sphere gas". Many(?) other gases have been studied. If I recall correctly, the hexagon gas is exactly solvable (where the things bouncing around are hexagons. Something like that. (The hexagon gas might be a special case of a translation surface??) One can get the various thermodynamic parameters for it.) To summarize: geometry is a special case of classical mechanics. But you've cut all that out. 67.198.37.16 (talk) 15:06, 22 April 2023 (UTC)

Less important, but still worth reviewing, is that there are different types of ergodicity. Perhaps this should go in a section called "types of ergodicity". There are classification theorems that show that most "commonplace" ergodic systems are isomorphic to one of the Bernoulli schemes. There are countably many Bernoulli schemes. There are other classification theorems that show that, for certain kinds of systems, there are uncountably many different kinds of ergodicity. These are popularly called "anti-classification" theorems. "Anti-classification" is some attempt at humor: the systems are still classifiable; there are just uncountably many distinct classifications. (The ergodicity class would be "enumerated" by the infinitely long sequence of digits that specify a specific point on the Cantor set.) 67.198.37.16 (talk) 15:59, 22 April 2023 (UTC)

Reply at https://en.wikipedia.org/wiki/Talk:Ergodicity#Recent_edits jraimbau for those who wish to read it. (talk) 16:59, 22 April 2023 (UTC)

Change Quality of Akima spline from Stub to Start

Akima spline
It has enough words to be considered so.
Supyovalk (talk) 18:33, 26 April 2023 (UTC)

@Supyovalk: I have done this but you could simply have done it yourself. --JBL (talk) 20:05, 26 April 2023 (UTC)