Wikipedia talk:WikiProject Mathematics

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Idempotency of entailment

I'm lost. I only got to Stats 3. Please help to source this stub and explain it in an educated layperson's perspective. Bearian (talk) 11:56, 7 March 2025 (UTC)

This article was clearly written for people who already know the subject. It is now a redirect. D.Lazard (talk) 15:25, 7 March 2025 (UTC)

That is sadly true of many math articles. —Tamfang (talk) 19:42, 7 March 2025 (UTC)

Not all mathematics topics have its own article, I suppose. WP:NEED? Dedhert.Jr (talk) 07:02, 10 March 2025 (UTC)

I meant that too many math articles are opaque to laymen, not that too many are redirects. —Tamfang (talk) 03:12, 9 April 2025 (UTC)

@Tamfang: I doubt it's true that most math articles are written for people already aware of the article's topic. It is true that most are written for people with expertise in the field, though. Michael Hardy (talk) 23:13, 24 March 2025 (UTC)

Rubin's Rules

Although not new to Wikipedia, I am new to project pages ... apologies if this is considered off topic. If I am understanding correctly... there is an approach called "Rubin's rules" for statistically combining multiple data models (e.g., from different experts). But we don't have an article on it in Wikipedia. I am hoping that someone who knows something about the topic will start an article about it. Thank you —Quantling (talk | contribs) 20:49, 31 March 2025 (UTC)

This is off-topic. https://en.wikipedia.org/wiki/Wikipedia_talk:WikiProject_Statistics seems a more appropriate forum. PatrickR2 (talk) 23:52, 1 April 2025 (UTC)

The statistics project seems to be moribund. So we may be the next resort. JRSpriggs (talk) 01:43, 2 April 2025 (UTC)

Agree it would be nice if someone could expand our coverage of multiple imputation topics, though it's unlikely I'll have time for it over the next few months. Rubin's rules are specifically for pooling together single-dataset statistics under the assumption these are normally distributed; see page 76 of his book and Section 5.2 of FIMD (or p. 66 of Allison 2002) for details. Preimage (talk) 03:23, 5 April 2025 (UTC)

math display block?

I apologize for asking what may be a simple user technical question, but I guess you folks will know: is there anything wonky with math display="block"? For example when I look at Clifford algebra#Quaternions many of the formulas are inline. Is it just me? Johnjbarton (talk) 23:08, 3 April 2025 (UTC)

There's some kind of Mediawiki layout bug in changes applied to Wikipedia today which causes broken layout for block math sitewide. I am not entirely sure but I think it may be related to attempts to fix scrolling bugs on mobile. I made a note at https://phabricator.wikimedia.org/T201233 but there might be a better place for it (or maybe it should be a new bug report). –jacobolus (t) 23:11, 3 April 2025 (UTC)

WP:ITSTHURSDAY. --JBL (talk) 23:25, 3 April 2025 (UTC)

Thanks! Johnjbarton (talk) 01:51, 4 April 2025 (UTC)

Unfortunately at least one editor added line feeds to "fix" the display block and I expect more will follow. Johnjbarton (talk) 15:28, 5 April 2025 (UTC)

An error in the article Truncated octahedron

Nowadays, the "math display=block" has become problematic (see the image). This happens the same thing to mobile phones other than PCs. Dedhert.Jr (talk) 14:28, 6 April 2025 (UTC)

It's a bug. The developers are saying they will revert until it is fixed but for some reason they are slow-walking the revert. See the phabricator link above. —David Eppstein (talk) 18:48, 6 April 2025 (UTC)

Nah. They have fixed the bug quickly. Dedhert.Jr (talk) 01:34, 8 April 2025 (UTC)

Doctrine (mathematics)

There has been a dispute as to (1) whether the topic is notable and (2) the sources are reliable or not. It can use some inputs from editors other than me (as personally I don’t see any issues other than more footnotes are needed). —- Taku (talk) 13:07, 5 April 2025 (UTC)

By the way, an editor (Onel5969 (talk · contribs)) who put tags to the article is even refusing to communicate, which seems like a very problematic attitude [1]. The editor's claim that the "2" sources (which 2??) are user generated isn’t making sense: for example, a lecture note isn’t wiki. If someone else tries to communicate with him (or her), it might be more successful. I don’t have any problem with valid concerns but the concerns have to have some sense to be understood. —- Taku (talk) 13:11, 5 April 2025 (UTC)

As for Onel5969, I think it would be better to discuss this on WP:NPP rather than here. I agree with splitting the article and I will look for other references. By the way, there seems to be a concept called "hyper-doctrines". Ref:Lawvere, F William (1975). "Introduction to Part I". Model Theory and Topoi. Lecture Notes in Mathematics. Vol. 445. pp. 3–14. doi:10.1007/BFb0061291. ISBN 978-3-540-07164-8.;Equality in hyperdoctrines and comprehension schema;Dagnino, Francesco; Rosolini, Giuseppe (2021). "Doctrines, modalities and comonads". Mathematical Structures in Computer Science. 31 (7): 769–798. doi:10.1017/S0960129521000207.;Emmenegger, Jacopo; Pasquali, Fabio; Rosolini, Giuseppe (2020). "Elementary doctrines as coalgebras". Journal of Pure and Applied Algebra. 224 (12). doi:10.1016/j.jpaa.2020.106445.;Zöberlein, Volker (1976). "Doctrines on 2-categories". Mathematische Zeitschrift. 148 (3): 267–279. doi:10.1007/BF01214522.--SilverMatsu (talk) 03:27, 6 April 2025 (UTC)

The question isn’t whether there are sources but it seems that the issue is, well, it is not clear what the issues are. (Basically the user in question isn’t making sense. For example, the user refuses to tell which sources in the article they consider are unreliable. My guess is wiki ones but they are not used as references.) So, I am asking for other editors to step in. For example, the article still has the notability tag, which in my opinion is not applicable. But it may not be a good idea for me to remove it. —- Taku (talk) 04:02, 6 April 2025 (UTC)

(I said "not applicable" since the notability tag should be used when there is a concern about the notability and it should not be put when there isn’t such a concern. Isn’t this obvious??? —- Taku (talk) 04:46, 6 April 2025 (UTC))

It seems to me like the situation before (where two very closely related ideas were discussed in one article of reasonable length, with one of them thinly sourced) was good for a reader interested in these topics, and the situation after your edits (where they are discussed in two different articles, one of which is very short and very thinly sourced) is less so -- WP:NOPAGE being the standard formalization of this. If this were a topic I cared or knew anything about, I would restore the status quo before your edits and then begin improving the content on doctrines at Strict 2-category, where by "improving the content" I mean "writing things based on reliable sources, with appropriate references added". --JBL (talk) 20:12, 7 April 2025 (UTC)

No, I don’t believe the two topics are closely related. As I understand, doctrine has some usage in algebraic geometry and that kind of discussion is clearly off-topic in the 2-category article. You don’t merge differential geometry and algebraic geometry into one just because they are both related as geometry. That was why the original merger of the two was a mistake. Note SilverMatsu above agrees with me on undoing of the merger. —- Taku (talk) 08:18, 8 April 2025 (UTC)

Revised 22:07, 10 April 2025 (UTC) following Chatul's comment below. Well given this response all I can say is it's no wonder other people are finding you frustrating to deal with. If a single mathematical object is used in two different fields, it is natural and appropriate to discuss both uses in a single article; we don't have separate articles Manifolds in topology and Manifolds in differential geometry because that would be ridiculous. At all points, the relevant text has asserted that there is only one mathematical object here, so it is difficult to treat as serious which seems incompatible with your claim that they are not closely related. It does appear that SilverMatsu agrees with you; oddly you don't mention the but there is a larger number of people who disagree. It is a shame that you have been arguing about this for more than a week without evidently devoting any energy to improving the content (where again by "improving the content" I mean "writing things based on reliable sources, with appropriate citations added"). --JBL (talk) 17:19, 8 April 2025 (UTC)

I was hoping for for a more compelling reason than that offered for a separate article. My own, quite naive, view is that 2-categories are an important separate subject from that of doctrines, which is comparatively marginalia which would have undue weight in the main article. Moreover, this certainly suggests scope for a separate article. Tito Omburo (talk) 17:26, 8 April 2025 (UTC)

Sorry. I think a metric space example below should be a better example. -- Taku (talk) 09:43, 9 April 2025 (UTC)

While I agree with you on substance, please respect AGF and NPA. -- Shmuel (Seymour J.) Metz Username:Chatul (talk) 18:00, 8 April 2025 (UTC)

I think the metric space example I gave below should be a better example of why having separate articles makes sense. (By the way, about content, my problem was with the notability mainly and that question is unrelated to the content of the article. A topic can be notable or not independent of the content; the content doesn't even have to exist at all. What matters is what exists outside Wikipedia. I just wanted to settle the question of notability first, since if the topic is not notable, the article shouldn’t be developed further but be deleted instead.) -- Taku (talk) 09:32, 9 April 2025 (UTC)

So, I have just put forward a proposal to remove the notability tag from the article. If anyone is interested, please voice your opinion, not on the notability but on the necessity to keep the notability tag. —- Taku (talk) 14:03, 6 April 2025 (UTC)

Ok. I should report that there is at least one editor who strongly believes there should be the notability tag. I guess the world isn't meant to make sense... -- Taku (talk) 06:12, 7 April 2025 (UTC)

I guess if you added reliable references to the article then the case for the tag would evaporate. Johnjbarton (talk) 17:50, 7 April 2025 (UTC)

The article already lists quite a few reliable sources, and as I said the editor who puts the tag in the first place seems quite confused; they even refuse to tell which sources in the article they think are unreliable. Basically I’m saying the case for the tag is simply bogus, a result of either confusion or miscommunication. Taku (talk) 08:01, 8 April 2025 (UTC)

Yes because you are communicating very poorly and not making a serious effort to understand the objections of other people. Zero people are asking you to make the list "Further reading" longer; multiple people are asking you to create a function F from "content in the article" to "reliable sources" with the property that for each statement X, F(X) is a reliable source that supports X. (Maybe, the situation was different a week ago; but this has certainly been the situation since you posted this notice here.) --JBL (talk) 17:25, 8 April 2025 (UTC)

By confusion and miscommunication, I meant those with the original user Onel5969 (talk · contribs) who put the notability tag and the unreliable tag to the article in the first place. The user has repeatedly refused to specify which sources they consider are unreliable (the user merely said "2 sources" are unreliable without saying which two and that unreliable sources cannot establish the notability.) I don't know how to explain that situation anything other than confusion or miscommunication. I didn't mean to complain about other people's opinions. For example, I have responded to your concern as to why we have two separate articles. I disagreed with you but the communication itself went fine, I think. To further respond, I think that part of the problem is that category theory things can be confusing. For example, from the category point of view, a metric space is nothing but an enriched category that satisfies some axioms. I don't think that's an argument for merging metric space into enriched category. That is, we shouldn't organize things here in Wikipedia purely according to math. -- Taku (talk) 09:19, 9 April 2025 (UTC)

I meant You brought this discussion here for more input. My input is that the obvious problem is that you keep repeating your own view without showing any sign of listening to the views of others (which personally I find straightforward and easy to understand, as they are based concretely in Wikipedia policies). This is not a good way to build consensus. --JBL (talk) 22:07, 10 April 2025 (UTC)

Green's function: dimensional inconsistencies and wrong scaling

See here. Aldiviva (talk) 14:03, 7 April 2025 (UTC)

Finding sources for obvious corollaries

I guess I'm kind of asking for help with sourcing in general, but I figured this would be a good venue to ask first. I've taken it upon myself to improve the sourcing for Difference of two squares and I'm finding it somewhat difficult to find actual sources. I'd imagine this is because elementary mathematics is taught in elementary courses and is not seen as publication-worthy (because, well, every mathematician knows these things). To be honest, I haven't put much effort in beyond a quick internet search for difference of squares commutative ring, but that didn't turn up anything and I'm honestly not sure what sort of research would turn up anything (because, like I said, I'm guessing it's not treated as publication-worthy). Thanks in advance, Gracen (they/them) 16:51, 9 April 2025 (UTC)

Is this a case where WP:BLUESKY applies? -- Shmuel (Seymour J.) Metz Username:Chatul (talk) 18:02, 9 April 2025 (UTC)

I would lean against that, for cases such as this (claims that a certain algebraic identity extends to a certain class of abstract algebraic systems). BLUESKY is really for the sort of things that are common knowledge to the wider public, not for things that should be obvious to any competent mathematician. And in the case of generalizations of algebraic identities to broader systems, one does have to check that the proof really does use the laws of the broader system and that one is not accidentally getting a division by zero or something. It's valid in this case because the proof uses only distributivity, commutativity of multiplication, and associativity of addition, and there is no cancellation of factors that might become zero, but those sorts of checks are the sort of thing we should rely on published sources for, not the attention to detail and expertise of Wikipedia editors. Another reason to rely on published sources is WP:DUE: does any published source consider it worth mentioning that this factorization extends to commutative rings? If not, why should we mention it? —David Eppstein (talk) 18:08, 9 April 2025 (UTC)

BLUESKY seems more like a group of opinions rather than in any way a recognized policy. There are some limited edge cases where I can imagine this being helpful, but in general, it's hard to argue you shouldn't source certain facts, especially on articles dedicated to those facts. Similarly, see WP:NOTBLUE. – Farkle Griffen (talk) 18:21, 9 April 2025 (UTC)

There are textbooks for elementary algebra. A quick search on Internet archive brings up some books you could probably use:[2]

For more general objects like "difference of squares commutative ring", introductory books on abstract algebra can be found the same way. If there's something specific you're trying to source, it might take skimming a few books before you find one that mentions it, but I've found that there's usually at least one source that has what I need. – Farkle Griffen (talk) 18:09, 9 April 2025 (UTC)

Much appreciated, thanks! For some reason I was under the impression that grade school textbooks weren't really accepted as sources, but in retrospect that doesn't make much sense. Gracen (they/them) 19:00, 9 April 2025 (UTC)

You can often find articles in journals written by / intended for high school teachers, e.g. you can find archived issues of The Mathematics Teacher at JSTOR, up through 5 years ago. For example searches for "difference of two squares" and "difference of squares" return 101 and 36 results, respectively. You can probably get access to these via Wikipedia:The Wikipedia Library if you can't read them otherwise. Such articles often have more context and in-depth discussion than a high school textbook would, for any specific topic, and also often discuss pedagogy, common student misconceptions, etc. –jacobolus (t) 19:07, 9 April 2025 (UTC)

Many thanks; I genuinely did not know such articles existed. I suppose my whole not publication-worthy thing sounds a bit silly now.... Also, I do have access to TWL, so that's quite nice Gracen (they/them) 19:23, 9 April 2025 (UTC)

I have often had good luck finding sources for obvious material in elementary algebra and geometry in the late 19th century and early 20th century textbooks available in full text on archive.org. I'm not so sure that would work well for abstract algebra, though. —David Eppstein (talk) 20:35, 9 April 2025 (UTC)

Also, for "difference of squares" identity, one may search in introducy textbooks on non-commutative rings, since every good such text book must say that this identity is not true for non-commutative rings. D.Lazard (talk) 18:17, 9 April 2025 (UTC)

As an aside, it's probably worth mentioning Elements II.5 in the article about the difference of two squares. –jacobolus (t) 19:27, 9 April 2025 (UTC)

higher polytopes

I question the value of articles like Heptellated 8-simplexes. Is there a good reason not to bundle all the simplices (and their truncations sensu lato) of dimension ≥5 into one article? Ditto for the hypercubes, cross-polytopes, demicubes; but perhaps not the E-families (forked Coxeter-Dynkin diagrams with branch lengths 1,2,n). —Tamfang (talk) 22:35, 10 April 2025 (UTC)

I agree and I've been WP:BLARing multiple such articles recently. They have a lot of content but very little in the way of adequate sourcing. As I wrote on some other recent ones, the only source that covers the actual topic of the article, Klitzing, appears to be neither reliable nor intelligible. —David Eppstein (talk) 22:39, 10 April 2025 (UTC)

That's a pity, as it's hosted on my personal site. —Tamfang (talk) 03:10, 12 April 2025 (UTC)

Why is the title of that article plural? WP:MOS requires the singular except when there is a special reason to make it plural. Michael Hardy (talk) 23:59, 11 April 2025 (UTC)

Knuth's up-arrow notation

Can someone take a look at Knuth's up-arrow notation? Over the past couple of days, I've been reverting a series of edits by an IP editor that, as a whole, seem to be between disruptive and approaching nonsense. I'm not certain of myself on this, though, and would appreciate some feedback, either confirmation of my reverts or telling me I'm way off base. I've also placing this note on the talk page. Thanks. ArglebargleIV (talk) 09:18, 12 April 2025 (UTC)

Requested move at Talk:Chebotarev's density theorem#Requested move 31 March 2025

There is a requested move discussion at Talk:Chebotarev's density theorem#Requested move 31 March 2025 that may be of interest to members of this WikiProject. Jeffrey34555 (talk) 15:55, 14 April 2025 (UTC)

Category:Mathematical series -> Category:Series (mathematics)

How do we feel about this? It seems like there is no discussion of this anywhere. Tito Omburo (talk) 00:44, 15 April 2025 (UTC)

The standard naming for categories is to match the main article for the category even when it looks stupid and the disambiguator is not needed for any ambiguity. I don't think there is much hope of convincing the people who discuss categories to do anything differently. The way to contest this is to find a different name for Series (mathematics) and let the category name follow from it. —David Eppstein (talk) 06:11, 15 April 2025 (UTC)

ok that makes sense. The procedural posture seemed dubious is all. Tito Omburo (talk) 13:01, 15 April 2025 (UTC)

Heyting and intuitionism

I was reading Heyting algebra, which cites an article by Heyting where he supposedly introduced Heyting algebras for intuitionistic formalisms. I couldn’t find the text of that article anywhere online, but my university library has it, so I took a scan of it. If anybody wants a copy feel free to reach out.

From my reading of the text (not a thorough one), it seems like it doesn’t introduce Heyting algebras. But I would welcome if someone else took a look too. Anselm Schüler (talk) 00:31, 16 April 2025 (UTC)