Wikipedia talk:WikiProject Mathematics/Archive/2020/Jan

Douglas Ulmer
Eyes and input would be appreciated here. Short version: COI edits at a page that survived AfD as a "no consensus" back in 2017. XOR&#39;easter (talk) 22:45, 3 January 2020 (UTC)

Gleason's theorem nominated for Good Article status
I've nominated Gleason's theorem for Good Article status, because after a few episodes of improvements, I've run out of ideas for further ones. XOR&#39;easter (talk) 18:02, 4 January 2020 (UTC)

You are missing the fact that there is now also a pretty elementary proof of Gleasons' theorem due to Keane and others. https://www.researchgate.net/publication/231919294_An_elementary_proof_of_Gleason's_theorem Richard Gill (talk) 06:34, 5 January 2020 (UTC)
 * As I mentioned over at the Talk page, I had thought that was already in the reference list at least. Thanks for noticing the omission; it is referenced and used now. XOR&#39;easter (talk) 16:49, 5 January 2020 (UTC)


 * I will begin a review soon; other reviewers are most welcome! Jakob.scholbach (talk) 20:21, 6 January 2020 (UTC)

Russell's paradox redirects
Please comment on the following set of redirects for discussion: Redirects for discussion/Log/2020 January 6 — Naddruf (talk ~ contribs) 19:16, 6 January 2020 (UTC)
 * Which leads to the question of what to do with Principle of comprehension, which also redirects to Russell's paradox, but is not mentioned there. Perhaps it should be re-redirected to Axiom schema of specification, instead.  I'd do it myself, but I am an expert, and I may be missing a popular use which should be redirected elsewhere.  — Arthur Rubin  (talk) 23:41, 6 January 2020 (UTC)

Inverse Pythagorean theorem
I have created a new article titled Inverse Pythagorean theorem. I'm not sure it's worth a separate article, but if so it needs more work. It's severely stubby in its present form. Michael Hardy (talk) 00:19, 30 December 2019 (UTC)

Worth it, I think. One could include a proof, history/origins of the idea, applications, etc. to flesh it out a bit more. Jordan Mitchell Barrett (talk) 07:26, 7 January 2020 (UTC)

Citation oddity
In Cartan connection, a citation was given as However, upon inspection, following that DOI, it seems is really what is being cited.

However, in the literature out there, everyone seems to be citing this as the first version. What's going on here? &#32; Headbomb {t · c · p · b} 15:43, 6 January 2020 (UTC)
 * The latter title appears to have more GS citations than the former, 136 to 17. Looking quickly over those 17, they include some pretty dubious items, like 3 by M. S. El Naschie. My guess is that the title was written incorrectly in one place and then carelessly copied into others. XOR&#39;easter (talk) 17:36, 6 January 2020 (UTC)
 * I'd say that's a plausible scenario. Either way, it's the second version in the article now. &#32; Headbomb {t · c · p · b} 18:49, 6 January 2020 (UTC)
 * Outside of WP articles, the main source of this first mistaken title seems to be the Springer Encyclopedia of Mathematics, e.g., search for the title in the the reference list at . -- 19:37, 6 January 2020 (UTC)
 * The origin lies in the fact that there is a (Russian translated) collected works of Cartan published by Kazan University in 1962 under the title "Affine, Projective, and Conformal Connection Spaces". — MarkH21talk 08:00, 7 January 2020 (UTC)
 * Interesting! I had been wondering if the paper had maybe been included under a different title in a collection. XOR&#39;easter (talk) 14:36, 7 January 2020 (UTC)

Draft:Fraïssé limit
A review is requested of whether this draft should be accepted as a separate article. Robert McClenon (talk) 10:34, 1 January 2020 (UTC)


 * To clarify: Draft:Fraïssé limit contains all the content of Fraïssé's theorem and Age (model theory), so if it is accepted, those two articles can be deleted and redirected to it. --Jordan Mitchell Barrett (talk) 07:21, 7 January 2020 (UTC)


 * Thank you, User:D.Lazard and User:Michael Hardy. Edits have been requested.  The draft is about mathematics, and I have forgotten more math than most people have learned.  Robert McClenon (talk) 20:06, 7 January 2020 (UTC)
 * I have accepted the draft. I am leaving the previous articles so that the proposal to merge can continue being discussed.  Robert McClenon (talk) 05:58, 8 January 2020 (UTC)

Merger proposal: Glossary of module theory -> Glossary of ring theory
Dear all. I have made a proposal that we merge "glossary of module theory" into "glossary of ring theory" (and rename the latter to "glossary of ring and module theory") at Talk:Glossary of module theory. Interested editors or editors that object to the proposal are invited to participate in the discussion. (This is really the style issue: I personally prefer few but somehow lengthy glossaries but, of course, the others might have a different preference.) -- Taku (talk) 23:57, 27 December 2019 (UTC)


 * So far, there have been one opposition and no support; accordingly, unless there is a surge?? of new supports, I will withdraw the proposal in a week or so. -- Taku (talk) 00:04, 9 January 2020 (UTC)

Categorization of mathematical functions possibly up for deletion at CfD
I guess some of you might be interested into a CfD discussion regarding multiple categories grouping special functions like trigonometric, hyperbolic, Jacobian and lemniscatic elliptic functions and their inverses:

Categories for discussion/Log/2019 December 15

The actual contents is organized/merged in a number of larger articles with incoming redirects from the actual function names (that is, the English and Latin names as well as common symbolic names) pointing to the corresponding info in them. These redirects are categorized in order to show up in the corresponding categories of the category system.

Some people interpret our guidelines on categories as if redirects would not to be included in categories and only articles should show up in categories (regardless of their title), while others (including myself) think redirects are appropriate to be included in cases such as this one (so that the actual keywords show up in the category system) and that the relevant guidelines explicitly support this particular usage.

Since people interested in mathematics are among those mostly affected by the outcome of this discussion I thought I would let you know. --Matthiaspaul (talk) 01:37, 13 January 2020 (UTC)
 * Personally, I have doubts about the Latin names being printable redirects or in categories, but that's an RFD question, rather than a CFD question. — Arthur Rubin  (talk) 02:15, 13 January 2020 (UTC)

Redirects for discussion on 32767, 32,767, 32767 (number)
There is an RfD on specific numbers at Redirects for discussion/Log/2020 January 13. Feel free to participate. — MarkH21talk 01:58, 13 January 2020 (UTC)
 * Update: speedy retargeted. — MarkH21talk 05:04, 13 January 2020 (UTC)

Parallel (operator)
Could someone check the the content of the article Parallel (operator). It says that "the parallel operator has $\infty$ as neutral element and for $a \in \overline{\mathbb{C}}$ the number $-a$ as inverse element. Hence $(\overline{\mathbb{C}},\|)$ is an Abelian group.|undefined"

It seems for me that the number $$-a$$ is an inverse element of a only if $$a\neq 0$$, because $$0 \| (-0)=0\neq\infty$$. Hence only $$(\overline{\mathbb{C}}-\{0\},\|)$$ is an Abelian group.

A further remark, a link Series-parallel duality to Parallel (operator) has been added to List of dualities. I don't think the subject belongs to duality (mathematics).--Cbigorgne (talk) 13:03, 12 January 2020 (UTC)


 * The problem is that the operator is not continuous at (0,0) and is not defined in the article for this value. Thus it is not a group. However, restricted to nonzero values, it is clearly a group, isomorphic to $$\mathbb C$$, through the multiplicative inverse function. D.Lazard (talk) 14:30, 12 January 2020 (UTC)
 * I have tagged or fixed the main mathematical flaws, which are all a consequence of the fact that $$0\|0$$ is an indeterminate form, and is therefore not defined. D.Lazard (talk) 18:21, 12 January 2020 (UTC)

Duality of the series and parallel operations corresponds in circuit analysis to duality of series and parallel circuits. Duality of series and parallel circuits can be interpreted as a special case of the duality of planar graphs. And duality of planar graphs, in turn, is closely related to polar reciprocation of polyhedra and, through it, to projective duality. Why would you think all of this should be unrelated to duality (mathematics)? —David Eppstein (talk) 00:37, 15 January 2020 (UTC)

Links to DAB pages
I have collected another batch of articles with math(s)-related links to DAB pages where expert help would be welcome. Seach for "disam" in read mode and for "{d" in edit mode; and if you solve any of these puzzles, remove the dn tag and post done here.


 * Cyclical monotonicity ✅ — MarkH21talk
 * Data hub ✅ XOR&#39;easter (talk) 17:14, 18 January 2020 (UTC)
 * Difference hierarchy ✅ JBL (talk)
 * Fermat’s and energy variation principles in field theory ✅ XOR&#39;easter (talk) 17:05, 18 January 2020 (UTC)
 * Jean-Pierre Ramis ✅ JBL (talk)
 * List of first-order theories ✅ D.Lazard (talk) 12:03, 18 January 2020 (UTC)
 * Locality-sensitive hashing ✅ XOR&#39;easter (talk) 17:23, 18 January 2020 (UTC)
 * Lusin's separation theorem ✅ XOR&#39;easter (talk) 17:16, 18 January 2020 (UTC)
 * Rigid analytic space ✅ — MarkH21talk
 * State space ✅ (though maybe someone should check my work) JBL (talk)
 * Subdivision surface ✅ JBL (talk)
 * Suspension (dynamical systems) ✅ XOR&#39;easter (talk) 17:23, 18 January 2020 (UTC)
 * Tautological one-form ✅ — MarkH21talk
 * Tensor reshaping ✅ (although this article is worth for AfD ot WP:TNT) D.Lazard (talk) 13:47, 18 January 2020 (UTC)
 * Vasiliev equations ✅ XOR&#39;easter (talk) 17:05, 18 January 2020 (UTC)
 * Zij al-Sindhind

Thanks in advance, Narky Blert (talk) 01:22, 18 January 2020 (UTC)
 * The case of Zij al-Sindhind looks tricky. I'm not able to figure out which al-Baghdadi is meant from the source provided; this may call for somebody who has more than a casual familiarity with medieval Islamic science. XOR&#39;easter (talk) 17:05, 18 January 2020 (UTC)
 * If this al-Baghdadi has a Wikipedia article, this can only be Ibn Sa'd becuse for the other entries of Baghdadi (disambiguation), the living dates do not correspond. But I have no way to know whether Ibn Sa'd is the one that is meant. D.Lazard (talk) 17:28, 18 January 2020 (UTC)
 * I've added Zij al-Sindhind to my Islam bookmarks folder also, in case someone there knows. Narky Blert (talk) 14:47, 19 January 2020 (UTC)

I've reverted your fix at Cyclical monotonicity -- see my edit summary for explanation. For everyone else, the question is the meaning of "correspondence" in the context of mutli-valued functions. --JBL (talk) 21:37, 20 January 2020 (UTC)
 * Isn't the article about vector-valued functions? It's only multi-valued if you don't think of a vector as a single object. In any case, the phrase seems to be directly copied from these notes, which uses the surjective map symbol. This really seems to mean an ordinary vector-valued function on Rn. — MarkH21talk 21:53, 20 January 2020 (UTC)
 * Okay, I did find a definition (pg 3) for "correspondence" as a bona fide function $$f: X \rightarrow 2^Y$$, with no conditions on surjectivity or injectivity. I suppose this is precisely what is described at Multivalued function. I find it to be silly terminology since a "multi-valued function" is still an ordinary "single-valued function" with the right codomain, but oh well I'm not an economist. — MarkH21talk 22:04, 20 January 2020 (UTC)

Penrose tiling
Penrose tiling, an article that you or your project may be interested in, has been nominated for a community 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. AIRcorn (talk) 06:42, 19 January 2020 (UTC)
 * I view this reassessment as the first shot in an attack on mathematics content in Wikipedia and an attack on the principle that Wikipedia should include and encourage articles on technical content. See the somewhat heated discussion at Wikipedia talk:Good article nominations for more. —David Eppstein (talk) 19:08, 20 January 2020 (UTC)
 * Its not. Its just some regular cleanup I do every so often of old GAs with tags. AIRcorn (talk) 19:25, 21 January 2020 (UTC)
 * Speaking generally, I have come to the view it might be ok not to summarize the whole article in the lead when the subject matter is technical. Especially lately, the technical template seems to be in use to indicate the lead contains some technical *precisions* which are simply not understandable without background knowledge. I see this is a matter of trade-offs; like in a board game, you need to make a sacrifice for the greater goal. *Precisions* in the lead are something that can be scarified (since non-math editors seems perfectly content to have a in-depth technical discussion in the body). —- Taku (talk) 23:21, 20 January 2020 (UTC)

Upcoming RFC
Please put Manual of Style/Medicine-related articles/RFC on pharmaceutical drug prices on your watchlists. Don't answer yet (we're still trying to decide whether anything needs to be polished up any more), but I'd really appreciate it if people who know about statistics/databases would plan to share your expertise with us once it opens (hopefully in another day or two). Thanks, WhatamIdoing (talk) 03:14, 22 January 2020 (UTC)