User talk:David Eppstein

I don't know where Ph.D is accepted; WP tends to favor PhD somewhat, though Ph.D. is acceptable, but I draw the line at failing to decide and using just one full stop. Chris the speller ^yack 22:25, 30 December 2025 (UTC)

It should have been obvious in Hee Oh that that was a typo and that the intended formatting was Ph.D. —David Eppstein (talk) 22:35, 30 December 2025 (UTC)

(delurk) I was ready to agree with Chris (without having read David's response), when I happened to see Ph.D in an article I saw for unrelated reasons in the New York Times. It's in today's issue, called "She Tried to Kill a President. He Loved Her Anyway." --Trovatore (talk) 22:56, 30 December 2025 (UTC)

Sometimes even the Gray Lady nods? I agree with Chris that we should use an even number of dots. —David Eppstein (talk) 23:05, 30 December 2025 (UTC)

FWIW MOS:ABBREV is the place that suggests PhD is preferred, or at least one of them. (But this seems to be a MOS guideline that not so many follow.) Russ Woodroofe (talk) 23:53, 30 December 2025 (UTC)

It also seems to apply only to usage "in tight quarters such as citations, tables, and lists". —David Eppstein (talk) 23:55, 30 December 2025 (UTC)

I read the advice there as giving the preferred form of the abbreviation, which should certainly be used in tight quarters. That is, I think the section head "Abbreviations widely used in Wikipedia" is important. It says that _many_ of them should be spelled out otherwise; I think that PhD is an exception. OTOH, are we getting a local consensus for :Ph:D: ? Russ Woodroofe (talk) 02:10, 31 December 2025 (UTC)

Is it actually widely used in Wikipedia, though? Or would it be without editors like Chris going around enforcing this sort of thing? —David Eppstein (talk) 02:12, 31 December 2025 (UTC)

So ".P.hD" it is, then. --JBL (talk) 00:18, 31 December 2025 (UTC)

Or "Ph:D" --JBL (talk) 00:27, 31 December 2025 (UTC)

Ṗ..ḣḊ. --Trovatore (talk) 02:38, 31 December 2025 (UTC)

That one almost makes sense. —David Eppstein (talk) 01:25, 31 December 2025 (UTC)

So you are saying that except in tight quarters we should use "Doctor of Philosophy" instead? No, I will go with PhD as the MoS suggests. Chris the speller ^yack 01:40, 31 December 2025 (UTC)

MOS:ABBREV does not provide guidance on PhD vs Ph.D., except in tight quarters. That should not be interpreted as saying it should be spelled out (as Philosophiae Doctor for Ph.D., or Doctor of Philosophy for Oxford's idiosyncratic DPhil), but neither should it be interpreted tendentiously as saying that Ph.D. is forbidden. It is merely a lack of guidance on specific style and spelling choices, just as we have on most other such issues. —David Eppstein (talk) 01:44, 31 December 2025 (UTC)

Yes, PhD is very widely used in WP. I searched for articles with "received his PhD" and with "received his Ph.D.", and they are nearly equal, and no, none of that is because I switched from one to the other. I have been fixing cases where one dot was missing, or was until David changed the Hee Oh article back to "Ph.D", which is simply not acceptable. Please refrain from saying "Chris is going around doing xxx", which implies a certain aimlessness and recklessness, while I see it as being productive. Changing "Ph.D" to "PhD" is an improvement, as it is changing it to an approved abbreviation, but reverting that change is not an improvement to the article. Chris the speller ^yack 05:14, 31 December 2025 (UTC)

reverting that change is not an improvement to the article Chris, David already indicated that was a typo, and fixed it, before their first response here. Take the win? --JBL (talk) 19:21, 31 December 2025 (UTC)

Minor correction: it was after Chris had pointed out here that it was a typo. —David Eppstein (talk) 19:33, 31 December 2025 (UTC)

Happy New Year to all! Chris the speller ^yack 02:28, 1 January 2026 (UTC)

Thanks! To you as well! —David Eppstein (talk) 06:24, 1 January 2026 (UTC)

Happy New Year!

David Eppstein,
Have a prosperous, productive and enjoyable New Year, and thanks for your contributions to Wikipedia.
BhikhariInformer (talk) 17:12, 31 December 2025 (UTC)

   Send New Year cheer by adding {{subst:Happy New Year fireworks}} to user talk pages.

BhikhariInformer (talk) 17:12, 31 December 2025 (UTC)

Thank you! —David Eppstein (talk) 06:24, 1 January 2026 (UTC)

	Happy New Year
	Happy New Year! May 2026 be your best year yet! BD2412 T 00:53, 1 January 2026 (UTC)

Thanks! Happy new year to you too! —David Eppstein (talk) 06:24, 1 January 2026 (UTC)

Categories you have created have been nominated for possible deletion, merging, or renaming. A discussion is taking place to decide whether this proposal complies with the categorization guidelines. If you would like to participate in the discussion, you are invited to add your comments at Wikipedia:Categories for discussion/Log/2026 January 2 § Category:Fellows of the Association for Computing Machinery by year on the categories for discussion page. Thank you. ^SMason_Garrison 04:02, 2 January 2026 (UTC)

Thank you for your input at this CFD nomination. At the discussion, would you be open to sharing any real-world connection you have to the topic? RevelationDirect (talk) 01:33, 3 January 2026 (UTC)

Look it up yourself. And while you're looking up things, see WP:AGF.

But to answer your implied bad-faith accusation: I don't care about what the article about myself says. I do care about the thousands of other articles I have created on fellows of learned societies, just like any Wikipedia editor who creates articles would care about the maintenance of those articles.

Additionally, I happen to think I am in a position to understand better than some editors how defining this sort of thing is taken to be in academic circles. —David Eppstein (talk) 01:35, 3 January 2026 (UTC)

I was being intentionally vague prior to re-reading the outing guideline and, I’m afraid that opaque wording left room for misinterpretation. Sorry about that; let me try again:

I don’t think you’re acting in bad faith here at all, but advocating only for what you feel is best for the encyclopedia. I also perceive what could be a potential conflict of interest per WP:EXTERNALREL.

That nomination is discussing the prestige of an award you appear to have personally won. And one of the ~900 articles that could be impacted is
David Eppstein. Ideally your expertise could strengthen your case while still being transparent: “I work in this field with this relationship to the award and within academic circles it’s treated as defining because …”

At the discussion, would you be open to sharing any real-world connection you have to the topic? RevelationDirect (talk) 02:59, 3 January 2026 (UTC)

Thanks so much for that post, that was perfect! RevelationDirect (talk) 04:31, 3 January 2026 (UTC)

I was interested to see this edit, particularly as I wasn't challenging notability. Could you please point me to the policy you are relying on, since in more than 20 years I haven't referenced a book listing, nor been challenged on removing refs for publications, cheers Jimfbleak - talk to me? 20:22, 3 January 2026 (UTC)

Let's start with WP:AUTHOR #3 and #4c: an author with multiple reviews of their books can be notable through those reviews. We should not remove the cause of notability from an article, so we should list the reviews rather than removing them.

We should also consider the fact that, especially on a WP:BLP, all material should be supported by WP:SECONDARYSOURCEs. The books themselves are primary sources. The reviews of those books are secondary. —David Eppstein (talk) 20:25, 3 January 2026 (UTC)

But you haven't listed the reviews you are referencing. If you think they are needed for notability (I don't), surely you should at least mention the reviews you are providing references for? Jimfbleak - talk to me? 20:38, 3 January 2026 (UTC)

You mean, stating the existence of the reference in the article text? That's not how references work. If we wrote "this work was reviewed in the American Journal of Archaeology" with a footnote to the review, that footnote would be a primary source for that claim: it is the book review itself, not someone else stating independently that the review was made. When we write that Cooney published the book The Cost of Death (either as prose or in a list of published books), with the same footnote, it is a secondary source for the claim that she published the book, because it is something someone else (the reviewer) wrote, supporting the claim, with evaluative material about the claim (making it a secondary source and not merely a database entry). Similarly, when a subject is notable through the existence of multiple published in-depth sources about the subject (WP:GNG notability), the correct thing to do is to use those sources as footnotes for material in the article, not to add article text saying that they're notable because of these sources.

Separately, listing reviews of books can be useful to readers who might want to find reliably published opinions about those books. Why destroy that resource? —David Eppstein (talk) 20:44, 3 January 2026 (UTC)

I'm not challenging the validity of the information, it just seems odd to me that you need to reference the self-evident existence of a book, but not mention in the text the reviews you are relying on for notability Jimfbleak - talk to me? 06:12, 4 January 2026 (UTC)

It seems strange to me that you think the article text should say something about notability, something that is internal to Wikipedia. We could use the reviews to say something about the content of the books, or how they were received, and leaving them in the article provides an opportunity for future editors to do that if they see fit. But we don't have to use them that way, and the fact that they also convey notability is not something that should be reader-facing. —David Eppstein (talk) 06:17, 4 January 2026 (UTC)

A persistent IP user on adding citation needed tags in the lede in Solid. Dedhert.Jr (talk) 07:24, 5 January 2026 (UTC)

Your revert was a false revert. I am not a vandal. I have cited sources. I advise you to look at the citations before reverting. Its a reputable source. And if not I have 10 more citations that will do the same thing, from mainstream legacy american media. ~2025-34140-84 (talk) 04:29, 6 January 2026 (UTC)

[Context: Special:Diff/1331313891 on Moving sofa problem.] A newspaper article can be reliable for claims like "Baek claimed a solution" but not for claims like "Baek's solution is correct". For that we need peer review in a mathematical journal, not newspaper journalism. —David Eppstein (talk) 06:19, 6 January 2026 (UTC)

@David Eppstein I do not remember that being official policy anywhere. As far as I am aware. Major legacy news sources reporting on it suffices for the article to say it was solved. Either way I have no doubt the article will be edited by other users in the future to change it to "solved" because reputable sources said so. ~2025-34140-84 (talk) 01:26, 7 January 2026 (UTC)

You can start with WP:NEWSORG "Scholarly sources and high-quality non-scholarly sources are generally better than news reports for academic topics ... Press releases from organizations or journals are often used by newspapers with minimal change; such sources are churnalism and should not be treated differently than the underlying press release." —David Eppstein (talk) 02:08, 7 January 2026 (UTC)

If I want to improve the history of any mathematical topics, I might be lost. Because I could not find which sources are reliable and have no knowledge of history. For example, how do I write better novelty about Euler's characteristic's history and background, even though I have found a magazine from Cambridge Press , which includes the 20 proofs of Euler's characteristic in Junkyard, but still I am questioning the better sources? Where should I start? Dedhert.Jr (talk) 02:01, 9 January 2026 (UTC)

Richeson's book is probably a decent source for that, but for the early history of this I think the Friedman source already cited is good. Anyway, there are scholarly journals on the history of mathematics such as Historia Mathematica; what you can find in those, or in scholarly monographs like Friedman's, is probably more careful in its conclusions than popularized treatments like Richeson's. My web site's focus is more on the proofs than on their publication, so I don't think it's a good source for the history of the problem. For the frequent (but dubious) claim that Descartes found this formula before Euler, see Descartes on Polyhedra and its sources. —David Eppstein (talk) 02:09, 9 January 2026 (UTC)

Okay. But what about the history of any mathematical topic? Surely, one example of an article is not enough. Dedhert.Jr (talk) 04:14, 9 January 2026 (UTC)

I think the advice to search for scholarly journals and monographs over popularized treatments is still sound. —David Eppstein (talk) 06:01, 9 January 2026 (UTC)

A discussion is taking place as to whether the article David M. Diamond, to which you have significantly contributed, is suitable for inclusion in Wikipedia according to Wikipedia's policies and guidelines or if it should be deleted.

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Hi David Eppstein: I'm noticing that the FAC nomination for "Rules of inference" article is currently being nominated by a philosophy editor and that there are no editors with 3-CNF experience, etc, to keep things consistent with computer science perspectives; could you give it a look when time allows? ErnestKrause (talk) 22:20, 12 January 2026 (UTC)

Have looked up the transparent version in this image. Since the current user was blocked, I have no idea how to revert the current image to the transparent background. Or can you help me to do it? Many thanks. Dedhert.Jr (talk) 14:13, 14 January 2026 (UTC)

The original version of that image did not have a transparent background. Unlike Wikipedia article content, there is a concept of ownership for images; they should not be changed to different images, especially not without agreement of the original uploader. If you want an image with a transparent background it should have a different name. —David Eppstein (talk) 18:17, 14 January 2026 (UTC)

(talk page stalker) @Dedhert.Jr: since there’s a transparent version in the history, you might try requesting a history split with a distinct name.—Odysseus1479 03:08, 15 January 2026 (UTC)

Indeed there is a transparency. But I rather create it by my own, but I might need its Cartesian coordinates before tracing with Inkscape from Geogebra. Dedhert.Jr (talk) 03:38, 15 January 2026 (UTC)

If you’re recreating it as a vector graphic (which has numerous advantages anyway), the difference in extension (.SVG vs .PNG) will suffice to avoid a filename conflict.—Odysseus1479 05:03, 15 January 2026 (UTC)

@Odysseus1479. Okay. A little off-topic here. I have made a different polyhedron File:Cell of the dual snub 24-cell (transparent, symmetry).svg, with recreation by myself. But do I need to write the whole coordinates from unsaved, sandbox, Geogebra 3D? Do I need to write something like "tracing from Geogebra 3D" or similar? From other images I have made, I have written the source for tracing from other Wikimedia images alongside their authors. But in this case? Dedhert.Jr (talk) 15:48, 15 January 2026 (UTC)

The article Homogeneous variety has been proposed for deletion because of the following concern:

Unsourced for 12 years. Makes no sense; might need an expert to make sense of it.

You may prevent the proposed deletion by removing the {{proposed deletion/dated}} notice, but please explain why in your edit summary or on the article's talk page.

Please consider improving the page to address the issues raised. Removing {{proposed deletion/dated}} will stop the proposed deletion process, but other deletion processes exist. In particular, articles for deletion allows discussion to reach consensus for deletion based on established criteria.

If the proposed deletion has already been carried out, you may request undeletion of the article at any time. Sorry for the template. Bearian (talk) 10:45, 22 January 2026 (UTC)

• Queer erasure, obviously. EEng 02:35, 9 February 2026 (UTC)

I know that the answer is in List of unsolved problems in mathematics, but there might be many unsolved problems that are not ready to be included in the list (WP:NOTABILITY is behind all of this), or, in other words, new unsolved problems are published somewhere else. But have no idea where I can find it. I hope I can collect the unsolved problems in the list I made (about polyhedra), apart from the discussion in Talk:Arithmetic billiards/GA1, the book from Princeton University Press published from the previous year , and many more . For the http://openproblemgarden.org/, it's dubious by telling the promotion titles and empty conjecture statement. Talk:Arithmetic billiards/GA1. Dedhert.Jr (talk) 08:14, 23 January 2026 (UTC)

Many conferences and workshops have open problem sessions and sometimes these are published. For instance searching for "Open Problems from CCCG" will find many from one particular computational geometry conference. Many are not notable enough to list, though. —David Eppstein (talk) 08:17, 23 January 2026 (UTC)

"Many are not notable neough to list, though". Like the problem in 2023 about finding the minimal of a cube's volume? I hope there is a high possibility to include the problrm in Cube, the same way for unsolved problem about the quasigeodesic of a cube . Dedhert.Jr (talk) 08:30, 23 January 2026 (UTC)

As a person with a Ph.D. in mathematics, I disagree with your suggestion to refrain from adding spaces. The algorithm in the TeX renderer is not especially good with spaces (for example, when one uses "\left(" for a function argument, it inserts a space before the "(" ). The very reasonable assumption by the makers of the rendering engine is that a human can make much better judgement about the fine-points of spacing, although there are some things that could be better automated (e.g. it could automatically add a slight space between the end of the argument of a square root and the end of the solidus, and it could ensure a slight gap between the end of the solidus and a closing parenthesis following it).

Regarding spacing, it's standard in well-typeset math texts to use slight extra spaces between factors in an expression to emphasize the application of a power to the preceding factor, and the start of the parenthesis for the next (although this sometimes works out on its own) and between terms in an expression that are themselves complicated, so that each separate term is a bit removed from the complications of the others. Likewise in serial inequalities ( F(x) < G(x) < H(x) ) to make the separately calculated expressions stand away from the relational operators. Finally, it is always necessary for the mathematical variables embedded in running text to be separated by slight extra spaces from the prior and following text: The math variables or embedded formulas should never run-together with the text. None of this latter spacing can be provided by the TeX rendering engine, and the font-templates "math" and "mvar" are (and should be) too dumb to pull it off.

You reverted my prior edits while I was working on far more, so rather than loosing them, I went ahead and inserted them over your reversion. If you want to go into 'edit-war' mode, or are offended that I imposed my new edits after you had reverted the prior (fewer) edits in the final section, it's on you to go in and revert them again. My position on the matter is that math in Wikipedia should be an easy read, and that in this particular case of Sterling's approximation, which is widely used outside of mathematician-only crowd, it's even more important for a general audience.
~2026-31703-6 (talk) 20:56, 23 January 2026 (UTC)

No really don't do this, it makes things ugly, difficult to edit and maintain, and impossible to keep consistent; even if you disagree about "ugly", that is still two very good reasons. Surely you can find some actual problem to fix instead? --JBL (talk) 00:42, 24 January 2026 (UTC)

I saw that you reverted a bunch of edits at WP:SWEEPS2025, which indicated that a bunch of articles were delisted. Was this a misclick, or is there a concern to address? Z1720 (talk) 20:07, 31 January 2026 (UTC)

Mouse slip. I am currently topic-banned from having anything to do with GAR so a deliberate edit would be a mistake. —David Eppstein (talk) 20:08, 31 January 2026 (UTC)

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--Lajmmoore (talk 22:46, 31 January 2026 (UTC) via MassMessaging

Your good article nomination of the article Lambek–Moser theorem is under review. See the review page for more information. This may take up to 7 days; feel free to contact the reviewer with any questions you might have. Message delivered by ChristieBot, on behalf of MCE89 -- MCE89 (talk) 03:24, 1 February 2026 (UTC)

I've contacted Smith609 (talk · contribs · blocks · protections · deletions · page moves · rights · RfA) and AManWithNoPlan (talk · contribs) for their thoughts on the citation bot's recent block. sjones23 (talk - contributions) 18:34, 2 February 2026 (UTC)

I am kind of terrible at color theory, so I doubt picking colors that are closer to monochrome. Furthermore, I reduced the transparency of the surface's teal color, so one can look the edges behind. Since I use Inkscape by tracing the screenshot polyhedral structure in Geogebra, I have no comments at all and I may have learn something if you give more comments about the color. And to your comment about the edges' color, this reminds about light blue surfaces with black edges . If you have some time, you won't mind giving some better portraits? Dedhert.Jr (talk) 01:54, 3 February 2026 (UTC)

The images in the linked paper (and the triaugmented prism) were all generated using https://prideout.net/blog/svg_wireframes/ — that way I get correct 3d geometry in a vector graphics format, more accurate than trying to trace over a bitmap, but it doesn't have the fancy lighting and reflection models that you would get from povray, and it is not even very good at z-ordering. So basically all you get is the polygons, in a valid projection, and any coloring model you feel like coding up yourself. The software's web site does have some code for adding a lighting model but it doesn't mix well with partial transparency. —David Eppstein (talk) 03:20, 3 February 2026 (UTC)

If I remember, I have tried to copy your code on File:Triaugmented triangular prism (symmetric view).svg in Visual Code Python. But in the end, I have to import the libraries (or whatever the names are), which end up in failure. Dedhert.Jr (talk) 01:15, 4 February 2026 (UTC)

Please stop attacking other editors, as you did on Talk:Directed acyclic graph. If you continue, you may be blocked from editing. Comment on content, not on other contributors or people. In addition to Talk:Directed acyclic graph, you have shown similar behavior on Talk:Square. I have posted this warning as a friendly reminder and gesture of good will as recommended at WP:CONDUCTDISPUTE. EulerianTrail (talk) 08:20, 4 February 2026 (UTC)

It is not a personal attack to point out that you added information to directed acyclic graph with a malformatted reference that looked superficially relevant and specific but failed to verify the added information, and to ask you what process led you to use that reference. —David Eppstein (talk) 08:25, 4 February 2026 (UTC)

@EulerianTrail: what exactly is the attack? Because I dropped by that discussion and see nothing ruder than an old lady at church remarking that the cinnamon rolls served at brunch were undercooked. Headbomb {t · c · p · b} 09:14, 4 February 2026 (UTC)

Insulting another editor's judgment, accusing an editor of not reading, and accusing an editor of using LLMs are all personal attacks that do not contribute to the article. Especially when I try to reason with and explain the source. EulerianTrail (talk) 15:24, 4 February 2026 (UTC)

Asking you questions about how you came to be making bad edits, together with a correct explanation of what is wrong with those edits, is not a personal attack. --JBL (talk) 17:22, 4 February 2026 (UTC)

Asking how someone came up with an edit is ok to ask. But making specific unfounded accusations is not. EulerianTrail (talk) 17:43, 4 February 2026 (UTC)

The specific accusation (that you added text not supported by the source) seems well founded; then I see some questions/speculation about how that might have happened. This could be a personal attack if the substantive objection to your edit were missing or incorrect, but that doesn't seem to be the case. Similarly, if someone writes "This edit is bad for [well specified reasons]; did you use an LLM?" they aren't being friendly but they are well within the boundaries of WP:NPA, certainly at least as much as a person leaving template warnings on the talk-pages of long-time users. --JBL (talk) 17:50, 4 February 2026 (UTC)

Thank you JBL. I though the text was supported by the source, I read through several graph theory books that I am familiar. I usually go through Diestel, Doug West, and Bondy & Murty at least. In this case I thought Bondy & Murty had the best sourcing. So, it is frustrating when spending so much time on carefully reading to be accused of something else. EulerianTrail (talk) 18:08, 4 February 2026 (UTC)

Thanks for also letting me know that the convention is to not use the built-in template warning on seasoned users when a policy issue appears to be broken. Next time I will try to make a friendly crafted message rather than a cookie cutter message. My apologies David if you felt offended by the template warning, I thought it was the friendliest way to settle this issue, but now I know better. EulerianTrail (talk) 18:17, 4 February 2026 (UTC)

Hi, what exactly is the meaning of Use dmy dates|cs1-dates=ly|date=January 2024 as opposed to Use dmy dates|date=February 2026 ? Denisarona 09:17, 4 February 2026 (UTC)

The dmy dates part says to format the publication dates of references like 4 February 2026. The cs1-dates=ly part says to format minor editor-facing dates like access-dates and archive-dates like 2026-02-04. This is one of the styles allowed by MOS:DATEFORMAT. —David Eppstein (talk) 18:06, 4 February 2026 (UTC)

On 6 February 2026, Did you know was updated with a fact from the article Quadratrix of Hippias, which you recently created, substantially expanded, or brought to good article status. The fact was ... that a photograph of an airplane propeller taken by a camera with a rolling shutter (pictured) may distort the propeller into curves resembling the quadratrix of Hippias? The nomination discussion and review may be seen at Template:Did you know nominations/Quadratrix of Hippias. You are welcome to check how many pageviews the nominated article or articles got while on the front page (here's how, Quadratrix of Hippias), and the hook may be added to the statistics page after its run on the Main Page has completed. Finally, if you know of an interesting fact from another recently created article, then please feel free to nominate it.

Z1720 (talk) 00:02, 6 February 2026 (UTC)

Have you ever tried to delete the image you want to? I would like to delete the image that I have merged from others and start to draw, but not sure with the result. If I upload a different drawing with the same name, people may undid my revision. Dedhert.Jr (talk) 08:17, 7 February 2026 (UTC)

If it's within a week of uploading and unused, you can tag it with {{g7}} but otherwise I think the process is a deletion request . —David Eppstein (talk) 08:30, 7 February 2026 (UTC)

Done manually. Dedhert.Jr (talk) 08:53, 7 February 2026 (UTC)

Your good article nomination of the article Lambek–Moser theorem has passed; congratulations! See the review page for more information. If the article is eligible to appear in the "Did you know" section of the Main Page, you can nominate it within the next seven days. Message delivered by ChristieBot, on behalf of MCE89 -- MCE89 (talk) 08:30, 7 February 2026 (UTC)

Your good article nomination of the article Circle packing theorem has passed; congratulations! See the review page for more information. If the article is eligible to appear in the "Did you know" section of the Main Page, you can nominate it within the next seven days. Message delivered by ChristieBot, on behalf of A.Cython -- A.Cython (talk) 21:32, 8 February 2026 (UTC)

A difficult one, but we got through it in the end. Ironically I immediately found myself demanding specific page numbers from another editor in Template:Did you know nominations/Group Architects, New Zealand. Anyway, thanks, A.Cython! —David Eppstein (talk) 21:53, 8 February 2026 (UTC)

Welcome to the strange world of WP, where everyone has an opinion and everything is (more or less) in flux. After 25 years, somehow this strange system still works, it just needs a little bit of extra work. A.Cython(talk) 00:19, 9 February 2026 (UTC)

Algebra has a good structure. Do you think Graph theory will have a similar structure, although I am unfamiliar with these subjects? Dedhert.Jr (talk) 02:16, 9 February 2026 (UTC)

It's not really a question of reordering, but algebra has a section with major branches of the field, while that appears to be missing from graph theory. See e.g. Algebraic graph theory, Extremal graph theory, Geometric graph theory, Graph enumeration, Structural graph theory (for which we don't really have an article; Graph structure theorem is only one very specific result), etc. There is a finer-grained subdivision into areas at . On the other hand, algebra is a big part of mathematics education and graph theory is not so much, so I don't think algebra's education section should be copied in graph theory. —David Eppstein (talk) 02:32, 9 February 2026 (UTC)

I have asked about the definition of a graph. Are there many variations of the definition of a graph, other than the directness? I hope I can cut off some technical parts and let them be explained in Graph (discrete mathematics). Dedhert.Jr (talk) 02:37, 9 February 2026 (UTC)

There are many ways to formalize the definition of a graph, with different sources using different formalizations because this has not been standardized and generally makes only minor differences to what one does with the graph. One important point of variation is whether a graph has a set of pairs of vertices as its edges or whether the edges of a graph are separate objects themselves (allowing generalizations to multigraphs etc). But also some people will specify what the vertices are, while others will say they can be any set, etc.; this makes a difference when talking about unions of graphs. Some definitions will allow graphs with an empty set of vertices; some will not. See also the recent debate on Talk:Group (mathematics) on the many different ways to formalize the definition of a group and how we should choose among them for our articles. —David Eppstein (talk) 02:42, 9 February 2026 (UTC)

I think this is difficult to write "One can understand that the graph is a mathematical structure containing the vertices and edges", and then write the next paragraph, "A graph can have orientation, which is called a directed graph; otherwise it is an undirected graph". Some polishing may be needed. You won't mind if you can supervise my edits? I'll search for the sources later. Dedhert.Jr (talk) 02:49, 9 February 2026 (UTC)

Okay. I have made several subsections regarding subareas of graph theory. In algebraic graph theory, I have added linear algebra and group theory for polynomials, spectral theory, and symmetry. The source mentions them. However, in the other subareas, even though the article gives the topics, I still cannot exactly find the sources, and yet there could probably be something missing that supposedly talks about what the most important topics are for each subarea. The only thing I could trust is through each book that is entirely about each subarea. For example, geometric graph theory mentions Steinitz's theorem, planar straight-line graph, intersection graph, Levi graph, etc., but most of these are probably from discrete and computational geometry; so, should I search for books on discrete and computational geometry? Does the four-color theorem studied mostly in extremal graph theory due to the study of coloring? I also cannot find some topics about the field of probabilistic graph theory, which in the end is called a random graph.

I won't mind if you want to add some more to the under-construction article. Dedhert.Jr (talk) 12:49, 9 February 2026 (UTC)

Four-color theorem is not extremal graph theory at all. It is about planarity (topological graph theory) and graph coloring (chromatic graph theory, if you want to give it a fancy name). Extremal graph theory is about maximizing the number of edges in graphs with given properties. —David Eppstein (talk) 17:57, 9 February 2026 (UTC)

Got it. Extremal graph theory studies the maximum number of edges. For topological graph theory, it is about graph embedding in a topological space, but I cannot find the sources on its contents about topological graph theory, especially when I was searching the list that includes the coloring problem, crossing number (although we have an article about the book anyway), and graph minors. For probabilistic graph theory, the only thing I could think of is Markov chain, but are there more? Also, is Ramsey theory part of extremal graph theory, or strongly connected basically? Dedhert.Jr (talk) 07:53, 11 February 2026 (UTC)

The theory of graph minors is used in topological graph theory, but really it belongs to structural graph theory.

As for probabilistic graph theory, see Random graph, Random minimum spanning tree, Rado graph#Finite graphs and computational complexity, Giant component, Category:Random graphs, etc. —David Eppstein (talk) 08:06, 11 February 2026 (UTC)

It's over than seven days. Do you think there are some missing topics in each field? Dedhert.Jr (talk) 08:27, 5 March 2026 (UTC)

Hi Eppstein! I noticed you added a external link (https://expandyourlimits.wordpress.com/) by revert on Diana Maynard, but the blog seems to be aboout a traveller, not about the article subject, a computational linguist. So I have removed the link. Xzkdeng (talk) 08:19, 9 February 2026 (UTC)

You obviously didn't read the "about" link on the blog, did you? If you had you would have learned that it is in fact the same person and not done something uninformed. —David Eppstein (talk) 08:24, 9 February 2026 (UTC)

Oh, I only read the first paragraph and didn't scroll down... Xzkdeng (talk) 08:27, 9 February 2026 (UTC)

Notable or not? Bearian (talk) 20:36, 9 February 2026 (UTC)

The article lists enough book reviews that I think he passes WP:AUTHOR. A few more: /[ https://doi.org/10.1007/s10680-016-9395-z], , . —David Eppstein (talk) 23:01, 9 February 2026 (UTC)

Thank you! Bearian (talk) 23:10, 9 February 2026 (UTC)

Hey, sorry if I haven't been so active with this review in the past few days. There have been a lot of things stressing me outside the website, and I've been having trouble keeping up with myself and my issues. I'll still try to get the review done as soon as I can, but like I said, it's been recently hard for me. — Alex26337 ^(talk) 03:47, 10 February 2026 (UTC)

Thanks for letting me know. And take your time; I'm not in a rush. —David Eppstein (talk) 07:27, 10 February 2026 (UTC)

Notable or not? I respect your opinions on academics. Bearian (talk) 02:27, 16 February 2026 (UTC)

Citations look low for psychiatry but maybe one can find enough book reviews for WP:AUTHOR? —David Eppstein (talk) 03:12, 16 February 2026 (UTC)

Insightful. Will do. Bearian (talk) 03:41, 16 February 2026 (UTC)

I'm somewhat dissatisfied with the present state of Lambert W function; it goes on an eclectic tour through the various interdisciplinary applications, which amount to stating where its characterising functional equation arises and convey little understanding.

(I would even deride it as representative of Wikipedia's fundamental limitations for math (the other being the policy against original research, though that has some shining exceptions like random permutation statistics), but that reflects my general bias of preferring it to contain sufficient tools for one's understanding to be functionally complete than expositions/statements of results, where I know site policy favours the latter.)

more importantly, its discussion of Lambert W as an exponential generating function is extremely barren (only existing in #Asymptotic expansions and #Tree counting and combinatorics, and only then barely). I propose a page on ${\displaystyle T(x)=-W(-x)}$, giving more details (specifically on its expansions about ${\displaystyle x=0}$ and ${\displaystyle x={\frac {1}{e}}}$ (which has a branch cut across ${\displaystyle x>{\frac {1}{e}}}$, but whose first term suffices for getting asymptotics)) then going on an eclectic tour through compositions of it with other e.g.f.s to (combinatorially and asymptotically) count (and get statistics of) composite structures involving trees (in particular endofunctions, whose digraph representations are sets of cycles of trees like how permutations' are sets of cycles).

It would largely draw from Riordan's Enumeration of Linear Graphs for Mappings of Finite Sets and Flajolet & Odlyzko's Random mapping statistics (note that this Wayback'd version is the best-quality copy I've found.)

I've started writing a page in my OEISwiki userspace, which I stress is only to be considered an extremely rough draft; all of the collapsed discursions are irrelevant and would be omitted in a Wikipedia page, many of its contents currently 'offloaded' into six math.StackExchange links would be included explicitly, and it would be much more idiomatic.

speaking of which, in the process of preliminary research for the next version, I arrived upon a result currently in a seventh MSE post (this time a question I have been racking my brain over to no avail). Though I'm aware it's likely outside your purview, would you happen to know where to look for a combinatorial (not Lagrange-inversion-based) proof of the fact that there are ${\displaystyle {n-1 \choose j-1}{n! \over k!}\left\{{n-j \atop n-k}\right\}}$ ways to arrange ${\displaystyle n}$ nodes into a forest of ${\displaystyle j}$ trees with ${\displaystyle k}$ leaves? (I strongly imagine it has been considered already, the question details my confusion (which chiefly lies in the binomial coefficient) further)

finally, there is the matter of name. Usually, the convention is to name a topic (subfield, theorem, function, etc.) after whoever was first to investigate it, or possibly the second if the first was Euler and naming it after him would cause confusion (ie. "Euler's number" ${\displaystyle e}$ and Euler(-Mascheroni)'s constant ${\displaystyle \gamma }$). Here, the former is not the case, but the latter (which I've seen used by a few papers) would be possibly more didactic in correspondence with Cayley's formula.

I am currently weighed down by studies and my dissertation, so can't guarantee any promptness in getting to this, but would like a reasoned second opinion on its usefulness and desirability. Drone Better (talk) 10:35, 16 February 2026 (UTC)

On 17 February 2026, Did you know was updated with a fact from the article Circle packing theorem, which you recently created, substantially expanded, or brought to good article status. The fact was ... that the circle packing theorem has been used to construct flattened maps of the human brain? The nomination discussion and review may be seen at Template:Did you know nominations/Circle packing theorem. You are welcome to check how many pageviews the nominated article or articles got while on the front page (here's how, Circle packing theorem), and the hook may be added to the statistics page after its run on the Main Page has completed. Finally, if you know of an interesting fact from another recently created article, then please feel free to nominate it.

HurricaneZeta^C 00:02, 17 February 2026 (UTC)

Your good article nomination of the article Perles configuration has been placed on hold, as the article needs some changes. See the review page for more information. If these are addressed within 7 days, the nomination will pass; otherwise, it may fail. Message delivered by ChristieBot, on behalf of Alex26337 -- Alex26337 (talk) 08:37, 20 February 2026 (UTC)

I saw you mention the article 24-cell in the depths of that other discussion, and... breathless. I am breathless. I would make a project of cleaning it up, but I am afraid to touch it. Stepwise Continuous Dysfunction (talk) 23:15, 20 February 2026 (UTC)

@Stepwise Continuous Dysfunction. Sorry for butting in. Go ahead! Dedhert.Jr (talk) 14:23, 20 March 2026 (UTC)

If you would like to work on the 24-cell article, please go ahead. I was not concerned about getting in anyone else's way, but rather expressing a kind of awe. The endnotes in 24-cell are so big, so multitudinous, so interlinked and cross-connected (I have found multiple closed loops) that they are, in their own way, a monument to human strangeness. The article really does need to be fixed, but doing so would erase something weird, and I have mixed sentiments about that. Stepwise Continuous Dysfunction (talk) 22:20, 20 March 2026 (UTC)

FWIW the user who is responsible for that (Dc.samizdat) is still active and there is a long discussion on their user talk here related to a similar issue at 600-cell -- see this old version. --JBL (talk) 23:30, 20 March 2026 (UTC)

Your good article nomination of the article Perles configuration has passed; congratulations! See the review page for more information. If the article is eligible to appear in the "Did you know" section of the Main Page, you can nominate it within the next seven days. Please also consider reviewing somebody else's nomination to help keep the backlog down. Message delivered by ChristieBot, on behalf of Alex26337 -- Alex26337 (talk) 05:03, 24 February 2026 (UTC)

Thanks! And thanks also for your own patience in this review. Your suggestions led to a lot of improvements to the article and that, more than the shiny green badge, is what I most hope to get out of the GA process. —David Eppstein (talk) 06:53, 24 February 2026 (UTC)

Somehow this original research has survived for decades. Bearian (talk) 01:19, 25 February 2026 (UTC)

I don't know much about this topic but I'm not sure it's fair to call it original research when its two references (one very badly formatted) are both published and heavily cited. —David Eppstein (talk) 03:03, 25 February 2026 (UTC)

Ok. Bearian (talk) 03:32, 25 February 2026 (UTC)

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--Rosiestep (talk) 09:27, 25 February 2026 (UTC) via MassMessaging

FYI on Schonhardt polyhedron, it appears that Wunderlich's octahedron has a similar structure to the Schonhardt polyhedron. Goldberg and Cromwell's Polyhedra cover this, although Goldberg has found another unstable polyhedron, which apparently looks like pentagonal bipyramids attached vertically-horizontally on one of their faces (see p. 224 for the illustration). Dedhert.Jr (talk) 03:09, 27 February 2026 (UTC)

Interesting. It does appear to be the same as or very similar to the Schönhardt polyhedron, rather later than Schönhardt. P.224? The pages on Goldberg run from 165 to 170. —David Eppstein (talk) 08:14, 27 February 2026 (UTC)

Cromwell's Polyhedra at page 224. Wonder you can add some information on Wunderlich's octahedron (or triangular antiprism), and I'll add a new redirect article. And for Goldberg's bistable polyhedron, I'll add this to Pentagonal bipyramid; do you mind if I ask for an illustration? I am trusting in your skill. Many thanks. Dedhert.Jr (talk) 10:34, 27 February 2026 (UTC)

On a second thought, I don't think that Goldberg's should be in a pentagonal bipyramid. It's just said "dipyramids". I'll retract my request on picture. Dedhert.Jr (talk) 10:45, 27 February 2026 (UTC)

Oh wait. It is. But it looks like stacked. Dedhert.Jr (talk) 11:06, 27 February 2026 (UTC)

If indeed Wunderlich is a mere rediscovery of Schönhardt, then there is no "information on Wunderlich's octahedron" to be added, except possibly for the information that it was rediscovered by Wunderlich. —David Eppstein (talk) 19:07, 27 February 2026 (UTC)

Described by Wolfram , Wunderlich's octahedron and Schonhardt polyhedron are appear to be the same polyhedron, 37 years differences. I can't find behind Wunderlich's discovery, probably because of behind the name of "bistable". And some sources use Wunderlich's for the honor of works .

Out of topic, do you think it is ready to have an article on Multistable polyhedron (jumping polyhedron, bistable polyhedron, or similar name), since I have found another source from Wunderlich's on shaky antiprisms ? Dedhert.Jr (talk) 11:26, 2 March 2026 (UTC)

Ok, I added a short paragraph about Wunderlich to Schönhardt polyhedron. —David Eppstein (talk) 01:33, 3 March 2026 (UTC)

Thank you. I have added an alternative name. Meanwhile, I'll put those into my list on uncreated articles for now. Dedhert.Jr (talk) 02:01, 4 March 2026 (UTC)

See the last paragraph of Polyhedra (book); this appears to be another example of the same kind. —David Eppstein (talk) 04:50, 4 March 2026 (UTC)

You protected Wall-Sun-Sun prime on November 8th, 2020. Since then, it has seen some edits and minimal vandalism. As it has been a significant amount of time, I suggest temporarily reducing the protection to see if it is still necessary.

P.S. This is coming from a novice editor who hasn't discussed anything like this before. Please let me know if my request is misguided. Senator Spectral (talk) 05:28, 12 March 2026 (UTC)

This is to prevent edits by a Wikipedia:Long-term abuse perpetrator, for whom this article was (before the protection) one of their regular targets, and who has made contributions to other number-theoretic target articles as recently as one month ago. Presumably, the semi-protection has prevented that from happening in this one. It is only semi-protection; logged-in and established users are welcome to edit the article. —David Eppstein (talk) 06:09, 12 March 2026 (UTC)

Okay, thank you for the clarification. Senator Spectral (talk) 04:52, 13 March 2026 (UTC)