User talk:David Eppstein

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Hi, and welcome to my User Talk page! For new discussions, I prefer you add your comments at the very bottom and use a section heading (e.g., by using the "New section" tab at the top of this page). I will respond on this page unless specifically requested otherwise. For discussions concerning specific Wikipedia articles, please include a link to the article, and also a link to any specific edits you wish to discuss. (You can find links for edits by using the "compare selected revisions" button on the history tab for any article.)

I'm trying to find an alternative solution after having different opinions. What I mentioned about these different opinions is that you mentioned the solution of breaking into "Geometry" (and another user added "Geometry and topology"). My different solution is by adding "Mathematical object" because subcategorizing by the fields could lead to the potential of unmatchable fields in mathematics articles (see the discussion of me and Bilorv lately), and we do have articles of curves, polygons, polyhedrons, and other objects such as Mobius strip and Borromean rings. However, the phrase "Mathematical object" may be ambiguous based on the fields as well, as our article says. So I prefer to find the alternative name of the subsection "Geometrical object", hopefully listing those objects. However, I am worried that the Mobius strip and Borromean rings may not be included and they are relevant to the topological topics. To put it plainly, are they both geometrical or topological objects, as they are unspecifically mentioned as mathematical objects? Dedhert.Jr (talk) 13:45, 31 March 2024 (UTC)[reply]

If they have to be only one, it is topological. But there is a lot of geometry in both articles. Also, the distinction between mathematical objects, mathematical theories, mathematical theorems, and mathematical problems is less clear than you may think; many of our articles cover both. For instance, is Euclid–Euler theorem about a theorem, or is it about even perfect numbers, as mathematical objects? —David Eppstein (talk) 16:46, 31 March 2024 (UTC)[reply]

I would probably say that Euclid–Euler theorem describes a theorem, explaining that a perfect even number has a form of prime number ${\displaystyle 2^{p-1}(2^{p}-1)}$, where ${\displaystyle p}$ is a prime number; so maybe they could be included as concepts and topics, or theorems specifically. The mathematical object, as I mentioned earlier, is ambiguous because of the phrase usage in different areas of mathematics. That's why I prefer to split up into "Mathematical concepts and topics" (including theorem, lemma, conjecture, and others) and "Geometrical and topological objects"??? (including points, lines, curves, polygons, tesselations, polyhedrons, honeycombs, and polytopes).

Maybe we could take more examples from our GA list. Squaring the circle, from my perspective, is talking about the problems in geometry that challenge the construction of a square with an area of a given circle; so this could be included in concepts and topics. Prince Rupert's cube mostly focuses on its object itself and less on its generalization including the problem of the Rupert property that exists in all polyhedra. Maybe you could share your perspective on these articles by their categorization? Dedhert.Jr (talk) 04:28, 1 April 2024 (UTC)[reply]

If the article were moved to the title even perfect number (displacing the current redirect), would it suddenly become an article about an object rather than an article about a theorem?

Prince Rupert's cube is less about a specific object and more about the counterintuitive fact that one can pass objects through holes in themselves.

Also, your proposed classification makes no room for objects that are not geometrical and topological, such as for instance prime number, to pick an obvious example. —David Eppstein (talk) 04:53, 1 April 2024 (UTC)[reply]

So, in conclusion, are you saying that we should break them into more categories by its field, as in "Geometry and topology"? If that's the case, then I have no other arguments against this. However, if we break them into "Geometry and topology", should we also have to break all of the concepts and topics into different areas by fields, as in "Algebra", "Arithmetic and number theory", "Graph theory", and others? That is what I'm illustrating about this scenario. Dedhert.Jr (talk) 05:02, 1 April 2024 (UTC)[reply]

No matter what categories we choose, we're going to need an "everything else" subcategory. See for instance the subdivision of sports into some specific sports and everything else, and the subdivision of music into albums, songs, classical compositions, and everything else. So what's wrong with geometry+topology / everything else? Why does it demand that we further subdivide? —David Eppstein (talk) 05:06, 1 April 2024 (UTC)[reply]

Oh. I see. I was trying to think about providing subcategories in the future. I think I will give a support to break into "Geometry and topology". Sorry. Dedhert.Jr (talk) 05:08, 1 April 2024 (UTC)[reply]

Hello David, I've responded to your GA comments, and I aim to read the rest of the article this next week. Jakob.scholbach (talk) 20:46, 31 March 2024 (UTC)[reply]

It is quite depressing to realise that only 99.99% of contributors and 99.963% of readers believe that we (including the encyclopedia) exist on planet Earth, Solar System, etc. I take the chance that almost everyone is aware of this. However it is even more astonishing to find that those who can read, and many who can write, the English language do not intimately know the names of every state of the United States of America - and that if you refer to, say, North Carolina you are not referring to a mix of a track released by the recording artist Shaggy sometime before the creation of Amazon (afterwhich some river is Southern USA is named). I find it incredible that very few Americans (those living between Mexico/Canada and Canada/Russia) know where Ghent is, or why it is a significant aspect in their history. It is for that reason that I put the name of the nation after the State, as I do counties in England, regions of Scotland, and states of Australia, India and Pakistan (I have to check in other nations...). I do not assume that every reader, or a significant percentage of them, actually would know which nation Maryland, Avon, Udder Pradesh, and Tasmania belong to. I add in that detail, which in no way diminishes the encyclopedia. That said, your subsequent edits cleared up the nationality issue nicely. LessHeard vanU (talk) 16:25, 3 April 2024 (UTC)[reply]

What I know about Ghent is "that city with the nice canalside cellar restaurant that we stopped at once on our way back from Bruges". But I suspect that's not the significant aspect of history you were referring to. —David Eppstein (talk) 07:03, 5 April 2024 (UTC)[reply]

Treaty of Ghent. However, if there is a good source* for your meal and notability can be established, then it could be worked into the article about the city. LessHeard vanU (talk) 14:50, 6 April 2024 (UTC) *not sauce![reply]

Well, I know more about Ghent than Dayton, at least. —David Eppstein (talk) 00:28, 7 April 2024 (UTC)[reply]

I thought that Pappus's centroid theorem, Dandelin sphere, and Napkin ring problem are part of the polyhedron. The Pappus's centroid theorem is about theorems involves the solid of revolution with the measurement properties such as surface area and volume, which might be included in calculus. On the other hand, Dandelin sphere talks about two spheres tangent to a plane inside of a cone, and Napkin ring problem is about finding the volume of a band of a sphere with given height of a hole.

I have no idea what was the reason they were reverted. Some clarification needed if I impertubably would like to know your answer, avoiding this misunderstanding. Thank you. Dedhert.Jr (talk) 05:36, 5 April 2024 (UTC)[reply]

A polyhedron is a thing with flat sides. Surfaces of revolution, spheres, and the spheres with holes of the napkin ring do not have flat sides. They are solid geometry, but not polyhedra. —David Eppstein (talk) 07:00, 5 April 2024 (UTC)[reply]

Please see my previously written reply here "Good idea!" which explains why I did this, to address @Beland's issue (an error on my part which I acknowledged), why my note is referenced, not WP:NOR or junk, and how I took care to ensure what I did does not break any of the articles which transclude this template. If you agree my fix is correct, please undo your undo, as I do not wish to be at all argumentative, and I cannot do that myself without appearing to engage in an edit war. Thank you @David Eppstein. Dc.samizdat (talk) 23:37, 5 April 2024 (UTC)[reply]

No. It is junk. It is a discursive essay on an ordering scheme that you appear to have made up. We should not be putting paragraphs of text into templates that are included in multiple articles at all. Articles should have their own text, not copies of boilerplate text from who knows where. And we should not be adding paragraphs of unsourced text to anything. The fact that your addition necessitates adding new sections of explanatory notes separate from the reference sections to multiple other articles is also problematic, but much less problematic than adding paragraphs of text to articles through templates and writing content not based on published sources. —David Eppstein (talk) 23:43, 5 April 2024 (UTC)[reply]

Please reconsider. I didn't make up the ordering scheme of the regular 4-polytopes by number of vertices, the SO(4) symmetry group of nature which generates these polytopes did. The text of my note is not "boilerplate from who knows where" but sourced by dozens of citations from Coxeter 1973 who orders his entire book, and his presentation of the regular 4-polytopes in particular, in this order, their natural order of increasing complexity. My discursive essay is to note that crucial geometric fact which Coxeter documented so fully, which is of fundamental importance to understanding the sequence of this series of increasingly complex Wikipedia articles. I moved my note into the template article which is the compendium of Coxeter's most important tables from Regular Polytopes, the essential table which every article on Euclidean geometry or the regular polytopes must have, collapsed but ready to hand, if it is to be understood. @Beland correctly pointed out that the text of my note should not be duplicated in multiple articles; I fully agree and moreover believe it is rightly an annotation to the table, not to every article that needs the table. That is what template transclusion is for. I respectfully submit that your rule that "we should not be putting paragraphs of text into templates that are included in multiple articles" is correct and reasonable, but too absolutely stated; it is a good rule, but every rule has its exception. I would add "except where the template article is the proper home for this information among many related Wikipedia articles, which need to be annotated by this information to be well understood, but should not duplicate the annotation". Dc.samizdat (talk) 01:09, 6 April 2024 (UTC)[reply]

@Dc.samizdat tldr. stop adding long off topic notes to articles. stop adding unsourced content. stop making excuses for these problems. it is disruptive and it makes the encyclopedia worse. —David Eppstein (talk) 01:18, 6 April 2024 (UTC)[reply]

The article Earth–Moon problem you nominated as a good article has passed ; see Talk:Earth–Moon problem for comments about the article, and Talk:Earth–Moon problem/GA1 for the nomination. Well done! 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 Kusma -- Kusma (talk) 09:41, 9 April 2024 (UTC)[reply]

[1] Dedhert.Jr (talk) 12:13, 9 April 2024 (UTC)[reply]

...and undoing everything by that user, even when "everything" includes obvious vandalism-reversion. Blocked 3 days for personal attacks and harassment. —David Eppstein (talk) 17:11, 9 April 2024 (UTC)[reply]

Hi there, I'm pleased to inform you that I've begun reviewing the article Ordered Bell number you nominated for GA-status according to the criteria. This process may take up to 7 days. Feel free to contact me with any questions or comments you might have during this period. Message delivered by ChristieBot, on behalf of Bilorv -- Bilorv (talk) 21:03, 11 April 2024 (UTC)[reply]

I'm puzzled about recent edits on the combinatory logic page in relation to the omission of CL's undecidability proof. Isn't removing the previous proof akin to denying the Church-Turing thesis? The thesis implies the equivalence of formalisms that capture "effective calculability/computability" with a formalism's respective undecidability typically then entailing a corresponding proof of the unsolvability of its version of the Halting problem - exactly what was originally provided (not by myself FWIW). That decidability is more commonly sheeted back to Turing machines seems to me to be more a quirk of history.

Consider the thought experiment whereby CL became the first computational model with all subsequent formalisms/languages then proven to be CL-complete (an interesting possibility given its earlier emergence). Would we really now dismiss all the familiar proofs of the unsolvability of the Halting problem as  "nonsensical" or "essentially a trivial statement that has nothing to do with actual undecidability"?

Showing undecidability with just a self-referential, general diagonalization argument (or even potentially something more exotic) also seems perfectly rigorous as discussed here

IMO it seems a bit of a shame to remove the original, more direct proof given how insightful it was in terms of:

1) being much more concrete (no encoding is needed! unlike the implicit coding of TM's in the traditional proofs)

2) giving a more immediate sense of its Godelian nature with the final flipping of perspectives.

I agree it's worthwhile to note CL's "intensionality" and that undecidability doesn't follow when the property under consideration is not the halting problem (while pointing out that CL's Turing-completeness is not then violated because of encoding). Ronald Monson (talk) 08:15, 13 April 2024 (UTC)[reply]

Hello,

on 6 March, you took this article from the GA-nomination list, and put some "citation needed" tags in the article. These tags are now replaced by references, and some were added in addition, so their complete number has raised from then 216 to 278 now. Would you please take a look on the present state of the article, whether the quotations are sufficient? Thank you. Dioskorides (talk) 10:12, 14 April 2024 (UTC)[reply]

It's not perfect, but much better. In "Analysis", two paragraphs end in unsourced sentences. Some notes (especially note [u]) still need a reference for their content. I didn't check carefully that any of the sources actually support the content they appear to support. —David Eppstein (talk) 16:27, 14 April 2024 (UTC)[reply]

I see one of the examples you have for reverting my example of a partition is that it is unsourced. However, the examples in the article are unsourced too. Why would it be important? PicoMath (talk) 10:25, 14 April 2024 (UTC)[reply] 

Not to speak for David, but: the more important reasons for reverting are (1) that your addition was very poorly written, and (2) that there is already a section (immediately below the "Examples" section) specifically about the phenomenon of set partitions induced by equivalence relations. --JBL (talk) 21:01, 15 April 2024 (UTC)[reply]

Oh, I see why. Thanks! PicoMath (talk) 00:47, 16 April 2024 (UTC)[reply]

Ummm... do you think the article Constant-recursive sequence is already quickfailed? I have taken the review, but after I read it, there are many problems, some of which I have to write down. I have never quickfailed the article before, so maybe you could add more comments for the second opinion? I think I will write them down right now. Dedhert.Jr (talk) 10:11, 17 April 2024 (UTC)[reply]

With entire sections with no source, I think you could quickfail it per WP:QF#1 (very far from criterion 2) or #3 (needs cleanup banners). For that matter, why is it a separate article from Linear recurrence with constant coefficients? Aren't they on more or less the same topic? —David Eppstein (talk) 18:12, 17 April 2024 (UTC)[reply]

Well. The nominator already improved by the comments, but it has already quickfailed. Do you think I should undo the failing nomination and continue to review, or wait for a few days to improve the article until they meet six criteria and then nominate it again? Dedhert.Jr (talk) 03:59, 19 April 2024 (UTC)[reply]

It's really up to you, how close you think it is in all the other criteria, and how much effort you're willing to put into it. —David Eppstein (talk) 05:55, 19 April 2024 (UTC)[reply]

Ummm... okay. Dedhert.Jr (talk) 06:01, 19 April 2024 (UTC)[reply]

An automated process has detected that when you recently edited Lambda calculus, you added a link pointing to the disambiguation page Nondeterminism.

(Opt-out instructions.) --DPL bot (talk) 06:10, 18 April 2024 (UTC)[reply]

On 23 April 2024, Did you know was updated with a fact from the article Descartes' theorem, which you recently created, substantially expanded, or brought to good article status. The fact was ... that the discovery of Descartes' theorem in geometry came from a too-difficult mathematics problem posed to a princess? The nomination discussion and review may be seen at Template:Did you know nominations/Descartes' theorem. You are welcome to check how many pageviews the nominated article or articles got while on the front page (here's how, Descartes' 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 suggest it on the Did you know talk page.

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