User talk:David Eppstein/2019a

Timeline of statistics
There is this History of statistics article but I propose that we (you) start a new Timeline of statistics article based on this article by Anirban DasGupta, which seems much more informative than any book by Stephen Stigler. If you know DasGupta in person I wonder if you would be able to convince him to release the article in a Wiki-appropiate license so that we can directly use it. Solomon7968 10:28, 2 January 2019 (UTC)

While you are at it would you be able to start a new article on Reinhard Siegmund-Schultze. See the discussion here and the mathematicians listed here in 's sandbox. Solomon7968 13:14, 2 January 2019 (UTC)

Copyright infringement
Hi, David! :) I am really sorry for bothering you, but I recently made my first Wikipedia page, which was completely removed because of Unambiguous copyright infringement. I tried to edit text to avoid direct copy and paste from other sources, but now I am not sure which parts are edited and which aren't. How can I check whether some text is copyright violation? I always tried to google in quotation marks "Test sentence test test" and if there are some results - the text exists and I cannot put it on Wikipedia. If not - I can use it and put it in the article. My question is - how to check for copyright infringement? Thank you for the info :) — Preceding unsigned comment added by Mtrkv (talk • contribs) 12:00, 7 January 2019 (UTC)
 * https://tools.wmflabs.org/copyvios/ can be helpful. But if you wrote it (or copied it, or copied it but then changed a few words) you should know already how you did it. —David Eppstein (talk) 16:32, 7 January 2019 (UTC)

I had to do a seminar on the subject, and some parts were copy/paste and a little bit of editing :) I don't remember what parts are modified and what aren't, because it was a mess of a seminar. Thank you for the link, I'll check what I'm allowed to put in the wiki article :) And thank you for quick answer! :D — Preceding unsigned comment added by Mtrkv (talk • contribs) 08:48, 8 January 2019 (UTC)

÷ vs ×
Hi there,

I've very new to Wikipedia editing and discussion, so bear with me and explain if I do things wrong.

Regarding https://en.wikipedia.org/w/index.php?title=Obelus&oldid=prev&diff=877266009 note that my inserted text is indeed about what the symbol stands for rather than the actual mathematical concept, and comes right after the text about encoding:

"A monadic × symbol is used by the APL programming language to denote the reciprocal function."

Now compare to the text for the × symbol, a text I didn't write: A monadic × symbol is used by the APL programming language to denote the sign function.

Imho, what I wrote is completely parallel. — Preceding unsigned comment added by A.Brudz (talk • contribs) 20:39, 7 January 2019 (UTC)
 * Sure, but it was also completely misplaced, because it has nothing to do with the obelus symbol, the subject of the article. Instead it is about a different symbol with a vaguely related meaning. —David Eppstein (talk) 22:44, 7 January 2019 (UTC)

DYK for Lola Álvarez Bravo
Cas Liber (talk · contribs) 00:03, 9 January 2019 (UTC)

Friendship paradox
You just reverted an entire article because you didn't like one sentence in the lead? As for the rest of it, there was no "removal", article was actually expanded based partly on sources you provided. Removing whole paragraphs without comment or participating in talk page cleanup discussion is definitely edit warring. You may want to read WP:EW and WP:EDITCONSENSUS. Cleaned up wording and put the rest back since you did not bother to explain your edits. You can always try to use the talk page. Fountains of Bryn Mawr (talk) 20:22, 11 January 2019 (UTC)
 * Apparently you have difficulty reading as well as writing. I disliked your whole style of writing and provided a particularly egregious example of your bad writing to explain why. Here's another: "In a 2001 paper Stanford University researchers Ezra Zuckerman and John Jost described how they conducted a survey and compared the predicted number of friends and friends of friends in the friendship paradox to the to the number of friends people thought they had in relation to the number of friends their friends had". Can you please diagram that sentence for me? It's just unreadable. And misplaced; you put it at the end of the article and removed the punch line. You just turned it into a bare description of someone's research with no explanation of how it connects with the topic of the article. Perhaps that is consistent with your arguments on talk where you show no understanding of how it connects and argue that because it is just someone's primary research it should be omitted. In short, you have missed the point and your rewrite turns the article into text that misses the point in exactly the same way. —David Eppstein (talk) 22:08, 11 January 2019 (UTC)

Notice of Edit warring noticeboard discussion
Hello. This message is being sent to inform you that there is currently a discussion involving you at Administrators' noticeboard/Edit warring regarding a possible violation of Wikipedia's policy on edit warring. Thank you. Fountains of Bryn Mawr (talk) 01:09, 12 January 2019 (UTC)

Notice of No Original Research Noticeboard discussion
There is currently a discussion at No original research/Noticeboard regarding an issue with which you may have been involved. Thank you. Fountains of Bryn Mawr (talk) 03:22, 12 January 2019 (UTC)
 * Please provide an explanation for why, as part of this discussion, you undid an edit on my talk page from several days ago in which I archived three months of old discussions, and cluttered up my talk page with nearly 70kbytes of unwanted material, in the process also removing several other editors' contributions here. I guess my imagination must be deficient because the only explanations I can come up with involve either pure vandalism or incompetence. I eagerly await your explanation, because it is surely more creative and interesting than that. —David Eppstein (talk) 05:46, 12 January 2019 (UTC)
 * Fountains keeps cutting himself with Hanlon's razor. EEng 11:41, 12 January 2019 (UTC)

" you undid an edit on my talk page from several days ago in which I archived three months of old discussions", my bad, I had an old version of the page up when I edited. Went to fix it but you already did. Fountains of Bryn Mawr (talk) 13:17, 12 January 2019 (UTC)

Friendship Paradox
I don't disagree with you at all. I just wanted to avoid a back and forth via edits and get something he recommends so that multiple editors can point out these issues. Squatch347 (talk) 17:30, 13 January 2019 (UTC)

Your GA nomination of De Bruijn–Erdős theorem (graph theory)
Hi there, I'm pleased to inform you that I've begun reviewing the article De Bruijn–Erdős theorem (graph theory) 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 Legobot, on behalf of Bryanrutherford0 -- Bryanrutherford0 (talk) 19:01, 14 January 2019 (UTC)

Daniel Medina
Hola David, es Daniel Medina quien escribe , a quien refiere esta pagina , he tratado de actualizarla y veo que no lo he hecho muy bien , que me recomendarías para evitar futuros problemas , tanto las imagenes como los textos son referentes a mi obra. saludos y gracias Daniel medina balbas (talk) 01:58, 24 January 2019 (UTC)
 * I do not read Spanish. But, in general, to avoid problems on Wikipedia, you should be editing topics based on published sources rather than personal knowledge, and particularly you should avoid editing an article about yourself. If there are inaccuracies in the article that you think should be corrected, you should use the article's talk page to request changes. But you should not consider the contents of the article to be under your control. The article is supposed to state (in plain English, not artspeak) what can be documented about you, not what you think about yourself. —David Eppstein (talk) 02:02, 24 January 2019 (UTC)

The approximate hyperbolic paraboloid known as Pringles
Hello David.

could be misinterpreted, they are clumsily inappropriate to indicate a product name.

You mention this as being "For instance, on top of what I already said…" With respect, I dealt with what you already said in the immediately subsequent edit summary. It seems that that edit summary was either not read or not understood. Although suspecting the former, good faith obliges me to assume the latter and therefore to expand the summary.

Firstly I think we can dispense with this can't we? "your phrasing comes across as more likely to mean English chips (French fries)..." I this. I said: "The difference between the phrasing of the two versions has no bearing at all on what kind of chip is implied", and I linked for good measure. If I'm missing a point then please bring it to bear.

I edited this passage: "The widely sold fried snack food Pringles potato chips resemble a truncated hyperbolic paraboloid. The distinctive shape of these chips allows them to be stacked in sturdy tubular containers, fulfilling a design goal that they break less easily than other types of chip."

thus: "The widely sold fried snack 'Pringles' resemble a truncated hyperbolic paraboloid. Their distinctive shape allows them to be stacked in sturdy tubular containers, fulfilling a design goal that they break less easily than chips."

As (twice) stated I removed references to Pringles being ‪"food", "potato", or "chips"‬ for two reasons: firstly that the terms in context are contentious, and secondly for being superfluous. You reverted, saying "…claiming that Pringles are *not* potato chips is definitely contentious…"

True, but irrelevant. Why address a claim that wasn't made? The point, I thought clearly stated, is that the status of Pringles as food, as potato, and as chips, are all (verifiably, from the linked Wikipedia Pringles article) contentious, the implication being that as such this article should not take a stand either way. From that article:

"...originally known as "Pringles Newfangled Potato Chips", but other snack manufacturers objected, saying Pringles failed to meet the definition of a potato "chip". The US Food and Drug Administration weighed in on the matter, and in 1975, they ruled Pringles could only use the word "chip" in their product name within the following phrase: "potato chips made from dried potatoes". Faced with such an unpalatable appellation, Pringles eventually opted to rename their product potato "crisps" instead of chips. This later led to other issues in the United Kingdom, where the term potato "crisps" refers to the product Americans call potato "chips". In July 2008 in the London High Court, P&G lawyers successfully argued that Pringles were not crisps (even though labelled "Potato Crisps" on the container) as the potato content was only 42% and their shape, P&G stated, "is not found in nature". This ruling, against a United Kingdom VAT and Duties Tribunal decision to the contrary, exempted Pringles from the then 17.5% VAT for potato crisps and potato-derived snacks. In May 2009, the Court of Appeal reversed the earlier decision. A spokesman for P&G stated it had been paying the VAT proactively and owed no back taxes."

Elsewhere in the article the base Pringles product is less than half potato content. Think about how much potato is an actual potato chip/crisp. Other varieties are based on rice, on wheat bran, on black beans, on barley. Corn Pringles, and rice Pringles have been available. All of which is…fine, obviously. But not potato. And not relevant to its shape, yet revealing as to why Pringles owners have had legal difficulties calling Pringles "potato chips". Their advertising campaigns differentiate between potato chips and Pringles. Search "food" on the Pringles article. Note the ten instances, and note that the only one of substance is the link to The New York Times opinion piece: Are Pringles "real food"? (which I recommend). If Pringles themselves cannot or find it convenient not to describe their product as food or potato chips how can it be right for Wikipedia to advance those assertions?

So far so contentious. As per the second point - of superfluity - point one simply doesn't matter. Not only is it undesirable to define Pringles in the precise terms given, it is redundant to define Pringles in any precise terms beyond "The widely sold fried snack "Pringles"". They are very well known. And wikilinked. And pictured.

You're clearly a prolific, erudite, and committed Wikipedian, not a Pringles shill. It's actually a bit of nonsense, isn't it? I'll admit I'm no fan of this fried snack, but that's not of consequence. The apparently peremptory and unthinking manner of your reverts riled me I admit, but here I'm motivated by the sublime mystical transcendence of mathematics; of geometry; of topology. Speaking of which, that "crisps/french fries" twaddle - how likely is it to be confused for fries when the whole point is that its shape compares to a hyperbolic paraboloid? Who is going to be reading this and thinking "oh yes, those famously elongated cuboids, that's what's meant here."? Come on. We're talking about the shape of the blimmin' thing. They are very, very famous. They manage very well without unconscious cheerleading habituation of their dubious not-even-claimed qualities in a tangentially relevant and *otherwise scientifically rigorous* article. If there is a life-form this side of Mars unfamiliar with Pringles, the link is right there, and a picture just below. They may or not be potato, or food, or chips, or lip-smacking meaty wafers or whatever. What they are, and what is relevant, is that they are an approximate hyperbolic paraboloid [fried snack] that stacks. See link for more info if you're really more interested in junk food than mathematical shapes.

I hope you won't be offended if I suggest that considered reflection precludes a third reversion of the edit. Cheers! Captainllama (talk) 17:34, 24 January 2019 (UTC)
 * So, you appear to think (1) we should avoid calling Pringles potato chips, (2) we should reinforce that by changing a comparison against other types of potato chip to one that is directly against all chips, pushing the opinion that Pringles are not chips, (3) it is appropriate to use the bare word "chip" rather than "potato chip", confusing our British readers (for whom this word means a French fry) in violation of MOS:COMMONALITY, (4) it's appropriate to reinstate your edits and post long unreadable screeds here rather than discussing them ON THE ARTICLE TALK PAGE BEFORE REPEATING THEM as WP:BRD suggests, and (5) in the course of that screed asserting that Pringles are not even food. Now after all that, why should I take your position seriously? —David Eppstein (talk) 18:33, 24 January 2019 (UTC)

YBC 7289 photo
I saw your good article candidate YBC 7289. The photo is very small (20kB) and I thought the article would benefit from a bigger one, so I looked for a little bit if I could find one. I found much better ones on the YBC website. Have you pursued this to see if they could be uploaded to Commons? Theodor Langhorne Franklin (talk) 21:04, 26 January 2019 (UTC)
 * I have not, but there is no evidence on that record that they have released it with a compatible open access license. —David Eppstein (talk) 21:11, 26 January 2019 (UTC)
 * I reached out to and was given permission from the Yale library. I uploaded the images to Commons Category:YBC_7289. The Yale library said they were releasing them into the public domain, so I filed an OTRS ticket. I informed them how to reach out to the OTRS team. Theodor Langhorne Franklin (talk) 18:16, 6 February 2019 (UTC)
 * Thanks for your efforts! I've added the images to the article. —David Eppstein (talk) 18:41, 6 February 2019 (UTC)

Accidental click
I was viewing the AfD because a related article is up for deletion. I accidentally clicked delsort because it popped up at the last minute as I was trying to leave the page. SL93 (talk) 23:42, 26 January 2019 (UTC)
 * Yeah, I realized that was the case when I looked at your edit summary on the AfD itself. Thanks for the explanation. —David Eppstein (talk) 00:04, 27 January 2019 (UTC)

FYI
I just created the article List of Wiley book series. Of them Wiley Series in Probability and Statistics (redlink) is probably of interest to you. BTW I am still waiting for you to reply to my above comment, see the top of your talk page. Solomon7968 12:58, 27 January 2019 (UTC)

Automatic notability

 * Hello, You contested two WP:PRODs, Janusz Malik and Rajko Lotrič. While PRODS can be contested for any reason I was perplexed at the rationale that apparently you think all Olympic athletes are "automatically" notable and became blown away that you are an Admin. On the first, the edit summary was "competed at 1984 Olympics; Olympians are automatically notable" and the second; "competed at Calgary Olympics; Olympians are automatically notable".
 * As an Admin I would think that all aspects of notability would be considered and not a blanket criterion that discounts other policies and guidelines or that a "presumption" of notability is an argument for inclusion possibly using only NOLYMPICS. Notability is a guideline and neither of the last two trump Neutral point of view, Verifiability, What Wikipedia is not, and Biographies of living persons. A subject participating in one event would seem better covered under that event than an unsourced permanent pseudo biographical stub, not benefiting Wikipedia from ignoring various policies.
 * "Automatic", inherent, or intrinsic notability, is not something I would expect from any knowledgeable editor, let along an Admin, and especially concerning a subject that placed third in a 1984 event with no other apparent notability and sourcing. Otr500 (talk) 19:11, 1 February 2019 (UTC)
 * It is easily verifiable that the athletes I unprodded were Olympians, so all your longwinded waffle about verifiability is for nothing. Also see WP:BEFORE — You are supposed to verify that notability cannot be established from additional sources before you try deleting the articles, rather than using the poor current state of an article as an excuse to initiate deletion proceedings. —David Eppstein (talk) 19:29, 1 February 2019 (UTC)
 * Thanks but I did do a before and "still" only see your "automatic" notability exemption, apparently for anyone performing in the Olympics regardless of actual notability by sources, as the only possible evidence. Still your right to contest though. Otr500 (talk) 22:21, 1 February 2019 (UTC)
 * Apparently you don't understand what WP:BEFORE means. It means you need to look around at the obvious places for where you might find sources that are not already in the article that would support a claim of notability. One of the most obvious places to look, in these cases, would be at the Polish Wikipedia articles for Malik, which is more detailed and well-footnoted. That doesn't work so well for Lotric, but a Google search for his name again finds plenty of sources. Since you said you didn't find anything at all, obviously you didn't even try those most cursory of checks. So what did you try? —David Eppstein (talk) 22:32, 1 February 2019 (UTC)

Cycle detection
Hi, I seem to have noticed a mistake in the Cycle detection section of Cycle (graph theory). The problematic sentence is:

"In an undirected graph, finding any already visited vertex will indicate a back edge."

It is clear that this sentence is only true for directed graphs, and false for undirected ones. Consider the following undirected acyclic graph:

1 -- 2

Let's start the exploration at node 1. We mark node 1 as visited, then look at its neighbors. Node 2 is unvisited, so we mark node 1 as its parent and push it onto the stack.

We now explore node 2, mark it as visited, and look at its neighbors. We find an already visited node (node 1), but this does not indicate a back edge, since node 1 is the parent of the current node.

You can easily convince yourself that finding an already visited node in a directed graph does indeed indicate a back edge, regardless of the parent relationship (consider the directed cyclic graph ).

I have tried correcting the mistake by changing "an undirected" to "a directed", but you keep reverting my edits. Best regards, Naim42 (talk) 20:52, 2 February 2019 (UTC)
 * It is false that already-visited vertices in directed graphs are always back edges. They could alternatively be forward edges or cross edges, neither of which form cycles. It is, however, true that the first *non-parent* already-visited vertex that you find in an undirected depth-first search will be a back edge (you will later discover the same edge as a forward edge) and that in undirected graphs all *non-parent* already-visited vertices come from cycle-producing edges. So while it is true that you have found a problem with the current wording, your attempted fix makes it much worse. —David Eppstein (talk) 22:01, 2 February 2019 (UTC)
 * Thank you for the clarification. Naim42 (talk) —Preceding undated comment added 22:21, 2 February 2019 (UTC)

Page restoration
Hey DE, could you please restore EDGAR Online and its talk page, which you just deleted via PROD? Sorry I missed the PROD, but I do think there will not be great difficulty demonstrating notability for this company, because it was a publicly listed company and we have WP:LISTED. Thanks! UnitedStatesian (talk) 17:21, 7 February 2019 (UTC)
 * Ok, done. —David Eppstein (talk) 17:25, 7 February 2019 (UTC)
 * Can you restore Talk:EDGAR Online? — BillHPike (talk, contribs) 22:50, 7 February 2019 (UTC)
 * It's just project banners, but sure, done. —David Eppstein (talk) 23:24, 7 February 2019 (UTC)

Question
I ended up on this page from a link at an Apple community forum help page, and wasn't sure if it should be made a redirect, deleted or left alone. Atsme ✍🏻📧 02:48, 9 February 2019 (UTC)
 * You mean Gecko (software without the close paren, or Gecko (software) with it? Leave both alone, I think. We can't create redirects to handle every other site's failure to parse punctuation in urls. —David Eppstein (talk) 06:34, 9 February 2019 (UTC)
 * Well, that's strange because when you click on this link it shows up as an unassessed article, and that's what confused me. Atsme ✍🏻📧 17:59, 9 February 2019 (UTC)
 * Maybe when you click it. When I click it I get to a page that tells me it doesn't exist, asks whether I really meant the version with the close paren, and gives me a link to create a new page with that title. —David Eppstein (talk) 19:02, 9 February 2019 (UTC)

I only captured the "unassessed article" portion. Below that is exactly what you described. Just wondered how unsuspecting readers would process the info. I'm thinking they would simply click on the correct wikilink. All the same, I figured it wouldn't hurt to double-check with someone far more knowledgeable about this stuff than I, so thanks for putting my mind at ease. Atsme ✍🏻📧 19:27, 9 February 2019 (UTC)

Cluster Analysis
Hi David, the copyright concerns in the Cluster Analysis page appeared only in the Evaluation section section since the commit ''02:40, 4 February 2019‎ Glokc (talk | contribs)‎. . (74,220 bytes) +6,890‎. . (Benchmarking frameworks and evaluation toolkits for the clustering algorithms added)'' but you removed all my extensions and refinements for the article. Can you please recover all refinements made before that commit?

And as for the copy-pasted content in the Evaluation section then I will solve this issue with the paper authors and let you know soon. --Glokc (talk) 04:48, 11 February 2019 (UTC)
 * That may have been where that specific copyright concern came from but I checked your second-earliest contribution to the article and already found copied text there. And you should not be trying to "solve this issue with the paper authors"; you should be putting material here in your own words. So no, I will not undelete your plagiarism. —David Eppstein (talk) 04:54, 11 February 2019 (UTC)
 * thank you for the clarification of your concerns. As for the copyright issues then the Clubmark paper is also published in the public domains: arXiv and The Clubmark project repository with the respective licenses. Also, the author(s) have emailed the required license to the permissions-en(at)wikimedia(dot)org.
 * Can you please clarify how can I recover refinements made to the Cluster Analysis page or what else should I do to recover and/or update them? --Glokc (talk) 05:49, 11 February 2019 (UTC)
 * I mean that all the made citations / copy-pastes contain references to the original scientific papers, which seems to be to proper way to deliver the trusted and valid information (facts). Let me know please what should I do with the made refinements to recover them (and/or refine them further). --Glokc (talk) 06:25, 11 February 2019 (UTC)
 * Even copying CC-BY text requires proper attribution to the original author!
 * Also that does not resolve the apparent WP:COI problem. The material you copied is largely an advertisement of Clubmark. Do not copy statements such as "industrial-grade", which is just WP:PEACOCK. Instead, Wikipedia prefers a neutral viewpoint. And IMHO Clubmark is not even well-placed in the cluster analysis article, because it is very much biased towards community detection, as far as I can tell; and it is also IMHO much too young (not independently used yet) to be worth mentioning at all. HelpUsStopSpam (talk) 13:48, 11 February 2019 (UTC)

New Question
I’ve read the comments about my additions to these pages and have changed the entry to remove any mention of IOHK. I have not mentioned bitcoin or any cryptocurrency. I’ve not said he works for IOHK. I’m new to Wikipedia and did not know that this was spam. I thought it was a good company to write about. Professor Wadler seems a notable person to me and the addition updates his page to take in his post since 2003. I think the Edinburgh and Google Scholar links are reliable.

Please contact me about where I am going wrong on this as I would like to be a reputable writer for Wikipedia. — Preceding unsigned comment added by Monica Poucheva-Murray (talk • contribs) 17:33, 13 February 2019 (UTC)

Your GA nomination of Rado graph
Hi there, I'm pleased to inform you that I've begun reviewing the article Rado graph 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 Legobot, on behalf of Bryanrutherford0 -- Bryanrutherford0 (talk) 23:40, 14 February 2019 (UTC)
 * Thanks, ! The level of mathematical depth in this topic led me to expect a very long wait for a review of the article; my other current nomination was sort of an apology for that, by way of "if you want to review a mathematics article and that one scares you, try this instead". So thanks for being willing to take it on despite that. —David Eppstein (talk) 23:50, 14 February 2019 (UTC)
 * Haha you're welcome! Discrete is not my branch of mathematics, but I think I'll be able to handle it. -Bryanrutherford0 (talk) 01:57, 15 February 2019 (UTC)

Your GA nomination of YBC 7289
Hi there, I'm pleased to inform you that I've begun reviewing the article YBC 7289 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 Legobot, on behalf of John M Wolfson -- John M Wolfson (talk) 00:41, 22 February 2019 (UTC)

Eight circles theorem
I see this configuration Eight circles theorem  Is nice. Do you write the article for it? — Preceding unsigned comment added by 117.6.86.35 (talk • contribs)


 * You think I have forgotten the sockpuppetry and self-promotion that led to Articles for deletion/Dao's theorem and Sockpuppet investigations/Eightcirclestheorem? —David Eppstein (talk) 06:15, 22 February 2019 (UTC)

I don't think so. I think You remmember it. So I send this configuration to you. You decide, I think this problem is really very nice. You can hate me, but anyway this problem is nice. I don't need name in here, but this problem really nice.

You see https://mathoverflow.net/questions/234722, and this configuration also is a generalization of Pascal therem https://mathoverflow.net/questions/272520 — Preceding unsigned comment added by 117.6.86.31 (talk) 07:07, 22 February 2019 (UTC)

Some years ago, I think wiki is forum, I mean I think wiki similarly with https://artofproblemsolving.com/. Now I know law of wiki, but the Eight circles theorem is very nice. I found about 30 generalization of classical geometry theorems. But I think Eight circles theorem is best nice. — Preceding unsigned comment added by 117.6.129.14 (talk) 01:12, 23 February 2019 (UTC)

I have written 72 articles of geometry in vi.wiki, you can see here https://vi.wikipedia.org/wiki/Th%E1%BB%83_lo%E1%BA%A1i:%C4%90%E1%BB%8Bnh_l%C3%BD_h%C3%ACnh_h%E1%BB%8Dc

I don't write them in English because my english is not good by another one. So If i can contribution for en.wiki, I only can contribution the result which I research. So there are some misunderstanding for me. — Preceding unsigned comment added by 117.6.129.14 (talk) 02:50, 23 February 2019 (UTC)

Please see Định lý tám đường tròn — Preceding unsigned comment added by 117.6.86.31 (talk) 01:30, 25 February 2019 (UTC)

Your GA nomination of YBC 7289
The article YBC 7289 you nominated as a good article has passed ; see Talk:YBC 7289 for comments about the article. Well done! If the article has not already been on the main page as an "In the news" or "Did you know" item, you can nominate it to appear in Did you know. Message delivered by Legobot, on behalf of John M Wolfson -- John M Wolfson (talk) 22:02, 22 February 2019 (UTC)

DYK for Marian Pour-El
— Maile (talk) 12:02, 25 February 2019 (UTC)

Derangement product proof
Thanks for your input. Did you mean something like:

I think if you assume the product of all permutations is I, and the conjecture is true for all derangements of permutations < k, then by induction on the fixed point permutations of k (all equal I over a particular set of fixed points) then as all perms=fixed point perms + derangements, derangements = I.

I can't see any other symmetry.

Darcourse (talk) 20:51, 3 March 2019 (UTC)
 * The symmetry is on the set of things being permuted, which don't have to be the numbers 1, 2, 3, ... "the set of derangements" is a symmetric concept (it doesn't depend on the choice or permutation of the set of things being permuted) so "the product of the set of derangements" must be a permutation that itself does not depend on the choice or permutation of the set of things being permuted. But (except for the case $$n=2$$) there is only one such invariant permutation, the identity. Or this would be true, if the product were defined in a way that is independent of commutation and association, but maybe that's not so easy. And in fact it's false in the exceptional case $$n=2$$, where the only derangement swaps the two elements and the product of all derangements continues to swap them. —David Eppstein (talk) 20:59, 3 March 2019 (UTC)

Rudrata Path
Hey David. Forgive me, I hardly understand how collaborating on Wikipedia works, but I hope it goes something like this. On the Hamiltonian Path Wikipedia article, in your revision here https://en.wikipedia.org/w/index.php?title=Hamiltonian_path&oldid=885578083, you undid my change to include the term Rudrata path as an alternative expression used for a Hamiltonian Path. The reason you cited was you could only find a "tiny number of apparently low-quality sources" on a Google Scholar search. However, I would argue that Rudrata path is a significantly used term, and should definitely be included as an alternate term. Notably, Dasgupta, Papadimitriou, & Vazirani in their Algorithms (2006) use the term Rudrata path. These are some of the biggest names in Computer Science and Algorithms at UC Berkeley. Furthermore, in UC Berkeley's main algorithms course (CS 170), many professors (including Elchanan Mossel) teach the concept using the term Rudrata path, so students mainly use that term. As such, it seems, at worst, harmless to include a reference to this alternative expression for a Hamiltonian path (alongside traceable path). Do you think you could allow my edit to go through? I would also further like to suggest we add the alternative term Rudrata cycle for Hamiltonian cycle (alongside Hamiltonian Circuit). — Preceding unsigned comment added by Chausies (talk • contribs) 03:14, 4 March 2019 (UTC)
 * Searching the book online at https://books.google.com/books?id=DJSUCgAAQBAJ found, again, zero hits for "Rudrata". But perhaps that's because the online version is incomplete. Where in the book is it? I need to see the context to determine whether they intend it seriously as an alternative term or whether (as sometimes happens in textbooks) they deliberately made up a fake term for an exercise to make it harder for students to search for the answer. And no, I can't allow it through until we have a reliable source. Your say-so (or mine) is not enough; we need published documentation. That's how Wikipedia works. —David Eppstein (talk) 07:10, 4 March 2019 (UTC)

Algorithms (2006) is a premier textbook for teaching Computer algorithms. When searching "Algorithms" on Amazon, it is in the top 3 results. Many institutions use it for their algorithms course. To this day, UC Berkeley uses it as their textbook for their main algorithms course (CS 170), as you can verify yourself here https://cs170.org/materials/. The textbook exclusively uses the term Rudrata path, making only a small note that Hamiltonian path is an alternate term. It's not some fake term used to obfuscate the concept for some problem. That is the main term used to refer to the concept in the book period. The Hamiltonian path problem is taught as the Rudrata path problem, etc. If you look in this PDF for the book (http://algorithmics.lsi.upc.edu/docs/Dasgupta-Papadimitriou-Vazirani.pdf), and simply look up "Hamiltonian path" in the Appendix, it'll tell you to "See Rudrata path", and point you to the page where it introduces and teaches the concept.

In the UC Berkeley algorithms course, that has always been the main term used to reference the concept. Furthermore, as mentioned previously, the celebrated computer science professors Christos Papadimitriou, Umesh Vazirani, and Elchanan Mossel all use it as their preferred term for the concept, just to name a few. If you don't believe my "say-so" that they are celebrated, please see their Wikipedia pages (which I have linked). Finally, I would like to note that, on Wikipedia, when searching "Rudrata path", it already automatically redirects you to the Hamiltonian path page (see Rudrata path). In that sense, the term has already been embraced. I find it only makes sense that, on the page itself, "Rudrata path" is mentioned as an alternatively used term, alongside traceable path. What do you think? — Preceding unsigned comment added by Chausies (talk • contribs) 06:08, 5 March 2019 (UTC)
 * I think that your attempts at puffing up this term fail to obscure the fact that it is very sparsely used. It can be included in the article with a proper reference (including page number) to the book, but I think that the better place would be later in the first section where Rudrata is already mentioned. —David Eppstein (talk) 07:47, 5 March 2019 (UTC)

Jesus
Jesus wept to see you revert good changes to enforce your personal fixation on retaining different date formats in the one article. It's like looking at a fatal traffic accident as you pass. Tony (talk)  03:31, 5 March 2019 (UTC)

ada delete
Hi David, I work at an art museum and we often use other galleries for reliable information. They typically have a better understanding of how to describe the art and the artists process. I think those sentences should be left. — Preceding unsigned comment added by LinthicumRyanR (talk • contribs) 13:32, 11 March 2019 (UTC)

Soviet/Russian mathematicians
Check my most recent edit to your created article Isabella Bashmakova where I added a few redlinks. Our articles on Soviet/Russian mathematicians are quite underdeveloped and creating the redlinks of the Bashmakova article seems a good way to rectify this. A. P. Yushkevich linked from Bashmakova was incidentally the only Soviet born to win the Kenneth O. May Prize. Solomon7968 01:46, 12 March 2019 (UTC)
 * Thanks. I don't suppose you know anything more about S S Petrova, one of the redlinks you added? She's mentioned briefly here but that's not enough to base an article on, and Svetlana Petrova is too common a name to easily search. —David Eppstein (talk) 02:03, 12 March 2019 (UTC)
 * The rest two redlinks? And the authors not linked as of this writing? Aleksandrov, Gnedenko, and Kolmogorov all could use expansion from Mactutor. Surpassing Mactutor won't be easy but scrapping the references seems well within reach. Mactutor lists some hard to find Russian journal references. Solomon7968 02:58, 12 March 2019 (UTC)
 * Well, I'm sure the others are interesting too. I asked about Petrova more particularly because my work on the article on Bashmakova was part of a project to increase the representation of women among mathematical biographies on Wikipedia. —David Eppstein (talk) 04:43, 12 March 2019 (UTC)

Pi approximations
Hello. Your rejection of my addition is not warranted. There are several other simple pi approximations in the article that do not cite sources. They don't need to; anyone with a basic calculator can easily check them. -Jesse Krase Jesse1919 (talk) 21:51, 16 March 2019 (UTC)
 * See WP:NOR. Wikipedia is not the place to publish your calculator-bashings. —David Eppstein (talk) 22:02, 16 March 2019 (UTC)

Number theory article
Hi -

It was a surprise to me that someone nominated the page now. It is clear that there were some minor issues that absolutely had to be addressed first (the section that needs expansion, the errors in citations) and some broader issues that needed more work (sources for the second half of the article -- though that's a bit of a tough issue, since many of the statements are second nature to a professional, and hence hard to source). Still, it is very helpful to have feedback.

Two issues:
 * What do you mean precisely by "one specific and contentious interpretation of the meaning of the tablet"? The tablet does contain a list of what is conventionally called Pythagorean triples, and they are labelled as such. As :for applications, the field is indeed wide open, but we mention at least two opposing views. We could also include a :more recent response to Robson - is that what you imply is missing?
 * As for why "half of the subfields are grouped into "Main subdivisions" and half into "Recent approaches and subfields"" - it is more or less clear that some subfields are much newer and well defined than others (the name "additive combinatorics" is less than 20 years old, though the field has been around since the 1960s, or in some sense for longer). Does the division seems too arbitrary or unnecessary? If so, we can talk about removing it, but I am sure I am not the only one who wonders where exactly the problem lies.

Also: wouldn't nominating the article for a B-class review be a logical first step, once the issues above are addressed? Best, Garald (talk) 03:27, 19 March 2019 (UTC)
 * The tablet contains a list of numbers. Saying that the list is of Pythagorean triples is interpretation. (They are not even triples, for one thing.) It is a reasonable choice, and a well-established one, to interpret them as one side and the hypotenuse of a right triangle. But the same numbers also have other interpretations: they have been thought to be a table of trigonometric values, or a set of exercises in solving quadratic equations. Unlike other tablets we don't have a picture of a triangle on the tablet itself to tell us that the geometric interpretation of the numbers is the correct one. Different historians have championed different interpretations. We should not take one as the only possibility. Robson is missing, yes, but it's not specifically her point of view that I find lacking; it's the thought that there might even exist a differing point of view and that these interpretations are only interpretations rather than being factual and absolute.
 * As for subareas: Yes, the division into established areas and recent-growth areas seemed arbitrary to me, and again, based on an idiosyncratic interpretation rather than being the established consensus of current scholarship in this area. Or at least, the article did not point to any published source providing a recent taxonomy of subareas and saying that we're following them, so it seemed more likely to be some editor's idiosyncratic interpretation rather than the consensus of scholarship. —David Eppstein (talk) 06:33, 19 March 2019 (UTC)

Directions
David - would you look at the location of Bonaire on this map, please? You will have to zoom out to see it in perspective to Venezuela. The coordinates are 68°28′W, 12°15′N, 80 kms off the coast of Venezuela). Bonaire has been described as being located northwest of Venezuela rather than directly north. Your thoughts? Atsme Talk 📧 21:30, 20 March 2019 (UTC)
 * You caught me preparing to travel to a different island northeast of Venezuela. Anyway, I don't feel strongly about it. Clearly if you go either directly south or directly southeast from Bonaire (or even southwest) you will hit Venezuela. The centroid of Venezuela seems to be somewhere between south and southeast. Caracas seems to be more purely southeast. If I were writing about it I would probably say north because it's both true and simpler, but I don't think northwest is inaccurate. —David Eppstein (talk) 21:36, 20 March 2019 (UTC)
 * Thank you, David. I promise, I'm not a seer, sorceress, or witch (on my mind since the Merlin marathon on Netflix). SMirC-wink.svg Have fun on your travels. Atsme Talk 📧 21:43, 20 March 2019 (UTC)

Articles for deletion/NeuroSpine Surgery Research Group
Hi, I sorted it there because the article bases itself at least partially on the notability of the persons involved. But you're right of course that an organization is not a person... :-) --Randykitty (talk) 16:23, 21 March 2019 (UTC)

kite (geometry)
This sentence, without sources, comes from the article on isosceles trapezoids:

Rectangles and squares are usually considered to be special cases of isosceles trapezoids though some sources would exclude them.

I just copied and pasted the sentence, changed "rectangles" to "rhombuses" (rhombi?) and changed "isosceles trapezoids" to "kites." That sentence needs sources too.

A quick Google search of "kite" will give you mutually exclusive definitions:

https://www.ck12.org/geometry/kites/lesson/Kites-GEOM/

A kite is a quadrilateral with two sets of distinct, adjacent congruent sides.

https://www.dummies.com/education/math/geometry/the-properties-of-a-kite/

A kite is a quadrilateral in which two disjoint pairs of consecutive sides are congruent (“disjoint pairs” means that one side can’t be used in both pairs).

But: https://www.mathopenref.com/kite.html

A quadrilateral with two distinct pairs of equal adjacent sides.

I started down this road because my daughter is taking high school geometry. She had a few questions about properties of kites, and her answer would have been wrong if she said a rhombus was a kite, You can look up quadrilateral family tree, and you will see some have branches that include kites, some do not. https://s3.amazonaws.com/files.betterlesson.com/files2/uploads99/1vdvl/public/8aff2a05893fc4eeaff922808fdea3663806af7f4c84564fbc256f2a430af2e3.png

Sorry about the formatting. I am new to this. I can get book references. In US high schools, they teach rhobuses are NOT kites. In college, they don't seem to care, because it is so trivial. But I think it is worth mentioning, because lots of parents and students use this as a source.

PS: I like this image the best, but again, it contradicts the others: https://www.mathsisfun.com/geometry/images/quadrilateral-class.svg — Preceding unsigned comment added by Danieltrevi (talk • contribs) 22:43, 26 March 2019 (UTC)

Part 2: Yes, that source does. First of all, it excludes rhombuses from being kites. "Definition: A quadrilateral with two distinct pairs of equal adjacent sides."

Later, it says A kite can become a rhombus In the special case where all 4 sides are the same length, the kite satisfies the definition of a rhombus. A rhombus in turn can become a square if its interior angles are 90°. Adjust the kite above and try to create a square. So I guess the source contradicts itself.

You want me to find a better source? Personally, I think the Wikipedia article should address the issue. — Preceding unsigned comment added by Danieltrevi (talk • contribs) 04:10, 27 March 2019 (UTC)