Wikipedia talk:WikiProject Mathematics/Archive/2019/Mar

Wikipedia:Miscellany for deletion/Draft:Bredon cohomology (2nd nomination)
There is a long-standing dispute flaring up again over a short, one-sentence-fragment draft at Draft:Bredon cohomology which needs input from editors familiar with mathematics topics. The crux of the issue is that the only editor interested in keeping the draft has not worked on it in five years, and nobody else who has interacted with this has the knowledge to edit topics of this complexity. If someone could help us work out what this draft is and where it should go, your efforts will be greatly appreciated. Thanks. Ivanvector (Talk/Edits) 16:29, 1 March 2019 (UTC)


 * I've removed some more spill-over from that debate. The page has been worked on enough that it's been promoted to an article, but it's a very short stub. More help there is still appreciated. Ivanvector (Talk/Edits) 17:18, 1 March 2019 (UTC)

Glitch prime?
I just stumbled on this video by Numberphile talking about a thing he called "glitch prime". I was surprised to see we don't have an article on that (or at least a redirect to an equivalent concept. Basically they're numbers, when expressed in a base, are an odd number of digits where all the digits is the maximum number in the base, and the middle digit is one less (e.g. 11011 in binary, 22222122222 in ternary, 99899 in base ten and so on), which also happen to be primes. I could be explaining this wrong, but that was my takeaway.

Not really sure if that passes any sort of WP:N standards, of if it's a 'thing' in math, but I was surprised not to have an article on them. Headbomb {t · c · p · b} 13:37, 5 March 2019 (UTC)


 * I looked around briefly, but found very little. These are listed at A265383, but there's not much fanout in terms of what they link to.  I'm not 100% sure, but my suspicion is that there just isn't enough out there to clear WP:N and sustain an article.  –Deacon Vorbis (carbon &bull; videos) 14:41, 5 March 2019 (UTC)
 * I don't see notability for their own article. They are a form of List of prime numbers which are a form of near-repdigit primes. Neither has an article. If they did (notatibility is very questionable) then "glitch prime" could have been mentioned there. PrimeHunter (talk) 15:49, 5 March 2019 (UTC)
 * Would a redirect to that make sense then? Or worth having a subsection in that list article? Headbomb {t · c · p · b} 19:02, 5 March 2019 (UTC)
 * I don't think they are notable enough for List of prime numbers. OEIS has thousands of prime number sequences. A redirect makes no sense if the target gives no indication of the meaning. PrimeHunter (talk) 10:30, 6 March 2019 (UTC)

Also, this is WP:OR, as the author of the video does not cite any source. So, this does not belong to WP. D.Lazard (talk) 12:31, 6 March 2019 (UTC)
 * The OR policy forbids an author from publishing their original research in Wikipedia. It absolutely does not forbid referencing a source that is itself engaged in original research. (Otherwise it would be forbidden to cite published mathematics research papers in WP.)  --JBL (talk) 17:46, 6 March 2019 (UTC)
 * In WP:OR, original research is defined as The phrase "original research" (OR) is used on Wikipedia to refer to material—such as facts, allegations, and ideas—for which no reliable, published sources exist. This is precisely the case of "glitch primes". D.Lazard (talk) 18:07, 6 March 2019 (UTC)
 * The Numberphile video is a published source; possibly you believe that it is not reliable, but that is a totally separate issue from WP:OR. --JBL (talk) 18:11, 6 March 2019 (UTC)
 * In WP:OR: Self-published material, whether on paper or online, is generally not regarded as reliable. In WP:SPS: Self-published expert sources may be considered reliable when produced by an established expert on the subject matter, whose work in the relevant field has previously been published by reliable third-party publications. An anonymous blogger, such as nunberphile, cannot fit this definition of a self-published expert. So, the fact that this source is not reliable is the result of Wikipedia's definition of "reliable". It is not a belief nor an opinion. D.Lazard (talk) 18:53, 6 March 2019 (UTC)
 * Numberphile is not an 'anonymous blogger', and neither is Simon Pampena . Headbomb {t · c · p · b} 18:56, 6 March 2019 (UTC)

Is Ngo best described as "Vietnamese-French" or "Vietnamese" in the lead?
Please see the discussion here. --173.79.47.7 (talk) 23:01, 6 March 2019 (UTC)

old Drafts found
Draft:Robust geometric computation Legacypac (talk) 03:19, 6 March 2019 (UTC)

Draft:Proto-value Functions. Robert McClenon (talk) 22:39, 6 March 2019 (UTC)
 * We already have an article on Proto-value functions, created in 2011. (This is the same topic but with different capitalization of the title). Both the draft and the article were created by User:GNrun. The article looks keepable; the draft should be disposed of in whatever way is correct. EdJohnston (talk) 23:06, 6 March 2019 (UTC)
 * I have tagged Draft:Proto-value Functions as a duplicate of an article. It will be available for comparison against the article for six months and then will self-destruct.  See G13 rather than Mission Impossible.  Robert McClenon (talk) 19:07, 7 March 2019 (UTC)

I have added these two drafts to WikiProject Mathematics/List of math draft pages. -- Taku (talk) 23:18, 6 March 2019 (UTC)


 * I am interested to see that there is a list of drafts. I will occasionally add the name of a draft here to permit the updating of the list by someone whose math knowledge is a little better than mine, which consists of having forgotten all of the higher math that I learned in college and still remembering first-year calculus because I learned it in high school.  Robert McClenon (talk) 19:07, 7 March 2019 (UTC)

I have moved Proto-value functions to Proto-value function. I left it as an orphaned article, i.e. no other articles link to it. I don't know which other topics should link to it. Michael Hardy (talk) 16:41, 9 March 2019 (UTC)

New Draft Found
Please categorize Draft:M* search algorithm Robert McClenon (talk) 01:37, 8 March 2019 (UTC)

The list was Taku's excellent idea. If other wikiprojects did this more good drafts could be improved. Legacypac (talk) 06:51, 8 March 2019 (UTC)

Entropy influence conjecture
If the new article titled Entropy influence conjecture should be kept, then it needs work. In particular, it's not all that clearly stated, and no other articles link to it. Michael Hardy (talk) 16:55, 2 March 2019 (UTC)
 * It almost makes sense to me, but since when does a "Boolean" function map to {-1, 1}? — Arthur Rubin (talk) 03:27, 3 March 2019 (UTC)
 * This conjecture showed up on Terrence Tao's blog, where it is explained much better. This article might be usefully merged into the section Analysis_of_Boolean_functions, with associated results. -- 03:39, 3 March 2019 (UTC)
 * The value of a Boolean function could be any two things, but as I understand it it's pretty standard for those two things to be -1 and 1 instead of 0 and 1 when you're going to do Fourier analysis on the function. —David Eppstein (talk) 06:58, 3 March 2019 (UTC)
 * That the codomain is {0,1} is the convention that I know, but (1) it's still into a set of just two values and (2) it makes it possible to write $ \prod_{i=1}^n x_i$ instead of the more complicated $ \prod_{i=1}^n (2x_i-1). $  Michael Hardy (talk) 21:46, 3 March 2019 (UTC)
 * I've cleaned the article up a bit and linked the article from one of its originators (Gil Kalai) so that it's at least not an orphan anymore. Unsure if the article meets notability standards as it's not a terribly well-known problem but it should be a bit better now at least. It could certainly be merged into Analysis of Boolean functions as suggested by (I would support that). — MarkH21 (talk) 07:38, 12 March 2019 (UTC)

Draft:Color and mathematics
So I don't know what should be done with this draft. The article title seems too vague, which is of course fixable and the topic itself seems legitimate (but I don't have a background to review the article itself myself). -- Taku (talk) 01:44, 15 March 2019 (UTC)
 * It looks like original research to me. Some of its content may of course have been published somewhere, but if you find those publications and turn that content into an article meeting Wikipedia standards, you'll have something so different from the draft that it will be effectively a completely different article.
 * That said, I see no urgency to delete these. --Trovatore (talk) 02:43, 15 March 2019 (UTC)
 * A vector space for color vision is not itself Original Research, but this draft probably needs revision to make clear what's derived from what. XOR&#39;easter (talk) 02:50, 15 March 2019 (UTC)
 * "Original research" is of course a term of art here; it doesn't mean that it's particularly original or makes any research contribution. The content seems pretty simple and I don't see anything obviously wrong (not that I've been over it with a fine-tooth comb), so it's quite likely that any particular statement in it is more-or-less sourceable.  But it's not clear that the exposition as a whole corresponds to anything in sources. --Trovatore (talk) 18:07, 15 March 2019 (UTC)
 * As far as I understand, this draft may be viewed as a tentative for describing the mathematical background of color space. So, the draft could be merged in color space, for making a section called "mathematical background" or "mathematical definition". But, for that, a lot of work is needed on the draft as well as on the target article. D.Lazard (talk) 10:09, 15 March 2019 (UTC)


 * (Thank you all for the responses). Following D.Lazard’s suggestion, I have put a merger tag; and, *hopefully*, someone knowledgeable can take care of the draft. Yes, the content looks fine; but I’m just not well equipped with the knowledge (or will power) to judge the content so simply moving it to mainspace seems wrong. —- Taku (talk) 09:14, 18 March 2019 (UTC)

The article "Compositional data"
This article doesn't seem to have much content to me. Is this not just giving examples where all data points lie on a simplex? It also happens to be almost entirely contained in Aitchison geometry (which seems to just define some operations on the simplex and a few isomorphisms, although perhaps their significance in statistics is greater than I can tell).

Seems to me like at least one of the two articles should be merged into the other or to Simplex (which itself needs some work). See the talk page discussion at compositional data and talk page discussion at Aitchison geometry that I just started. — MarkH21 (talk) 06:21, 12 March 2019 (UTC)


 * Compositional data is currently a very very stubby article. It currently has _nothing_ on the normal distribution of logits, along with their variance matrices and singular-value decompositions of them, etc. Obviously if one is to be merged into the other then Compositional data is the one that should survive. Michael Hardy (talk) 05:50, 13 March 2019 (UTC)

It is also obvious that if two of these are merged, then Aitchison geometry would be merged into Compositional data and not into Simplex, since analysis of compositional data is the purpose of Aitchison's work. Michael Hardy (talk) 17:03, 14 March 2019 (UTC)


 * Got it, thanks for the help! I may go ahead and do that if there is no objection. Would you be able to add the content that you mentioned? — MarkH21 (talk) 22:27, 14 March 2019 (UTC)


 * I'm not sure the article titled Aitchison geometry shouldn't exist. Possibly when Wikipedia's coverage of the topic of compositional data analysis becomes somewhat complete it will be obvious that it should. Michael Hardy (talk) 05:48, 15 March 2019 (UTC)


 * My understanding is that Aitchison geometry is a set of transformations and a structure on a simplex used to study data that lies on a simplex (i.e. compositional data), right? It's the sample space of compositional data and seems to be better served as a section of the article on compositional data. It doesn't seem like the article compositional data (which is 15 years old!) and Aitchison geometry will each be expanded so greatly in the near future that Aitchison geometry should be a standalone article. But when it does, we could split Aitchison geometry into its own article?
 * This is just my (non-expert) opinion, but I think both article would be improved in their current (and foreseeable) state if we made Aitchison geometry a section of compositional data. — MarkH21 (talk) 18:49, 15 March 2019 (UTC)
 * For now that's probably the best way. But if the article gets expanded a lot later then a separate article may make more sense. Michael Hardy (talk) 17:38, 18 March 2019 (UTC)

Thanks for your input! I've done the merge now, made some other revisions to the writing, and added some links to the article / pointing at the article. — MarkH21 (talk) 07:04, 19 March 2019 (UTC)

Sieve of Eratosthenes and sieve theory
There's a dispute and discussion ongoing at Talk:Sieve of Eratosthenes over whether the lead of the article should mention sieve theory. Please participate with your opinions. —David Eppstein (talk) 16:06, 19 March 2019 (UTC)

Notice of RfC on Infobox inclusion at FLT
Apologies for bringing up an old issue. Just posting a notice that an official RfC has been posted for the FLT infobox debate: Talk:Fermat's Last Theorem. Hopefully this can lead to the debate being effectively and peacefully closed in either direction. — MarkH21 (talk) 07:32, 19 March 2019 (UTC)


 * Re "peacefully", if no one gets stabbed as a result of this issue, I will be very disappointed ;). --JBL (talk) 16:10, 19 March 2019 (UTC)

Karen Uhlenbeck
Regarding Karen Uhlenbeck's win of the Abel prize, wrote on Wikipedia talk:WikiProject Women in Red that "This article has the opportunity to appear at ITN today. Please help improve the article. We need to expand the Research section to explain why she won the Abel Prize. Please help!". My feeling is that this project is more likely than WIR to include people who understand her research well enough to help, so I am copying the message here. —David Eppstein (talk) 19:57, 19 March 2019 (UTC)


 * I've added some details to her work on minimal surfaces and Yang–Mills theory. I'm not an expert in the field though but it could certainly be expanded further by any passing geometric analyst. — MarkH21 (talk) 20:35, 19 March 2019 (UTC)


 * There's quite a bit more than can be added; in particular, the Donaldson survey has quite a bit of information that can improve the Research section. I don't have time to do this now, but perhaps someone else may find themselves up to the task. — MarkH21 (talk) 01:26, 20 March 2019 (UTC)

Infobox edits (thankfully not about FLT)
I am about to run off to work so can't deal with this properly, but attention is definitely needed with respect to the edits to mathematician infoboxes by this user:. There have been some reversions (e.g. by at Paul Erdos and by me at Andrey Markov and Alexander Grothendieck), but there are many more. Courtesy ping:. --JBL (talk) 13:26, 18 March 2019 (UTC)
 * The same editor has also created Kolmogorov's theory of 1941, which deserves clearly to be nominated for AfD. It would better to be nominated by an editor who knows turbulence theory. D.Lazard (talk) 14:14, 18 March 2019 (UTC)
 * PS: this article has been made a redirect to Turbulence by another editor, while I was writing my previous post. D.Lazard (talk) 14:18, 18 March 2019 (UTC)
 * All infoboxes edits by this user have now been reverted. D.Lazard (talk) 15:56, 18 March 2019 (UTC)
 * Hello, many of you reverted my edits for as one of you said, because I didn't summarize, I consider my goal is not only to summarize but also to unify as much information as possible on the main page with the associated pages, but also to keep it comprehensive, i.e. "summarized". As far as my conception of "known for" is concerned, I don't have a narrow minded approach towards the concept of 'known for" that I presume one of you have, a mathematically ignorant person may or may not "know" a person or his name because of his direct "contributions" to knowledge. Also, to back up my argument, I'll also mention you 3 few "good","protected" and a "featured" article that have the same format of representation of "known for" field that I tried to edit in my editing of Paul Erdős' article. Please have a look at the following articles: Richard Feynman, John von Neumann and Paul Dirac. The 3 aforementioned articles are rated "featured, "good" and "semi-protected" respectively also have a lengthy collapsible list. Also, to avoid super-lengthy infoboxes, I added collapsible lists, as it'd hence, be intuitively understandable to the reader that the associated field may contain long/medium sized information. My request to you people would be not to revert the articles and to allow my previous edits, as it'll both unify and summarize the articles' infoboxes. Debaditya2000 (talk • contribs) 1:47 pm, Today (UTC−4)
 * I'm afraid there is a general consensus that collapsible lists are not appropriate in articles. If you want to try to override that consensus in the articles you are editing, work on those articles' talk pages.  I haven't checked your edits, and haven't analysed your comment here to see if there are other things you want which are contrary to established consensus.  — Arthur Rubin  (talk) 05:20, 19 March 2019 (UTC)
 * If there is a general consensus, then it should apply to every list and if, there is a general consensus on something which is contradictory of the established well written articles' (as I gave a few references earlier) formats then I think it is plausible that having collapsible lists are no violation, of Wikipedia policies, rather it's fundamentally within it, which is sharing as much information as possible. I repeat, when there is an inclusion of a collapsible list, it is intuitively understandable to the reader that the associated field may contain long/medium sized information. However, the list itself doesn't make the infobox too long, as there is an option to shorten or open a list, which is absent in general, non-collapsible ones. I think I have provided enough justification, so I shall continue to do what I think is needed to for the article for it's betterment, in accordance to Wikipedia policies with reference to "Good/Featured/Protected" articles. Thank you.Debaditya2000 —Preceding undated comment added 07:53, 19 March 2019 (UTC)

The question set by is about the style of the field "known for" in infoboxes of mathematicians. Debaditya2000 edits consist of providing a field containing only, which allows display a long list that seems copied from articles titled "List of things named after ...". IMO, this breaks the purpose of infoboxes, which is to provide a synthetic view. For people with many important contributions, giving a short synthetic summary of them is very difficult, but a long indiscriminate list is certainly not the right solution. This needs a discussion here. Until reaching a consensus here, must not pushing his personal ideas by editing again infoboxes. D.Lazard (talk) 10:06, 19 March 2019 (UTC)

I don't agree, with providing a "synthetic view" which seems rather "insincere"/"superfluous" for view in infoboxes, rather to provide an informative yet, summarized view and I repeat for the 3rd time "intuitively understandable for the reader" type of a view. Just like in these articles: Richard Feynman, John von Neumann or Paul Dirac, which have used the same formats that I tried to present in my editing. Which seem again to have copied from List of things named after Richard Feynman, List of things named after John von Neumann and List of things named after Paul Dirac. And all these articles are rated. Hence, it doesn't matter whether it is copied or not, it matters whether the information provided thus forth is correct or incorrect. So, rather than to continue this long and unproductive discussion, I think my allowance should be granted ASAP. — Preceding unsigned comment added by Debaditya2000 (talk • contribs)


 * Infoboxers seem to be after the ultimate IB: the recursive one! The whole WP is to be turned into one, clearly laid out IB, making it easy for third parties, superficial readers, common-sense afficionados, ... This is to where indiscriminate use of IBs will lead.
 * Seriously, I think that an IB-entry "known for", allowing for more than three items should not be contained within an IB. I am strictly against "granting allowance" alongside these intentions. Purgy (talk) 13:51, 20 March 2019 (UTC)

Merely a wrong aspect ratio, or something else?
is plainly wrong, and is used in the article titled Voronoi pole. Is this simply a result of using the wrong aspect ratio? Michael Hardy (talk) 20:43, 21 March 2019 (UTC)
 * I'm not sure we have to diagnose how it was broken to agree that it is a bad image and should not be used. —David Eppstein (talk) 21:17, 21 March 2019 (UTC)

Merge of double torus and triple torus to n-torus?
I just noticed that there are the stubs Genus-two surface and Genus-three surface which would probably be better suited as redirects to the section n-dimensional torus of Torus. The articles don't say much and have few links pointing towards them. Respective proposals: genus two and genus three. — MarkH21 (talk) 19:37, 25 March 2019 (UTC)


 * A more appropriate section is – a 2-torus is a regular (genus 1) torus, and a 3-torus is a 3-manifold ($$S^1 \times S^1 \times S^1$$).  I'd generally think it would be preferable to merge the genus 2 and 3 surface articles into a single Genus g surface (or whatever-named) article (maybe there's already something like this? I haven't really looked yet), with a  pointer from the "Genus g surface" section of the Torus page.  –Deacon Vorbis (carbon &bull; videos) 20:25, 25 March 2019 (UTC)
 * Oops! Yes, thanks for pointing that out (that was the section I meant)! Sure, I can do that. Similarly, the same should perhaps be done for Three-torus and the dimension n torus section.— MarkH21 (talk) 22:20, 25 March 2019 (UTC)

Nomination of Portal:Areas of mathematics for deletion
A discussion is taking place as to whether Portal:Areas of mathematics is suitable for inclusion in Wikipedia according to Wikipedia's policies and guidelines or whether it should be deleted.

The page will be discussed at Wikipedia:Miscellany for deletion/Portal:Areas of mathematics until a consensus is reached, and anyone is welcome to contribute to the discussion. The nomination will explain the policies and guidelines which are of concern. The discussion focuses on high-quality evidence and our policies and guidelines.

Users may edit the page during the discussion, including to improve the page to address concerns raised in the discussion. However, do not remove the deletion notice from the top of the page. North America1000 12:38, 26 March 2019 (UTC)

Postmodern mathematics
Folks here might be interested in WT:WPP about some concerns I had on this article. –Deacon Vorbis (carbon &bull; videos) 14:07, 27 March 2019 (UTC)
 * It does look rather OR-ish and essay-like. The brute-force solution would be to redirect it to Philosophy of mathematics, which is not great, but is better. XOR&#39;easter (talk) 00:05, 28 March 2019 (UTC)
 * See (and discuss there) WikiProject Deletion sorting/Mathematics. D.Lazard (talk) 04:13, 28 March 2019 (UTC)
 * More permanent link — MarkH21 (talk) 05:03, 28 March 2019 (UTC)

(Inappropriate) postnominals again
Everyone remember this fun from last year (continued here)? This time it started on Claude Shannon (talk page discussion for masochists) and seems to have progressed to ridiculousness -- note the inclusion on Paul Erdős again (which I have reverted). Some assistance dealing with this would be welcome. --JBL (talk) 23:13, 27 March 2019 (UTC)
 * "Progressed to ridiculousness", indeed! I'd support a massive rollback (I presume there's some admin tool that can do this). XOR&#39;easter (talk) 23:54, 27 March 2019 (UTC)
 * I ended up doing it by hand (not so hard, actually, since he stopped after "only" 100 or so disruptions) -- there is now a discussion at ANI (perm) in case anyone cares. --JBL (talk) 12:58, 28 March 2019 (UTC)

Notation malfunction
I found this in an article:
 * Pr(X ∈ g−1(F) )

It is coded as follows:
 * Pr(X ∈ g−1(F) )

Obviously this was intended to look like this:
 * $$ \Pr(X\in \overline{g^{-1}(F)} ) $$

Often one avoids inline "TeX" because of bizarre mismatches in font size and alignment. Nowadays we have the following sort of thing:
 * $ 2+2=4 $

Just how well that works is a matter on which I am not ready to opine, although some instances look good to me. So one could reasonably replace what I found, maybe. But still it would seem a good idea to fix the "overline" text-decoration feature, if possible. Michael Hardy (talk) 19:14, 30 March 2019 (UTC)


 * I prefer TeX myself, but for a CSS approach, span style="padding-top: 4px; border-top:1px solid" will give a better result:
 * Pr(X ∈ g−1(F) )
 * -- 20:05, 30 March 2019 (UTC)

AfD on a mathematician needs attention from independent editors
The AfD on Rick Norwood (a mathematician and comics publisher) has drawn attention from editors who personally know him due to a Facebook post by the subject (courtesy ping). Any reviews from independent editors would be greatly appreciated. — MarkH21 (talk) 00:23, 31 March 2019 (UTC)
 * These two AfDs connected to the subject (although not about math) have also been affected: Articles for deletion/Manuscript Press (his publishing company) and Articles for deletion/John Blair Moore (an article he created). — MarkH21 (talk) 00:40, 31 March 2019 (UTC)
 * I asked for help in the form of citations of reliable sources which have reviewed or commented on my work. MarkH21 has informed me that this is against Wikipedia policy.  I've been editing Wikipedia for 14 years, and had not come across this rule before, but I apologize for breaking it, and will heed MarkH21's advice. Rick Norwood (talk) 01:31, 31 March 2019 (UTC)
 * I tend to agree that this is not against the rules, although I haven't asked for it during the 6 times Arthur Rubin has been nominated for deletion. — Arthur Rubin  (talk) 04:09, 31 March 2019 (UTC)
 * Good for you. There are more than three hundred living topologists who have articles on Facebook, and I don't know how many mathematicians, and I doubt more than ten percent meet the stringent requirements that MarkH21 wants to apply.  However, I am basing my defense less on my mathematics than on my expertise, writing, and publishing in the area of comic strips, where I really am one of the top people in that field. Rick Norwood (talk) 12:36, 31 March 2019 (UTC)

Poorly written sentence
I'm trying to fix a poorly written sentence in the topology article. It includes multiple uses of "we". But another editor is reverting my improvement. Also, the key terms in the section containing the sentence should be wikilinked (which I did, but the other user reverted). Could someone please take a look at the article? Jrheller1 (talk) 00:32, 27 March 2019 (UTC)
 * Your concerns about this sentence are valid, but as other editors have pointed out, your "fixes" have had problems. I have suggested a fix that does not distort the underlying concept, perhaps this will suffice. --Bill Cherowitzo (talk) 18:17, 27 March 2019 (UTC)
 * "The definition of an open set determines the nature of continuous functions, compact sets, and connected sets" is the cleanest version of the sentence. What exactly is incorrect about this version of the sentence?  Also, how is it helpful to readers to remove the wikilinks to the key concepts from that section? Jrheller1 (talk) 22:44, 27 March 2019 (UTC)


 * A better wording might reflect that the definitions of continuity, compactness, etc. are based on/use the open sets. To be annoyingly precise, it is not really the definition that determines those sets. If you switch one definition with an equivalent one (but not "the same"), then the other sets don't change. — MarkH21 (talk) 23:00, 27 March 2019 (UTC)


 * What exactly is incorrect about this version of the sentence? I personally wouldn't say that it's incorrect, just that it's not at all clear what the meaning of that string of words is supposed to be. What does "the definition of an open set" mean? What is "the nature of" continuous functions, etc., and how is it "determined"? (Honestly though I'm not sure such a sentence is needed there at all.) --JBL (talk) 23:08, 27 March 2019 (UTC)

Multiple people have complained about "nature of", so maybe "The definition of an open set completely determines the continuous functions, the compact sets, and the connected sets" would be better. I don't understand what is unclear about "definition" and "determines". But as JBL stated, the sentence might not even be necessary. Jrheller1 (talk) 04:45, 28 March 2019 (UTC)

So I changed two sentences to:
 * The definition of an open set completely determines the continuous functions, the compact sets, and the connected sets. A choice of open subsets is called a topology.

Another user changed it back to this version:


 * If the collection of subsets that are designated as open is changed, then this affects which functions are continuous, as well as which sets are compact and which sets are connected. A choice of subsets to be called open is a topology.

Which of these two versions is better? Jrheller1 (talk) 15:07, 31 March 2019 (UTC)
 * This does not belongs to this page but to Talk:Topology. Nevertheless the second version is slightly better, as the singular in "the definition of an open set" is confusing. Nevertheless both formulations are badly written. I'll propose a better version by editing the article. D.Lazard (talk) 15:16, 31 March 2019 (UTC)