Wikipedia talk:WikiProject Mathematics/Archive/2016/Apr

Maryna Viazovska
I've created a stubby new article titled Maryna Viazovska. It could probably use more work. Michael Hardy (talk) 16:13, 31 March 2016 (UTC)
 * And now it's been proposed for deletion — see Articles for deletion/Maryna Viazovska. —David Eppstein (talk) 19:40, 31 March 2016 (UTC)

Would everybody who can opine on this post their thoughts at this page for discussing the proposed deletion. Michael Hardy (talk) 03:29, 1 April 2016 (UTC)


 * Update: So far the Keep sentiment seems to be ahead of the Delete sentiment. Michael Hardy (talk) 20:31, 3 April 2016 (UTC)

April 2016 Disambiguation links
The following math-related terms are in our list of the 1,000 most linked disambiguation pages for April 2016. Any help in fixing links to these pages would be appreciated:


 * Decomposition method (6 links)
 * Function field (5 links)
 * Grothendieck duality (5 links)
 * Leibniz's rule (5 links)
 * Sieve method (5 links)
 * Tree diagram (5 links)

Cheers! bd2412 T 04:10, 5 April 2016 (UTC)

RFC on Gödel's incompleteness theorems
See Talk:Gödel's incompleteness theorems for a formal RFC on whether Gödel's incompleteness theorems should espouse the viewpoint "that formal systems are entirely formal and consist of only formal content" (see RFC for full proposal), and please weigh in if you have an opinion. —David Eppstein (talk) 18:50, 5 April 2016 (UTC)

The "nowrap" template doesn't work.
In the article titled Magma (algebra) one finds this code:
 * M × M → M

But what I see is this:
 * M
 * × M → M
 * × M → M

The whole point of the "nowrap" template is to prevent this kind of wrapping. Michael Hardy (talk) 19:11, 2 April 2016 (UTC)


 * I presume you mean the one in the lead. It works for me, however wide I make the window it is never broken by wrapping. Even if I make the window as narrow as possible and the text as large as possible, which actually makes the M × M → M too wide for the window on its own, it still is one one line. Testing it in this paragraph it also works as expected, and the CSS looks fine.-- JohnBlackburne wordsdeeds 19:54, 2 April 2016 (UTC)
 * WP:VPT might be a better place for finding out why this might be happening and how to fix it, since it is more general than for just mathematical formulas. But I have also been seeing the same thing with the math template, which is also supposed to not wrap but perhaps implements that differently. —David Eppstein (talk) 19:55, 2 April 2016 (UTC)
 * Same method;  by way of the   class.   21:21, 2 April 2016 (UTC)

I can reproduce it with up-to-date Chrome 49.0.2623.110 (64-bit). The line break seems to happen after the arrow for me, if I change the window to a suitable width to force the break to appear. &mdash; Carl (CBM · talk) 21:07, 2 April 2016 (UTC)
 * It appears to be a Chrome bug that allows breaks when nested element are encoutered, in this case, .  21:21, 2 April 2016 (UTC)
 * Yes. I see it in Chrome, but not in IE. YohanN7 (talk) 13:49, 7 April 2016 (UTC)

A new draft at AFC for your consideration
Please review Draft:Kundu equation. If you do not know how to perform an AFC review please simply post your assessment to the draft's talk page. Roger (Dodger67) (talk) 11:50, 24 March 2016 (UTC)


 * I'm a mathematician, but confused also. I think, but am not sure, that it's the same as the Eckhaus equation, also known as the Kundu–Eckhaus equation.
 * Another issue is that the creator of Draft:Kundu equation has the username Anjan Kundu, which implies conflict of interest. Joseph2302 (talk) 18:54, 7 April 2016 (UTC)


 * The Kundu equation, also called the Kundu-NLS equation is a generalization of a nonlinear Schrodinger equation. The Kundu–Eckhaus equation is a specialization of the Kundu-NLS equation. See for example, . --Mark viking (talk) 19:14, 7 April 2016 (UTC)

"Surface"
The usage and topic of surface is under discussion, see Talk:Surface -- 70.51.45.100 (talk) 05:50, 8 April 2016 (UTC)

\int\limits
is apparently going around and changing every integral on Wikipedia from this:
 * $$\int_a^b f(x)\,dx$$

to this:
 * $$\int\limits_a^b f(x)\ dx$$

Note: In addition to having the limits placed far above the integration sign, the thin space between the integrand and differential is replaced by a full space. Do we agree on the global application of this style decision to all of our math articles?  S ławomir Biały  18:57, 31 March 2016 (UTC)


 * I oppose this LaTeX construction in all cases -- I do not think there is ever a good reason for it. --JBL (talk) 19:01, 31 March 2016 (UTC)


 * From some LaTeX documentation I remember that this form is recommended only for multiple integrals (\iint, \iiint, \idotsint). Boris Tsirelson (talk) 19:11, 31 March 2016 (UTC)


 * I am happy to restrict my comments to the case of single integrals. --JBL (talk) 22:54, 31 March 2016 (UTC)


 * Limits above and below are fairly rare in my experience. Placing a limit below for integration over a region is the only common use case I know. The changing of typographic styles for the sake of personal preference in an already existing article is discouraged, in the same way that we discourage LaTeX <-> HTML conversions. --Mark viking (talk) 19:20, 31 March 2016 (UTC)
 * I'm glad someone brought this up. I didn't want to step on anyone's parade, but I see no good (or even bad) reason for making these changes. Bill Cherowitzo (talk) 22:26, 31 March 2016 (UTC)
 * So should  generally be changed to  ? I.e. is $$\int\limits_a^b$$ always changed to $$\int_a^b$$? —  crh 23   &thinsp;(Talk) 16:58, 6 April 2016 (UTC)
 * While there seems to be agreement that  is more common than   and would be preferable in most instances, my opinion is that going from article to article changing typographical style according to personal preference was the main problem here. If the editor in question used   in a completely new article, it would be a little odd, but not a big problem. So my sense is that going from article to article enforcing   is problematic, too--it could lead to pointless edit wars. I'd be in favor of adding the preference for   to MOS:MATH instead. --Mark viking (talk) 18:04, 6 April 2016 (UTC)
 * If this is indeed consensus (which looks to be likely), an addition to MOS:MATH would be great. My reason for asking is this could be added to the AWP list of typos, to be automatically corrected whenever WP:AWB is used to edit a page. Any thoughts? Would there be a problem having  blindly removed whenever it occurs immediately after  ?—  crh 23   &thinsp;(Talk) 20:37, 6 April 2016 (UTC)
 * Possibly, because constructions like $$\iint\limits_D$$ are completely normal. I can't think of a one-variable situation where one would want to use , though, so maybe changing that situation is fine.  Ozob (talk) 12:30, 8 April 2016 (UTC)
 * The only possible problem I can see is if someone uses  to produce that. Could that happen? —  crh 23   &thinsp;(Talk) 14:05, 8 April 2016 (UTC)
 * Who knows? We have a lot of editors, registered and anonymous, with all levels of TeX. I guess it does happen somewhere. Can AWB do the replacement only if there is no "!" before "\int\limits"? Boris Tsirelson (talk) 15:42, 8 April 2016 (UTC)
 * Yes, it is a pretty full regex engine. The problem is predicting any other weird ways of using  for multiple integrals. —  crh 23   &thinsp;(Talk) 16:10, 8 April 2016 (UTC)
 * I can think of a one-variable situation which \limits would be used. Normally in an inline, as opposed to displayed, setting, things like \lim_{x\to a} and \sum{n=1}^x have subscripts and superscripts to the right rather than directly above and below, whereas in a a displayed setting they are above and below.  But in some instances (not most) it makes sense to use the format used in displayed setting when one is in an inline setting.  This can happen when there are no lines of text directly above and below the line in which the notation appears. Michael Hardy (talk) 21:34, 10 April 2016 (UTC)

Fortifying wikiquanta
This project is mostly physical (and advertised on wikiproject physics), but may interest some mathematicians, too. Boris Tsirelson (talk) 11:02, 14 April 2016 (UTC)

More help needed at AfC
Greetings and salutations. Draft:Dragonfly algorithm is a draft sitting at AfC which I could really use input on. Thanks in advance.

Oh, and if you're in the mood, there is a stale draft, Draft:Subdivision curve, which I also could use some help evaluating. Thanks in advance.  Onel 5969  TT me 13:25, 17 April 2016 (UTC)

New Math rendering now on Beta
https://twitter.com/physikerwelt/status/720310670512631808 --Physikerwelt (talk) 18:08, 14 April 2016 (UTC)
 * My first thought was: what's new? MathML already worked on Firefox. Then I noticed I now get SVGs in Chrome. Unfortunaltely, they are just as ugly as the PNGs, but at least they're scalable :) Can we at least switch to STIX for the default font? Computer "Modern" looks incredibly midevil...  19:21, 14 April 2016 (UTC)
 * technically that's not a problem, but is ther consensus for that change?--Physikerwelt (talk) 21:05, 17 April 2016 (UTC)
 * , I'm positive an RfC with both fonts being showcased (with screenshots) will establish a consensus soon enough.  10:45, 18 April 2016 (UTC)

The beta page can be found at http://en.wikipedia.beta.wmflabs.org/wiki/Math --Salix alba (talk): 23:13, 14 April 2016 (UTC)
 * I think it looks beautiful. Ozob (talk) 02:24, 15 April 2016 (UTC)

Darboux frame
I think in the "Definition" section that "(the unit tangent)" and "(the unit normal)" should be interchanged. That is "(the unit tangent)" should be where "(the unit normal)" is, and "(the unit normal)" should be where "(the unit tangent)" is. MGilly9 (talk) 09:26, 18 April 2016 (UTC)
 * If you mean that the formulas for "unit tangent" and "unit normal" should be interchanged in, you are wrong. If you mean that the ordering of the three unit vectors must be changed, this is not so clear. The order of the vectors in a frame is a question of convention, and any convention is valid. However, it is not natural that the two tangent vectors are separated by the normal vector, and avoiding this imply to exchange the first two vectors, as you are asking for. Nevertheless we have to follow the literature, and before making this exchange, one has to look on the reliable references for the most common convention. D.Lazard (talk) 10:13, 18 April 2016 (UTC)
 * It looks like there are some equations with T, t, u whose left-hand sides should be double-checked.  S ławomir  Biały  11:53, 18 April 2016 (UTC)

For those with any knowledge of clade-type computations/presentations
Could you have a look at this effort, here, to use clade diagrams to summarize pharma business acquisitions. My take at present is that the images created are devoid of standard quantitative meaning—nothing is captured by vertical and horizontal line lengths, as far as I can tell—and so they are a misapplication of this maths/graphic presentation method. Moreover, I argue that they are misleading (presenting a time axis, but not making spacing of events proportionate to the historical time differences), much harder to maintain (consider adding entries to a std Table versus this graphic), more likely to diminish article quality (in their ambiguity of content, again, over a std Table with clear headings), and therefore practically amenable to decay as a result. I would add to this, in this esteemed maths context, that they would make those who trained us, and other purists in methodology and meaning (and Edward Tufte more generally), turn in their graves/beds. After having a look at the User page and at a couple of pages linked on that sandbox page, leave your opinion here, regarding the overall effort? Thanks for your opinion. Cheers. Le Prof Leprof 7272 (talk) 01:37, 23 March 2016 (UTC)
 * Sorry about the inappropriate posting above. I have opened a discussion in the appropriate forum, here: Wikipedia_talk:WikiProject_Companies, for anyone who is interested Jytdog (talk) 03:28, 23 March 2016 (UTC)
 * Jytdog moved the question to a new forum, the one where it is least likely to be viewed with rigour, see last comment and link. I reply there. I stand by the fact that maths is an appropriate venue to call for experts, and that it was appropriate to call out to you you at this location, to ask your input. All coming from mathematics, I would appreciate if you state for the record, if you have any real knowledge on this matter (have ever actually done a cladogram-type computations). Transparency, please. Le Prof Leprof 7272 (talk) 15:45, 23 April 2016 (UTC)

Need insights
See Talk:Area of a circle. I am not asking for support for either side, but for input from those with higher math education than either me or the IP.--Jasper Deng (talk) 20:14, 23 April 2016 (UTC)

Changes by Yonathanyeremy
I just reverted a change by and looking at their other ones I can't see anything else that I agree with. Anyone else like to have a quick check and perhaps say what on earth is happening thanks. Dmcq (talk) 13:07, 25 April 2016 (UTC)


 * I saw this edit to Paul Erdős and didn't care enough to try to decide whether to revert. Many of the others are similar, changes to links that are pretty innocuous and neither obviously improvements nor obviously vandalism.  (Sorry this is probably not helpful.) --JBL (talk) 22:17, 25 April 2016 (UTC)


 * I've undone a few more of his changes. I'm curious to know why he's doing these.  Ozob (talk) 23:57, 25 April 2016 (UTC)

Cyclic function
We have a short article titled cyclic function that is not in very good shape right now. In particular, can anyone understand this final sentence?:
 * Cyclic functions can be used in solving problems by substituting a function for its cyclic pair.

Michael Hardy (talk) 21:31, 25 April 2016 (UTC)


 * Tentatively, it's about the universe of mathematical problem solving: there is a class of problems in which one is to solve an algebraic equation involving a cyclic function (or one with a similar property), and by iterative substitution one arrives at an equation that is more easily human-solvable. --JBL (talk) 22:14, 25 April 2016 (UTC)


 * Based on Google, it looks like "cyclic function" usually means "periodic function". So even though there's at least one prominent hit for the meaning of "cyclic function" given in the article, I think it might be better for cyclic function to redirect to periodic function.  Ozob (talk) 00:04, 26 April 2016 (UTC)

Kundu equation (again)



 * is editing both of these articles, and adding content about the Kundu-Eckhaus equation to Kundu equation. In my view, the Kundu-Eckhaus & Eckhaus equations are the same equation, and so all the information should be on that article. The Kundu equation is a separate equation IMO. Thoughts? Joseph2302 (talk) 12:07, 26 April 2016 (UTC)

Dear Editors,

Let me explain  this issue briefly. An integrable generalization of the nonlinear Schroedinger equation with additional quintic nonlinerity and a nonlinear dispersive term given by
 * $$ \psi_t+\psi_{xx} -2  c |\psi|^2q+\kappa^2|\psi|^4\psi \pm 2i

\kappa (| \psi|^2)_x \psi=0,    $$ proposed in (kundu|1984) is   known as the Kundu-Eckhaus equation (more details on this equation with its other aspects, applications and references can be found in my Sandbox). Eckhaus equation introduced later is a particular case of the Kundu-Eckhaus equation (with   $$  c=0 $$) and therefore not the same equation as incorrectly mentioned in that Wiki page. Note that while the Eckhaus equation  is linearizable,  the Kundu-Eckhaus equation is  reducible  only to the nonlinear Schroedinger equation through the same transformation. On the other hand, the Kundu-Eckhaus equation can be derived from the Kundu equation as a particular case. Therefore IMO there may be three logical options: (1)  Eckhaus equation  can go as a subsection under Kundu-Eckhaus equation, (2) Kundu-Eckhaus equation can go as a subsection under Kundu equation, (3) Kundu-Eckhaus equation can go as an independent entry.

Hope to get your valuable suggestion/opinion/advice. Anjan.kundu (talk) 06:45, 27 April 2016 (UTC) April 27, 2016


 * Hello Dr. Kundu. Thank you for adding this to Wikipedia.  I think your contributions are valuable and interesting.  A slight caution is that, generally, Wikipedia discourages editing a topic that one has too close a connection to (for example, articles about eponymous concepts named after ourselves).  Some editors can be a little aggressive in their pursuit of stamping out apparent "self-promotion".  Of course, when a concept is named after a person, that person is also often uniquely the most qualified person to write about that topic, so it's something of a mixed bag.  I, for one, think your contributions are good, and not overly self-promotional, but please don't take it personally if others see the situation differently.  My advise would be to edit other articles in your area of expertise, since you obviously know the literature in this field quite well.  I've made some edits at Kundu equation (mostly spelling corrections), but it needs some more work, and I'm sure other editors will eventually want to clean it up some more.  Thanks,  S ławomir  Biały  14:29, 27 April 2016 (UTC)

Hello Prof. Slawomir Biaty, Thank you very much for your valuable comments and  advice. Hope other editors would also  agree to it with more suggestions and finally the 'tag' marked now to the contribution of Kundu equation could be removed.

With best regards. Anjan.kundu (talk) 05:09, 28 April 2016 (UTC)

Dashboard course
It appears that a Dashboard.wikiedu.org course (Calculus I at Howard University) is getting active with 5 student editors working on several calculus related pages. I have just reverted two of them on Integration by substitution before I realized that this was part of a sponsored program. I believe my reverts were the correct thing to do, but I am wondering whether or not I should have been more proactive in pointing out what the problems with the edits were. There are several issues involved here that I think should be addressed by project members. I have seen this type of project several times already and in each instance the program has left messes on several pages that have had to been cleaned up by us. Is there a way to inform the program directors that while the intentions of this program may be good and noble, the direct consequence is that a lot of unnecessary cleanup work is being created for us and perhaps there are other ways to achieve their ends without over-burdening the project editors. As WP editors we do not act as referees for the material presented on the pages, we do not evaluate, nor correct – unless backed up by a reliable source. By an extension of the philosophy upon which that position is based, should we be acting as teachers of the, in this case, Howard University students? Howard U. is not paying us a salary, nor does it have any control over who we are; I think the university should be concerned about that. Any comments, suggestions, etc. Thanks. Bill Cherowitzo (talk) 04:48, 26 April 2016 (UTC)
 * There's the education Noticeboard, which can be used if needed. Joseph2302 (talk) 06:42, 26 April 2016 (UTC)
 * Education noticeboard is at WP:ENB: WP:EN redirects to Naming conventions (use English) — crh 23   &thinsp;(Talk) 09:44, 26 April 2016 (UTC)
 * Link fixed, thanks. Joseph2302 (talk) 12:02, 26 April 2016 (UTC)
 * Or you could contact who appears to be the Wikipedia education person associated with Wiki Ed/Howard University, Washington, DC/Calculus I (spring 2016). Joseph2302 (talk) 06:47, 26 April 2016 (UTC)
 * Also Joel Lewis reverted some edits to limit of a function that were related to this program. It looks like all edits to these articles were reverted and that the edits were made by at least three distinct students in that program.  This suggests that the students are encouraged not only to review the articles, but also to edit them.  That is a problem, in my opinion.  While there is no rule against people unfamiliar with a topic making edits, typically for major edits such as these, one should generally expect that the editor is familiar both with how Wikipedia works, and with the topic area.  Correction: this edit to antiderivative was reverted, by me.   S ławomir  Biały  09:57, 26 April 2016 (UTC)
 * I've notified Ian (Wiki Ed) about this discussion, so hopefully he'll be able to help/advise. Joseph2302 (talk) 12:02, 26 April 2016 (UTC)
 * I have to say that I'm distressed by this whole situation. These students are being asked to contribute to well-developed articles written by experts, and they just don't have the competence to do so.  Their contributions so far have shown they don't understand calculus and they don't know how to write.  The students who haven't edited yet are unlikely to be any better.  I'm sure they're being graded on their contributions; do they all get an F because they can't write with style and depth of professional mathematician?  They're in an impossible position.  Ozob (talk) 12:41, 26 April 2016 (UTC)
 * I just noticed that the students are required to edit the articles: "Add 1–2 sentences of new information, backed up with a citation to an appropriate source, to a Wikipedia article related to the class." This is most worrying indeed.  It seems like the students are editing mostly the leads of articles, which is in fact the hardest part to write, requiring the most experience (both as a Wikipedian and as a content expert).  I think these assignments should be put an end to.   S ławomir  Biały  12:57, 26 April 2016 (UTC)
 * I looked through the case studies at and was impressed.  There are some excellent ideas for student editing of Wikipedia.  However, a common thread seemed to be that the students can be reasonably expected to be knowledgeable about the articles they are supposed to edit.  For example, the students might be asked to write a research paper on a topic not covered in Wikipedia; writing the research paper already makes the student more knowledgeable about the subject than what can be gleaned from Wikipedia, so it's not unreasonable to ask them to write an article.  Another common thread is that the process is long, usually spanning a whole quarter or semester.  Often the students must submit drafts for the instructor to review, so they are not permitted to do a slapdash job.  I expect that a course structured like some of the case studies but focused on mathematics would be excellent both for the students and for Wikipedia.  Ozob (talk) 23:29, 28 April 2016 (UTC)
 * Yes, I agree with this. But, to reiterate a point I think we agree on, that was emphatically not the case here.  One does not simply unleash the students willy-nilly with no preparation.  There is an expectation that, if they are going to edit the encyclopedia, that they actually should do a good job, not turn Wikipedia into a personal scratchpad for half-baked (or indeed, completely unbaked) homework assignments.   S ławomir  Biały  00:05, 29 April 2016 (UTC)
 * Yes, some of those case studies look like valuable projects. I did note that science and mathematics topics are mostly missing and I expect that this is partially due to the fact that this type of writing is more challenging and harder to get right. These difficulties can be overcome, but I think it requires that the instructor be more directive and involved with the students than would normally be the case. However, this may cause a problem since topical specialists may not feel comfortable in this expanded role, and some would certainly feel that the more time spent on writing issues, the less time will be available to devote to the subject at hand. I think we have seen what results when an instructor doesn't move in this direction. Bill Cherowitzo (talk) 04:27, 29 April 2016 (UTC)
 * Under the conditions Ozob mentions, it can turn out pretty good, even for technical articles. The section S-matrix in one-dimensional quantum mechanics is the result of such a project. YohanN7 (talk) 08:26, 29 April 2016 (UTC)
 * There's no reason not to revert substandard edits. You should treat them like any other Wikipedia editor (good or bad); their additions need to be high enough quality, and they must be reliably sourced. And you're right - it isn't your job to clean up after them. Let me figure what's going on and try to steer them in a better direction. My apologies for the trouble caused. Ian (Wiki Ed) (talk) 13:39, 26 April 2016 (UTC)