Wikipedia talk:WikiProject Mathematics/Archive/2015/Feb

Irreducibility (mathematics) needs help in a bad way
Irreducibility (mathematics) is awful as a disambiguation page, and really should either be moved to Irreducibility (disambiguation) and simplified to conform with MOS:DAB, or turned back into an article describing the primary usage of this term with respect to mathematics. Cheers! bd2412 T 18:59, 1 February 2015 (UTC)


 * I confess that I'm responsible for turning the page into a disambig page. I do believe there is no uniform definition of "irreducibility" in mathematics, aside from the usual English sense of "not reducible". For example, "irreducible" as in irreducible representation, one as in irreducible polynomial and one as in irreducible component (of a topological space) have nothing in common. -- Taku (talk) 00:53, 2 February 2015 (UTC)


 * It's not a disambiguation page. It's possibly been mislabelled as such, but it's really a collection of distinct but related uses of a term in mathematical discourse.  It would certainly be ideal for someone to link to a more specific meaning of the term in mathematics, but (as often is the case) the usage of a term in mathematics often has more to do with analogies than "this usage or that one".  Such pages are useful and important, but should not be treated like "disambiguation pages".  If their designation as such confuses various editors, then re-designate them to a more appropriate category.  Such pages are very useful and should be allowed and encouraged to stay.  Taku has my full support here.   Sławomir Biały  (talk) 01:06, 2 February 2015 (UTC)


 * Ok. How do you call that page then? I have just fixed some incoming links (most of times to irreducible representation). The fix was no-brainer. It's very unhelpful for us to direct the readers to Irreducibility (mathematics) instead of "irreducible representaion", when the latter is meant in linking the term. I can ask: on what occasions do we want to have a link to Irreducibility (mathematics)? "A page that must not be linked" is more or less a disambig page. -- Taku (talk) 01:22, 2 February 2015 (UTC)


 * The title "Irreducibility (mathematics)" seems perfectly reasonable as a title for such a page. Why should there even be a question?  I think the issue is that there is some template on that page that tells all the dab-droids that it's a disambiguation page.  Remove that template, and the problem is solved, as far as I can tell.  Of course, we should link as many things to a specific page as possible, using discretion.  But it's wrong to say that each and every time for which the concept of irreducibility appears in a mathematics article that it needs to be completely nailed down to one of the articles.  That's what a "disambiguation" page entails, and that's clearly not what we have here.  Sławomir Biały  (talk) 01:45, 2 February 2015 (UTC)
 * User:R.e.b. has fixed the problem by replacing the dab template by sia. It's not really a dab, because the thing that is ambiguous is not the word "irreducibility" but the concept: what kind of decompositions are we talking about? Set index articles are the right way to handle conceptual rather than verbal ambiguities, and don't have such severe formatting and linking constraints as dabs. —David Eppstein (talk) 02:25, 2 February 2015 (UTC)

Yes, SIA was the answer to my question (though why we need to have a distinction is beyond me, reminding me of tax code). To Sławomir, no, I think it is "wrong" to have a link to irreducibility (mathematics), because readers have to look at the list and choose the correct destination. Doesn't that make the page precise a disambig page? (or SIA as some would prefer). Anyway, the problem has been solved so it's ok now. -- Taku (talk) 12:28, 2 February 2015 (UTC)

Lewis Carroll
The page currently contains the following material:

''Speculation on Dodgson's sexuality[edit] Dodgson's nephew and biographer Stuart Dodgson Collingwood wrote: And now as to the secondary causes which attracted him to children. First, I think children appealed to him because he was pre-eminently a teacher, and he saw in their unspoiled minds the best material for him to work upon. In later years one of his favourite recreations was to lecture at schools on logic; he used to give personal attention to each of his pupils, and one can well imagine with what eager anticipation the children would have looked forward to the visits of a schoolmaster who knew how to make even the dullest subjects interesting and amusing.[73] Despite comments like this, and the fact that his pictures of children were taken with a parent in attendance (many in the Liddell garden),[39] modern psychological interpretations of Dodgson's friendships with young girls and of his related work—especially his photographs of nude or semi-nude girls—have led some late twentieth century biographers to speculate that he was a paedophile, including Morton N. Cohen in his Lewis Carroll: A Biography (1995),[74] Donald Thomas in his Lewis Carroll: A Portrait with Background (1995), and Michael Bakewell in his Lewis Carroll: A Biography (1996). All of these works more or less assume that Dodgson was a paedophile, albeit a repressed and celibate one.[page needed] Cohen, in particular, claims Dodgson's "sexual energies sought unconventional outlets", and further writes: We cannot know to what extent sexual urges lay behind Charles's preference for drawing and photographing children in the nude. He contended the preference was entirely aesthetic. But given his emotional attachment to children as well as his aesthetic appreciation of their forms, his assertion that his interest was strictly artistic is naïve. He probably felt more than he dared acknowledge, even to himself.[page needed] Cohen goes on to note that Dodgson "apparently convinced many of his friends that his attachment to the nude female child form was free of any eroticism", but adds that "later generations look beneath the surface" (p. 229). He and other biographers[who?] argue that Dodgson may have wanted to marry the 11-year-old Alice Liddell, and that this was the cause of the unexplained "break" with the family in June 1863,[26] an event for which other explanations are offered. Biographers Derek Hudson and Roger Lancelyn Green (Green also having edited Dodgson's diaries and papers) stop short of identifying Dodgson as a paedophile, but concur that he had a passion for small female children and next to no interest in the adult world; in the last ten years[dated info] several other writers and scholars have challenged the evidentiary basis for Cohen's and others' speculations regarding this interest of Dodgson. In addition to the biographical works that have drawn the foregoing conclusion, there are modern artistic interpretations of his life and work that do so as well, in particular, Dennis Potter in his play Alice and his screenplay for the motion picture Dreamchild, and Robert Wilson in his film Alice. In a 2015 BBC programme The Secret World of Lewis Carroll experts indicated their belief that a photograph of a naked teenage girl, was the oldest Liddell girl Lorina, and was the work of Dodgson. The programme speculated that this was the possible cause of the break in the relationship between him and the Liddell family. Will Self in the same programme called Dodgson 'a heavily repressed paedophile. Without a doubt.' [75][76]''

Note the abundance of footnotes. How much of this should be retained? Tkuvho (talk) 16:52, 2 February 2015 (UTC)


 * What does this have to do with the Mathematics project or mathematics? Dodgson may have been a mathematician among other things, but his biography does not have our rating template. JRSpriggs (talk) 04:45, 3 February 2015 (UTC)
 * Well I think it should. He did important work both in mathematics and logic. Tkuvho (talk) 14:18, 3 February 2015 (UTC)


 * I think this discussion is better kept at Talk:Lewis Carroll. Ozob (talk) 14:26, 3 February 2015 (UTC)

M-theory
Hello mathematicians,

I just wanted to let you all know that M-theory is currently a featured article candidate. While this is not exactly a math topic, it's related to some very exciting areas of modern mathematics such as geometric representation theory, categorification, and noncommutative geometry.

It would be great if someone here could review the article. Even if you're not an expert on math or physics, I would love to hear your views and whether you find the writing accessible.

Thanks. Polytope24 (talk) 05:01, 4 February 2015 (UTC)

Help with Covering in topology/graph theory
Hi all, I've got a handful of links that go to the disambiguation page Covering in a mathematical sense but I can't figure out which article they need to point to. Could I interest a local math maven in taking a look?

List of articles with ambiguous links to "covering"

Thanks, -- Ja Ga  talk 21:39, 6 February 2015 (UTC)


 * ✅ D.Lazard (talk) 10:56, 7 February 2015 (UTC)

Lie algebra extension
Do we have an article on Lie algebra extensions (under some unexpected name) or perhaps a section on it? In case we don't, and if nobody is in the process of writing one, I might write one. It would parallel group extension. YohanN7 (talk) 16:07, 5 February 2015 (UTC)


 * There is a section Affine Lie algebra, but I do not know of any standalone articles. --Mark viking (talk) 19:59, 5 February 2015 (UTC)


 * Thanks. For a start, I have rewritten Wigner's theorem from scratch. There are clearly connections between the subjects due to the projective representations popping up as a result of Wigner's theorem. YohanN7 (talk) 12:14, 7 February 2015 (UTC)

Navbox for "classes" of matrices?
Given that we have this neat navbox for prime number classes, I wonder if we should create a similar one for different types of matrizes. However, I'm not a mathematician (just an economist ;-) ), so apart from the ones commonly seen in economics, I don't know which of these matrices are important, let alone how to categorize a navbox. Is it a good idea though? --bender235 (talk) 15:02, 26 January 2015 (UTC)


 * I made Template:Prime number classes but don't think I know enough to make a proper version for matrices. I like the idea though. List of matrices may help with the grouping if somebody wants to give it a go. PrimeHunter (talk) 15:17, 26 January 2015 (UTC)
 * On second thought, I will make a crude version based on just copying most of List of matrices. I will post later when a draft is ready. PrimeHunter (talk) 15:24, 26 January 2015 (UTC)
 * I have created Matrix classes based entirely on copying every link (including red links and links with the same target) in List of matrices. Others are very welcome to make improvements. PrimeHunter (talk) 16:22, 26 January 2015 (UTC)


 * I think the template needs a little more focus. Right now it has too many different kinds of matrices; most of the entries have no relationship to each other besides the fact that they're matrices.  A comprehensive navbox would be too big, and a suitably sized navbox is necessarily more focused.  I think it would useful to have a template that discussed types of matrices that are generally of interest within linear algebra proper (sparse, banded, Hermitian, idempotent, etc.) and left out matrices which are of interest because they arise in applications (DFT, Bezout, adjacency, etc.).  Ozob (talk) 04:00, 27 January 2015 (UTC)


 * And it looks like this:


 * YohanN7 (talk) 07:07, 27 January 2015 (UTC)


 * To give a perspective, the box looks too large, to me. I suppose it is probably hard to decide on what to include and what to exclude. (The choice would likely reflect editor's background.) -- Taku (talk) 04:30, 29 January 2015 (UTC)


 * Please be bold and make any improvements. I haven't added it to any articles but just wanted to quickly make a framework for others by indiscriminately copying the whole list without evaluating anything or looking for other groupings or potential additions in Category:Matrices. PrimeHunter (talk) 00:51, 8 February 2015 (UTC)


 * That is like asking someone to do the work for you. Will not happen. I like the thing. But it is too large, so I ask you to rinse out some. (Like stuff you've never heard of.) It can always be put back later. YohanN7 (talk) 01:02, 8 February 2015 (UTC)

Imaginary point
The article titled imaginary point has sat around for years with almost no attention. It lacks references. If the article should indeed exist, could someone cite some geometry textbook there? Michael Hardy (talk) 01:05, 5 February 2015 (UTC)


 * How about merging it to rational point? I have put tags proposing the merger. -- Taku (talk) 01:24, 5 February 2015 (UTC)


 * Call me arrogant if you like, but I can't shake the feeling that there is good reason that there are no solid references: the concept as defined in the stub appears (to me, at least) to be mathematical nonsense in the purely geometric context. I've expounded at Talk:Imaginary point. —Quondum 02:18, 8 February 2015 (UTC)

Is this award for real or is it a hoax?
Please see Stampacchia Medal. The external links do not seem to go anywhere. Is this a hoax? Having an award for such a narrow field as Calculus of variations seems unlikely to me. JRSpriggs (talk) 02:57, 8 February 2015 (UTC)


 * Check all the links. One of the references is and one of the the external links (only linked on the pdf icon due to a syntax error) is page 17 of . Clearly not a hoax. PrimeHunter (talk) 03:21, 8 February 2015 (UTC)


 * Here is the announcement of this year's prize by VARANA. It is real. Calculus of variations is a huge field, as it is basically calculus in infinite dimensions. It forms the foundation for both classical and quantum field theories in physics. --Mark viking (talk) 03:34, 8 February 2015 (UTC)


 * Thanks. Someone who knows Italian should fix the majority of the links which do not go anywhere. JRSpriggs (talk) 03:51, 8 February 2015 (UTC)

Draft help needed
Hermann Mayer is writing a draft about Rouben V. Ambartzumian and asked for help via IRC. The subject seems notable with sources such as this, but the draft is a CV that's largely based on Ambartzumian's own publications, not on what third-party coverage we have. Getting full access to the references would be a significant effort for me; thus I'd prefer if someone else could give Hermann Mayer a helping hand and improve the draft so that it can be accepted. Huon (talk) 23:55, 8 February 2015 (UTC)

Where should "Hindu numerals" redirect?
Where should "Hindu numerals" redirect, to Hindu–Arabic numeral system, or to Arabic numerals? Paul August &#9742; 13:59, 10 February 2015 (UTC)

Links in Math tags
Hi,

I had a look at https://en.wikipedia.org/wiki/Wikipedia:Rendering_math with the intention to figure out what else is needed after MathML got the default rendering mode for math-tags.

I think it will take a while to get rid or the requirement that people have to learn tex. The visual math input plugin I have investigated see http://math-min.wmflabs.org/w/extensions/MathSearch/modules/min/index.xhtml produces some reasonable results, but is not production ready yet.

However, I get the feeling that the other main disadvantage Unable to place wikilinks on parts of formulae. is easy to fix.

The only question that is open to me is how to call a tex macro for that. Maybe \wref or just \w could be an option so that Could replace https://en.wikipedia.org/w/index.php?title=Mass%E2%80%93energy_equivalence#MassEnergyEquivalence

What do you think?

PS: Even though, there are some characters that do not exists in TeX's math mode, the third disadvantage Lacks some characters (such as Cyrillic script) is already solved from my point of view. --Physikerwelt (talk) 15:19, 7 February 2015 (UTC)
 * My general feeling is that placing links inside math formulas is a bad idea. It interacts badly with some features of rendered math (such as the one where you can click on a formula to embiggen it), the link coloring distracts from the meaning of the formula, and often the pieces of the formula are small making the links non-obvious. It's almost always better to put links on nearby text. So I don't see this as a high priority. —David Eppstein (talk) 18:46, 9 February 2015 (UTC)


 * The problems mentioned in mw:Extension:Math/Roadmap appear to be more crucial. Any progress there? --Quartl (talk) 18:58, 9 February 2015 (UTC)
 * Ah you are referring to the double subscript ... use braces to clarify problem. I'll double check if that's fixed in upstream and ask the ops team to deploy the fix in production. I do not want to be the judge in spacing questions. The W3C defines the sizes and spacing rules, or is there a problem with the generated MathML? --Physikerwelt (talk) 21:30, 9 February 2015 (UTC)
 * I wasn't referring to a specific problem mentioned on the page. Many of them result in ugly or even unreadable output and it seems the majority of them have not been resolved yet. --Quartl (talk) 21:45, 9 February 2015 (UTC)
 * I have created a task for double subscript bug... https://phabricator.wikimedia.org/T89044 to ensure that this will be fixed and no red error messages will appear. Unreadable and ugly are two different things to my mind. If something is unreadable, it needs to be fixed before moving ahead; Currently, I do not see anything that I could not read in my browser on that page. Ugly seems to refer to refer to personal preferences. --Physikerwelt (talk) 22:05, 9 February 2015 (UTC)
 * Formulas where symbols overlap or are too close together are unreadable. Ugliness is not that subjective as you think since our reference is the output produced by LaTeX. Remember that we look at these formulas every day (I have MathML enabled). For example, the extra space after inline formulas is a major headache and should definitely be removed. Could you please organize the reported bugs into subsections such as open, fixed, reported, wontfix? For some problems that cannot easily be fixed we can think of workarounds such as inserting extra brackets or spaces, but we need to know which ones. Btw. to ask all readers to install some add-on is not a solution. --Quartl (talk) 05:13, 10 February 2015 (UTC)
 * PS: Lately I have encountered formulas that don't display at all in MathML, currently almost all the formulas in de:Drehmatrix. Purging the page doesn't help. Seems to be a caching problem. --Quartl (talk) 06:12, 10 February 2015 (UTC)
 * I do not want to argue against you, but we need to differntiate between differend kinds of problems. Howerver, MathML is different from TeX and some rendering is supposed to look different by definition. This does not relate to horizontal distance bug https://github.com/mathjax/MathJax/issues/948 that has not been fixed. I'll implement your suggestion to organzie the potential problems as soon as I can. --Physikerwelt (talk) 09:39, 10 February 2015 (UTC)
 * "Ugliness is not that subjective ... the extra space after inline formulas is a major headache" I think the juxtaposisitioning of these two sentences maximally undermines your point. It is not possible that some minor aesthetic thing like this is a top priority. --JBL (talk) 13:35, 10 February 2015 (UTC)
 * No it doesn't since all I'm concerned about is readability. I encourage you to continuously enable MathML and use Firefox or another Gecko-based browser as your working environment (apologies if you are doing this already). --Quartl (talk) 14:14, 10 February 2015 (UTC)
 * I'm with David that the priority seems wrong; for example, it's not that too important to implement a feature so that people don't have to learn tex. Many math editors, both existing and potential, already know tex. On the other hand, some very basic features are currently lacking. Maybe it's just me but I really want a "commutative diagram" support. This is very important; in some areas of math (e.g., category theory and homological algeba), commutative diagrams are like integral signs in calculus; without them is inconceivable. Mathematics is a little more than computing integrals after all....
 * Finally, i don't want to just complain but would like to acknowledge how much I (and presumably we) appreciate your work on the math support. My big thanks to you for the work. -- Taku (talk) 02:30, 10 February 2015 (UTC)
 * I totally agree. Commutative diagrams are something that would be really nice. Howerver, I think those have to be represented as image. http://www.w3.org/TR/MathML3/chapter6.html#interf.graphics
 * Currently, we would need to support that for all rendering modes. If we had only one rendering mode, this is something that should be fixable much easier, e.g. by just enabeling the appropirate mathjax extension. However, to switch to only one rendering mode, we need to implement PNG to SVG conversion. See https://phabricator.wikimedia.org/T78046 for the details --Physikerwelt (talk) 09:39, 10 February 2015 (UTC)
 * There is a linux utility pdf2svg that's available in the Ubuntu repository, for what it's worth. In the past, I've used a hack involving an appropriate combination of pdfchop and pdf2svg.  See File:Commutative diagram SO(3, 1) latex.svg for an example.  (Apologies if you already know about this.)   Sławomir Biały  (talk) 14:11, 10 February 2015 (UTC)

Do you see align environments?
Hi!

I cannot see anything sensible in the "m=2" section of the article Abel's binomial theorem. (There seems to be some attempt to load an image of some kind; but the result just is a warbled space.) I looked at the source text, and noted that it contains a latex align environment (within wp math-mode).

Now, I could easily rewrite this; but if this is only some problem with my browser, I shouldn't. Therefore, I'd like to know whether the m=2 example is legible for the rest of you. JoergenB (talk) 18:27, 8 February 2015 (UTC)


 * I just took a look and everything seems fine to me. (Windows 7 - Chrome - MathJax enabled) Bill Cherowitzo (talk) 18:36, 8 February 2015 (UTC)


 * It looks fine to me on the iPad, iOS8, PNG rendered LaTeX. --Mark viking (talk) 18:58, 8 February 2015 (UTC)


 * Firefox + XP + PNG = Firefox + XP + MathML = fine. It is nice that we have so many options for math display (none of which work in full). YohanN7 (talk) 17:10, 9 February 2015 (UTC)


 * What environment are you using? RockMagnetist(talk) 17:32, 9 February 2015 (UTC)
 * Firefox, possibly a too old version; under Linux, employing Fluxbox.
 * Thanks for your answers! Clearly, I should not try to fix this by changing the article; but instead should consult our IT experts. JoergenB (talk) 17:32, 10 February 2015 (UTC)

Could anyone please proofread my new section?
See Cauchy_product. Thanks. --Mathmensch (talk) 16:34, 9 February 2015 (UTC)


 * You have left out something from most of the sums. Each of them should have a variable of summation and its lower and upper bounds. But only two of those are shown in most of the sums. So your meaning is far from clear. JRSpriggs (talk) 17:46, 9 February 2015 (UTC)


 * Thanks. I fixed this. --Mathmensch (talk) 09:13, 10 February 2015 (UTC)


 * I want to point out that a less notationally demanding approach is to use convolution: think of a series as a function on the integers with support contained in the nonnegative integers. In this viewpoint, Cauchy product is a convolution. -- Taku (talk) 20:40, 9 February 2015 (UTC)


 * I guess to mention convolutions in this context is advantageous, but I would still use the sum notation, because otherwise, if you want to calculate the product of the series and want a series (as needed for example in finding a non-recursive expression of a sequence using generating functions) or a number (as needed if the series are not easily calculated), you would have to insert the convolution definition, and this would be even more fiddly, so let the article do it for you. --Mathmensch (talk) 09:13, 10 February 2015 (UTC)


 * Thanks for fixing the lower limits of summation. However, I now notice that the conclusion which you reach for n+1 is not in the same form as the inductive hypothesis for n, even if you move the first coefficient through the sums. JRSpriggs (talk) 08:14, 11 February 2015 (UTC)


 * Thanks, it should be fixed now. --Mathmensch (talk) 09:23, 11 February 2015 (UTC)

Mathematics of finance
Wikipedia has many pages in the field of mathematics of finance, for example Category:Mathematical finance, and more. None of those articles belong to this project and many are project-orphaned. Just wondering why they can't call this project home? Thanks in advance, Ottawahitech (talk) 14:42, 11 February 2015 (UTC)


 * There is nothing wrong in principle with a mathematics of finance article being part of WP:MATH, but I think it needs to be decided on a case by case basis. Some articles, like Malliavin calculus are firmly in the math camp. Others, like Cash on cash return is about a financial ratio--the financial aspect of quantity is the important thing, not the simple division used. --Mark viking (talk) 23:04, 11 February 2015 (UTC)


 * Agree. (As I understand it, whether an article has been tagged for WP:MATH is merely a consequence of whether someone has bothered to so tag it.)  --JBL (talk) 23:54, 11 February 2015 (UTC)

Vladimir Voevodsky, univalent foundations, and homotopy type theory
There is something funny going on at the articles univalent foundations and homotopy type theory. Apparently, Vladimir Voevodsky is editing (as User:Vladimirias) these articles, and getting some push-back from User:Foobarnix (including edit wars, etc.). I don't have time to look into the details at the moment, but probably someone uninvolved should have a look, and defuse this situation. WP:BITE is relevant. Sławomir Biały (talk) 12:49, 10 February 2015 (UTC)

It seems pretty clear here that Vladimir Voevodsky's edits are inappropriate, as they praise himself quite a bit and contain a large amount of unreferenced material/OR. However, mathematicians frequently let famous mathematicians get away with inappropriate behavior on the internet. It wouldn't be appropriate for a congressman to make similar edits about himself, or a CEO or a musician.Brirush (talk) 14:29, 10 February 2015 (UTC)


 * Yes, there is unreferenced material there. But, after all, he is the world's leading expert on homotopy type theory and univalent foundations.  While we should certainly not allow this niche of Wikipedia to become his personal blog, I think there is also a reasonable expectation that much of this stuff is written up elsewhere in much gorier detail so, in principle, is at least reference-able.  A less confrontational approach, it seems to me, would be to ask Vladimir if he can supply some better references, perhaps dropping him a note on his talk page.  I'm not seeing an unduly large amount of self-praise, at least nothing that can't be fixed by normal WP:PEACOCK editing.  But as I've said, I've not really had the time to investigate that closely.   Sławomir Biały  (talk) 14:40, 10 February 2015 (UTC)
 * I agree that finding references for the new material would fix the problem.Brirush (talk) 14:46, 10 February 2015 (UTC)
 * Hello, I would be happy to provide references to the material that you think needs further references. Please make notes on the page and I will try to supply the references.Vladimirias (talk) 22:02, 10 February 2015 (UTC)
 * @Vladimiras The new version with references is excellent. I withdraw everything I said, with an apology. Thanks for responding quickly!Brirush (talk) 23:28, 10 February 2015 (UTC)

The conflict of interest and presumed self praise is not the only (or even the main) issue. Of particular concern to me is an apparent tendency of Voevodsky (=VV) to couch the history of the subject in terms that mention only his own work. For example, see the edits by VV on 9 February 2015 which deleted the entire section Univalent foundations in the HoTT article with the comment, “Section on the Univalent Foundations removed since it did not contain any information about Univalent Foundations.” The purpose of that section was to report the controversy that surrounds the usage and definition of the term 'Univalent Foundations'. Many of the researchers do not agree with VV’s use of the term. For example, see Michael Shulman’s comment on 20 December 2014 beginning, “Vladimir, could you provide some evidence that UF is not a subfield of HoTT?”
 * response by foobarnix

A more explicit example of VV trying to frame the history of the subject occurred with his edit of edit of 1 February 2015‎ which deleted the paragraph beginning,
 * This includes, among other lines of work, the construction of homotopical and higher-categorical models for such type theories...

This deletion was almost immediately reverted by another HoTT researcher Peter LeFanu Lumsdaine. I could provide more examples.

VV has commented on my talk page
 * There is also nothing wrong with a text on a page being written by someone who is a specialist or even a creator of the subject that the page is about.

I agree. But is it usual for a scientist to add to his own biography article in Wikipedia statements such as,
 * In 2009 he constructed the univalent model of the Martin-Löf type theory in simplicial sets. This was a major step in the development of homotopy type theory, and led to his programme of using it as a foundation for all mathematics. In such a role he calls it univalent foundations.” [emphasis mine]

BTW, this statement has no citations.

Another problem with many of the VV edits is the lack of usable citations. Very many of his citations reference the web based GitHub repository hosting service. This blog is a truly wonderful resource for mathematicians, and VV has contributed a lot to their usefulness. But these sites are of almost no help to the typical reader–even a mathematician–and are very much an Inside baseball resource. And, typical of such blogs, many of the links are already dead (check it out).

I certainly agree that VV was perhaps the most important researcher in Homotopy Type Theory. But he is not the only one. And by his own words, for example in his Bernays lectures video of lecture 1 2  3, he is leaving the field to work on other things. And I agree that we are fortunate to have him help to write the history. But, quite frankly, some of his statements in WP are simply incorrect. --Foobarnix (talk) 00:32, 11 February 2015 (UTC)


 * Indeed, the objections by Foobarnix look rather convincing. Maybe, several different points-of-view should be included. Boris Tsirelson (talk) 06:55, 11 February 2015 (UTC)


 * At Talk:Homotopy_type_theory I have proposed a merger including all points of view, and both phrases in the title. Michael Shulman (talk) 23:33, 12 February 2015 (UTC)

Vector space
Various attempts recently have been made to rewrite the lead at the mathematics good Article vector space. I note that the lead was something that was specifically discussed in great detail at the good article nomination, the peer review, and the featured article nomination. No one has given any clear reason to rewrite the first paragraph (apart from a vague sense of excess verbosity). Now an editor who has (apparently) forgone the use of discussion pages thinks that is misleading to refer to a vector space as a mathematical structure where elements can be added together or scaled by numbers, seemingly in deference to a Bourbaki-style viewpoint that a vector space is a four-tuple $$(V,F,+,\cdot)$$ consisting of a set V, field F, binary operation +, and function $$\cdot:F\times V\to V$$ satisfying the usual rules. Is this an appropriate perspective for the lead of an article that will likely be read by high-school students with no mathematical background?

There are other issues with the proposed revision of the lead, which are rather more serious than any perceived abuse of language in the first sentence though. The most obvious issue is that a sentence there is duplicated for no apparently good reason. Secondly, the sentence "The scalars may be real numbers, complex numbers, rational numbers, or any field" is not grammatical as written (a real number is not a field). But also, it is not exactly true either: the scalars of a vector space cannot belong to any field. Rather (as it says in the Good Article version of the lead) "there are also vector spaces with scalar multiplication by complex numbers, rational numbers, or generally any field." This makes it clear that what notion of scalar one has in mind depends on the vector space.

I've reverted twice, given that the proposed revision has these obvious deficiencies. I think more eyes are needed there. Sławomir Biały (talk) 14:02, 13 February 2015 (UTC)


 * I wrote him a message that he is too much mathematically correct for this non-mathematical encyclopedia. Boris Tsirelson (talk) 15:12, 13 February 2015 (UTC)

Could maybe anyone proofread my next new section?
Markov%27s_inequality

and

Markov's_inequality

Thanks. --Mathmensch (talk) 15:20, 13 February 2015 (UTC)


 * Commented there. I think it's too much detail for a non-mathematical encyclopedia.  — Arthur Rubin  (talk) 16:13, 13 February 2015 (UTC)

Buchstab function
Buchstab function: We don't seem to have an article listing special functions arising in analytic number theory. Should we? (We do have one on arithmetic functions; those have the positive integers as their domains.) Michael Hardy (talk) 22:01, 15 February 2015 (UTC)
 * is a near orphan. Probably other articles should link to it; and
 * does not tell us who Buchstab is. It says it's also called "Buchstab's function", suggesting that it's named after a person.
 * Perhaps it was not obvious that the first reference of the article was a paper by Buchstab? I couldn't find much about Buchstab (probably it would be easier for someone who reads Russian) but apparently he is the same Alexander Buchstab redlinked as the advisor of Ilya Piatetski-Shapiro (and not mentioned but probably should be on Gregory Freiman). His name has been variously transliterated as Buchstab, Bukhstab, Buhštab, Bukhshtab, and probably other variations. —David Eppstein (talk) 22:50, 15 February 2015 (UTC)
 * I found a published obituary and from it started a new article: Alexander Buchstab. —David Eppstein (talk) 22:14, 16 February 2015 (UTC)

Lattice path categorization
I categorized Lattice path under Cat-Enumerative combinatorics, please refine as needed. Thanks. MicroPaLeo (talk) 21:44, 17 February 2015 (UTC)

Root group
I've prodded root group and abelian root group. Although there are a fair number of occurrences of the phrase "root group" in the mathematical literature, they all appear to refer to something else (more than one other thing). While the concept defined in the article makes sense mathematically (a group in which every element has a pth root, for p in some given set) it doesn't seem to be known under this name. But I'd be happy to be proven to be mistaken and get the articles properly sourced and unprodded. —David Eppstein (talk) 06:30, 18 February 2015 (UTC)

Laver property has "graduated" from AFC to mainspace
It was previously discussed here while it was a draft, now that it is in mainspace do with it as you will. Roger (Dodger67) (talk) 17:49, 18 February 2015 (UTC)

1 for hypotenuse and 90 for the angle that is opposite of the hypotenuse
the post was edit request for Pythagorean Identities:where$$\sin^2(x)+\cos^2(x)=1^2$$ when x is > or equal to 1 the following examples are true.I don't know if this is original research or not but it states that for all integers bigger than one and equal to one, examples: c,d,e show that the hypotenuse which faces the angle of right angle triangles is one, and 90 degrees for the angle which is opposite of the hypotenuse, and in radian: 90 degrees is$$\frac{\pi}{2}$$. I don't see these examples listed in any article concerning trigonometric functions.


 * c)$$f^{1}(x)=\frac{1}{x}+\frac{x-1}{x}=1$$


 * d)$$f^{2}(x)=\sin^{-1}\sqrt\frac{1}{x}+\sin^{-1}\sqrt\frac{x-1}{x}=90$$


 * e)$$f^{3}(x)=\cos^{-1}\sqrt\frac{1}{x}+\cos^{-1}\sqrt\frac{x-1}{x}=90$$


 * f)$$\sqrt\frac{x-1}{x}$$
 * where $$\sqrt{x-1)}$$ is a slope and included in $$\tan^{-1}\sqrt{x-1}$$

199.7.157.45 (talk) 15:32, 5 September 2014 (UTC) Although this is original research,It fits in the discussion of trigonometry project group because it's a fact for a right angle triangles to have the bigger angle to be the inverse of the tangent $$\sin\tan^-1 (4)$$ and for the smallest angle it's  inverse of tangent $$sin\tan^-1\frac{1}{4}$$, the tangent being the inverse of the slope or the biggest angle,where the biggest angle being 90 degree.Trenteans123 (talk) 08:55, 19 February 2015 (UTC)
 * cos A={c^2+b^2-a^}/{2×b×c}
 * c^2=a^2+b^2

New bug in our math notation rendering
The align environment has lately begun to put an inappropriate lack of spacing in this like this:

\begin{align} a & = some expresion \\ & = some other expression \end{align}

Thus:

\begin{align} a & = \text{some expresion} \\ & = \text{some other expression} \end{align} $$

There should be a space between a and "=", but it's not there. Michael Hardy (talk) 22:37, 15 February 2015 (UTC)
 * What math rendering preferences and browser are you seeing this in? It looks ok to me with client-side mathjax as well as not-logged-in. —David Eppstein (talk) 22:52, 15 February 2015 (UTC)
 * I can confirm the bug. I'm on iPad with MathML with png and I see no space between a and =. -- Taku (talk) 00:04, 19 February 2015 (UTC)


 * Png + Firefox on XP desktop = ok. YohanN7 (talk) 06:35, 19 February 2015 (UTC)
 * Please file a bug report —Th e DJ (talk • contribs) 12:14, 19 February 2015 (UTC)

Comment on Draft:Sacks property wanted
I can't speak for the other editors having reviewed Draft:Sacks property, but I can say frankly that I am not able to pass a qualified judgement. Could some of you gals/guys add a comment here that I can pass on? Or review it yourself? Thanks, -- Sam Sing! 18:12, 19 February 2015 (UTC)
 * It looks like a typical short new article in research mathematics. The fact that Shelah put the subject of the article in the title of one of his papers is enough by itself to convince me that the topic is notable. It's quite WP:TECHNICAL, but perhaps unavoidably so considering its subject matter. So while some improvement would be welcome, I don't see any reason to prevent its creation. —David Eppstein (talk) 18:33, 19 February 2015 (UTC)
 * , I agree. --JBL (talk) 18:35, 19 February 2015 (UTC)

Thank you and. Did you get a ping from my use of U? I did not get one from JBL's use of reply to above. Similar to Sacks property, could you comment on Draft:Kane's Method. -- Sam Sing! 21:36, 19 February 2015 (UTC)
 * I did get the ping, yes. Re Kane's method: too equation-heavy and too much unsourced material to accept yet. It should be cut down to a description of the method, not a derivation of it, and ideally every paragraph should have at least one footnote. —David Eppstein (talk) 22:06, 19 February 2015 (UTC)
 * Thanks, I'll pass your comment on. -- Sam Sing! 23:21, 19 February 2015 (UTC)

Is this web source adequate?
This web source: http://faculty.kutztown.edu/schaeffe/Tutorials/General/Polygons.html is being used to verify a long list of pretty names for naming polygons. Does this source represent, a) a reliable authority and b) sufficient use to establish the encyclopedic value of such a list? &mdash; Cheers, Steelpillow (Talk) 16:11, 14 February 2015 (UTC)
 * I'm happy to improve the published documentation, and ordered one mathematics dictionary to see if it'll help, but so far the referencing is basically up to 20-gon which all have articles. There's certainly some sources if you want to go to old books like this 1888 one on GoogleBooks, not to say old names are going to help what's used in modern books. Tom Ruen (talk) 17:18, 14 February 2015 (UTC)
 * It's a plausible naming method, but not one I've seen before. In fact, to the best of my recollection, I've never seen the string "kai" within a word in a mathematical paper before.  On the whole, I wouldn't consider it a reliable source, unless schaeffe's credentials can be established.  I'm pretty sure I've seen pentaicosagon for a 25-gon.  — Arthur Rubin  (talk) 18:15, 14 February 2015 (UTC)
 * Regardless of the reliability of the personal web page of an obscure mathematics professor on subjects concerning ancient Greek nomenclature, I think the fact that this level of sourcing is the best that can be found for these names indicates that they are not in common use and should not be described on Wikipedia as if they are in common use. —David Eppstein (talk) 18:16, 14 February 2015 (UTC)
 * If Coxeter were still around, we could ask what reference he used. But I can't think of a way that we could now possibly determine "common use" for numbers over 20, except possibly 30, 40, 50, 60, 100, 1000, and 10000.  — Arthur Rubin  (talk) 18:27, 14 February 2015 (UTC)
 * Textbooks might be good.... — Arthur Rubin (talk) 18:41, 14 February 2015 (UTC)
 * I'll keep looking. A web source credited to John H. Conway is here, and George W. Hart repeats here . Norman W. Johnson has web source copied here . Johnson's names are more used with the polyhedra and 4-polytopes, like pentagonal hexecontahedron for a 60-hedron, pentagonal icositetrahedron for a 24-hedron, rhombic triacontahedron for a 30-hedron, tetracontoctachoron for 48-cell, and hecatonicosachoron for 120-cell, etc. So whatever varied systems are in use in polygons, polyhedra or higher, I think they can be traced and documented in some agreeable format. Tom Ruen (talk) 18:46, 14 February 2015 (UTC)
 * And I'd suggest that that is the core of the problem. No one system stands out as mainstream, they are all just different fringe suggestions. &mdash; Cheers, Steelpillow (Talk) 20:11, 14 February 2015 (UTC)
 * Luckily, the only articles we have on polygons with over 20 sides are 24, 30, 257, 1000, 65537, and 106. Of these, chiliagon (1000) has the best sourcing: the name goes all the way back to Descartes (except that he uses chiliogon), along with myriagon (Descartes: myriogon, 10000). The articles for 257 and 65537 just use the n-gon naming, so there is no problem there. Megagon (106) is a little shaky: no doubt it deserves an article, given the multitude of sources using it as an example; but it doesn't seem to be called "megagon" usually (and linguistically, it's a little shaky as "mega-" meaning 106 only started with SI). Instead a descriptive phrase along the lines of "polygon with a million sides" seems to get used instead. Icositetragon (24) and triacontagon (30) could be justified as fortunately these are prefixes that you find in common names for some polyhedra (e.g. deltoidal icositetrahedron, rhombic triacontahedron). Double sharp (talk) 04:24, 15 February 2015 (UTC)
 * Triacontagon is safe! Coxeter uses it in Regular Polytopes (p.249). And this (Topics in Mathematics for Elementary Teachers: A Technology-Enhanced Experiential Approach by Sergei Abramovich) gives (p.89) pentadecagon (15), hexadecagon (16), octadecagon (18), icosagon (20), icositetragon (24), triacontagon (30), and tetracontadigon (42). Dr. Euler's Fabulous Formula: Cures Many Mathematical Ills by Paul J. Nahin gives (p.46) icosagon (20), triacontagon (30), and tetracontagon (40), as well as giving up for the 5242880-gon ("?-gon"). Double sharp (talk) 04:31, 15 February 2015 (UTC)
 * I'm not surprised that up to triacontagon can be properly sourced. The rhombic triacontahedron is pretty well known. It's some of the higher ones, like 42 and 46 in the table below, that I'm more dubious about. (It's plausible we might have a name for the 96-gon, though, as that's the one Archimedes used to approximate $\pi$.) —David Eppstein (talk) 08:06, 15 February 2015 (UTC)

The Handy Math Answer Book by Patricia Barnes-Svarney and Thomas E. Svarney gives a table of names (pp.413–4). So far all the names I found sources for are below: they're all from the Svarney list except for: 1-gon (Coxeter, Regular Maps, p.388), 24-gon, 42-gon (Abramovich), 1000-gon, 10000-gon (the second ones from Descartes), and 1000000-gon (sources at megagon; this is kind of a fringe name, as I can't find many sources deriving it, but I do not think there is any other Greekish name for it).

I think this table includes the only names that would get derived regularly (and 24, 42, 46, 106 are just from one-off occurrences). I doubt any other polygons have been named anything other than n-gon, except perhaps as examples for name construction like 46-gon here.

While an extrapolation of the way Svarney constructs 46-gon (tens + kai + units for 21- to 99-gon) would give icosikaitetragon for 24-gon and tetracontakaidigon for 42-gon, they do not spell these out, and it appears that these names are not used at all barring one or two occurrences. (The top result for icosikaitetragon on Google Books is a mistake: the object being discussed is a polyhedron, so it should really be icositetrahedron or icosikaitetrahedron.) Double sharp (talk) 07:29, 15 February 2015 (UTC)

Standard names
OK, so after searching for a while on Google Books, it looks like the following are the only names that seem to be standard (in that they will often appear in a listing of polygon names, and do not vary much between sources): I've bolded the names I think we should use on Wikipedia. They're all articles, except 50-, 60-, 70-, 80-, 90-, and 100-gon. (I'm choosing "hecatontagon" over "hectagon" because the former is closer to the etymological source. They usually appear together as alternatives, but "hectagon" seems more popular on Google Books because it's a common typo and has been used for different meanings. Incidentally, alternative meanings are also why "megagon" has so many hits.)
 * Hmm, reconsidering: MathWorld and Wolfram Alpha appear to understand hectogon and not hecatontagon, and "hecto-" is more familiar as it's already an SI prefix (albeit not a commonly used one). So, changed my recommendation to hectogon. Double sharp (talk) 10:51, 18 February 2015 (UTC)

On my choice of nonagon over enneagon for the 9-gon: this was a bit difficult, as enneagon is etymologically superior and it fits well with enneadecagon and enneacontagon (where the nona- forms are just about unknown). But I went for nonagon because it's much more common, and because enneagon seems to often have non-mathematical connotations. Double sharp (talk) 10:34, 18 February 2015 (UTC)


 * What is just as important as giving the list itself is giving the sources from which you derived it. That way interested people, be they fellow editors or visiting readers, can check for themselves that the sources both support the names and are adequately reliable. There is no harm in giving two names if they are both verifiably significant. &mdash; Cheers, Steelpillow (Talk) 16:25, 18 February 2015 (UTC)
 * Here's some: one two three four. This (Dr. Math) might not absolutely qualify as an WP:RS, but is useful in that it agrees with the other lists, thus showing that at least for the numbers of sides I posted there are standard names. (Megagon isn't in any of these lists, but sources for that are on its article, and it does not appear to have any other name in common use.) Double sharp (talk) 05:18, 19 February 2015 (UTC)
 * Here's an old list from Charles Sanders Peirce, which seems to attempt to go very close to the original Greek (hence following Johnson's forms pentecontagon, hexecontagon, hebdomecontagon, ogdoëcontagon, enenecontagon, and creating new coinages like tessaragon). These, I guess, are referenceable alternative names.
 * As for the notability of these polygons: I originally thought of a strict cut-off at 12-gon, and strict demands for any higher ones to show their notability, but it seems clear from my 2012 AfD that this is never going to get consensus. So I think perhaps we could simply have an article on every polygon that has a standard name (i.e. a name that is used and agreed on by multiple sources), plus 257-gon and 65537-gon (as these have obvious notability). Double sharp (talk) 05:23, 19 February 2015 (UTC)
 * OK, carried out that plan: now everything with a standard name gets an article (only the ones in the table above), and nothing else does. Double sharp (talk) 07:53, 19 February 2015 (UTC)
 * Here's three that only occurred once: tetracontadigon for the 42-gon (first reference above), triacontakaidigon for 32-gon and hexacontakaitetragon for the 64-gon (here) So these names could be mentioned, but the primary usage should be just 32-gon, 42-gon, and 64-gon. Double sharp (talk) 05:41, 19 February 2015 (UTC)
 * P.S. I have no doubt that both names should be given usually, but the article can only be at one of them (with a redirect from the other), and it becomes irritating to keep saying "tetradecagon or tetrakaidecagon". Double sharp (talk) 07:05, 19 February 2015 (UTC)
 * One more source (except 14, 19, 24, 106). Double sharp (talk) 07:10, 19 February 2015 (UTC)
 * All of those sources that I can access given simply list a few example polygons (one or two refused access). That does not make them notable enough for their own articles. For that, they need some unique and notable discussion, as for example the chiliagon has received (hence the failure of that RfD). Even for a simple listing in the polygon article, several of those alternative names are clearly obscure (to coin a phrase) and, per WP:UNDUE, should not be included. The fact that people are scratching around the Internet seeking - and failing to find - sources to bolster their claims does not bode well for those claims. &mdash; Cheers, Steelpillow (Talk) 08:50, 19 February 2015 (UTC)
 * Yes, chiliagon should indeed have been kept (although that didn't seem so clear at the beginning of the AfD), but somehow all the articles like tridecagon also managed to be kept despite lacking much unique and notable discussion (a list of polygons articles seems like an interesting solution).
 * Of course they only list a few example polygons. Isn't that the point? And I'd argue that the use of these names in single instances, like "triacontagon" or "40-gon (tetracontagon)", but not in crazy cases like the 5242880-gon, speaks in favour of the fact that tetracontagon is standard for the 40-gon but something like pentacosiicositetrakismyriadischiliaoctacosioctacontagon isn't for the 5242880-gon.
 * The third and fourth ones I linked to give a large table with all names from 3–20, and then in tens from 30–100, and then 1000 and 10000. Given that two sources are deriving these particular names in exactly the same way seems to speak well for their being standard. Here is another that uses exactly the same names up to 100, and MathWorld (in its form as the CRC Concise Encyclopedia of Mathematics) also uses the exact same names, so that's four already using the same names. Standard? I think so. The fourth source even provides a general system to make every name from 21- to 99-gon, but you'll notice I didn't add it as this system doesn't seem to have been repeated explicitly elsewhere (and isn't always followed – note their use of "-kai-", which seems not to be the common form for the 24-gon).
 * You'll notice I didn't include all of Peirce's names, which contain lots of etymologically correct but unused things like heccædecagon (16-gon); I only included his names for 40-, 50-, 60-, 70-, 80-, and 90-gon because these were taken up and proposed again by Conway and Johnson (true, their endorsement isn't in RSes yet, but given that they are following something stated in an old RS it should count for something). So it seems to satisfy the second condition under WP:UNDUE: the names from tessaracontagon to enenecontagon may be a minority view, but it is easy to name prominent adherents, so it seems to be a significant enough minority, something that heccædecagon doesn't qualify for. Double sharp (talk) 03:07, 20 February 2015 (UTC)
 * I guess that every polygon has a different story to tell and we just have to take them one at a time. The problem we face is that some editors have boundless energy and a habit of going, "look at this piece of belly-button-fluff I found in this obscure paper, it simply has to go on Wikipedia" and before you know it, it is across a dozen articles and more, with a degree of OR worked in for luck. An example of this is where this discussion topic came in. Is there any way to contain such uneducated and ill-considered enthusiasm? &mdash; Cheers, Steelpillow (Talk) 11:08, 20 February 2015 (UTC)

Root group
Should Root group and Abelian root group be deleted? Michael Hardy (talk) 18:05, 20 February 2015 (UTC)
 * See four sections up in this talk page. —David Eppstein (talk) 21:50, 20 February 2015 (UTC)


 * Just for the record, I tried to find in-depth references for root group, but failed. There are mentions out there, some corresponding to the prose in the article, but nothing that would demonstrate notability. It seems somewhat related to a p-group, but I don't know the field well enough to determine if a redirect is warranted. --Mark viking (talk) 22:41, 20 February 2015 (UTC)

Any comments on Draft:Cokurtosis?
Comments on Draft:Cokurtosis are welcomed. Use, or use directly in the draft. -- Sam Sing! 00:00, 23 February 2015 (UTC)


 * This submission looks fine, except for the minor stylistic issue that the "Properties" section shouldn't be a list of bullets. Ozob (talk) 03:39, 23 February 2015 (UTC)

Adding a Proof template?
I tried to start a discussion on the talk page of WikiProject Mathematics/Proofs to add a template Proof (see suggestion). This page seems to have unfrequent visitors as no answer has been posted in one month, so I thought I would post to here to gain more discussion. Here is what I would like to suggest:

EtudiantEco (talk) 06:04, 25 February 2015 (UTC)

Core math, science and technology topics
Someone from this project may be interested in reviewing and cleaning up the two lists of maths articles here: Core math, science and technology topics. Not only is calendar included in the top nine articles, but the top six articles are not a subset of the top nine --76.14.68.103 (talk) 07:31, 23 February 2015 (UTC)


 * I edited the top 9 list so that it wasn't so ridiculous. However that page hasn't seen any edits since June 2013 so I'm not sure it's being used for anything anymore.  Ozob (talk) 12:48, 23 February 2015 (UTC)
 * This does rather duplicate Vital articles, I'm not sure what the purpose of the core list is.--Salix alba (talk): 07:16, 25 February 2015 (UTC)
 * In a semi-joking defence of "calendar", for thousands of years, a central preoccupation of mathematicians was to establish "calendars" (that is, to ascertain patterns in the heavens for marking time). This is no small achievement of mathematics, given that the same kind of patterns were discovered, in many cases independently, by every ancient civilization on the planet.   Sławomir Biały  (talk) 19:37, 25 February 2015 (UTC)

Smooth maximum is an orphan
No articles currently link to smooth maximum. Michael Hardy (talk) 02:35, 26 February 2015 (UTC)

General complaint 608
On Examples

IN WHICH an article talks about a structure, and most (if not all) of the examples of the structure are examples of a special case.

Do we need to list the letters P, Q, and the number 6 as being bogus? And explain why they are bogus? Is it not sufficient to just say "All garthices (such as the letters P, Q, and the number 6) are bogus?"

If we took an axe to these examples, the resulting article would often be content-free, and I am tempted to conclude the examples were added just to disguise the lack of content. --192.75.48.8 (talk) 16:11, 25 February 2015 (UTC)


 * Can anyone decipher this? --JBL (talk) 16:21, 25 February 2015 (UTC)


 * Proposing removal of content from sections as per deletion process outlined inWP:POINTLESSEXAMPLES. Something something consensus, something encyclopedic something? --192.75.48.8 (talk) 16:30, 25 February 2015 (UTC)
 * No, not at all. Maybe the poster could give an example article?MicroPaLeo (talk) 16:41, 25 February 2015 (UTC)
 * The second comment makes me think it's just trolling. --JBL (talk) 16:59, 25 February 2015 (UTC)
 * I thought so, but the IP made a good edit in an article, so it seems worthwhile trying to find out if there is more. You could be right. MicroPaLeo (talk) 17:02, 25 February 2015 (UTC)


 * The first sentence has a point: suppose in an article on group theory, all the examples given are Abelian. While not wrong, the examples leave out an important class of groups. It would be good for the poster to provide pointers to articles where this is the case. The second point I think is kvetching about math articles that list a bunch of examples of a mathematical structure without well-describing properties of the structure itself. I have seen article like this, too. Both of these are just a fact of life on WP: articles are incomplete and could use improving. --Mark viking (talk) 17:20, 25 February 2015 (UTC)


 * One might lodge the same complaint against just about any treatment of groups for someone totally unfamiliar with the concept. The classic undergraduate texts of Hungerford and Herstein come to mind.  For pedagogical purposes, it is often useful to focus first on a special case that does not contain all of the nuances of the full theory.   Sławomir Biały  (talk) 19:32, 25 February 2015 (UTC)

All examples of anything are necessarily special cases. Michael Hardy (talk) 02:37, 26 February 2015 (UTC)
 * But one should take care when selecting examples. Quercus durata, would not be a good example for the sole species in the lead section of an article or if only a small number of species were mentioned in a short article on section Quercus of the genus. 'Q. alba could be ideal in the lead, but one could use Q. douglasii or Q. virginiana or Q. arizonica as examples, all of which are also endemics. If not as desirable as Q. alba or Q. robur, they would be good additional mentions, could be reasonable examples, and not bad choices like Q. durata. Not all special cases are equal. Although this is a biology example, and in math one may have a case where all examples are equal, you mention "special cases," meaning they are not. Examples should be chosen with care and clearly show understanding of the topic. MicroPaLeo (talk) 04:30, 26 February 2015 (UTC)

Stars and bars (combinatorics)
In Theorem two, the solution of the problem is $$\tbinom{n + k - 1}{n}$$? I think it's $$\tbinom{n + k - 1}{k}$$. --Eric4266 (talk) 03:47, 26 February 2015 (UTC)


 * You are thinking of $$\tbinom{n + k - 1}{k - 1}$$ (you are dividing objects into k sets, so you need k &minus; 1 separators). This is equal to the solution given in the article.  See the proofs section of the article.  Ozob (talk) 13:40, 26 February 2015 (UTC)

Polyadic space
Polyadic space is a new article. Currently no other articles link to it. Michael Hardy (talk) 20:50, 15 February 2015 (UTC)


 * I have added links to it from Alexandroff extension and Dyadic space. --Joshua Issac (talk) 14:56, 27 February 2015 (UTC)