Wikipedia talk:WikiProject Mathematics/Archive/2017/May

Combinatorial Mathematics Society of Australasia
Combinatorial Mathematics Society of Australasia is newly created article which was moved directly to the mainspace from User:McKay/sandbox by its creator. The draft does not seem to have been submitted for review, and based upon its name it might fall within WP:WPM's scope. Anyway, I was wondering if someone from this WikiProject would mind taking a look at it and assessing it. Most of the sources cited appear to be primary ones, so it's not clear where the organization satisfies WP:NORG. -- Marchjuly (talk) 13:22, 1 May 2017 (UTC)

Additional eyes please on Exponential response formula
I'm requesting that some editors with more experience with math topics take a look at a relatively new article, Exponential response formula, by a relatively new editor,. I haven't looked at enough of the articles in this project to have a good idea what constitutes sufficient notability, or how examples should be styled. Thanks.  &mdash; jmcgnh  (talk) (contribs)  00:45, 17 April 2017 (UTC)
 * FWIW, it is definitely a real thing and probably one can find textbook references. I suppose it is possible that the material exists under other names (but I don't have suggestions, sorry). --JBL (talk) 00:57, 17 April 2017 (UTC)
 * I have redirected to ordinary differential equation. --Izno (talk) 11:43, 17 April 2017 (UTC)
 * That table is horrible! --JBL (talk) 13:34, 17 April 2017 (UTC)
 * This has been unredirected and the creator has approached me on my talk page:
 * "Hello Izno, I'm trying to bring here information which the encyclopedia does not have. I spent much a day of my free time reading articles and writing topic on math to share my knowledge with others. Wikipedia had no word about material which I'm trying bring here. I don't think that deleting the page without any word, message or discussion is an appropriate act. I don't feel that I'm welcome here and don't understand reasons for your hatred of new people on the platform. The page on which you did redirection removing whole my article has nothing about ERF. If you are a mathematician, please let's talk how can we improve it. Wandalen (talk) 15:54, 22 April 2017 (UTC)"
 * The target article does cover ERF in that it covers the precise-same content as the topic called an "ERF" as presently in the article.  CC. Perhaps this is a less-general article to redirect it to, but I would guess the content already exists on Wikipedia, if not exactly in the form you have added. This is normal editing behavior. --Izno (talk) 00:15, 24 April 2017 (UTC)
 * By "the target article covers the same material" you mean that there is an entry in that awful table? This obviously does not preclude a stand-alone article.  (Even more thorough coverage would not preclude it: for independently notable solution methods, I would expect an article like ordinary differential equation to have a brief summary and a  link.) Also, to the extent that what you are doing is making substantive discussion about the fate of the article (as opposed to drawing the attention of other editors), the article talk page is a much better venue. --JBL (talk) 01:41, 24 April 2017 (UTC)
 * The talk page of an article is occasionally insufficient, especially when the topic has been broached already in a more-communal venue. I could also have left a "Look over here again". As for "awful table", I would tend to agree, that table is awful. But regardless of the presentation there, I would expect this to be at a more-general article than one dealing specifically for the "response function" that is simply a typical solution to a linear ODE. --Izno (talk) 02:02, 24 April 2017 (UTC)
 * I am afraid I don't understand your last sentence; what is the referent of "this"? --JBL (talk) 02:05, 24 April 2017 (UTC)
 * The information regarding an ERF. --Izno (talk) 02:23, 24 April 2017 (UTC)

Izno help me to improve the page, please. I'm going to contribute to the page on weekends if you won't throw it in garbage. Saying ERF is typical solution to ODE is same as saying wolf is a mammal, lets make redirection from wolf page on mammal page and put all mammals in a table. Appreciate any help. Wandalen (talk) 17:21, 24 April 2017 (UTC)
 * There is less here than meets the eye. All the facts in the article would fit in a new line in Ordinary differential equations, and are covered adequately in Green's function.  See Talk:Exponential response formula.  — Arthur Rubin  (talk) 14:31, 1 May 2017 (UTC)

Alladi–Grinstead constant
Greetings all. Earlier today, I noticed a new page, Alladi–Grinstead constant, which looked in need of cleanup and reworking. I took a stab at it, but someone with a stronger background in number theory could probably do better. Another new page, Lueroth constant, should perhaps be merged into it, since the one constant is just the exponential of the other less one. XOR&#39;easter (talk) 17:25, 1 May 2017 (UTC)

Templates and Navigation for Mathematics Articles
I've been working out a Template for "A Series on Discrete Mathematics", based on some of these:

More examples of these sort of things:


 * Template:Science
 * Template:Philosophy_sidebar
 * Template:Platonism
 * Template:General_physics
 * Template:Electromagnetism

Examples more related to specific Mathematics topics


 * Template:Calculus
 * Template:Group_theory_sidebar

I think these sort of templates would add some structure to the Mathematics part of Wikipedia. What are people's thoughts on this? --- Popcrate (talk) 09:41, 8 May 2017 (UTC)

Relevant discussion at WP:ANI
There is a discussion at the administrators' noticeboard concerning the edits of to Series (mathematics) and Talk:Series (mathematics) that members of this project might be willing and able to comment on. Sławomir Biały (talk) 13:57, 8 May 2017 (UTC)

Citation overkill proposal at WP:Citation overkill talk page
Opinions are needed on the following: Wikipedia talk:Citation overkill. A permalink for it is here. Flyer22 Reborn (talk) 06:35, 9 May 2017 (UTC)

Normed algebra
Normed algebra has been proposed for deletion. Presumably it should be unprodded, but it's in pretty bad shape and needs help to make it more clearly notable first. Anyone want to have a go? —David Eppstein (talk) 05:49, 8 May 2017 (UTC)
 * Maybe merge into "Banach algebra"? Boris Tsirelson (talk) 08:36, 8 May 2017 (UTC)
 * "Normed algebra" usually means "finite dimensional Banach algebra". But in the area these are studied, I believe the standard term is actually "normed algebra", so I feel that's not quite an appropriate merge target.  Sławomir Biały  (talk) 10:11, 9 May 2017 (UTC)
 * Why f-dim? For example, take the ring of all smooth functions on some compact manifold (e.g., a circle). Then the ring is normed, say, with the sup norm (assume there is a metric on the manifold). But it's not Banach; how do you call that ring? -- Taku (talk) 23:06, 9 May 2017 (UTC)
 * Sure, there is such a mathematical structure. However, we have a theory of Banach algebras (with nontrivial theorems, not just definitions and examples); have we such a theory of normed algebras? Boris Tsirelson (talk) 03:40, 10 May 2017 (UTC)
 * Of course it make sense to allow infinite dimensions, but usually "normed algebra" refers to the finite-dimensional case in my experience. See Hurwitz's theorem (composition algebras), for example.   Sławomir Biały  (talk) 09:19, 10 May 2017 (UTC)
 * According to the lede of our Banach algebra, an infinite-dim case is allowed. Anyway, I do agree with both of you that the focus of the study is probably on the finite-dim case. -- Taku (talk) 09:44, 10 May 2017 (UTC)
 * I want to point out that a normed field is, as of this writing, a red link. But presumably it should be discussed in the "normed algebra" article; this argues against the merger. -- Taku (talk) 23:25, 8 May 2017 (UTC)

Mathematical universe hypothesis
Edit war here about a writer who may be a crackpot; someone with subject expertise please take a look? — swpb T 17:07, 5 May 2017 (UTC)
 * Perhaps you should try participating on the article talk page and not just demanding that others do so? --JBL (talk) 22:14, 5 May 2017 (UTC)
 * Umm...I did exactly what you're supposed to do when you suspect something is wrong but don't know enough about the topic – I asked for help from people who self-identify as knowing about the topic. What is your problem? — swpb T 13:17, 10 May 2017 (UTC)
 * It looks like you have made significant edits to the article and may be a participant in the edit war. Per WP:BRD, it is best to first discuss issues leading to the edit war on the article's talk page, to attempt to come to consensus. You appear to not have done that and instead have come directly to WP:MATH to appeal for help. That approach is no great sin, but as an editor with nearly 60,000 edits, you know better. --Mark viking (talk) 19:19, 10 May 2017 (UTC)
 * Right. In addition, your edit summaries have basically no content, so it is extremely difficult for anyone to tell what you think the problem is.  --JBL (talk) 21:19, 10 May 2017 (UTC)

Graham's number
There is a discussion on the talk-page concerning whether the current first sentence (including its footnote) is correct, encyclopedic, and appropriately supported by citation. More voices would be welcome. --JBL (talk) 23:44, 10 May 2017 (UTC)

XOR, (Exclusive or), page needs some help
The lead paragraph needs help, in particular. There's been a "needs verification" template on the page since 2013. Currently the lead paragraph reads as:  Exclusive or or exclusive disjunction is a logical operation that outputs true only when inputs differ (one is true, the other is false). It is symbolized by the prefix operator J[citation needed] and by the infix operators XOR (/ˌɛks ˈɔːr/), EOR, EXOR, ⊻, ⊕, ↮, and ≢. The negation of XOR is logical biconditional, which outputs true only when both inputs are the same. Personally, I couldn't find a solid example of J being a symbol for Exclusive Or (maybe it's used in a specific programming language?) Any thoughts? - Popcrate (talk) 06:39, 11 May 2017 (UTC)
 * ✅ I added a source. It's not from programming, it's from the Polish notation for mathematical logic. —David Eppstein (talk) 06:49, 11 May 2017 (UTC)

Computer code is original research?
Some sample code was added to Shanks' square forms factorization. I put a citation needed tag on it. Now the original author has made changes to it. This makes me think that it is his own code. Is this wp:OR? Bubba73 You talkin' to me? 17:58, 14 May 2017 (UTC)
 * Code is generally either OR or copyvio. That's one reason why pseudocode is usually preferable. —David Eppstein (talk) 18:23, 14 May 2017 (UTC)


 * This code says that it avoids overflowing 64-bit integers. Bubba73 You talkin' to me? 19:05, 14 May 2017 (UTC)
 * I agree with David. The Gowers and Wagstaff paper has a pseudocode description of the algorithm on pages 11-12. Probably better to summarize that than provide OR C code. --Mark viking (talk) 20:49, 14 May 2017 (UTC)


 * There is also pseudocode in Wagstaff's newer book ("The Joy of Factoring"). Does someone want to do that job?  Bubba73 You talkin' to me? 21:47, 14 May 2017 (UTC)

Equivalent definitions, again
Three years ago the article "Affine space" was attacked by a non-expert. His position: the notion of affine space (like any other) must have just one definition treated literally; not only the structure, but also its implementation (encoding in the set theory) must be fixed once and for all; otherwise mathematics is not rigorous. The attack was repulsed, but, bothered by the vulnerability, after a short discussion here, I built a bastion against possible attacks of this kind: equivalent definitions of mathematical structures. A quote therefrom: A person acquainted with topological spaces knows basic relations between neighborhoods, convergence, continuity, boundary, closure, interior, open sets, closed sets, and does not need to know that some of these notions are "primary", stipulated in the definition of a topological space, while others are "secondary", characterized in terms of "primary" notions.

Now we observe another attack toward "Series (mathematics)" (see "Relevant discussion at WP:ANI" above); User:Hesselp insists on a single definition of a series as a sequence (of terms). For now the article defines a series as (a special case of) an infinite expression. Another equivalent definition in use is, a pair of sequences (terms, and partial sums). Regretfully, this case is not covered by my "bastion", since the set of series is itself not quite an instance of a well-known mathematical structure (though some useful structures on this set are mentioned in our article). And still, it would be useful to write something like A person acquainted with series knows basic relations between terms and partial sums, and does not need to know that some of these notions are "primary", stipulated in the definition of a series, while others are "secondary", characterized in terms of "primary" notions. Implementation need not be unique. When several implementations are in use, should we choose one? or mention them all "with due weight"? or what? Any opinion? Boris Tsirelson (talk) 16:40, 12 May 2017 (UTC)


 * @Tsirel.  Five remarks. a.   Mentioning different worded - equivalent - definitions in "Series (mathematics)" :  no objections from my side.   Provided the wording is logically consistent and complete. b.   To be able to judge to which extend the 'infinite-expression' version satisfies this condition, the notion infinite expression should be clear first: the link to Infinite expression is not sufficient. See Talk:Infinite expression, and the unanswered questions A-E in Talk page 18:49, 10 May 2017. c.   Moreover, as every expression,  also an infinite expression should refer to some (mathematical or non-mathematical) object.   The 'infinite-expression' version leds to the self-referreing: "A series is an infinite expression.... denoting a series." Isn't it? d.   On: "User:Hesselp insists on a single definition of a series as a sequence (of terms)." Not at all. See section  Definition in this edit. e.   The Bourbaki-definition (series = the couple: sequence; its sum sequence) refers to the former (also Cauchy's) meaning of 'series':  a sequence of terms allowing partial sums. -- Hesselp (talk) 18:49, 12 May 2017 (UTC)


 * (a): I am glad. (b) "an infinite tree labeled with symbols of various types" (quoted from that talk page) — I am able to turn this hint to a definition; I agree that our "Infinite expression" article gives only informal explanation (for non-mathematicians), not a definition; and again, we are not a professional mathematical encyclopedia... (c) sure; see my (b) above; and in general an expression has no value (but in "good" cases it has); (d) I am glad (again; see my (a) above); (e) nice. Boris Tsirelson (talk) 19:15, 12 May 2017 (UTC)
 * It's tempting to try to define infinite expressions as infinite sequences of symbols (as non-infinite expressions are usually defined as finite sequences of symbols) but that turns out to be problematic, for instance because things that people would recognize as infinite expressions can have more than one end. That's why I hinted at using parse trees instead, in the quote you found. But I don't know of any source that actually formalizes them that way or any other... —David Eppstein (talk) 05:40, 13 May 2017 (UTC)
 * Carl could know more... I only remember "Borel codes" (for Borel sets); but they are not widely known, and worse, they are usually defined just for the case, not as a special case of general "infinite expression". But anyway, as for me, "infinite expression" is terribly expensive (far not economical) implementation; not accessible to most undergraduates, is it? Overkill. Boris Tsirelson (talk) 06:08, 13 May 2017 (UTC)
 * For series? Definitely. —David Eppstein (talk) 06:16, 13 May 2017 (UTC)

It is somewhat ironic that, although mathematics is one of the most precise fields, the basic concepts are often not defined identically. For example, the talk page of the article on "function" shows much effort about how to present that concept in a way that is both accurate and accessible to those learning basic algebra and calculus. The same applies to "series": it is a standard, basic concept, which everyone agrees on. But, because it is typically defined in calculus and lower-level books, the definitions that are often given in the books lack something that would be present in a graduate level text. This does not mean, however, that we should try to present "series" in the style of Bourbaki. Instead, we should follow the sources and present the same general understanding that they convey. To some extent, I agree with the proposition above that in articles about *elementary* subjects, it is not necessary to focus too heavily on axiomatics. Of course, more advanced articles will naturally have a more axiomatic focus. &mdash; Carl (CBM · talk) 20:00, 12 May 2017 (UTC)


 * Then, maybe, it is desirable (whenever feasible) to first give an informal explanation, but afterwards, closer to the end of the article, give rigorous definition(s)? Boris Tsirelson (talk) 20:07, 12 May 2017 (UTC)


 * I think this can be reasonable, but only when there are clear formal definitions in the literature. In many cases, it turns out that advanced texts simply don't bother giving definitions of concepts such as "series", which they assume the reader is familiar with, while introductory texts give only informal definitions. In such cases, I think it is better to avoid trying to invent a formal definition out of thin air (although certainly many people could create one). If numerous sources all find it possible to discuss a concept without a formal definition, we can certainly do so as well. &mdash; Carl (CBM · talk) 20:09, 12 May 2017 (UTC)


 * Well. But for series, if I am not mistaken, we need not invent it, since Hesselp gave us such sources. Boris Tsirelson (talk) 20:13, 12 May 2017 (UTC)
 * And surely it would be an overkill, to first define infinite expression in general. A sequence (or two) is much more economical implementation (while not the most intuitive one, which is typical: either intuitive or economical...). Boris Tsirelson (talk) 20:15, 12 May 2017 (UTC)
 * I agree with Carl that we lack a formal definition of a series, which covers all aspects of the concept and is widely accepted. In fact, the situation is similar to the case of a sum: There is no definition in Addition, and it is difficult to give one, as "sum" denotes the processus (operation) as well as its result. Another example is Line (geometry), where the usual "Definition" section is replaced by a section Line (geometry), which contains a discussion that is strongly related to this one. In any case, a series is not a sequence nor a pair of sequences nor an expression. It is an object which is built from a sequence. Who think to a Taylor series as a sequence? D.Lazard (talk) 20:43, 12 May 2017 (UTC)
 * Yes... Likewise, who thinks on a real number as a cut in rationals?.. "Object built from a sequence", yes. Lot of objects are (for instance, words, queues, stacks, and even files). In programming this is a matter of "abstract data type"; a pity that we have no such notion in mathematics. We have "structure (up to isomorphism)", but this does not cover all needs. Boris Tsirelson (talk) 20:48, 12 May 2017 (UTC)
 * So... should we add a section "Definitions versus descriptions" into "series" (and a number of other articles, such as "Formal power series")? Boris Tsirelson (talk) 20:51, 12 May 2017 (UTC)

I stand puzzled. Some notions are primitive (undefined), some are defined, and some appear to be... elementary? undergraduate? Well, I do not argue about names. But let us imagine that we are preparing a proof of a theorem for verification on a proof assistant. In the middle we face series. What now? Say "this theorem is not formalizable in ZFC"? Surely not. Surely we continue. What does it mean? A vague term whose meaning is determined implicitly by the context, case-by-case? Boris Tsirelson (talk) 05:02, 13 May 2017 (UTC)
 * There are two answers. Firstly, the concept of series is too wide for being the subject of a general theorem: what is common between a numerical series and a formal power series except that both are infinite sums? By the way, in the lead of the article, I have implicitly defined an infinite sum as a process (algorithm), but I have, as usual, left ambiguous whether a sum is a process or its result. My second answer (which is not incompatible with the first one) is that one has to proceed similarly as in synthetic geometry for defining a line: a series is a pair consisting of a representation (an algorithm for computing the sequence of its coefficients), and the operations that are defined on series (convergence or not, addition, ...). This is what is called a category in Axiom (computer algebra system). Also, the package "mgfun" of Maple (software)  uses this way of defining/representing series for making algorithmic many operations on functions, such as computation of limits, indefinite integrals, ... (see the dynamic dictionary of mathematical functions, which is not a proof assistant, but the output of an automatic prover). D.Lazard (talk) 09:03, 13 May 2017 (UTC)
 * (1) I did not mean a theorem about series, but a theorem whose proof uses some series ("in the middle" of the proof).
 * (2) Now you basically treat series as an abstract data type! Nice, but this is outside mathematics (unless you include all the computer sciences into math). And you cannot use this meaning of series in a theorem (neither in formulation nor in proof), otherwise you really do something outside ZFC (no matter, whether you present a theorem to a human or computer). Boris Tsirelson (talk) 09:46, 13 May 2017 (UTC)


 * I don't have much to add to D. Lazard. But I want to mention a few things: it seems, in some instances, series refers simply to a formal series; e.g., "series" as in Hilbert-Poincare series. This suggests to me, a series is a more of a heuristic concept than an explicitly defined concept. For example, in algebraic geometry, one talks about a situation in which a geometric figure "degenerates" to another figure (this example is meant to suggest "elementary" is irrelevant). One can formalize this but the point is that this is something heuristic or intuitive as a concept. "Series" seems like a similar case.
 * I also point out you don't need infinite expression to define a (formal) series. Completing a polynomial ring (in one variable) gives the ring, an element of which is a formal power series. Finally, the use of infinite expressions in mathematics can be very problematic since for example one wonders how to make sense of power series in (uncountably) infinitely many variables. -- Taku (talk) 23:10, 13 May 2017 (UTC)


 * Here is another instance when an infinite expressions can be problematic. If I remember correctly, in functional analysis, you can consider a sort of series or summation over a filter. The idea is that this allows, for example, one to extend the theory of separable Hilbert spaces to general Hilbert spaces; e.g., one can have an expansion in terms of an uncountable orthonormal basis instead of a countable orthobornal basis. (The simpler and standard approach is to abandon the idea of expansions.) Yet another example: formal Laurent series do not form a ring, since the definition of multiplication is unclear (the usual way out is to consider only the Laurent series with finitely many negative terms.) The point is that, to be rigorous, you need some mathematical apparatus like ring theory or set theory (filter) to handle cases like these instead of infinite expressions. -- Taku (talk) 23:37, 14 May 2017 (UTC)

Representation theory of the Lorentz group -- a good article nomination
Representation theory of the Lorentz group is currently a good article nominee, nominated by. I have started reviewing the article, but there is a fundamental disagreement here: the article is, in my opinion, much too long and covers topic in a level of detail that should better be deferred to related articles. YohanN7, of course, is of a different opinion, stated here.

Can someone please have a look and weigh in at the nomination talk page? Jakob.scholbach (talk) 15:25, 15 May 2017 (UTC)

Envelope model (again)
The opinions of learned mathematicians would be helpful at Articles for deletion/Envelope model, a discussion that appears to be dominated by those with the attitude that advanced topics have no place in Wikipedia, and deserve to be TNT'd.  Sławomir Biały  (talk) 13:02, 16 May 2017 (UTC)

Popular pages report
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Envelope model
I've made a copy of this deleted article at User:Michael_Hardy/Envelope_model. Users should feel free to edit it to bring it into a form that would justify restoring it. Michael Hardy (talk) 19:00, 24 May 2017 (UTC)

Liouville space
Is the article titled Liouville space worth keeping? It says it's the Cartesian product of two Hilbert spaces. Isn't that somewhat trivially a Hilbert space in its own right? The article doesn't indicate why such a concept is useful. Michael Hardy (talk) 18:31, 24 May 2017 (UTC)


 * Probably, a misunderstanding. The (single) source says roughly that Liouville space consists of operators on a given Hilbert space (and operators on the Liouville space are the superoperators on the Hilbert space). If at all Cartesian product is relevant, it is the product of a basis to itself. Or alternatively, a tensor product of the Hilbert space to itself. Boris Tsirelson (talk) 19:00, 24 May 2017 (UTC)
 * Ask Google for superoperator Liouville space. Boris Tsirelson (talk) 19:06, 24 May 2017 (UTC)

Edits to number articles
has been making edits to number articles, removing apparently significant mathematics facts, usually without an edit summary. For example, 90, 87, 86, 85, 82, and so forth all the way down to 1. Similarly highly questionable edits (with the same misleading boilerplate edit summary) were made to all of the small integers through about 20, e.g., 2, 3, 4, 6, 7, etc.

I believe that changes affecting many articles should be discussed, and consensus obtained before implementing them. I am not sure what criteria the editor is using to exclude properties as sufficiently interesting, but it seems to be entirely subjective and not based on any guidelines. Indeed, Notability (numbers) actually does demand at least three mathematical properties of numbers. Mersenne primes, aliquot sequences, repdigits, palindromic numbers, Harshad numbers, Erdős–Woods numbers, and a host of other properties, all seem like the kinds of properties that articles about specific numbers should discuss, but I note that these have apparently now been expunged from our number articles. I do not particularly trust this user's editorial judgement on what numerical properties are due weight for inclusion. I am inclined to revert all of these edits, pending discussion and consensus, but that should await community support. Sławomir Biały (talk) 11:53, 16 May 2017 (UTC)


 * These articles certainly need a "full copy-edit and revision". I'd be inclined to remove the "5 is the number of songs by GarageBand" cruft and leave the mathematics in place, but that begs the question of what the articles are for. At the moment they're a hybrid of properties of the integer, dab page and trivia and should possibly be split onto multiple pages. Certes (talk) 12:56, 16 May 2017 (UTC)


 * This is not about the pop culture stuff (which, curiously, was entirely left alone in this massive culling of content), but the actual encyclopedic mathematical facts about the number, many of which are actually sort of important (e.g., Mersenne prime, Fibonacci number, etc).  Sławomir Biały  (talk) 13:05, 16 May 2017 (UTC)


 * For the numbers 1-10, the articles are clogged and I may have accidentally deleted a few facts that could be kept (Mersenne primes). For facts such as "aliquot sequences" (or Harshad numbers in bases other than 10) I stand by the fact that they are *NEVER* encyclopedic in this way. Power~enwiki (talk)  —Preceding undated comment added 18:35, 16 May 2017 (UTC)
 * 5 isn't even a Mersenne prime. "The first four Mersenne primes (sequence A000668 in the OEIS) are 3, 7, 31, and 127." What are you talking about? Power~enwiki (talk) 18:59, 16 May 2017 (UTC)
 * It's the third Mersenne prime exponent.  Sławomir Biały  (talk) 19:06, 16 May 2017 (UTC)
 * Which is currently in the 5 article. I request you retract some of your inflammatory remarks. Power~enwiki (talk) 19:14, 16 May 2017 (UTC)
 * Ok, I have removed that assertion. You also apparently in the same edit deleted the fact that 5 is a good prime.  Was this explained in your edit summary or on the talk page?  You removed the fact that $$S_5$$ is the smallest nonsolvable symmetric group, and that there are five exceptional semisimple Lie groups. Was this explained in your edit summary or on the talk page?  If not, please restore these facts or supply a justification for their removal.
 * From 4, you removed that it is the smallest Smith number. I believe that this was not addressed in your edit summary, which was "Full copy-edit and revision," along with other facts.  Please restore this and other facts that you probably mistakenly removed in the course of your "copy edit".  Lots of content was also apparently (mistakenly?) removed from 3.  (For example, that 3 is a Heegner number, which is actually an important number-theoretic property.)  The edit summary was again "Full copy-edit and revision", which makes me think that you did not intend to remove any facts from the page, but you did.  Likewise, please make sure that you did not remove any facts during your copy editing of 2,6,7,8,9,10, and so forth, without explaining the reasons, either in an edit summary or on the discussion page.  (E.g., that 7 is a Heegner number, or that it is the lowest known dimension of an exotic sphere.)
 * Generally for large-scale changes like these, it is better to get consensus before implementing them. It may still be better to revert so that the mistakenly removed information remains there, but if you want to go through the sequence of edits and restore the facts that you mistakenly deleted one at a time, that would probably be best.
 * I personally think that all edits should be reverted, and if an individual fact merits removal, you should at the very least indicate in an edit summary what you are removing and why. But I will await community input before implementing this.   Sławomir Biały  (talk) 19:39, 16 May 2017 (UTC)
 * Indeed, these edits by Power~enwiki are too much bold. Boris Tsirelson (talk) 20:12, 16 May 2017 (UTC)
 * I have to agree. At first they looked ok, but as I looked at more and more they seemed to get fairly extreme. I think it would be best to revert and discuss. My preference would be to remove most of the base-dependent properties Power~enwiki removed (like "palindromic and a repdigit in bases 14" at 90) but to leave most of the rest intact. Of course I'm happy to go with whatever the consensus determines. - CRGreathouse (t | c) 22:02, 16 May 2017 (UTC)
 * These are almost all egregiously trivial; I'm not sure how being a good prime or a Smith number is comparable to being a Fibonacci number or a square number. If there's one you believe otherwise, I encourage you to re-add it, as long as you don't re-add nonsense like "a repdigit in base 14". Power~enwiki (talk) 19:49, 25 May 2017 (UTC)

Erdős numbers
User:Solomon7968 has been removing all mention of Erdős numbers from many articles about mathematicians. Most people consider this information to be significant. He mentions that one other editor agrees with him. This overlooks the fact that tens of editors (perhaps hundreds) do not agree with him––namely all the people who went to the trouble of mentioning the Erdős number in the first place. I urge Solomon7968 to slow down, at least until there is more discussion of this sweeping change.––Toploftical (talk) 19:33, 25 May 2017 (UTC)
 * I spot-checked 10 of his edits today, and the only one I disagree with at all was on Richard Schelp (which was already reverted). Having an Erdos number of greater than 1 is definitely not worth mentioning in the lede of a mathematician's biography. Power~enwiki (talk) 19:43, 25 May 2017 (UTC)
 * I reverted six of them last night, but left in place a larger number of these edits. I think this information can and should be mentioned, but only on cases where there is something more significant to say about the connection rather than the mere fact of having an Erdős number. E.g. one of the ones I reverted was for Arthur Rubin, whose by-far-most-cited publication was one with Erdős. In my view, Solomon7968's apparent attitude that this must never be mentioned is far too strict. —David Eppstein (talk) 20:16, 25 May 2017 (UTC)
 * (edit conflict) I think the standard David Eppstein has been applying (Erdos numbers should be included when they are defensibly significant, as for long-term collaborators) is a correct one. Most mathematicians should not have their Erdos numbers in their biographies.  --JBL (talk) 20:20, 25 May 2017 (UTC)
 * That sounds about right. How about this compromise?  An Erdős number of 1 is worth mentioning.  2 or greater is not significant.--Toploftical (talk) 20:23, 25 May 2017 (UTC)
 * I don't think all Erdős numbers of 1 are worth mentioning. And on the other hand, significantly higher Erdős numbers can be worth mentioning, when they are particularly surprising or have been repeatedly noted by sources, as for instance with Danica McKellar's Erdős number of 4. —David Eppstein (talk) 20:46, 25 May 2017 (UTC)
 * I would agree with Joel and David, this looks like a reasonable approach. I am not in favor of a strict numerical cut-off as there are going to be special circumstances. For instance, a young researcher having an Erdős number of 2, since a 1 is now impossible, is probably playing a significant role in furthering the type of mathematics that Erdős worked on, so, depending on the co-authors this could be notable and will become moreso as time goes on. On the other hand, I do not consider my own 3 as particularly notable and would not include it in my own biography. I also reverted some of these edits and note that the reasons given in Solomon7968's edit summaries really did not apply, the titles just sounded like they might.--Bill Cherowitzo (talk) 20:51, 25 May 2017 (UTC)
 * Bill, I would like to know your rationale behind your reversion of my edit on Terence Tao. The article just mentions that his E number is 2. How exactly does that distinguishes him from 11,009 other individuals? This basically amounts to insulting someone whom NY Times calls "one of the greatest mathematicians in the world", not to mention that he is also a member of the elite Fields club. Solomon7968 22:16, 25 May 2017 (UTC)
 * As I hope I implied above, I am advocating a case by case determination. My reasoning in Tao's case is a good example. Terence is a well-known and highly respected mathematician whose interests significantly overlap those of Erdős. What is notable about his Erdős number is that it is not 1, as many might think it would be. This has to do with age differences and circumstances, and in no way reflects on Tao's abilities. To state that mentioning this fact is an insult to Tao implies that you think that an Erdős number is some kind of rating system–a POV that is totally without merit. I, like many other mathematicians, have talked with Paul about problems that I had been working on. He briefly told me that these problems were "too hard" and nothing further developed. Had I been working on easier problems, perhaps I would have had a lower Erdős number. This says nothing about my abilities. --Bill Cherowitzo (talk) 17:29, 26 May 2017 (UTC)
 * Yes, I think the relevant point about Tao is not "His Erdős number is two" but "Despite the famous photo of Tao as a child with Erdős, he never ended up publishing any research with Erdős before Erdős's death, so his Erdős number is only two." But without a source the connection between the photo and the unexpectedly-high Erdős number comes across as WP:SYNTH. Is there a source that states it in these terms? —David Eppstein (talk) 18:14, 26 May 2017 (UTC)

Women in Mathematics
So I have come across this List of women in mathematics, and will be going through it to improve the articles. While this is probably more biography related, I thought I would post about it here because of its relevance to mathematics. I was wondering if anybody has some research tips/advice, wants to help, or has any general thoughts. - Popcrate (talk) 07:56, 27 May 2017 (UTC)

Good article nomination
Fields are a new good article nomination. The article is a level 4 vital article. I am looking forward to your review (follow the instructions at the top of the talk page of the article to start a review); thank you. Jakob.scholbach (talk) 19:34, 30 May 2017 (UTC)
 * I found a number of extreme typesetting crudities in the article that looked like something by primitive cavemen; for example
 * x−p/q
 * instead of
 * x − p/q
 * or
 * $$ A \otimes \dots Z \, $$
 * instead of
 * $$ A \otimes \cdots \otimes Z \, $$
 * (with \cdots and with \otimes appearing both before and after the dots).
 * I also found something like "If any element has a multiplicative inverse...", which in normal English usage could be construed as meaning "If there is any element that has a multiplicative inverse". But that is not what was meant; rather it means "If it is the case that any element, no matter which one, has a muliplicative inverse", but that is rather verbose. I just changed "any" to "every", which is unambiguous. Michael Hardy (talk) 00:08, 31 May 2017 (UTC)

template for the theorems
I came across this template in Brahmagupta–Fibonacci identity (old version). I personally dislike the use there and do not find its output really helpful in this case. I also haven't come across it anywhere else yet. So I'm wondering what other math editors think of it and whether there is some consensus regarding its use or even awareness of its existence.--Kmhkmh (talk) 14:05, 30 May 2017 (UTC)


 * Seems like it's not in terribly wide use: Special:WhatLinksHere/Template:Math_theorem --JBL (talk) 16:09, 30 May 2017 (UTC)
 * I agree that the use on B-F identity looks horrible. --JBL (talk) 16:10, 30 May 2017 (UTC)


 * In general I would say that I am not fond of it. I was uncomfortable with it when it first appeared on B-F, but felt that I had been hassling the editor who put it there a little too much, so I let it slide. Taking a broader view, I would now say that it may be okay to use if the article is about a theorem (with a name), but it should only be used once on such pages and only for the subject of the article.--Bill Cherowitzo (talk) 21:42, 30 May 2017 (UTC)


 * Substantively, the article was identical 5 years ago; to be honest, I think that the older version looked better! (A number of minor edits to the body have been on net a small positive, but the lead was crisper and not burdened with the ugly template.) --JBL (talk) 22:12, 30 May 2017 (UTC)
 * Relatedly, the use of equation numbers adds extra width to the formula for very little added informational value. The effect of this is that, on a mobile device, the equation's font size is shrunken proportionally, making it impossible to read. —David Eppstein (talk) 22:23, 30 May 2017 (UTC)
 * I have removed the formatting from this article. (But not the equation numbers.)  --JBL (talk) 16:22, 31 May 2017 (UTC)