Wikipedia talk:WikiProject Mathematics/Archive/2015/Nov

Draft:Kuratowski, Ryll-Nardzewski measurable selection theorem

This was submitted by an IP who did not response to a request for more context. It has become eligible for deletion under WP:CSD#G13 as an abandoned draft, but I have reprieved it in case anyone feels like picking it up. JohnCD (talk) 09:57, 29 October 2015 (UTC)

I don't agree with the comment there. The statement seems very clear and precise. I would push this out as a stub to mainspace. Certainly, it could use improvements, but that doesn't seem like a compelling reason to decline the submission. I'm not an expert in that area, but this seems like a really fundamental result that we should have an article on, even if it's just a stub that lacks a lot of context. A minor quibble: the title should be "Kuratowski and Ryll-Nardzewski measurable selection theorem". Sławomir
Biały 12:49, 29 October 2015 (UTC)

@Slawekb: Fancy that! I was just browsing this talk page and came across this section. I was the reviewer who originally declined the article. I had just begun at AfC and my decline decisions weren't always as fine-tuned as they are now. I've looked again and I'm prepared to accept this article to the mainspace. Before I do, however, I'd just like to make sure I get the title right. I ask because this source uses different hyphenation ("Kuratowski-Ryll Nardzewski"). Thanks! /wia /tlk /cntrb 04:34, 3 November 2015 (UTC)

Ryl-Nardzewski is Czesław Ryll-Nardzewski, so the hyphenation is correct. But the comma is confusing. Sławomir
Biały 11:05, 3 November 2015 (UTC)

Excellent, thanks! /wia /tlk /cntrb 13:34, 3 November 2015 (UTC)

Disambiguation of Binomial

Binomial has recently been converted into a disambiguation page. Any assistance in fixing the thirty now-broken incoming links would be appreciated. Cheers! bd2412 T 03:32, 2 November 2015 (UTC)

• This has been done. Cheers! bd2412 T 18:49, 3 November 2015 (UTC)

Markov chain draft

Hi all, there is a draft at Draft:Markov chains on a measurable state space that I'd be prepared to accept so long as the math is correct and it isn't too similar to the content at Markov chain. Would someone versed in this area of mathematics be willing to have a quick look? Thanks! /wia /tlk 15:32, 4 November 2015 (UTC)

Quite a good job! Thanks to Adam Nielsen. Yes, the math is correct. At "Markov chain" we have only a small remark (Sect. "General state space") on this matter. Boris Tsirelson (talk) 17:07, 4 November 2015 (UTC)

Admin requested

Could an admin with a maths background please look over Talk:Complex affine space#Requested move 13 October 2015 and assess the consensus (or lack thereof). I tried to read it and make some sense of it, I really did, but whatever maths I was taught in high school isn't enough to get through it. Cheers, Jenks24 (talk) 13:19, 6 November 2015 (UTC)

Regretfully, User:Sławomir Biały did not answer my question "Slawomir, do you withdraw the move request now? " of 17:24, 18 October 2015 on that "Requested move". I guess that after major changes made in that article, there is no more need to move it. Its content is already adapted to its current title. Boris Tsirelson (talk) 15:12, 6 November 2015 (UTC)

Paul J. Nahin stubbed

I have created a stub for Paul J. Nahin, who is not noted for being a mathematician per se, but for writing some well-reviewed biographies of other mathematicians and mathematical concepts. Any help in appropriately expanding this would be much appreciated. Cheers! bd2412 T 15:28, 9 November 2015 (UTC)

Help needed

Someone needs help proof-reading a mathematics article: Wikipedia:Village pump (miscellaneous)/Archive 51#I need a contingent correction. WhatamIdoing (talk) 04:24, 10 November 2015 (UTC)

There is an ongoing discussion of whether Wikipedia articles should include detailed proofs/derivations. The Euler's critical load article is essentially the detailed derivation of a theorem already stated in the article Buckling. Before we spend a lot of work editing the new article, perhaps we should discuss whether it should exist at all. Mgnbar (talk) 13:21, 10 November 2015 (UTC)

Link to math portal?

I have seen (look right)

being added to the "See also" section in an article or two. I don't have a big problem with it, but things like these should be governed by policy and consistently used/not used in my opinion. YohanN7 (talk) 15:14, 11 November 2015 (UTC)

Indeed, with some effort I've found one here: Calculus#See_also. It should be enough that the "areas of mathematics" template occurs there. Boris Tsirelson (talk) 21:19, 11 November 2015 (UTC)

I don't really know why it has to be "consistent". It's imaginable that it's a reasonable thing to expect readers of extremely general math articles to want to look at, but not readers of more specialized ones, so I think we shouldn't reject out of hand the idea of using editorial judgment at the individual-article level.

That said, if we just removed it from article space entirely, it wouldn't break my heart. --Trovatore (talk) 21:23, 11 November 2015 (UTC)

Wikifying the mathematics of Euclid's Elements

I find the page on Euclid's Elements is lacking in its mathematical and geometrical content. Nowhere is a list of its propositions (so there is also no links to the wikipedia pages where they are discribed) But I am a bit wondering what is a good way to improve this?

I was thinking about just a wikified index page per book /set of books to the propositions, definitions, common notions and postulates. I think many of which allready have their own wikipedia page.

But I am wondering is this a good idea? are there better ways (navboxes or something like that?) lets first discuss what a nice way would be to start this project of wikifying the elements.

It will be a quite big task so better to think what is a good way to do it before I / you / we start it. WillemienH (talk) 09:34, 12 November 2015 (UTC)

Multidimensional integrals before one-dimensional integrals?

There is a discussion at Talk:Integral#Adding sections on the multivariate integral before the standard integral in one dimension? of relevance to this project, concerning this edit. Sławomir
Biały 21:02, 12 November 2015 (UTC)

The discussion at Talk:Integral has evolved into a suggested major restructuring. Given my history with the editor making the proposal, we could use some third input. Also, I would very much prefer it if this proposed restructuring were brokered by a more competent mathematics editor. (The errors this editor made here do not fill one with confidence.) Sławomir
Biały 14:45, 13 November 2015 (UTC)

Coordinate system, frame or basis

I am writing the section affine space § coordinates, and I have encountered a terminology problem that involves a lot of articles, in fact, most articles that deal with coordinates.

The first part of the problem is '"what is the name of a coordinate system defined by an origin and a basis of the associated vector space?" This is sometimes called [an [affine coordinate system]], but this term is ambiguous as barycentric coordinates are also an affine coordinate system. Thus, I would prefer to call it a Cartesian coordinate system, as, as far as I know, Cartesian coordinates need not be defined by an orthonormal frame. Thus my first question is "do reliable sources require that Cartesian coordinates are based on an orthonormal frame".

While looking for an answer to this question in WP, it appeared that the article Frame (geometry) does not exist, and that most Wikipedia article use "coordinate system" or "basis" when "frame" should be used. The fact that "coordinate system" is not a synonymous of "frame" is exemplified by the fact that Cartesian and polar coordinates of the Euclidean plane are based on the same orthonormal frame. Another example is the awful first sentence of Translation of axes. "Basis" is also used instead of "frame", for example in Basis (linear algebra) § Geometry. Although confusing, this may be acceptable when all components of the frame are of the same nature. It is not for a frame consisting of an origin and a basis of the associated vector space.

IMO, we need a coherent terminology. When we will get a consensus, a lot of articles will need to be edited accordingly. D.Lazard (talk) 10:15, 16 November 2015 (UTC)

For the first question, I would say "linear coordinate system". I don't think it is desirable to achieve uniform terminology in all of our articles, because different fields of mathematics use terminology in slightly different ways. For example, in linear algebra, we would often just say "coordinates", where it is understood that we mean linear coordinates. Cartesian coordinates are also called rectangular coordinates. I think it would be very confusing to refer to general linear coordinates as Cartesian coordinates, where there are no "rectangles" to speak of, just parallelograms. I don't doubt that you can find this use somewhere in the literature, but I don't think we should push that usage. On the issue of frame versus basis, here it obviously does depend on the area of mathematics. In linear algebra, "frame" is sometimes used as a synonym for "basis" (and sometimes it means just a spanning set). In affine geometry, an "affine frame" is something else: a basis and choice of origin. More generally, in geometry a frame is whatever gives a reduction of a structure group to the identity. Thus, the moving frame (repère mobile). Sławomir
Biały 12:05, 16 November 2015 (UTC)

A coordinate system is a continuous (usually C^∞) injective map from an open set in an n-dimensional manifold to Rⁿ. JRSpriggs (talk) 04:02, 17 November 2015 (UTC)

Unfortunately this is only the definition of local coordinate systems on manifold. It is much too technical to be used for Cartesian coordinate system, as everybody, who knows about manifolds, certainly knows already Cartesian coordinates. Also this definition is a non-sense for affine coordinate systems, as affine spaces exist over any field. It is a part of above mess that many articles of WP refer to JRSpriggs's definition, without any link to the primary definition in elementary geometry. For example, Cartesian coordinate system does not says that Cartesian coordinates are related to an orthonormal frame, and none of Orthogonality, Orthonormal basis, Orthonormal frame mentions Cartesian coordinates. D.Lazard (talk) 10:33, 17 November 2015 (UTC)

Jacobian Conjecture: Suggested text removal

I would like to draw attention to the section "Suggested Removal" that I posted to the JC article.

L.Andrew Campbell (talk) 03:55, 18 November 2015 (UTC)

Suggested removal done. D.Lazard (talk) 10:41, 18 November 2015 (UTC)

AfC submission

See Draft:Symmetrization Methods. Thank you, FoCuS contribs; talk to me! 18:20, 19 November 2015 (UTC)

As for me, this is good enough. Maybe the context could be richer, but the same can be said about quite many "old" math articles on WP. Let it exist and grow on the wiki. Boris Tsirelson (talk) 19:05, 19 November 2015 (UTC)

Thanks for the input, Tsirel - I've moved the article to mainspace. Perhaps you could drop by and make sure it is in the correct categories? Thanks. Take it easy. Onel5969 ^{TT me} 14:24, 21 November 2015 (UTC)

Nice; I did. Boris Tsirelson (talk) 15:13, 21 November 2015 (UTC)

RefDesk question: Continuous mathematics?

There is a question at the ref desk that confused me, as it made me find out that Continuous mathematics redirects to Numerical analysis. Is there an obvious reason why this is a good idea? I am going to change the redirect to mathematical analysis, but I would hope that somebody reverts me if I am wrong. —Kusma (t·c) 15:28, 24 November 2015 (UTC)

Axonometric projection

Could use some help here. Talk:Axonometric projection#Types of axonometric projections. There is a disagreement over the taxonomy of parallel projection. We need some input. Thanks! SharkD  Talk  05:22, 25 November 2015 (UTC)

Implicit curve

What software did you use to create File:Fl-sin-cos-nivk-s.svg? I am looking for 3D software that can output SVG. SharkD  Talk  05:26, 25 November 2015 (UTC)

I created an EPS-file of the object, transformed it with pstoedit into a FIG-file (xfig) and exported the result into a SVG-file. Another way is: use ps2pdf and pdf2svg.--Ag2gaeh (talk) 10:48, 25 November 2015 (UTC)

AfC submission

See Draft:Enoch Lewis, a biography this time. Best, FoCuS contribs; talk to me! 12:20, 25 November 2015 (UTC)

Another AfC draft!

Hi all, Draft:Banach Game is in the AfC queue and I would be happy to accept it if the math checks out. I noticed in the second reference that the formulation of the problem is given as $x_{n+1}<x_{n}$ for every $n<\omega$, but I did not know if $\omega$ is an ordinal or merely a variable. /wia /tlk 04:54, 25 November 2015 (UTC)

In this case, I would interpret $\omega$ as an ordinal. So $n<\omega$ is just another way of saying that $n$ is a natural number.

If $0<x_{\omega }<x_{n}$ for any $n<\omega$, then sum of the series would always be infinite. That is, it could never converge to an element of X. JRSpriggs (talk) 21:26, 25 November 2015 (UTC)