Wikipedia talk:WikiProject Mathematics

The Princeton Companion to Mathematics

I just got the book a a preset a very pleased I am too with it. Of course I immediately dipped into he centre and also started looked up things I know about in the index. Very interesting. I didn't find much or anything about the things I thought of which indicates if it really was comprehensive it would be a bookcase of books - it is pretty huge as it is. I seem also to have been corrupted by Wikipedia, I kept thinking I should edit this to add wikilinks and better citations. Where it differs from WP mainly is it is much more chatty and readable with things like "Why should nonequivalence be harder to prove than equivalence? The answer is that in order to show....", or "For fun, one might ask a fussier question:". On further references it can say things like "For further details n sections 1-4 the reader is referred to standard textbooks such as ...". I can thoroughly recommend the book.

The book has a small section in its introduction on "What Does The Companion Offer That the Internet Does Not Offer?" (I feel like quoting WP:STYLE about the capitalization!) and I have to agree with what it says: that the internet is hit and miss, sometimes there's a good explanation sometimes not. The articles are drier just concerned with giving he facts in an economical way and not reflecting on those facts. And it doesn't have long essays on the fundamentals and origins, the various branches , biographies of mathematicians and the influence of mathematics. Not that I agree with all that, basically I think what it amounts to is one wouldn't make oneself comfortable, get a cup of coffee and curl up to read the articles in wikipedia. The book has a problem with that too as it is so heavy but otherwise it is a far better read overall.

Does a book like this have lessons for us? Should WP style be a bit more chatty? Or should we be dry and economical and just inhabit a different domain from books like this? Dmcq (talk) 12:18, 9 January 2009 (UTC)

It's more than being a little less chatty; at the moment Wikipedia's policies sometimes run counter to very standard mathematics conventions. If we can't even say "we" or "note that" in proofs, it's a while before will get anywhere near informal, comfortable chattiness. If this ever makes it to a vote, we could argue that style manuals do want prose to be "engaging"...

Unfortunately, it's difficult to write chatty prose while still covering everything in an appropriate sequence like an encyclopedia should. Leon math (talk) 03:31, 10 January 2009 (UTC)

If you ask me, Wikipedia is not suited for mathematics articles. Most of these current policies are rather useless... --Point-set topologist (talk) 18:15, 11 January 2009 (UTC)

You can still write a good article. That's what matters. Ozob (talk) 01:34, 13 January 2009 (UTC)

I have an incredably stupid question

An editor had earlier comment at the page Iowa class battleship that the two mathematical formulas in the paragraph below were actually the same:

That same year (1935), an empirical formula for predicting a ship's maximum speed was developed, based on scale-model studies in flumes of various hull forms and propellers. The formula used the length-to-speed ratio originally developed for 12-meter (39 ft) yachts:

${\mbox{Speed}}={\sqrt {1.408\times {\mbox{waterline length}}}}$

and with additional research at the David Taylor Model Basin would later be redefined as:

${\mbox{Capital Ship Speed}}=1.19\times {\sqrt {\mbox{waterline length}}}$.

It quickly became apparent that propeller cavitation caused a drop in efficiency at speeds over 30 knots (56 km/h). Propeller design therefore took on new importance.

Sine I have failed four separate remedial level math classes at collage, and haven't passed a math class with a grade better than C- since seventh grade, I was wondering if someone from this project could independently verify that the two formulas are in fact the same. TomStar81 (Talk) 04:08, 10 January 2009 (UTC)

$1.19\times {\sqrt {\mbox{waterline length}}}={\sqrt {1.19\times 1.19\times {\mbox{waterline length}}}}={\sqrt {1.4161\times {\mbox{waterline length}}}}$

So it is pretty close. --fvw* 04:13, 10 January 2009 (UTC)

They are indeed the same thing (except that in the second equation a lower precision is used). Specifically,

${\sqrt {1.408}}\approx 1.187$

which rounds up to 1.19. In math (or science), one would say that for the second equation one just "took out" the "1.408" from under the square root. Also, for future questions of the sort, you can go to Wikipedia:Reference desk/Mathematics. Cheers. RobHar (talk) 04:21, 10 January 2009 (UTC)

The "new articles" list on the "current activity" page

...is working again. Michael Hardy (talk) 17:48, 10 January 2009 (UTC)

A better "prime"

Look at this:

Ψ(t) = −log(π) + Re(ψ(1/4 + it/2)), where ψ is the digamma function Γ′/Γ.

In "displayed" TeX, I'd write the digamma function as

${\frac {\Gamma \,'}{\Gamma }}$

or in some contexts like this:

$\Gamma \,'/\Gamma \,$

I don't want to change an "inline" thing to TeX, since that causes comical mismatches of size and alignment, but the "prime" is barely visible. Is there a better, more legible, way to write a "prime" in non-TeX notation, and if not, can one be created? Michael Hardy (talk) 16:26, 11 January 2009 (UTC)

Well I am certainly no expert on formatting matters, one hack may be to change the font size on the prime. One simple way to do this would be:

Γ′/Γ or Γ′/Γ

But I think there are more refined ways to control the font size. I suppose neither of these look that much better. Thenub314 (talk) 16:59, 11 January 2009 (UTC)

Γ´ uses an acute accent rather than an apostrophe Γ' (too vertical) or a single quote Γ‘ (too curly). I think it's a little better as an acute accent than as the other two. If you don't know how to type it (on my Mac keyboard it's option-e space) you can copy-and-paste from this example. —David Eppstein (talk) 17:10, 11 January 2009 (UTC)

Measure (mathematics)

I am not sure how this article ever got to GA (luckliy it was demoted). I am starting a rewrite now; any help there would be appreciated (in particular, a good lede is necessary). --Point-set topologist (talk) 18:17, 11 January 2009 (UTC)

It was listed for 3 months in the early days of GA, before the criteria became more exacting. Geometry guy 19:21, 11 January 2009 (UTC)

What are you dissatisfied with? Boris Tsirelson (talk) 18:59, 11 January 2009 (UTC)

Well for a start, the article does not explain many important concepts in measure theory, nor does it include any applications to probability theory (apart from the Lebesgue integral) etc... I would think that it is fairly clear that the article is not up to par but as you are a measure theorist, it would be good to know your opinion. PST

I see. If you really feel you can do it better, then of course you should try. Yes, I know many things about measures that do not appear now in the article. However, 14 more specialized articles are mentioned in "See also". Do you want to (partially) merge them to "measure"? Or do you want to add something not present in these 14 articles? In the latter case, are you sure it should be added to "measure" rather than to these more specialized articles? Boris Tsirelson (talk) 21:46, 11 January 2009 (UTC)

I want to add some brief descriptions of these specialized concepts. In particular, something has to be there on the Lebesgue integral and the Haar measure. PST

Topic outlines

I think that these articles should be deleted: Topic outline of algebra, Topic outline of arithmetic, Topic outline of calculus, Topic outline of discrete mathematics, Topic outline of geometry, Topic outline of logic, Topic outline of mathematics, Topic outline of statistics, Topic outline of trigonometry. Charvest (talk) 20:12, 11 January 2009 (UTC)

Why? — Carl (CBM · talk) 01:07, 12 January 2009 (UTC)

Against apparent consensus here (there is a somewhat abortive thread in the archives), User:Transhumanist has gone ahead and moved all of the articles [[List of basic X topics]] to [[Topic outline of X]]. This is a bit distressing since, as far as I am aware, there is no indication anywhere in the manual of style on this massive proposed change (which has its source somewhere off in the rarely-used "Portal" namespace). This entire project appears to be Transhumanist's pet project, and has not been handled in a transparent manner. Instead of going through and changing huge numbers of articles, without attempting to obtain consensus (or disregarding a lack of consensus), an appropriate course of action would have been to draft a suggested Wikipedia guideline, and then solicit comment. The current proposal does have some discussion, but mostly in sundry talk-page archives. In this light, Charvest's request is quite reasonable, if a bit WP:POINTy. These changes should be reverted since the current articles do not follow the standard naming conventions for lists. siℓℓy rabbit (talk) 01:38, 12 January 2009 (UTC)

First of all, wikipedia is an encyclopedia, not a fixed syllabus, so "topic outline" is not appropriate - the state of art of knowledge is a constantly changing. Secondly, most of these articles are pretty rubbishy and I don't see the point in them. Take Topic outline of algebra for example. Even if this is changed back to List of ... it is still rubbishy. What does this article say that isn't already in the main algebra article ?

My opinions on these articles are:

• Topic outline of algebra - delete,
• Topic outline of arithmetic - merge with arithmetic,
• Topic outline of calculus - delete ,
• Topic outline of discrete mathematics - merge with discrete mathematics ,
• Topic outline of geometry - merge with geometry,
• Topic outline of logic - there's a lot here so keep or merge,
• Topic outline of mathematics -delete
• Topic outline of statistics - merge with statistics,
• Topic outline of trigonometry merge with trigonometry

Charvest (talk) 09:58, 12 January 2009 (UTC)

modified Charvest (talk) 21:55, 14 January 2009 (UTC)

Are you aware that these were titled List of basic algebra topics, etc., until they were unilaterally renamed a couple days ago? — Carl (CBM · talk) 12:57, 12 January 2009 (UTC)

I wasn't initially aware, but Silly Rabbit pointed this out above. A list which consists simply of the most commonly used terms is basically a glorified see also section and might as well be put in the main articles, rather than have separate pages, unless they are particularly extensive lists. Charvest (talk) 15:38, 12 January 2009 (UTC)

I would suggest that the portal is the ideal place for these pages. Martin 13:24, 12 January 2009 (UTC)

Having a look at the portals: Portal:algebra, Portal:geometry etc it seems the portals are much better presented and contain most if not all of the information in the lists. Between the main articles, the portals and the lists there is massive overlap. The lists should go. Charvest (talk) 15:38, 12 January 2009 (UTC)

I think the lists are useful, in the "List of basic topics" form. I agree they are glorified "see also" lists, but that makes them very good for including in the "see also" section of basic articles like Algebra, where it would be impractical to include a long list of links, but where naive readers are likely to be interested in a list of topics to browse. — Carl (CBM · talk) 23:52, 12 January 2009 (UTC)

Okay, so some people find them useful so they should be kept. But would a different namespace be more appropriate (i.e. Portal)? Personally I think categories do a better job of helping someone browse or find the article they want. Martin 00:03, 13 January 2009 (UTC)

I think this should be done on a case-by-case basis. Maybe most "List of basic X" really are "Topic outlines" and should be moved over to Portal namespace. I don't know. But I am definitely opposed to any blanket move from "List of basic" to "Topic outline" in the mainspace since, in principle, these denote different things. For instance, "Topic outline of geometry" ideally would contain some rather non-basic things such as differential geometry (which isn't there!) or algebraic geometry (also not there!). siℓℓy rabbit (talk) 02:13, 13 January 2009 (UTC)

I think that topic outlines for major parts of mathematics is a great idea. But to call the execution merely 'lacking' is too kind. Can these reasonably be improved? If not, I'd prefer deletion to keeping them in their present state. **CRGreathouse** (t | c) 03:59, 13 January 2009 (UTC)

To make these useful I think a greater amount of description is required. Topic outline of ecology adds a brief sentence to each term which makes it into more useful article. --Salix (talk): 08:11, 13 January 2009 (UTC)

I've nominated the worst of these articles for deletion at: Wikipedia:Articles for deletion/Topic outline of algebra Charvest (talk) 22:09, 14 January 2009 (UTC)

Modulo cleanup

Go to modulo and click on "what links here".

• Some of these times should be rewritten to say [[modular arithmetic|modulo]] so that the reader sees "modulo" and clicks and sees modular arithmetic.
• Some of these times should be rewritten to say [[modulo operation|modulo]] so that the reader sees "modulo" and clicks and sees modulo operation.

In the modular arithmetic article, 63 and 53 are congruent to each other modulo 10.

In the modulo operation article, "modulo" is a binary operation and (63 modulo 10) = 3.

The modulo article is far more general than just arithmetic.

—Preceding unsigned comment added by 75.72.179.139 (talk) 22:02, 11 January 2009 (UTC)

Michael Hardy (talk) 21:51, 11 January 2009 (UTC)

......I've now taken care of the most egregious cases. Next there are the subtler cases that may require more delicate thought. Michael Hardy (talk) 23:23, 11 January 2009 (UTC)

Additive number theory

I recently created Category:Additive number theory and I'd like help/feedback.

• What should the category name be? Additive number theory seemed best to me, but any of {arithmetic | additive} {number theory | combinatorics} would seem to be possible, and there are surely others.
• Should the category be under Category:Number theory or the narrower Category:Analytic number theory? It's usually considered one of the major branches of analytic number theory because of its heavy use of the circle method and related techniques, but they're a priori distinct.
• What other articles should be included? I just did a quick pass, but I'd expect that there are more.
• What should the category page say? I just have boilerplate text at the moment, which could be fine, but if there are any distinctions that need to be made ("not to be confused with Subtractive Number Theory") or related fields ("similar to Combinatorial Subtraction, but different because CS uses butterflies and rainbows instead of sumsets").
• Any other comments?

CRGreathouse (t | c) 20:28, 12 January 2009 (UTC)

Additive number theory sounds like a good name. IMO it should be a sub-category of Analytic number theory. That's all my opinions. RobHar (talk) 22:03, 12 January 2009 (UTC)

Something has to be done about this junky article

I am seriously concerned about the article on manifolds. First of all, it seems (from an uninvolved user's point of view) that a group of people rejected this article from becoming featured simply because they couldn't understand this. I am glad at least that it was rejected but there should seriously be some restrictions on the people who vote (some people seem to think that if they can't understand it, no-one else can) (if anyone has the time, just have a read through the article). But here is a specific section (the article is never going to be featured at this rate):

Other curves

Manifolds need not be connected (all in "one piece"); an example is a pair of separate circles. They need not be closed; thus a line segment without its end points is a manifold.

By definition, a 'closed manifold' is a compact manifold without boundary. A line segment without its end points is just R and is therefore a trivial manifold. Why mention these obvious facts? PST

And they are never countable; thus a parabola is a manifold.

????????????? For a start, they can be countable (0-dimensional manifold), and does the implication make sense (even assuming that the first statement is true)? Its like saying that X is never Y; so if Z is not Y, it must be X. PST

Putting these freedoms together, two other examples of manifolds are a hyperbola (two open, infinite pieces) and the locus of points on the cubic curve y² = x³−x (a closed loop piece and an open, infinite piece). However, we exclude examples like two touching circles that share a point to form a figure-8; at the shared point we cannot create a satisfactory chart. Even with the bending allowed by topology, the vicinity of the shared point looks like a "+", not a line (a + is not homeomorphic to a closed interval (line segment) since deleting the center point from the + gives a space with four components (i.e pieces) whereas deleting a point from a closed interval gives a space with at most two pieces; topological operations always preserve the number of pieces).

Nothing wrong with this fortunately. :) PST

I can give (if necessary) similar criticizm of almost all other sections. Recently I re-wrote the lede: I would seriously consider re-writing the whole article and deleting some of the sections there. --Point-set topologist (talk) 20:59, 12 January 2009 (UTC)

From a quick glance the article seems to be better than 98% of our articles. Deleting content is pretty delicate. What is trivial to you may not be so to other readers, so be very careful and thoughtful. Jakob.scholbach (talk) 21:23, 12 January 2009 (UTC)

From another glance at this change log it looks like most of the changes you made were unconstructive

Not true: I expanded the lede as well as made some cleanup to other sections in the article. --Point-set topologist (talk) 22:00, 12 January 2009 (UTC)

, if not harmful. For example, removing reasonable content as per "delete nonsense section" is pretty bad.

I rewrote this section in a much better manner (that is why I used 'nonsense') and merged it into the lede. So in effect, I did not delete it. --Point-set topologist (talk) 22:00, 12 January 2009 (UTC)

I have reverted your recent edits. Jakob.scholbach (talk) 21:33, 12 January 2009 (UTC)

Hi Jakob,

I did not intend my edits to manifold to be unconstructive. I deleted that section because I had already summarized it in the lede (so basically I merged that section into the lede). Maybe I should have made this more explicit (I guess this is kind of what Taku did (on a major scale) to ring (mathematics) although his intentions were good). I also rewrote the lede in the way I did after reading why this was rejected in FA; so basically I made it more accessible. I am adding that section back but if you still feel the same way you can revert it. I just feel that there has been a misunderstanding.

PST (Point-set topologist)

I reverted. It appears that you have delted a lot of my additional material in your rv. Could you please have a look at that diff (of your rv)? --Point-set topologist (talk) 21:57, 12 January 2009 (UTC)

I have to say I side with Jakob.scholbach. The introduction should be short and to the point describing what he article is about. The edits put too much into the introduction. And even if the introduction does say something it should probably be mentioned again in a more precise way later rather than stuff being removed elsewhere to put into it. The introduction should be chatty and accessible and just introduce the article so people know whether they are looking at the right place and have a quick summary. Dmcq (talk) 09:03, 13 January 2009 (UTC)

Freak software bug

I just did a minor edit to Cauchy principal value. After the edit, every line of TeX in the article looked like this:

Failed to parse (Cannot write to or create math output directory): \lim_{\varepsilon\rightarrow 0+} \left[\int_a^{b-\varepsilon} f(x)\,dx+\int_{b+\varepsilon}^c f(x)\,dx\right]

I've seen this a number of times lately. It will probably go away soon, but just when is completely unpredictable. Why is this happening? Michael Hardy (talk) 19:41, 13 January 2009 (UTC)

Because someone broke a server. For now a purge should fix it. See WP:VPT#Error_message_in_http:.2F.2Fen.wikipedia.org.2Fwiki.2FPlanetary_gearing. Algebraist 20:04, 13 January 2009 (UTC)

Shannon–Hartley theorem

There are a number of (bolded red) parsing errors in this article, related - I think - to mathematical equations. Would someone more familiar with this area take a look? Thanks! -- John Broughton (♫♫) 20:56, 13 January 2009 (UTC)

Looks fine to me. Most likely a transient server-side problem; this happens from time to time. --Trovatore (talk) 21:02, 13 January 2009 (UTC)

This sounds like the same thing as the thread above. Algebraist 21:05, 13 January 2009 (UTC)

How to make SVG diagrams

This question sometimes comes up and it bears answering as often as possible, since a lot of people have never heard that we should be using SVG, and of those who have, few seem to have an easy way of actually accomplishing it. This is addressed at Help:Displaying a formula#Convert to SVG, but their proposed solution relies on a somewhat arcane and arbitrary invocation of two different utilities, followed by a roundabout filtration through two major software packages, which is necessitated by one of them (pstoedit) requiring a costly proprietary plugin to work properly. And the end result is still unusable if your diagram has diagonal lines. Here's the right way:

pdflatex file.tex
pdfcrop --clip file.pdf tmp.pdf
pdf2svg tmp.pdf file.svg
(rm tmp.pdf at the end)

Both pdfcrop and pdf2svg are small, free (if new and somewhat alpha) programs that work properly. I advocate pdflatex since with the alternative, you might be tempted to go the route of latex→dvips→pstopdf before vectorizing, and that runs into a problem with fonts that has to be corrected with one of the arcane invocations above. (There is a correct route, which is to replace that chain with dvipdfm, that I have never seen anyone suggest. Somehow, the existence of this useful one-step solution to getting PDFs from plain latex is always ignored.)

I have proposed at the talk page of that Help article that this procedure replace the existing one. It has been road-tested on, most notably (for the complexity of its images) Triangulated category and found to work quite well. Since the interested parties hang out here more than there, I'm soliciting feedback from whatever TeXperts and hackers might be lurking. Ryan Reich (talk) 04:23, 14 January 2009 (UTC)

Thanks for this, I'm quite happy to know this. Also, btw, on macs texshop uses pdflatex as default since pdf's are native on macs. RobHar (talk) 04:59, 14 January 2009 (UTC)

Since writing this, I have investigated Inkscape's internals and found that the following pstoedit invocation is also good:

pstoedit -f plot-svg -dt -ssp tmp.pdf tile.svg

It also makes smaller SVG files, sometimes (with the large ones) by quite a bit. This invokes the GNU libplot, and I cannot decide whether this piece of imperfect software is preferable to the one which is pdf2svg; let it be your call if you use it. Ryan Reich (talk) 20:59, 14 January 2009 (UTC)

...except that it couldn't make a nice SVG out of the pictures now at Cone (category theory), whereas pdf2svg could. I don't think I can really recommend pstoedit for this task. Ryan Reich (talk) 04:26, 15 January 2009 (UTC)

brahmagupta and Cauchy

Please see Negative and non-negative numbers. Katzmik (talk) 18:10, 14 January 2009 (UTC)

A meaningful illustration of vector spaces

Does anybody have an preferrably an illustration (or an idea for one) to illustrate the concept of vector space? I'd like to nominate that article for FA soon, but I feel without a good lead section image it's only half as beautiful. Thanks! Jakob.scholbach (talk) 20:56, 14 January 2009 (UTC)

Cut paste move

I tagged Krull–Schmidt theorem with {{db-histmerge}}, since there was a WP:CUTPASTE move done to it. The ndash article has no new (relevant) history to it, all of the history is in the hyphen article, which is now a redirect. Can an admin fix this? JackSchmidt (talk) 00:28, 15 January 2009 (UTC)

Done, I think. — Arthur Rubin (talk) 02:01, 15 January 2009 (UTC)

Thanks! JackSchmidt (talk) 14:22, 15 January 2009 (UTC)

List of mathematics categories

We have Wikipedia:WikiProject Mathematics/List of mathematics categories which is used as worklist by mathbot to fill in the list of mathematics categories.

Question: can this list of categories be also useful to Wikipedia readers, after some formatting changes or prettifying perhaps? Then we could move it to the article namespace, at list of mathematics categories, and treat it in the same way as the other mathematics topics. Oleg Alexandrov (talk) 07:08, 15 January 2009 (UTC)

Gauss–Jacobi mechanical quadrature

Gauss–Jacobi mechanical quadrature is vaguely written. In particular, what does the function p_n(x) have to do with the statement that follows it? Could someone who knows the answer to these questions clarify by editing the article. Michael Hardy (talk) 05:26, 16 January 2009 (UTC)

What a mess

Can anyone help with Grey relational analysis? Michael Hardy (talk) 05:49, 16 January 2009 (UTC)

stable module category: many formulas not rendered

http://en.wikipedia.org/wiki/Stable_module_category