# Wikipedia talk:WikiProject Mathematics/Archive/2011/Nov

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## Desargues' theorem

An image from Desargues' theorem is scheduled to become picture of the day this coming Wednesday, Nov. 2. So now would be a good time to look over the article and make sure it is as good as it could be for the readers who come to it from the front page. See the article and its talk page for details. —David Eppstein (talk) 21:19, 31 October 2011 (UTC)

The first thing I noticed is there are no inline cites, it's a problem but it's probably not the kind of thing that an be fixed in two days.--RDBury (talk) 01:27, 1 November 2011 (UTC)
Actually for the general audiences at least it might be useful to state an euclidean/affine version in terms of elemtary geometry.--Kmhkmh (talk) 01:42, 1 November 2011 (UTC)

Interesting. It says "A diagram of Desargues' theorem, created using Adobe Illustrator. Based on File:Desargues theorem.svg, created by User:DynaBlast." It's an improvement over the picture by DynaBlast in this respect: none of the three depicted lines meeting at the center of perspectivity is parallel to the axis of perspectivity. In DynaBlast's version, one of them is parallel. DynaBlast's version is metrically identical to my earlier version that it superseded; mine had no colors. Mine was based on another identical diagram I drew on graph paper in 1999. Wikipedia didn't exist until 2001, so I could not have imagined that my picture's grandchild would have this career. Michael Hardy (talk) 02:24, 1 November 2011 (UTC)

## Recent MOS changes for transpose

Opinions on this? I found the code particularly helpful when it was in. Rschwieb (talk) 01:58, 1 November 2011 (UTC)

It was in for all of 11 days, with the editor removing what he had added previously. I don't think adding wikicode is necessary in that or other examples (and arguably if it's added to one it should be added to all). Editors can and are encouraged to look at the source of any formatting they don't know, which I'm sure is how most of us learn these things.--JohnBlackburnewordsdeeds 02:21, 1 November 2011 (UTC)

## bluetulip.org

This link was recently added to the Ellipse article. It generates simple problems in conic sections and checks the answer if you type one in. (A similar link is in Factorization.) This doesn't seem to be excluded by ELNO but I'm not sure you can call it a "unique resource" either since you can find similar exercises in any precalculus text. The general question is whether external links are appropriate if they only contain exorcises or drills with no factual information, assuming they are well intentioned. My feeling is no, WP is not a textbook so articles should not be offering a list of exercises at the end as if it were. But I can see how some people might consider such links useful so I'm looking for other opinions.--RDBury (talk) 12:10, 2 November 2011 (UTC)

I also vote no -- that's not the sort of resource one should go to an encyclopaedia to find. --Joel B. Lewis (talk) 13:56, 2 November 2011 (UTC)
I'm not sure of the exact guideline on this, but looking at the site, it had nil reference value, and does not seem to be related to the encyclopedic nature of Wikipedia. As I understand it, Wikipedia is not supposed to be pedagogical. I'm pretty sure that someone familiar with the policy will find a good reason to exclude it. Quondumtalkcontr 14:42, 2 November 2011 (UTC)

## When are conjectures encyclopedic?

I just got a note questioning this edit. My reasoning is that conjectures are not facts and therefore the rules for verifiability do not apply. From what I can find though there seems to be little guidance from policies and guidelines as to what rules should be applied. My thinking is that the conjecture should meet some criteria for notability adapted from WP:N. Such as:

• If the conjecture is mentioned in a reliable secondary source.
• If the conjecture was made my a well-known mathematician (the celebrity factor).
• If the truth of the conjecture would aid in the solution of a notable unsolved problem.

This reminds me of the discussion on mnemonics here a while ago in that it's a question of when non-factual material should be included in Wikipedia. On the principle that (with apologies to T.H. White) "Everything not forbidden will eventually be added to Wikipedia," I think whether or not things like mnemonics, conjectures, unsolved problems, etc. are encyclopedic should be covered by guidelines more than it is.--RDBury (talk) 01:49, 3 November 2011 (UTC)

I don't see any problem with the guidelines here. "Simmons conjectures that..." is a fact that can be handled like any other fact. In wikipedia's thousands of articles about history, politics, literature and much more, facts of this nature need to be dealt with every day. Is it verifiable? Is it relevant to the article? I think it's OK for an encyclopedia to mention unsolved problems and conjectures, provided that there are sources to demonstrate that people are interested in such things. It's a matter of editors making judgements on what should be included; it's right and proper that the guidelines leave some room for judgement and consensus-building. Jowa fan (talk) 02:08, 3 November 2011 (UTC)
What Jowa fan said. If you discriminate against conjectures as a blanket rule, then that's Riemann out of the window, which would be absurd.
In general I think the Wikipedian community in general is getting just a little bit hung up on what is or what is not allowed as content, based upon a set of more-or-less arbitrary rules for inclusion that are being Pharisaically interpreted, honed, filed down, chopped up, squeezed out and then slapped over every single entry, at the expense of the overall philosophy of an encyclopedia, that is: to inform and educate. And if you don't agree that this is what an encyclopedia is for, then I'm afraid I have to disagree in the strongest terms. --Matt Westwood 06:38, 3 November 2011 (UTC)

To me a conjecture is notable if it has been noted in reliable sources, no different from lots of other things. Its unprovenness does not give it any special status that prevents us from writing about it, nor does it excuse us from finding adequate sources. In particular, re the original poster's assertion "conjectures are not facts and therefore the rules for verifiability do not apply": no, whether someone has made a conjecture or not is definitely a fact and should be verifiable. For instance, when one goes back to the original sources, one often finds things that later authors say are conjectures but which the original author stated less strongly. In the edits in question, two questions were stated as conjectures in an unverifiable form, with no references and without even enough information to reliably identify the mathematicians in question. Their removal, until sources could be added, was appropriate. —David Eppstein (talk) 07:07, 3 November 2011 (UTC)

Actually the person the person who added the conjectures stated they came from OEIS, which I believe the consensus is that it is reliable. My point is that not every conjecture in a research paper somewhere should be mentioned in a Wikipedia article. Research papers and sites like OEIS are reliable sources of fact, but I don't think the fact that "Relatively obscure mathematician X made a conjecture about even more obscure sequence Y" is encyclopedic even if it is verifiable.
@Matt Westwood, please read what I'm proposing before dismissing it. You're claiming I'm trying to remove Riemann from WP which is ridiculous. Riemann would pass all three of the criteria I gave and I'm only suggesting that a conjecture pass at least one before it's included. If you don't like the idea then give a valid reason, don't use some silly strawman argument. I understand that many Wikipedians get frustrated with all the guidelines and policies, but I disagree that they are arbitrary and in general unhelpful. Guidelines are very helpful when removing something that does not belong on Wikipedia, otherwise the reason you have is give is that you don't like it. The person who added the material obviously did think it was appropriate and without some kind of guidelines on what should be included and what shouldn't it's a matter of one person wanting it and the other not wanting it with no rational way to decide between them. The guidelines and policies are not always states as clearly as they should be, and I believe in IAR as much as the next person, but Wikipedia houses a huge amount of useless cruft and getting rid of it is hard enough; having guidelines helps the process by by keeping it from appearing arbitrary and helping to stave off edit wars.--RDBury (talk) 08:06, 3 November 2011 (UTC)
No I am not. I'm complaining about the fact that there is a culture developing of deletion-uber-alles. I was setting up an extreme case (which some would call a "straw man") pointing out the foolishness of deleting conjectures purely because they are conjectures and therefore not truths. You go away again and read exactly what I said. And I stand by it 100%. I utterly, utterly despise deletionism.
My approach, rather than just complacently delete the statements in question out of hand would have been to add a tag "requires sources" or whatever. Then at least the OP would have a nudge to go back and see whether the problem can be fixed. --Matt Westwood 08:28, 3 November 2011 (UTC)
I don't understand why this is worth making a fuss about. Someone added a statement to an article, someone else deleted it, and now it's being discussed. This is normal process: the system seems to be working as it should. There's no need for additional guidelines to cover this situation. In fact, I think it would undesirable to have a guideline that stifled discussion in cases like this. Is this an isolated incident, or can anyone point to more edits showing that the handling of conjectures is a problem that needs solving? Jowa fan (talk) 09:42, 3 November 2011 (UTC)
The statement "Fred Bloggs conjectures that XYZ" needs a reliable source like any other statement. The problem appears to be the use of OEIS as a source in this case: I think we all accept it as a reliable source for sequence properties, but some editors seem to object to leaning too heavily on comments by OEIS editors. Notability and reliability would certainly be more obvious if one could find a journal article by Bloggs. In the specific case here, the Simmons conjecture does appear to be notable, listed here and in some Martin Gardener columns. -- 202.124.72.1 (talk) 14:33, 3 November 2011 (UTC)

I like RDBury's criteria. They are moderate, flexible, and would keep out the worst offending material. Rschwieb (talk) 17:23, 3 November 2011 (UTC)

## Apostrophe position in "one's complement"

Hi folks, just passing on a question from an anon about the apostrophe in One's complement. Does anyone have a source on hand to verify? The Interior (Talk) 15:30, 4 November 2011 (UTC)

Not a source as such, but I remember this from college: ones' complement and two's complement. The former because it's the complement of a whole load of ones, so the plural genitive form ones' is used; the latter because it's the complement of a single two, so the singular genitive form two's is used. Once you understand that point then anything else is grammatical ignorance like misuse of its and it's. --Matt Westwood 20:16, 4 November 2011 (UTC)
I have (perhaps unwisely, but in AGF) amended all the links to "one's complement" to "ones' complement" on the grounds that the latter is grammatically correct, even though it appears that the literature in general prefers the "one's" format. Now: my view is that an encyclopedia should prefer to publish "what is correct" in preference to "what is popular", and in this case there is a robust grammatical and technical reason why "ones' complement" is correct. I also appreciate that the point is subtle and the problem is compounded by the existence of "two's complement" which is correct in the "two's" form.
Also note that this has not been a completely useless exercise - I have also tidied up a number of untidy redirects so as to make any further change (e.g. back to "one's complement" if it is regretfully so decided) easier. --Matt Westwood 08:42, 5 November 2011 (UTC)
Perhaps best to centralize at WT:WikiProject Computer science#Ones' complement or one's complement? Dmcq (talk) 09:54, 5 November 2011 (UTC)

## Mass overcategorization of maths articles

Brad7777 (talk · contribs) is indiscriminately adding mathematics articles to Category:Subdivisions of mathematics despite them (the one's I've checked) already being in more appropriate categories. I've tried explaining but he's dismissed what I've written and continued. Can anyone else get him to stop so we can undo the damage (I've asked him to do that but I doubt he will).--JohnBlackburnewordsdeeds 00:04, 5 November 2011 (UTC)

I have to agree that the category is being added to some that shouldn't be. Just be careful in scaling it back so that everything that should be under the category tree of Category:Subfields by academic discipline‎ is. Greg Bard (talk) 02:18, 5 November 2011 (UTC)
I don't think any articles should be in the category. However, even taking them all out would leave an anomaly, as some of his edits removed mathematical articles from appropriate categories. — Arthur Rubin (talk) 02:21, 5 November 2011 (UTC)
He added them to some articles that are not "subdivisions" of anything, such as Zermelo–Fraenkel set theory. ZF is a specific collection of formal sentences, not any sort of field of study (it's an object of study but not an area of study). By way of contrast, of course set theory itself should be in some such category; set theory is a field of study, not a collection of formal sentences. --Trovatore (talk) 02:26, 5 November 2011 (UTC)
@Arthur Are you under the impression that mathematics has no subdivisions or do you just think mathematics is otherwise somehow more special than the other areas (and fields) covered under the category tree of Category:Academic disciplines.Greg Bard (talk) 02:34, 5 November 2011 (UTC)
No; as mathematics has subdivisions, they should be categories; an article rarely represents a "subdivision" or "field" of mathematics. I dud say "never", but set theory would be a field even if it wasn't a category. But is descriptive set theory a "subdivision of mathematics", or just a field within set theory? — Arthur Rubin (talk) 02:41, 5 November 2011 (UTC)
Speaking as one whose dissertation is in the general area of descriptive set theory, my feeling is that it's a field within set theory. But one can disagree without being completely absurd; Charles Matthews claims (hope I'm not misquoting him) that it used to be viewed more as a part of general topology. --Trovatore (talk) 02:55, 5 November 2011 (UTC)
Internal set theory? That's a little less clear. It's equiconsistent with ZF set theory, but it's not really the same. — Arthur Rubin (talk) 02:43, 5 November 2011 (UTC)
I don't know much about IST, but the article claims it's a formal theory. No formal theory should be categorized as an area of mathematics; they're completely different things. Formal theories are studied; they are not areas of study. --Trovatore (talk) 03:03, 5 November 2011 (UTC)
I've now fixed them, removing articles from that category as well as Category:Calculus which articles were added to despite more specific categories already being there, and in a couple re-adding better removed categories. I've not been able to check whether the pre-existing categories made sense: mostly I glimpsed them only briefly and the article not at all. But it should be a near empty category with no specialist mathematical articles: if an article is found that doesn't fit in one of the existing subdivisions it would make sense to create a new subdivision for it. I've left a further note on the editors talk page, in the hope he will read and take note of the guidelines though that may be too optimistic. --JohnBlackburnewordsdeeds 02:57, 5 November 2011 (UTC)
I have already undone changes regarding this category (you make me look like such a rebel!) Brad7777 (talk) 16:56, 6 November 2011 (UTC)
(We all of learn as we go, making mistakes until they are pointed out to us. Most of start though by editing one or a few articles, not hundreds!)--JohnBlackburnewordsdeeds 21:22, 6 November 2011 (UTC)

See also a related CfD: CfD:Category:Branches of mathematical analysis--JohnBlackburnewordsdeeds 22:03, 6 November 2011 (UTC)

## Move of Tetromino to Tetrimino

Input at Talk:Tetrimino#Move of Tetromino to Tetrimino would be welcome. Thanks, ἀνυπόδητος (talk) 11:56, 6 November 2011 (UTC)

## Mathematics, applied mathematics and mathematical sciences

Brad7777 (talk) 16:46, 6 November 2011 (UTC)

It's worked fine for years the way it is. -- 202.124.75.16 (talk) 11:35, 7 November 2011 (UTC)
I believe the purpose of "Mathematical sciences" is to capture mathematics, statistics, and operations research, since the latter two are not always considered "mathematics", not by mathematicians or by people in the other fields. On the other hand applied mathematics is considered to be part of mathematics, although not part of pure mathematics. — Carl (CBM · talk) 12:34, 7 November 2011 (UTC)
I think it would be better off if the category Mathematical sciences was removed. It seems a silly made up term to me and not generally useful. Better to just have mathematics without any qualification instead. The category mathematical science occupations makes good sense though. Dmcq (talk) 12:36, 7 November 2011 (UTC)
My guess is that will upset somebody who think that statistics are not mathematics (that people could be either a mathematician or a statistician, it's a relatively common viewpoint). — Carl (CBM · talk) 12:57, 7 November 2011 (UTC)
Would they call themselves scientists? or applied mathematicians? Dmcq (talk) 13:04, 7 November 2011 (UTC)
Having had a look at the Statistics page how about 'Mathematical arts' instead of 'Mathematical sciences'? Dmcq (talk) 13:09, 7 November 2011 (UTC)
I don't know whether they would call themselves scientists, but there are definitely some statisticians who would not call themselves mathematicians of any sort, and some mathematicians who would not call statisticians mathematicians either. This is why there are so many departments of "Mathematics and Statistics" at universities but not departments of "Mathematics and Abstract Algebra" or "Mathematics and Graph Theory". Here is a different paper that also takes the distinction for granted [1].
I certainly prefer "mathematical sciences" over "mathematical arts", the latter sounds too much like either medieval terminology or mathematical art. — Carl (CBM · talk) 13:15, 7 November 2011 (UTC)
I prefer the arts and where it is used they can call in mathematicians or statisticians to perform their arcane arts. You can see it with the quote Mathematical theorems are true; statistical methods are sometimes effective when used with skill." Mathematicians do the same as statisticians when they tackle real world problems, they try and use their skills to be effective rather than prove a theorem, theorems are about the models if anything, not the real world. Science is just the wrong word to describe that and I believe art is a much better way of having people think of it. Tell a mathematician that they're engaged in a science and they'll make it more formal, if it is an art they'll try and be useful. It is like programming, the art of computer programming is a great work and an inspiration. The science of programming conveys an altogether different idea of formal walkthroughs and failed projects or a very mathematical view of it all. Dmcq (talk) 14:14, 7 November 2011 (UTC)
We could do an end run round the problem and have a category 'Mathematical disciplines' which could include the things that Mathematical sciences category includes. Dmcq (talk) 14:28, 7 November 2011 (UTC)
That has the same problem - statistics, and operations research, are often not considered disciplines of mathematics, they are considered separate fields. — Carl (CBM · talk) 14:30, 7 November 2011 (UTC)
In which case they wouldn't fit into mathematical sciences either. And I really don't think either art or science with anything would get widespread support - those categories and articles about mathematical sciences were set up sometime last year and seem to have languished since with no one in interested in them. Dmcq (talk) 14:44, 7 November 2011 (UTC)

Just to clarify that, contrary to what Dmcq says, the term "Mathematical sciences" is not made up. It is the name of many university departments of mathematics etc. Google it, you'll see. My understanding of the term is that it is exactly designed to encompass the kinds of disciplines that we are discussing here. So, while people may not be happy to call math a science, it is a rather common thing to do. I am personally fine saying that math is not a natural science, nor a social science, but rather a mathematical science. RobHar (talk) 15:10, 7 November 2011 (UTC)

Just checked around more and you're right. Why on earth have they done that? I've never seen a listing of sciences including things like mathematics or OR or statistics and it doesn't employ the scientific method. I guess on Wikipedia we've got to follow common name however silly, it just seems such a bad idea to me. Dmcq (talk) 15:55, 7 November 2011 (UTC)
I suppose I probably answered my own question when I said 'mathematical science occupations' made sense, if the university is fitting people for a vocation then they'd see no problem with just removing the given which is 'occupation'. A bit like Masai with their cows. Dmcq (talk) 16:09, 7 November 2011 (UTC)
I have often heard mathematics classified within the umbrella of science. It is, I believe, a more recent trend to exclude mathematics from the term science. These terms aren't as rigid as you may think they are. For example, many people don't count the social sciences within science. I guess I'm saying that just because the term science appears in the term mathematical sciences doesn't mean that there's a claim that the mathematical sciences are sciences. RobHar (talk) 16:59, 7 November 2011 (UTC)
I've searched a bit more with google at the older usage and it looks to me like it may come from the term physico-mathematical sciences and not what I was saying. Dmcq (talk) 17:39, 7 November 2011 (UTC)

I don't really understand the debate here. I guess if all else fails, we can ask Oxford's DPMMS or the MSRI at Berkeley exactly what it is that they do... Sławomir Biały (talk) 19:13, 7 November 2011 (UTC)

As far as I was concerned it was an argument about having the category:Mathematical sciences including maths and statistics and OR and suchlike. I don't like it but I concede now that it seems to be what is the more common name. Dmcq (talk) 22:59, 7 November 2011 (UTC)

## Automedian triangle

Automedian triangle is a fairly new article that I find quite unclearly written. Can someone clarify it? Michael Hardy (talk) 21:51, 7 November 2011 (UTC)

from here:
If a triangle is isosceles, the triangle formed by the second intersections
of the medians with the circumcircle is also isosceles, by symmetry.
The converse is not true: a non-isosceles triangle which gives an isosceles
triangle via the medians is called an automedian triangle because of the
relationship between the size of its medians and of its sides.
Some geometrical properties of an automedian triangle are derived.

The full paper is [2] but I can't read it all.--JohnBlackburnewordsdeeds 22:06, 7 November 2011 (UTC)

Better now? —David Eppstein (talk) 01:30, 8 November 2011 (UTC)

Far better now! The initial sentence was incomprehensible; now it's crystal-clear. Thanks to David Eppstein. Michael Hardy (talk) 12:29, 8 November 2011 (UTC)

## Desargues' theorem!

Look at this: http://stats.grok.se/en/201111/desargues%27_theorem

On November 2nd, the day the picture at the top of this article was on the main page, the article was viewed about 6300 times. On a typical October day, it was viewed around 50 or 60 times. On October 26th, it was viewed 720 times (might that have been the day when it was announced it would be on the main page?).

But on November 2nd, it was never edited a single time. Why not? Michael Hardy (talk) 22:14, 7 November 2011 (UTC)

Why would it be? It got a good work over the day before from the history, so presumably had few issues that needed addressing. And apart from Today's Featured Article other articles on the front page seem to get little or no vandal attention (or at least that's my experience from 3 Do You Know?'s and Pythagorean Theorem which was similarly featured via the picture on 9 October).--JohnBlackburnewordsdeeds 22:40, 7 November 2011 (UTC)
Actually there are still some significant problems with the page (for instance, the lead is horrid – it is written for math graduate students), but, for me, the real world required my attention and I just ran out of time to fix them (and by the way, kudos to David Eppstein for doing an excellent job with the material he had to work with). However, I had thought about the issue of editing the page on Nov. 2nd and rejected the idea. My feeling at the time was that I wanted the large influx of visitors to have the same experience (good/bad/neutral) with the page and I didn't want the page to be a "moving target". Right now I'm having a hard time trying to justify why that should matter. Bill Cherowitzo (talk) 04:39, 8 November 2011 (UTC)
@JohnBlackburne: Well, the obvious punctuation corrections that I did on November 7th needed to be done, and with 6300 views, you'd think someone would have noticed that.
@Bill Cherowitzo: The main problem in the lead is that it seems to presuppose that the reader knows what projective spaces are, but to say that it's written for math graduate students is nonsense. The other terms are explained in the paragraph in which the theorem is stated, so that I'd expect secondary-school pupils who read it patiently to understand it in a minute or two. And most math graduate students probably wouldn't be familiar with those terms without reading that paragraph. Michael Hardy (talk) 12:27, 8 November 2011 (UTC)

Bates–Young paradox is a new and very unclearly written article. If there's something legitimate here, it's hard to tell that from what appears. Michael Hardy (talk) 12:20, 8 November 2011 (UTC)

Looks like a spoof. Just prod it. They set up Bates-Young Constant as well. Dmcq (talk) 12:35, 8 November 2011 (UTC)
Seems like they were prodded already. Oh well AfD then. Dmcq (talk) 12:40, 8 November 2011 (UTC)
Gone as a hoax. The references and people were made up and the contents were rubbish. Dmcq (talk) 13:16, 8 November 2011 (UTC)

## Named after Pythagoras and Abel

We now have a list of topics named after Euclid, which can almost certainly be expanded, and a list of topics named after Alfred Tarski.

But we have no list of topics named after Niels Henrik Abel, nor a list of topics named after Pythagoras. Michael Hardy (talk) 15:29, 8 November 2011 (UTC)

I think it would be worth doing Brad7777 (talk) 21:27, 9 November 2011 (UTC)
Isn't that what a DAB page is for, e.g. Abel (disambiguation), Pythagoras (disambiguation)? Or if the articles are related by more than just name so they are all associated with the person, then they should be mentioned in the article for that person.--JohnBlackburnewordsdeeds 21:38, 9 November 2011 (UTC)
Really? Do you really want to put everything that is in the list of topics named after Leonhard Euler into the article about him? Or similarly for Riemann, Gauss, and Erdos? Michael Hardy (talk) 00:48, 10 November 2011 (UTC)

A rough draft is at User:Michael Hardy/Named after Pythagoras. Work on it if you can contributed and you're so inclined. Michael Hardy (talk) 01:46, 10 November 2011 (UTC)

Now moved to list of things named after Pythagoras. Michael Hardy (talk) 05:54, 10 November 2011 (UTC)
Isn't that just a content fork of Pythagorean? -- 202.124.72.91 (talk) 06:43, 10 November 2011 (UTC)

We also have no list of topics named after Thomas Bayes. Michael Hardy (talk) 01:46, 10 November 2011 (UTC)

We have Euclidean, Bayesian and Abelian. Is there some reason to have a list page for every dab page? -- 202.124.72.91 (talk) 06:45, 10 November 2011 (UTC)
I've never seen a sillier straw man than this idea that there should be a list for every dab page. Look at the list of topics named after Leonhard Euler and tell me which dab page you think it corresponds to. Michael Hardy (talk) 15:24, 10 November 2011 (UTC)
Mostly because of WP:PTM, I think. Dab pages are not allowed to be "lists of things named after", unless there is "significant risk of confusion". For instance, the link to Euclid–Mullin sequence should probably not be included on Euclidean (disambiguation) (nor the separate Euclid (disambiguation)), and diligent wikignomes would probably remove it if it were added there. —David Eppstein (talk) 07:16, 10 November 2011 (UTC)
That makes a twisted kind of sense, as long as the "lists of things named after" page is linked from the dab page, which it generally isn't. -- 202.124.74.118 (talk) 08:25, 10 November 2011 (UTC)

## "Originality" of calculations

Members of this WikiProject may be interested in Wikipedia talk:No original research#Possible enhancement of WP:CALC. Yaris678 (talk) 14:50, 10 November 2011 (UTC)

## Square pyramidal number

I'm having a dispute with an anonymous editor on Square pyramidal number who wants to add a section proving the summation formula for these numbers. My feeling is that the proof (the obvious induction, written badly in the first person and tediously drawn out into many algebraic formulae) does not aid the readers to understand the subject any better and is therefore not a constructive contribution to the article. The anon is characterizing my removal of the proof as vandalism. Third opinions welcome. —David Eppstein (talk) 21:57, 10 November 2011 (UTC)

Well, let's start with the obvious: removing the proof is not vandalism. My view after reading it is that its length is far out of proportion to its value, so even not for its issues it would be unsuitable. So I think removing it is the right thing.
On the other hand, it's entirely possible that for the target audience the induction proof is not obvious, and there may be value to its inclusion. Was it is to be included, I would suggest a one-line proof giving the inductive step only.
CRGreathouse (t | c) 22:19, 10 November 2011 (UTC)
1) I don't see it like "dispute". In my opinion it is not fair to remove something before reading it. Did you try to read it and to understand it? It's not difficult, it is not long. Of course I can remove something in the proof, but I want to be super clear for math beginner users.
User:86.24.46.135 22:35 , 10 November 2011 (GMT)
2) If the "(proof is not written to Wikipedia standards (see MOS:MATH) and is overly long; a short proof might possibly be reasonable here, see WT:WikiProject Mathematics" the user can collaborate, without removing it, formatting it... Remove some content is vandalism.
User:86.24.46.135 22:35 , 10 November 2011 (GMT)
uh, another thing... The induction is only a proof that the formula is right. It doesn't explain how to find the formula. This formula was not obtained in a empirical way.
User:86.24.46.135 22:54 , 10 November 2011 (GMT)
The proof should only be in if special interest in the actual proof has been shown in the literature or if it is quite short and doesn't break up the flow - a short proof can contribute to understanding an article. We can also indicate the main steps of a proof without giving a full proof if that is of particular interest. There should always be a reference which which supplies a proof and people can look up details there if the proof has no special intrinsic interest. Wikipedia isn't a textbook. Dmcq (talk) 23:12, 10 November 2011 (UTC)
I don't understand why Wikipedia isn't a textbook. Wikipedia could be the reference of the knowledge, at every level. Are we interested in making dullpedia? Why wikipedia has to be levelled to the bottom?User:86.24.46.135 14:41 , 11 November 2011 (GMT)
To do not be vague, I don't understand why I can read a little information on wikipedia, then I have to switch to a classical paper book to find more.Why I can't find a complete treatment on wikipedia???Why someone is against to add info on wikipedia? User:86.24.46.135 14:54 , 11 November 2011 (GMT)

There are more illuminating proofs of this result than a straight induction. Sławomir Biały (talk) 15:05, 11 November 2011 (UTC)

It's in the very first policy mentioned in WP:5P that Wikipedia is an online encyclopaedia, the relevant bit is WP:NOTTEXTBOOK. Really it is better to guide people to where they can read things in a proper textbook if they want the details of a proof and be certain it isn't something somebody here cooked up themselves. Dmcq (talk) 15:12, 11 November 2011 (UTC)
I should mention that there are reasonable arguments that are made from time to time that Wikipedia should be more textbook-like. But those arguments don't belong here or in the article, they should go to WT:NOT. Also see Wikiversity and Wikibooks (or other projects like the Proof Wiki, PlanetMath). CRGreathouse (t | c) 15:20, 11 November 2011 (UTC)
This makes me think that we could make more use of cross-linking to Wikiversity. A Wikiversity page could certainly include a more detailed proof. Nageh (talk) 20:06, 11 November 2011 (UTC)

The anonymous has performed seven reverts, two after being warned about WP:3RR. I've filed a report at 3RR/N: [3]. —David Eppstein (talk) 21:03, 11 November 2011 (UTC)

## POTD for Sun.

Another math related image File:Helicatenoid.gif is scheduled to be placed on the main page this weekend. The caption to be used is at Template:POTD/2011-11-13; it seems main-page-worthy to me but it might do with another check or two. It might also be a good idea to check over the articles the caption links to since they will be getting increased traffic. Theorema Egregium might also get a bump since the image is used there as well.--RDBury (talk) 01:42, 12 November 2011 (UTC)

## Cite needed for catenary bridges

I've brought this up here before but I suppose it won't hurt to ask again. A little while ago I went through the catenary article and removed the unsourced material in preparation for a GA review. I left in one statement to the effect that a simple suspension bridge follows the catenary curve. To me this is an obvious statement since this kind of bridge is basically a hanging cable which is big enough and flat enough to walk on. Another editor is apparently challenging the statement though and keeps removing it, so it seems that a cite is needed to keep it in the article. Unfortunately I am unable to find a reference so if anyone else can provide one I would appreciate it greatly. I think it would be a shame to remove the statement from the article since it provides a "real world" example of the subject, not to mention that it ties the entire section in with the rest of the article.--RDBury (talk) 12:32, 12 November 2011 (UTC)

I'm not even sure that such a bridge does follow a catenary. It will definitely be a catenary if it is free-hanging, but it's not - it suspends a road underneath it. Somewhere in one of my calculus text books (I'll go and hunt it down if you like) there's an example which analyses the shape of a chain whose weight is proportional to horizontal length (which is the approximate model for a suspension bridge) and it turns out this is modelled by a parabola. Therefore the deletion may be appropriate, although if I'd been the deleter I'd have mentioned why I'd deleted the contentious statement. --Matt Westwood 12:38, 12 November 2011 (UTC)
D'oh! I'm talking rubbish. Ignore all the above. --Matt Westwood 12:39, 12 November 2011 (UTC)
Well I just stuck catenary bridge into google books and the first entry back was http://books.google.co.uk/books?id=0u5G8E3uPUAC&lpg=PA514&dq=catenary%20bridge&pg=PA514#v=onepage&q=catenary%20bridge&f=false which seems to be pretty definitely about them. Dmcq (talk) 12:53, 12 November 2011 (UTC)
@Dmcq: You searched on "catenary bridge" and found a book referring to the term you searched for. The reference says in effect that that kind of bridge is known as such (which may be true), but be careful that this is not a misnomer – I suspect it is.
@Matt Westwood: why the retraction? AFAIK your characterisation of catenary/parabola is correct (but don't take my word for it). Quondumtalkcontr 14:29, 12 November 2011 (UTC)
No, there's nothing wrong with it as such, it's just that this was not the point of what RDB was originally getting at. And it was all part of the article on suspension bridges, so I didn't actually contribute anything of any intellectual worth. --Matt Westwood 19:06, 12 November 2011 (UTC)
You suspect those bridges do not form a catenary? I don't know where you get that idea from but I guess I better search further for something with the actual maths in. Dmcq (talk) 14:52, 12 November 2011 (UTC)
I agree with RDBury. If by "simple suspension bridge" we mean a bridge in which the deck follows the curve of the supporting cables then this is in effect just an increase in the mass per unit length of the cables, so the deck and cable will follow the same curve as a cable hanging under its own weight i.e. a catenary (assuming deck is of uniform thickness etc. etc.). This seems to be almost self-evident. The bridges called "catenary bridges" in the reference found by Dmcq have this form. On the other hand, if the deck is horizontal, the the curve of the cables deviates from a catenary and in the limiting case where the weight of the cables is neglible compared to the weight of the deck, it becomes a parabola - see this analysis by Ira Freeman. I suspect there is some confusion here over what is meant by "simple suspension bridge". Gandalf61 (talk) 15:35, 12 November 2011 (UTC)
Perhaps the complaint was because the cables of standard suspension bridges seem to be called the catenaries even though they are more like parabolas. Catenary bridges though are ones where the deck if there is one follows the cable and means exactly the same as a simple suspension bridge as far as I can make out, I don't see evidence of them even using less material in the middle which would change the shape a bit. Dmcq (talk) 15:59, 12 November 2011 (UTC)

By the way, there's a broken wikilnk from simple suspension bridge to a section title in catenary that doesn't exist as a section any more. —David Eppstein (talk) 17:10, 12 November 2011 (UTC)

In a normal suspension bridge, such as you might cross in an urban area, the cables follow a parabola, which is covered a bit into the technical part of the article. By simple suspension bridge I mean, following the article we have on them, ones that follow the curve of the cable and mostly appear in action movies set in jungles, though there are some notable nonfictional ones. The article did explain this distinction but I commented it out for the time being since it's off topic unless you can relate the material to the catenary curve somehow and that relies on the statement that so called catenary bridges actually follow a catenary. @Dmcq, The link you gave does call them catenary bridges but it doesn't actually state they follow catenary curves, leaving the possibility of a misnomer as mentioned. I kept running into this kind of thing when I was searching for a reference, authors keep mentioning a catenary while talking about this kind of bridge without giving something citable. The curve is different if you don't assume the weight per unit length is constant, in fact there is a formula for the density of a cable which will follow the graph of any given function (if twice differentiable), though the density you get is negative when the second derivative is positive.--RDBury (talk) 18:01, 12 November 2011 (UTC)
It seems obvious, since the bridge as a whole is just one slightly thickened cable. -- 202.124.74.120 (talk) 04:15, 13 November 2011 (UTC)
That's what I keep saying but it looks like you found some good references anyway. Thanks for adding them to the article and the other improvements. The article may now be ready for a GA review.--RDBury (talk) 21:35, 13 November 2011 (UTC)

## List of trigonometry topics

List of trigonometry topics is currently an unorganized list. Maybe we should work on organizing it. Michael Hardy (talk) 20:01, 12 November 2011 (UTC)

I see that there's a proposal to merge that page into outline of trigonometry. There's been heated opposition on this page to moving list of X topics to outline of X, for numerous values of X. I can see merging them into a page, but I think maybe "list of trigonometry topics" is the better title. Michael Hardy (talk) 21:25, 12 November 2011 (UTC)
List of trigonometry topics does need organizing i agree with that. The list seems pointless in a state as it is (can't see many people using it, just being put off). Outline of trigonometry I think is fairly well done, and I don't think it needs to include the concepts from List of trigonometry topics, so i wouldn't agre with merging it. Personally, I like some of the glossaries in Category:Glossaries on mathematics and think Glossary of trigonometry would be a usefull Brad7777 (talk) 22:16, 12 November 2011 (UTC)

I've started a draft at User:Michael Hardy/trig list, with the idea that when it's ready it will get moved to List of trigonometry topics and then I will merge the edit-histories of the two. Michael Hardy (talk) 23:37, 12 November 2011 (UTC) ....I've started moving items from the section called "from the current list" into the sections above it, eliminating it from that bottom section when it appears in an organized section above. I included one of them in two sections; I think we should allow that when appropriate. I haven't limited it to topics that were already there. Michael Hardy (talk) 23:41, 12 November 2011 (UTC)

The user-space draft continues to evolve. Work on it if you're so inclined. Michael Hardy (talk) 03:51, 14 November 2011 (UTC)
Let's avoid renaming things to "Glossary..." The status of these articles seems uncertain in the light of some recent deletion discussions. Sławomir Biały (talk) 13:45, 14 November 2011 (UTC)

### moved

I've moved the user-space draft to List of trigonometry topics and merged the edit histories.

The new organized list makes the lists deficiencies clearer. So do something about those if you can and are so inclined. Michael Hardy (talk) 02:13, 15 November 2011 (UTC)

## Hermite's cotangent identity

Hermite's cotangent identity is a new article. Do what you can for it. Michael Hardy (talk) 02:22, 15 November 2011 (UTC)

## reorganisation of analysis categories

User Brad7777 has undertaken a massive reorganisation of categories related to mathematical analysis, see http://en.wikipedia.org/w/index.php?title=Special:Contributions&limit=500&target=Brad7777 This should probably be watched. Tkuvho (talk) 10:09, 11 November 2011 (UTC)

I just checked a random edit by Brad7777 here and found that it added the following characterisation of a Cauchy sequence: a sequence whose elements become arbitrarily close to each other as the sequence progresses Is this accurate? Tkuvho (talk) 10:14, 11 November 2011 (UTC)

It's been the first sentence of Cauchy sequence for a long time, but I wouldn't say it's accurate. Maybe "almost all of the elements of the sequence are arbitrarily close" would be more accurate. Sławomir Biały (talk) 12:04, 11 November 2011 (UTC)
That first sentence may be correct or not depending on how you interpret it. The second sentence is a better characterization. It says "... given any small positive distance, all but a finite number of elements of the sequence are less than that given distance from each other.". JRSpriggs (talk) 12:36, 11 November 2011 (UTC)
I think the slight inaccuracy is ok in that list. Sławomir Biały (talk) 13:28, 11 November 2011 (UTC)
I'm more worried about what [4] suggests. I think the entire List of real analysis topics (and any other articles that this user has edited substantially) should be reviewed for inaccuracies. Sławomir Biały (talk) 14:10, 11 November 2011 (UTC)
Yes would be great if List of real analysis topics was reviewed for inaccuracies and possibly improved (thats the only page i have edited substantially) also you may want to compare it to the accuracy of [5] before I made any edits. Brad7777 (talk) 18:51, 11 November 2011 (UTC)
I did not knowabout the sandbox at this time sorry Brad7777 (talk) 10:24, 17 November 2011 (UTC)

## Kummer's theorem

Kummer's theorem is a new article, still someone short, and stating but not proving the result. So far the only source cited is PlanetMath. Michael Hardy (talk) 18:20, 15 November 2011 (UTC)

## CALC

There's a dispute at Wikipedia:Mediation Cabal/Cases/13 November 2011/Usage share of operating systems that could probably use input from some people who know something about mathematics. Specifically, is identifying the median number out of ~10 numbers (all listed in the article) a sufficiently simple and routine operation as to be permitted under CALC (the {{supplement}} WP:NOTOR#Simple_calculations says that simple descriptive statistics are okay, but CALC itself is more concerned with arithmetical transformations), or is picking out the middle number such a mathematically challenging exercise that doing so is impermissible OR?

(The amount of heat makes me wonder whether someone believes that the median gives short shrift to the "right" operating system, i.e., if this is a meta-dispute for an underlying problem, especially since most people opposed to providing a median in the text appear to approve of providing basically the same information in a graphic image.) WhatamIdoing (talk) 16:38, 16 November 2011 (UTC)

It seems obvious that finding the median is a simple operation allowable under WP:CALC. The real dispute is whether that calculation is appropriate for that article, and that question apparently requires mediation or other outside intervention. Certainly more complex calculations are (appropriately) done frequently in Wikipedia articles. CRGreathouse (t | c) 16:56, 16 November 2011 (UTC)
It may seem obvious that finding a median is a simple operation, but in practice is is never a trivial question as to whether such an operation is appropriate on the data in any particular instance. That's the thrust of the argument against using it. If you think a statistical operation is simple, you don't understand it. --Matt Westwood 20:20, 16 November 2011 (UTC)
I do understand it quite well, at least as of the Dor-Zwick paper. Your objection is to the suitability of its selection, not to the calculation itself. I don't disagree, but that's not germane to the issue at hand. CRGreathouse (t | c) 14:13, 17 November 2011 (UTC)
I'd be happier taking hyperbolic cosines than medians in most circumstances where the question might arise, at least there wouldn't normally be a question why I was doing it and really they're both easy operations. The question might be to get the median of 3 businessmen, 5 hobos and 10 young out of work youngsters. Give me a catenary any day. Dmcq (talk) 15:57, 17 November 2011 (UTC)
Again, though, you're not arguing about the complexity of the operation but the suitability of the collection over which the median is taken. I agree that this is a legitimate issue, just like the issue of the inclusion of those disparate entities in the article itself. I just don't think it's an issue of calculation.
I'm intentionally avoiding the particulars of this dispute—of which so far I am ignorant—so as to focus entirely on the mathematical issue rather than the content dispute.
CRGreathouse (t | c) 16:05, 17 November 2011 (UTC)

## Conjugates in field extensions

At present there are two articles that seem to cover conjugates in field extensions, Conjugate (algebra) and Conjugate element (field theory). Could someone who is versed in the subject have a look to see if they can be merged? By the way, Conjugate elements currently redirects to Conjugacy class. Is this appropriate? Isheden (talk) 16:53, 17 November 2011 (UTC)

## Request for 3rd mathematical opinion at Talk:E (mathematical constant)

I and User:Cpiral disagree over a change he wants to make to the article E (mathematical constant): he's not accepting my arguments, I'm not accepting his, and we've reached an impasse. Can someone else take a look and see what they think. The thread starts here.--JohnBlackburnewordsdeeds 22:56, 17 November 2011 (UTC)

## Categorization

Brad7777 keeps creating and populating categories such as Category:Articles on branches of mathematical analysis. I believe this is inappropriate overcategorization (and an awkward name). Any ideas about this? Jakob.scholbach (talk) 12:37, 11 November 2011 (UTC)

Yes, another variation on Category:Branches of mathematical analysis which I nominated for deletion as we already have Category:Mathematical analysis (the discussion is here). This is the fourth thread on this page in a matter of days on Brad7777's changes to article categorization. The current structure has been stable for a long time and really shouldn't be so dramatically reorganised without first establishing consensus.--JohnBlackburnewordsdeeds 12:54, 11 November 2011 (UTC)
Well, we have a silly situation where Algebra isn't allowed to be in Category:Subdivisions of mathematics because it has to go instead into the subcategory Category:Algebra. And there are many other such oddities in the category system. Creating Category:Articles on areas of mathematics and such like is a clumsy solution, and it would be better to have some discussion and a consensus before making thousands of edits to recategorise articles. But I think it's a real issue that's worth addressing somehow. Jowa fan (talk) 13:00, 11 November 2011 (UTC) (edit conflict; agree that consensus should happen before reorganisation)
yes, Algebra should ideally be in Category:Subdivisions of mathematics (or field, branch etc, doesnt really matter) but it can't be because it is in Category:Algebra which is a subcategory of Category:Subdivisions of mathematics (hence i tried Category:Articles on areas of mathematics; I could have used branch/subdivision etc criticism on that is essential missing the point). Algebra is a X of mathematics (let X be a branch,field,subdivison whatever suits you). Therefore it should be in a category along the lines of Category:X of mathematics, such that this bit of information is displayed on the the article (for this example, it being Algebra.) Subcategories of Category:X of mathematics make more sense being of the form Category X of Y (with Y belonging to Category: X of mathematics). i.e a subcategory of "branches of mathematics" should be "branches of algebra". But having all categories of the form Category:Y in Category:Mathematics naturally puts them in the category Category:X of mathematics. This category should somehow contain the articles on "Y" without having to remove them by also containing subcategories Category:Y on the same categorical level as them; so that the articles on "branches of mathematics" can include the category "branches of mathematics" on there article page; instead of the loss of this information! This could also be done by creating a category like for example Category:Categories for X of mathematics which would be a subcategory of Category:X of mathematics.

Brad7777 (talk) 18:03, 11 November 2011 (UTC) I think it's clear that we should not have both Category:Articles on branches of mathematical analysis and Category:Branches of mathematical analysis. That's just silly. I don't have an opinion on whether Category:Branches of mathematical analysis should be kept. Sławomir Biały (talk) 13:35, 11 November 2011 (UTC)

My own view: we have Category:Subdivisions of mathematics (soon hopefully to be renamed) at the top level, but below that we have names for the subdivisions/areas/branches and should use those. So one is Category:Mathematical analysis, and within that there should be further sub categories such as as Category:Calculus, Category:Differential geometry and so on. Articles can of course be in multiple categories. Many articles are poorly categorised or need further categorisation.
But there is no need to prepend "Articles on" to any category as they are all articles. There is no need to prepend "branches of", except at the highest level, as all of these areas of mathematics are some branch or sub-branch. Doing so just adds an extra layer or two which makes the categories less useful and creates more work maintaining them. And given the above issues with 'articles on' and 'branches of' how it it decided when an article or category goes in one of these? If all should then existing categories should be renamed via CfD not new ones created.--JohnBlackburnewordsdeeds 13:50, 11 November 2011 (UTC)

There's now a new category Category:Articles on areas of mathematics. Do we need this, what's the difference between a subdivision and an area. Besides I notice subdivisions is being named fields of mathematics. Are we next going to get branches of mathematics? Dmcq (talk) 13:58, 11 November 2011 (UTC)

Thinks of the trunks of mathematics, the roots, the flowering, the seeds ;-) Dmcq (talk) 14:02, 11 November 2011 (UTC)

I don't see a point in having separate categories Category:Mathematics, Category:Subdivisions of mathematics, and Category:Articles on areas of mathematics. What extra useful meaning do the extra words convey? —David Eppstein (talk) 19:56, 11 November 2011 (UTC)

I think it is just the same as subdivisions. There is no need to distinguish between articles and categories in something like that. It should be deleted. Dmcq (talk) 12:05, 12 November 2011 (UTC)

### Yet more categories

The rather new (but good, in my opinion) Category:Theorems in calculus has been (seemingly needlessly) forked into Category:Theorems in differential calculus, Category:Theorems in integral calculus, Category:Theorems in multivariable calculus, Category:Theorems in vector calculus, with articles (apparently randomly) assigned to these subcategories. For instance, Fubini's theorem is in Category:Theorems in integral calculus but not Category:Theorems in multivariable calculus. There really aren't even that many theorems in calculus to necessitate any subcategories. Any opinions on restoring the original Category:Theorems in calculus and nuking the rest as overcategorization? Sławomir Biały (talk) 14:05, 11 November 2011 (UTC)

I'm for nuking all these new categories and restoring the original ones and structure: I don't see any reason for them and nothing wrong with what we had before this started.--JohnBlackburnewordsdeeds 14:18, 11 November 2011 (UTC)
lol not randomly assigned, if i did not add enough catgeories to an article someone else can update it, thats the idea of wikipedia! agree with the nuking for the reason that there are not many theorems in calculus, what do you suggest for example, Category:Theorems in real analysis]]? leave or remove? Brad7777 (talk) 17:25, 11 November 2011 (UTC)
Leave Category:Theorems in real analysis. Sławomir Biały (talk) 17:52, 11 November 2011 (UTC)

Many of Brad's edits seem perfectly ok to me, since many of our top level categories are over-populated. But I think some of the new categories are problematic. Also, I'm not quite sure what Brad was thinking with this edit. Nothing prevents a category from being in both a parent and child category, and in this case that seems appropriate. I think maybe Brad could use some guidance in what the purpose, aims, and structure of categories are (by someone who understands and appreciates them better than I do). Sławomir Biały (talk) 17:52, 11 November 2011 (UTC)

In general parent (or more generally ancestor) categories are removed when a child category is added. In the particular example you give, I agree with Brad.
CRGreathouse (t | c) 18:19, 11 November 2011 (UTC)
You agree that topology is not a subdivision of mathematics, and instead should only be available through the category geometry? That seems perverse to me, but again I don't really appreciate categories much. Sławomir Biały (talk) 18:29, 11 November 2011 (UTC)

There seems to be a little confusion on how categories work. WP:MATH needs to designate a few particularly important organizational categories that will contain ALL appropriate articles regardless of whether or no they are already in a subcategory. Any "divisions" or "fields of" category you come up with will certainly qualify. So therefore, Algebra can go under "fields" (or "divisions") and "Algebra" just fine. Greg Bard (talk) 20:24, 11 November 2011 (UTC)

Agree with that in as much as there should be designated organizational categories with the property that contain all appropriate articles regardless of if they are already in a subcategory; but the problem still arises with for example Mathematics which ideally should be in something along the lines of Category:Formal sciences. Brad7777 (talk) 21:49, 11 November 2011 (UTC)
A subcategory should be regarded as a subset of the category by reference. Anything in a subcategory should not also be in its parent category or any ancestor category, unless it is of especial importance to the ancestor category and it is not obvious that the subcategory is the place to look for it. JRSpriggs (talk) 08:26, 12 November 2011 (UTC)
Well said, and very clarifying. This seems to be consistent, mostly, with Brad's aims. I'm not sure how common my counterexample was, but it really seemed like the exception rather than the rule. Sławomir Biały (talk) 10:01, 12 November 2011 (UTC)
Apparent problems include; Category:Topology belonging to Category:Geometry and hence not Category:Subdivisions of mathematics, and similarly Category:Calculus belonging to Category:Mathematical analysis and hence not Category:Subdivisions of mathematics Brad7777 (talk) 10:10, 12 November 2011 (UTC)

Why on earth can't we follow the classification from Zentralblatt or the AMS? I though this encyclopaedia tried to base itself or verifiability. It would solve a lot of problems and conflict. If the area is also part of another thing like Game theory in Economics there will be a problem but at least we'll be able to easily describe the problem and hopefully solve it. Dmcq (talk) 12:29, 12 November 2011 (UTC)

To Brad7777: I think that Calculus is properly a subcategory of (Mathematical) Analysis. However, Geometry should be a subcategory of Topology rather than the other way around. In general, the more general (inclusive) or abstract category should be the parent of the more specific (narrower) or concrete category. JRSpriggs (talk) 02:46, 13 November 2011 (UTC)
The problem with that is someone who doesn't know what topology is might find it easily going down. In Mathematics Subject Classification for instance we have 'Geometry and Topology' as the main heading which makes things easier. Dmcq (talk) 23:23, 13 November 2011 (UTC)
Geometry a subcategory of topology? That makes no sense to me. One of them has been studied for thousands of years before the other one even existed. Were all those ancient Greeks really doing topology, if only they knew? I don't think so. I would be much happier having them as top level categories. Relatedly, I'm a little uncomfortable having Category:Order theory be a subcategory of Category:Combinatorics. There is plenty of combinatorial material in order theory, but also plenty not, for instance more algebraic approaches via lattice theory, articles like linear continuum which are closer to real analysis, or transfinite order theory which is more closely related to set theory and mathematical logic than it is to combinatorics. —David Eppstein (talk) 23:32, 13 November 2011 (UTC)
I agree with David. The ICM classification may be a nice guideline (since the AMS classification is way too detailed). Sasha (talk) 07:50, 14 November 2011 (UTC)
The ICM classification gets my vote as a basis for the categorization. Dmcq (talk) 14:16, 14 November 2011 (UTC)
If we do follow one of these standard maths categorizations, which I think is a good idea, could I make a special pleading for calculus to be included at the top rather than just as part of analysis. For people on the more applied side the stuff about special differential equations and solutions might not seem so closely connected. Dmcq (talk) 14:26, 14 November 2011 (UTC)
I'm not sure that any of the classification systems developed by research mathematicians are relevant to our purpose here, which is to develop an encyclopedia suitable for everyone. The case of calculus is a good point. While mathematicians might put it as a subset of analysis, that's not really useful from the point of view of developing a category system that works for all potential readers. Sławomir Biały (talk) 14:58, 14 November 2011 (UTC)
I don't agree with following the ICM Classification. With Category:Calculus for example, being placed in Category:Mathematical analysis (which is strictly right so should remain there) prevents it from also being directly placed in Category:Fields of mathematics. For non-mathematicians this may be confusing! Category:Fields of mathematics should be treated slightly different to most categories. There should be some sort of official notice saying that relevent categories can be placed in this category even if they belong to subcategories. I would go as far as saying relevent articles should be allowed in it also, (it could be a useful category). Brad7777 (talk) 17:28, 14 November 2011 (UTC)
I don't see why Calculus should be top-level instead of under Analysis. I don't see how this would hinder a layman reading Wikipedia. Such a layman doesn't delve through the categories, to find information on Calculus; he just goes to the Calculus article. Mgnbar (talk) 17:47, 14 November 2011 (UTC)
Again, I'm really not a great connoisseur of categories, but something doesn't seem quite right with the view that categories are only meant for a certain privileged class of readers/editors. Sławomir Biały (talk) 18:13, 14 November 2011 (UTC)
What do you think categories are in Wikipedia for? I believe they are there so people can browse related articles. I don't believe they are there to provide a Linnaeus type classification to Wikipedia which is the impression I get from that comment. Dmcq (talk) 18:16, 14 November 2011 (UTC)
Well, to be honest, I think categories exist to fuel the OCD impulses of certain editors; I see no value in them. But since we're going to have them, we should recognize that a categorization can itself be subjective and biased. Wikipedia:Category says that categories should be verifiable and maintain a neutral point of view. (I have wrestled with this issue in the past, in the preposterous "fields of mathematics" at Mathematics.) So I vote that the categorization of mathematics articles on Wikipedia adhere to some mixture of citable organizations (MSC, Zentrallblatt, etc.) Mgnbar (talk) 19:31, 14 November 2011 (UTC)
A research point of view (which is what the category systems you advocate convey) is different from a neutral point of view (which would at least attempt to meet the needs of our secondary school readers as well as the needs of research mathematicians). —David Eppstein (talk) 19:38, 14 November 2011 (UTC)
Okay, so tell me your citable classification. Now, to put that less snidely: Maybe some K-12 educational organizations, or governmental education agencies, have classifications that we can use? And by "use" I mean "reconcile with the research-focused classifications, and any other classifications we must consider". Mgnbar (talk) 19:53, 14 November 2011 (UTC)
While it is obviously desirable to have a citable model category system that suits our purposes, this seems unrealistic. Indeed, it is not an essential requirement of Wikipedia:Categorization. That only requires that membership of an individual article to an individual category should be citable (in principle). We don't need a citation for the system of categories as a whole. (Although we can obviously adopt certain features of other categorization system that are compatible with our aims.) Sławomir Biały (talk) 20:18, 14 November 2011 (UTC)

────────────────────────────────────────────────────────────────────────────────────────────────────

It just seems to me that there are two ways to resolve this: (A) argue about it for a long time, until most people lose interest and the few survivors write the policy, or (B) find some citable classifications, follow them, and be done with it. Approach (B) has the advantage of lessening the subjectivity and bias inherent in classifying such things. Approach (A) has the advantage that argument is usually more fun than diligent research. Mgnbar (talk) 20:45, 14 November 2011 (UTC)

The preceding edit of mine seems a bit hostile, upon re-reading. Sorry about that. But it does seem to me that using an established classification system, rather than inventing one from scratch, is more likely to lead to an acceptable categorization quickly. Mgnbar (talk) 22:02, 14 November 2011 (UTC)

Couple of points to ponder: 1) is there anything intrinsically bad (evil, undesirable, unfashionable, aesthetically displeasing, blasphemous, whatever) in having lots of little categories as opposed to a few big ones? Is there a problem with certain concepts being in more than one (or quite a lot of) category/ies? 2) Have we debated using MSC 2010 yet? — Preceding unsigned comment added by WestwoodMatt (talkcontribs) 22:28, 14 November 2011 (UTC)
Our categories are inclusive rather than exclusive so we can base them on some advanced math system for inclusivity and then just put in whgat they say are the branches in school as well. It doesn't matter too much if some things are at multiple levels if there is a reason for it, it is just a bad idea to duplicate thing in an upper level for no good reason. Dmcq (talk) 22:41, 14 November 2011 (UTC)

### Yet more and more categories

Now there is Category:History of geometry (as distinct from Category:History of mathematics). Considering that, until relatively recently, all mathematics was geometry, this seems like overcategorization to me. What are our thoughts about this? Should Brad stop creating new categories? Sławomir Biały (talk) 20:24, 14 November 2011 (UTC)

see Wikipedia:Categories for discussion/Log/2011 November 15 Brad7777 (talk) 10:27, 17 November 2011 (UTC)
Another near empty fork of a parent category that's already subcategorised is a sensible way. I think I've said so already but Brad7777 should stop his single handed efforts to reshape mathematics categories to fix problems only he is seeing. His changes so far should be undone as they have generated far more trouble than problems they've solved (the many discussions here and on his talk page, edit conflicts on many articles and at least three CfDs in a week), and any future such changes should be proposed here first.--JohnBlackburnewordsdeeds 20:40, 14 November 2011 (UTC)
Wikipedia:Categories for discussion seems more appropiate to discuss Category:History of geometry. "What are our thoughts about this?" I don't agree, i think it would be useful to add the many historical uses of geometry to this category for a start (lots of pages mention it). "Brad7777 should stop his single handed efforts to reshape mathematics categories to fix problems only he is seeing" sorry, but my eyes are all i have, (and i use 2 hands.) "His changes so far should be undone as they have generated far more trouble than problems they've solved" yes i seem to have sparked a couple of drama queens (unintentionally), but perhaps you should actually count the amount of edits i have done that are helpful. (funny enough, all of them i intended to be helpful.) Brad7777 (talk) 23:47, 14 November 2011 (UTC)
The reaction suggests that you probably should stop creating new categories, if nothing else. We don't need to diffuse every category into smaller ones. Sławomir Biały (talk) 23:55, 14 November 2011 (UTC)
Personally I choose to diffuse categories that have over 100 articles, and create new ones if i could put atleast 10 articles in it Brad7777 (talk) 00:07, 15 November 2011 (UTC)
Remember we're here to discuss the encyclopaedia and edits to it, not editors. No-one doubts your intentions but I recall having to undo hundreds of your edits only ten days ago. Others have been undone by other editors; still others have been raised here or at CfD so are awaiting the outcome of those discussions. And so on. Despite your intentions you seem largely to be creating work for other editors.--JohnBlackburnewordsdeeds 00:58, 15 November 2011 (UTC)
i think my first major change placing articles on subdivisions of mathematics in the category subdivisions of mathematics wasnt to create work for other editors, but to make the encyclopedia better for the majority of users (who are not editors and not mathematicians). It was your choice to undo my edits, without leaving it for Wikipedia:Categories for discussion.(+ there will always be an infinite amount of work for editors.) however, since then i have taken the reasoning into account (the parent-child category point as stated on Wikipedia:Categorization) and not made the same mistake, instead i have tried to work around it around it for the accessability of the general users of wikipedia, accepting decisions, and adapting as necessary. I seem to have upset a few elitist wikipedians with my enthusiam, who do not see the point in categories anyway except how it benefits themselves. "The central goal of the category system is to provide links to all Wikipedia articles in a hierarchy of categories which readers can browse, knowing essential, defining characteristics of a topic, and quickly find sets of articles on topics that are defined by those characteristics." I stand by that. Brad7777 (talk) 11:35, 15 November 2011 (UTC)
Indeed. Then how does removing superellipse from Category:Curves, and leaving it only in Category:Algebraic curves, help readers find that article? It's not even an algebraic curve (except in extremely special cases). It isn't enough just to remove ancestor categories and rely on the existing categorization being optimal. An article might be in a child category because it sometimes, but not always, has applications to that particular area. Removing parent categories will then make it harder, not easier, for someone to find it. I think you will need to use some editorial judgment in what categories are most appropriate (our most important rule here is WP:IAR). For me, it's the lack of evidence of this that I find most worrying. Sławomir Biały (talk) 12:58, 15 November 2011 (UTC)
I agree, but I have to follow Wikipedia:Categorization. Perhaps Category:Curves is a appropiate category for Allincluded (thanks for sharing this template). (also seems silly to be finding Category:spirals in Category:curves as not all spirals are curves!!). I realize the point about something also belonging to an ancestor category, but perhaps then the article should not actually be apart of the parent category, but instead just be a child of the ancestor category. In the case of Superellipse, if it is only apart of Category:Algebraic curves under certain conditions then either 1) it could belong to Category:Algebraic curves and a different child category of curves like for example Category:Curves in Cartesian coordinate systems (seems a temporary way out although that could be a useful category), or better in my opinion 2) stay in Category: Curves aswell but add the Allincluded template to curves, and make sure all its subcategories can only contain curves. That would make things easiest. Brad7777 (talk) 16:24, 15 November 2011 (UTC)
Category:spirals in Category:curves is entirely appropriate. The category system is not meant to be a strict taxonomy it more a navigation aid, there are holes all over the system which help navigation, generally following the principle of least astonishment. Yes you expect to find spirals included in the class of curves and yes you expect to find Spiral galaxy in spirals. Categorisation is not a transitive relation.--Salix (talk): 19:59, 15 November 2011 (UTC)
I was thinking more along the lines of Ulam spiral, but Spiral galaxy seems a good example that i hadnt even noticed. I just wonder about somebody navigating from (for example) Category:Geometric shapes (in order to look at the articles on them), once they enter a category like Category:Spirals how are they to distinguish between which are geomtric shapes and which are not? Shouldn't Category:Geometric shapes have {{all included}}, containing only the geometric shapes from its subcategories, for this purpose? Brad7777 (talk) 20:24, 15 November 2011 (UTC)

────────────────────────────────────────────────────────────────────────────────────────────────────Please bear in mind that no written rule should be followed blindly. Every set of rules is inadequate to describe the real world or how we should interact with it. So you must always exercise caution and use common sense. Make sure you understand what is going on before you act. Instead of making massive changes in categories, you should make a separate judgement in each case after you have experience using the articles and categories in question. JRSpriggs (talk) 20:33, 15 November 2011 (UTC)

### Category:Italian mathematicians

The category Category:Italian mathematicians (and categories like Category:Xth-century Italian people for numerous values of X) have been entirely decimated by Brad7777 . Someone will definitely need to fix this. The {{allincluded}} template seems relevant. There is, after all, no guarantee that someone browsing Italian mathematicians will wish to do it by year. We can keep the intersection categories, but we should restore the original parent categories too. (This is a textbook example of non-diffusing categories.) Sławomir Biały (talk) 13:30, 15 November 2011 (UTC)

I agree, {{allincluded}} should be added.Brad7777 (talk) 16:32, 15 November 2011 (UTC)
List of Italian mathematicians perhaps this should be worked on. Brad7777 (talk) 18:37, 15 November 2011 (UTC)
Same issue with Category:Theoretical physicists has, for some reason, been entirely split into theoretical physicists by nationality. Considering that we already have physicists by nationality, this seems unnecessary for someone wishing to browse physicists by nationality, and unhelpful for someone wishing to browse theoretical physicists. I think all of these edits should be undone. Should we start a CFD on Category:Theoretical physicists by nationality? Sławomir Biały (talk) 13:36, 15 November 2011 (UTC)
CfD here: Wikipedia:Categories_for_discussion/Log/2011_November_15#Category:Theoretical_physicists_by_nationality. Sławomir Biały (talk) 13:40, 15 November 2011 (UTC)

### ...and more

This morning, someone created Category:Mathematics of ancient history and started moving stuff out of Category:History of mathematics. Not only do I find this new category unnecessary, but the title is a bit dubious. Also, apparently the only way to get to these articles from Category:History of mathematics is by navigating to it through Category:Mathematics by era, and then selecting a relevant subcategory before you ever even see an article! Enough is enough! Someone undo all of Brad's edits and block him. Sławomir Biały (talk) 14:22, 16 November 2011 (UTC)

Consider that the following is necessary to get to any articles about ancient Greek mathematics: Category:History of mathematicsCategory:Mathematics by eraCategory:Mathematics of ancient historyCategory:Greek mathematics (4 levels deep). That seems too long to walk. Sławomir Biały (talk) 14:37, 16 November 2011 (UTC)
or Category:Mathematics and cultureCategory:Mathematics by cultureCategory:Greek mathematics (3 levels deep)

Brad7777 (talk) 17:19, 16 November 2011 (UTC)

or Category:History of mathematicsCategory:Mathematics by cultureCategory:Greek mathematics (3 levels deep) Brad7777 (talk) 17:24, 16 November 2011 (UTC)

I believe that at this point a user-conduct RFC is fully warranted. That would be the next step to take, before a block, I think, if he won't voluntarily stop his disruption on his own. —David Eppstein (talk) 17:46, 16 November 2011 (UTC)

In partial defence of Brad I would say that quite a lot of cleanup of in the category system is needed, yesterday morning Category:Geometry had 220 articles, clearly too many. I manged to move about 30 of those to more appropriate places. Someone else, I presume Brad, has also managed to drop the number to more respectable 131. So there some good work going on there. If your doing cleanup of the system it will mean some movement and creation of categories - I created Category:Contact geometry and Category:Spherical geometry as there seemed to be nowhere appropriate to put some articles.
I don't agree with all of Brads creations, a few too many levels of depth for my tastes, yet for the most part it falls within Wikipedia:BOLD, revert, discuss cycle. The problems is that bold actions in the category system take a lot of work to revert and discussions seem to happen here or on CFD. Brads also new and enthusiastic and going to fast for the rest of the community. Perhaps whats needed is a page like /Mathematics category reorganisation where changes could be proposed before causing too many problems and actually gaining some Wikipedia:Consensus before changes.--Salix (talk): 18:14, 16 November 2011 (UTC)
I think /Mathematics category reorganisation seems like a very good idea to propose changes; to gain Wikipedia:Consensus without flooding this section in WT:WPM. I have added the following to Category:History of mathematics to allow faster browsing of catgeories:
• "Use this tree to browse the categories more quickly. Click the + symbol by each category to expand it."

let me know what you think Brad7777 (talk) 10:11, 17 November 2011 (UTC)

### And more...

Category:Theorems in fourier analysis (with incorrect capitalization), and articles removed from Category:Theorems in analysis and Category:Fourier analysis. Sławomir Biały (talk) 20:54, 16 November 2011 (UTC)

Thanks for pointing that out, I added a speedy rename request.

I thought it would make sense to merge the categories (hence remove them from the parents) as Category:Theorems in fourier analysis is in both Category:Fourier analysis and Category:Theorems in analysis. I see you have removed most of the theorems from Category:Theorems in fourier analysis with the note "Obtain consensus before creating any more categories.", leaving only Bochner's theorem and Convolution theorem in it.

No, they are theorems in harmonic analysis, of which Fourier transforms are a part.--LutzL (talk) 12:27, 17 November 2011 (UTC)
Parseval's theorem, Carleson's theorem, Balian–Low theorem and Poisson summation formula are definitely apart of Fourier analysis. I believe the rest of them are apart of Fourier analysis. They may also be used in the more general study of harmonic analysis, but that does not stop them from also being used in Fourier analysis! Some of these theorems would also be a part of complex analysis and functional analysis, its not like they can only be a part of one or the other. Perhaps you did not know that Fourier transforms are also a part of Fourier analysis? Brad7777 (talk) 17:44, 19 November 2011 (UTC)

## Reliability of MathPages.com

I've found several math articles (e.g. Dedekind number, 1729 (number), History of calculus, Tetrahedron) using MathPages.com as a reference. The consensus here seems to be that although the site is more than suitable for the External links section, it does not meet the criteria for a reliable source. There seems to have been no input from this project in the discussion though and the site seems authoritative, so I'm wondering if an overly literal interpretation of WP:V was being applied. In any case, I'd like to add a discussion of the site to Wikipedia:WikiProject Mathematics/Reference resources and create a template for linking to the site since there are links in over a hundred articles. I'm also wondering if a Wikipedia article should be created for the site, I'm not finding many independent sources for it however.--RDBury (talk) 02:33, 17 November 2011 (UTC)

At least in the Dedekind number case, it's being used only to source a simple calculation that could probably have gone unsourced. That seems unobjectionable to me (but I think I was the one to put it there, so maybe I'm not neutral in this case). —David Eppstein (talk) 03:41, 17 November 2011 (UTC)
Interesting; I've added a link to a personal links page; but what is MathPages? Is it a one-man project (by e.g. Kevin Brown, who seemingly wrote all these books), or is there an organised group, or a wiki, or e.g. a math department behind it? JoergenB (talk) 21:23, 17 November 2011 (UTC)
I assume it's just him. CRGreathouse (t | c) 21:52, 17 November 2011 (UTC)
Update: I went ahead and created template:MathPages and added it to five articles. It's pretty basic so if someone with template skills wants to add some bells or a couple of whistles I'd appreciate it.--RDBury (talk) 11:02, 18 November 2011 (UTC)

MathPages is a one man project (I think). And although many of the essays are excellent and on the ball, they are the opinion of just one man. As such, care needs to be taken when using it as a source. In particular, on several subjective issues the essays aren't entirely neutral. One particular issue is that Kevin doesn't cite any sources. This carries the risk that he is using wikipedia as a source for some of his statements. Consequently, referencing Mathpages may lead to circular sourcing without it being detected. Still the pages tend to give very good expositions of basic facts.TR 12:02, 18 November 2011 (UTC)

The issue of the reliability of MathPages has come up several times uring FAC discussions. In the end these tend to be resolved by replacing the cites with more sources which pass WP:V more clearly.TR 12:07, 18 November 2011 (UTC)

## Kolmogorov structure function

Could someone in the field verify the references? The article is so badly written than I can't match statements to references, and some of the references are copied by name from another article. I've tried to clean up the article, but the editor who has repurposed the article is adding references faster than I can check them. Other problems include:

• Improper Capitalization In Section Headings
• Use of level 1 headings. (My latest edit moved all the level 1 headings to level 2, but I have no idea whether some of the level 2 headings should be level 3.)
• Absolutely no < ref> tags; all "references" are raw URLs
• Reference to a paper presented at a conference, but not published (!)
• Multiple section headings named "Main property", include two in a row.

I thought this was near enough to one of the fields (coding theory and information theory) in which I am expert than I could understand it, but the editor objects to my changes, so perhaps it isn't.

Also I would like someone to note that the 6 tags I've added in the heading are minimal; I could probably find 4 or 5 more which are relevant. — Arthur Rubin (talk) 00:10, 19 November 2011 (UTC)

There are other issues. For example, the abstract of the 2004 article "Kolmogorov's structure function and model selection" says:
In 1974, Kolmogorov proposed a nonprobabilistic approach to statistics and model selection. Let data be finite binary strings and models be finite sets of binary strings. Consider model classes consisting of models of given maximal (Kolmogorov) complexity. The "structure function" of the given data expresses the relation between the complexity level constraint on a model class and the least log-cardinality of a model in the class containing the data. We show that the structure function determines all stochastic properties of the data: for every constrained model class it determines the individual best fitting model in the class irrespective of whether the "true" model is in the model class considered or not. In this setting, this happens with certainty, rather than with high probability as is in the classical case. We precisely quantify the goodness-of-fit of an individual model with respect to individual data. We show that-within the obvious constraints-every graph is realized by the structure function of some data. We determine the (un)computability properties of the various functions contemplated and of the "algorithmic minimal sufficient statistic.".
There are a few sentences borrowed verbatim into the page. I do not have access to the rest of the article, if someone has -- please check the rest. Sasha (talk) 01:36, 19 November 2011 (UTC)
After looking at the entire '04 article, perhaps my remark is unfair (the page is not copy-paste, except for a few scattered sentences). Sasha (talk) 01:43, 19 November 2011 (UTC)
If ever there was a case for WP:TNT... And references to a book with no page number have to be treated as worthless, since they're not truly verifiable. -- 203.171.196.201 (talk) 11:02, 19 November 2011 (UTC)
I note that the article has been prodded. Sławomir Biały (talk) 13:16, 19 November 2011 (UTC)

Does Fermat's Last Theorem in fiction fall into the scope of this WikiProject? If so, {{Maths rating}} should perhaps be added to the talk page and the article be added to List of mathematics articles. Now I am aware the article is not directly about a mathematical topic, but rather a list of appearances of a mathematical topic in works of fiction. However, the same could be said about an article such as Gödel Prize, which is also not directly about a mathematical topic. So does this list fall into the scope of this WikiProject? Toshio Yamaguchi (talk) 16:13, 19 November 2011 (UTC)

## Two new AfDs

I have nominated the following articles for deletion that are in the scope of this project: Semiotics of the structure and Ashay Dharwadker. Sławomir Biały (talk) 14:07, 20 November 2011 (UTC)

## Random matrix

In spite of efforts by many editors (incl. myself), the random matrix article is still in poor shape. Help is welcome. Sasha (talk) 16:33, 20 November 2011 (UTC)

## Third opinion needed at Discrete Poisson equation

Slffea has been very intent on removing content from Discrete Poisson equation, and I have been reverting him (three times now). I have tried to engage the editor at User talk:Slffea, but without much avail. Please comment at Talk:Discrete Poisson equation. Thanks, Sławomir Biały (talk) 22:37, 20 November 2011 (UTC)

Might be worth also looking at this diff: http://en.wikipedia.org/w/index.php?title=Modal_analysis_using_FEM&diff=prev&oldid=461622024 --Joel B. Lewis (talk) 01:20, 21 November 2011 (UTC)

## "Stellated" Octahedron: Another Regular Polyhedron?!

An anonymous editor (that's me) and some other guys are having an intellectual debate over whether the stellated octahedron, stella octangula, small stellated octahedron, and great octahedron are regular polyhedra. (Just like Gadhafi, Q(w)addafi, and Kaddafi are all dead.) This article really needs some special attention from the crew. See the talk page for more info. 20:05, 19 November 2011 (UTC)

There are multiple definitions: "yes" by some, "no" by others. It is very unfortunate that regular polyhedron seems to use multiple definitions interchangeably. -- 202.124.73.78 (talk) 09:37, 21 November 2011 (UTC)
It's been resolved, thanks to Tom Ruen and some other ppl. Because of all this, the length of the talk page has more than tripled, and the article itself has been upgraded from Stub-class to Start-class. But the game's not over. We should create a list of incomplete polyhedron-related articles. — The Doctahedron, 68.173.113.106 (talk) 22:53, 22 November 2011 (UTC)
Lists (with titles like the one you give, in main article space) are not for that purpose: they're for helping readers find articles to read, not for helping editors find articles to edit. And what's wrong with using Category:Polyhedron stubs for this purpose? —David Eppstein (talk) 22:55, 22 November 2011 (UTC)

## India Education Program

The Wikipedia:India Education Program is a program where college students are asked to work on WP pages as a course assignments; there are probably others but this one has appeared in my radar twice now. I'm conflicted about this kind of thing. On one hand it might be a great way of getting some improvements done on some important articles that are otherwise being neglected. On the other hand it seems like getting volunteers from WP to evaluate students' assignments is taking away work from a starving TA somewhere; as a former starving TA myself I'm a bit sensitive about that kind of thing. In any case, a disproportionate number of the assigned articles fall under this project and many of the students are new to WP, so there may be an uptick in amateurish, if well-intentioned edits to the assigned articles and it might be a a good idea to keep an eye on them. Lists of assigned articles can be found here and the math related articles are mainly in the section 'College Of Engineering, Pune'.--RDBury (talk) 17:44, 20 November 2011 (UTC)

There was a special report in Signpost a couple of weeks ago that gives more background on the issues and challenges arising from this program. Gandalf61 (talk)
Thanks, very informative and it sounds like others were having the similar experiences with the IEP edits as I was. I'm not clear on where things stand now though; the report makes it sound like the project has ended and people are just going through the wreckage to figure out what went wrong. But new articles are still being tagged with the project's banner (see [6]) so I assumed there will be a bunch more edits coming from the project.--RDBury (talk) 11:03, 21 November 2011 (UTC)
I think the student work has finished now. The project banner tagging is probably just fixing missing banners. The work now is checking articles for copyvios and making sure they make some sense.--Salix (talk): 12:09, 21 November 2011 (UTC)
Ok, false alarm then. I've already added about 10 of the courses to my watchlist but it won't hurt to leaven them there for a while. Thanks.--RDBury (talk) 21:09, 21 November 2011 (UTC)

## Hilbert transform

I have nominated this as a good article, and thought I would mention it here. Thenub314 (talk) 07:07, 22 November 2011 (UTC)

I'm planning to add some review comments, although I've never reviewed an article for GA before (I've been on the other end of a GA review a few times, though). I would appreciate some help from someone who knows the process better. There are some issues that need to be addressed in the article. I hope that someone has the time and energy to address these as the review process is underway. Also, more readers and comments are welcome as well. Sławomir Biały (talk) 13:24, 22 November 2011 (UTC)

## Opinion requested at Cauchy product

See Talk:Cauchy_product#Summations regarding the "Cauchy product" of finite sequences. Thanks. Jowa fan (talk) 23:16, 22 November 2011 (UTC)

## file deletion proposal

Cumulative distribution function

I have proposed deletion of this file: Wikipedia:Files_for_deletion/2011_November_22#File:TnormCDF.png The vertical axis says "probability density", and that is false, and cannot be edited. The values of a cumulative probability distribution function are probabilities, not probability densities. The values of a probability density function are probability densities. This is obvsiouly not a probability density function. Michael Hardy (talk) 05:54, 22 November 2011 (UTC)

Michael Hardy, given that the R source code is right there on the page, it was pretty easy to edit. Other methods of changing might have included asking me (the content creator) to change it. I don't really get why this is a big deal. 018 (talk) 21:01, 26 November 2011 (UTC)

## Specific article on Transform

I think we should create and article Transform (mathematics). We used to have one, but in 2009 it was changed by Christophre (talk · contribs) to a redirect to Integral transform. Unless anyone has a good reason not to, I will bring back this version of the article. Yaris678 (talk) 13:07, 24 November 2011 (UTC)

I wouldn't hold up that earlier version as a shining example of what Transform (mathematics) could be. It is entirely sourced to a single textbook of what looks like an introduction to integral transforms. I think that it is probably better to rewrite the article from scratch than to go back to an earlier flawed version of the article that is already subsumed by the significantly better integral transform article. Sławomir Biały (talk) 13:13, 24 November 2011 (UTC)
Perhaps the article should redirect to List of transforms instead.--RDBury (talk) 05:24, 25 November 2011 (UTC)
I think that ultimately we want a specific article, but I suppose one way to work towards that is to redirect to the list and then start expanding the lead for the list. If it becomes too big for an list lead then we can move it in to the specific article and cut the list lead down to size. Yaris678 (talk) 14:55, 25 November 2011 (UTC)

## Real analysis and List of real analysis topics

The article Real analysis does not seem very good at all, even though it is arguably is the most fundamental mathematical discipline towards grasping higher leveled mathematics.

• It contains no history section, with no mention of its role in the sense of Calculus or other developments around it.
• The scope is limited to:
• Order properties of the real numbers
• Relation to complex analysis
• and the Key concepts section is basically a list

In the see also section, there is a link to List of real analysis topics which would be of more interest to anybody looking at real analysis for key concepts, but this also need working on. I have made aload of edits (some are possibly innacurate, sorry). But i think this page would be more appealable if instead it was changed to Glossary of real analysis, similar to for example Glossary of field theory or Glossary of category theory. Especially because of the importance of this discipline. should it be worked on/renamed or even reverted?? Brad7777 (talk) 22:42, 12 November 2011 (UTC)

I agree the article needs work, but I don't think renaming it to "Glossary..." is the right way to go. Thenub314 (talk) 02:51, 13 November 2011 (UTC)
I noticed some topics (some articles on convexity for example) losing "general" tags like "mathematical analysis" in favor of very specific tags (like "convex analysis"). I would be surprised if this slew of 50 similar changes by Brad7777 in the last 40 minutes did more good than harm. I have not paid close attention to the situation though. I noticed the long discussion above, but I couldn't tell if a mandate arose or not. Does this really have to continue? Rschwieb (talk) 18:51, 17 November 2011 (UTC)
"Each article should be placed in all of the most specific categories to which it logically belongs. This means that if a page belongs to a subcategory of C (or a subcategory of a subcategory of C, and so on) then it is not normally placed directly into C." see Wikipedia:Categorization Are you suggesting for example, articles on convexity should also be in Category:Mathematical analysis? Why is this? Brad7777 (talk) 17:57, 19 November 2011 (UTC)
This agenda of tucking things neatly away in very specific categories where nobody will think to look for them is fine if everyone's cool with it. I'm just doublechecking if anyone is still aware of it. It's not as if categories are important for finding articles, so I don't care very much. Rschwieb (talk) 04:06, 20 November 2011 (UTC)
How would you make them more useful for finding articles? Brad7777 (talk) 17:19, 20 November 2011 (UTC)
I think what user Rschwieb is getting at is the fact that excessive categorisation can make articles difficult to find. Take, for example, Category:Calculus. You will look in vain for intermediate value theorem there. To find the latter, you have to go to Category:theorems in calculus. Some people may find this to be an inconvenience rather than a convenience. Tkuvho (talk) 17:42, 20 November 2011 (UTC)
It is immediatley obvious that intermediate value theorem would be found in Category:theorems in calculus for anybody looking for it from Category:Calculus. Some people may find this extra step inconvenient but most people would know this is more efficient then having every single article to do with calculus, directly in Category:Calculus. Looking at...

... I think it could be improved so that it is easier to find relevant articles. For example I think there should be

Category:Applications of calculus (containing relevant articles from applied mathematics and in other areas of mathematics) in Category:Calculus.

The subcategories should be more predictable. Brad7777 (talk) 17:10, 27 November 2011 (UTC)

Putting Calculus of variations into Applications of calculus does not seem a recipe for predictability. Sławomir Biały (talk) 21:03, 27 November 2011 (UTC)

## New category for theorems and conjectures about prime numbers

I created a new category at Category:Theorems and conjectures about prime numbers which I want to fill with the entries from Category:Conjectures about prime numbers and with proven theorems. Another user reminded me of the fact that this creates a redundancy with Category:Conjectures about prime numbers. Category:Theorems about prime numbers does not exist. I do not think it is really necessary to create seperate categories for theorems and conjectures, but I might be mistaken with this thought. Input and feedback welcome. Thanks. Toshio Yamaguchi (talk) 16:13, 22 November 2011 (UTC)

Just create a cat for theorems, then put both cats in your theorems and conjectures category. Or just crosslink them. Dcoetzee 17:30, 22 November 2011 (UTC)
I think you could have just proposed the renaming of Category:Conjectures about prime numbers to Category:Theorems and conjectures about prime numbers. However I have added Category:Conjectures about prime numbers to Category:Theorems and conjectures about prime numbers instead of Category:Prime numbers and I have also placed Category:Theorems and conjectures about prime numbers into Category:Prime numbers, (to go with this flow).

Having a look at...

...you to have to go through Category:Theorems and conjectures about prime numbers first to get to Category:Conjectures about prime numbers. To me, it suggests either i) Category:Theorems about prime numbers does need to be created, in which case I would then think Category:Theorems and conjectures about prime numbers should be scrapped or ii) Category:Conjectures about prime numbers should be scrapped Brad7777 (talk) 15:50, 27 November 2011 (UTC)

I've WP:BOLDly created and populated Category:Theorems about prime numbers and emptied Category:Theorems and conjectures about prime numbers. CRGreathouse (t | c) 08:23, 28 November 2011 (UTC)

## Category for prime numbers

I noticed that Category:Prime numbers contains conjectures, theorems and other information about prime numbers in general. I would like to create a category for individual prime numbers, such as 2 (number), 3 (number), 5 (number) etc. So should this category perhaps be renamed to make that name free for a category containing individual primes? Toshio Yamaguchi (talk) 18:26, 25 November 2011 (UTC)

I do not think that that is a good idea. We already have List of prime numbers. And many prime numbers are represented by redirects to articles which cover many numbers, some prime and some not. So this would not work for them. JRSpriggs (talk) 03:15, 26 November 2011 (UTC)
Note Category:2 (number) already exists, I guess this could be added to Category:Prime numbers, (it is a child category of Category:Integers) although i think as it only contains 3 articles, it probably should be deleted. For the articles 2 (number), 3 (number), 5 (number) etc, i would add Category:Prime numbers to them. There is no point in creating for example Category:Individual prime numbers to place them in. However I think alot of the current articles in Category:Prime numbers could and should be diffused into its current subcategories. To JRSpriggs, Category:Classes of prime numbers‎ already exists and that works fine. Brad7777 (talk) 16:18, 27 November 2011 (UTC)
Oppose categorization of integers by property. Most articles are about small integers with many properties and none of them are defining characteristics. A lot of similar categories were deleted at Wikipedia:Categories for deletion/Log/2005 April 14#More number categories. Category:Prime numbers starts with List of prime numbers so it's easy to get from the category to a longer list without holes for primes without articles. PrimeHunter (talk) 16:58, 27 November 2011 (UTC)

## Categories for discussion nomination of Category:Perfect numbers

Category:Perfect numbers, which is under the purview of this WikiProject, has been nominated for deletion. If you would like to participate in the discussion, you are invited to add your comments at the category's entry on the Categories for discussion page. Thank you. — Arthur Rubin (talk) 17:30, 27 November 2011 (UTC)

See #Category for prime numbers above for how I found it; the individual perfect numbers probably shouldn't be in the category; it had been deleted in 2005 in the CfD mentioned there, and the remaining articles in the category number 3, and the category is unnecessary for navigation between them. — Arthur Rubin (talk) 17:32, 27 November 2011 (UTC)

## List of mathematics problems named after places

List of mathematics problems named after places is no longer a userspace draft. It needs work. In particular:

• Some of the items have comments somewhat like dictionary-style definitions; others don't. The ones that don't should get something.

Michael Hardy (talk) 23:59, 26 November 2011 (UTC)

It needs a better title, since many of the items in the list are not problems. —Mark Dominus (talk) 17:22, 27 November 2011 (UTC)
How about List of mathematics topics named after places? Ozob (talk) 17:37, 27 November 2011 (UTC)

Also see Lists of things named after places, a new article. Michael Hardy (talk) 18:00, 28 November 2011 (UTC)

## Truncated subtraction

There is an operation, "truncated subtraction", sometimes considered in recursion theory and other contexts, which is a sort of subtraction on natural numbers, except that if the answer would have been negative, the result is 0 instead. That is:

0 ∸ x = 0
Sx ∸ 0 = Sx
Sx ∸ Sy = x ∸ y

Where "S" denotes the successor operation.

We don't have an article on truncated subtraction, and I was not able to find it under another name. Do we have it under another name? —Mark Dominus (talk) 19:05, 27 November 2011 (UTC)

The article on primitive recursive functions calls it limited subtraction, but we don't have an article on it under that name either. —Mark Dominus (talk) 19:13, 27 November 2011 (UTC)

primitive recursive function also calls it proper subtraction. —Mark Dominus (talk) 19:35, 27 November 2011 (UTC)

Related: This is a special case of saturation arithmetic. I'd have no problem with having a short article on truncated subtraction, redirecting those various other terms to it, and linking it to saturation arithmetic. Dcoetzee 00:26, 28 November 2011 (UTC)
It is indeed, but I think it needs separate treatment from saturated subtraction, which is studied in very different contexts and for different reasons. I will start an article shortly; the only reason I didn't already was that I couldn't quite believe that there was an elementary topic that was not already covered in Wikipedia. —Mark Dominus (talk) 02:51, 28 November 2011 (UTC)
It hardly requires a separate article I'd have thought. Perhaps a title redirecting to an appropriate article with it in I'd have though. It has hardly any separate interest from recursion theory. Dmcq (talk) 11:55, 28 November 2011 (UTC)
I'll do some research and see what I can find out. Based on very cursory investigation, I think it seems to satisfy the WP:GNG. —Mark Dominus (talk) 15:53, 28 November 2011 (UTC)

## Basic concepts of/introduction to ...

There is an AfD on Basic concepts of quantum mechanics that raises some important questions for many technical articles:

1. Should there be separate articles for explanations at different knowledge levels?
2. If so, how many levels, and how can readers be guided to the level that is appropriate for them? RockMagnetist (talk) 00:29, 29 November 2011 (UTC)

## Devs discussing MathJax

It looks like the developers are discussing MathJax on the dev mailing list [7] and things are looking promising. Main issues seems to be suport for mobile browsers. Brions added a note at User talk:Nageh#MathJax integration into stock MediaWiki.--Salix (talk): 07:52, 29 November 2011 (UTC)

That's very good. What happened to the MathML support anyone know? Firefox supports MathML but sticking on the experimental MathML support in my preferences doesn't seem to make any difference. Dmcq (talk) 12:33, 29 November 2011 (UTC)
The issue is the math program that Mediawiki has been using. It produces ugly HTML, as everyone knows, which is why we have ways to force image display when needed. The MathML output was never really implemented, it apparently can do even less with MathML than it can with HTML. That's why enabling MathML doesn't seem to do anything. The program is also written in Objective Caml, an obscure language, so none of the core developers particularly wants to work on it.
Back in July, Brion Vibber, one of the lead devs, proposed reducing the options to just "all images" and "source only" [8]. This week, he seems to have found time to work on it again [9].
I suggested MathJax in July, and someone else suggested it yesterday, and Brion is looking into that. So it is possible we will have three options: MathJax, images, and source. I think that would be an improvement over the current situation, and ideally it would make MathJax available to the majority of readers. — Carl (CBM · talk) 12:52, 29 November 2011 (UTC)
I wish people would stop calling it "ugly HTML"; it simply isn't. Let's compare a simple formula as TeX HTML and MathJax would render it.
Taken 2ω1 = 2ω = c (from here), which TeX would output as:
<span class="texhtml">2<sup><i>ω</i><sub>1</sub></sup> = 2<sup><i>ω</i></sup> = c</span>

Now compare this with MathJax' output, which spews out this:
Pretty isn't it? If TeX HTML is ugly, then what the hell would you call this? Don't get me wrong; I'm not dissing MathJax, I would love to see it in action, and maybe even have it's output generated server-side (no dependenciy on JavaScript!), but simple HTML output is not ugly. Edokter (talk) — 13:28, 29 November 2011 (UTC)
Obviously, people were not referring to the HTML source when stating the HTML output is ugly. Also, it is not the point of MathJax to support server-side rendering, because MathJax allows scalable rendering via fonts rather than pre-rendered images. If you would like to see more "pretty" HTML source set your MathJax rendering to MathML. I don't consider MathML/XML rendering very "pretty" either, but that is entirely subjective. Nageh (talk) 13:45, 29 November 2011 (UTC)
When I said server-side, I ment the server should generate the HMTL, not images, so it would still be scalable, but not burden the browser with having to render the HTML itself (which is pretty slow). The resulting HTML can be cached just like the TeX images are now. Edokter (talk) — 14:04, 29 November 2011 (UTC)
It isn't the HTML itself that is pretty or ugly, it's the actual display. For example browsers tend to be very bad at subscript and superscript positioning, in my experience. And the amount of work it takes to format nontrivial things in wikitext/HTML is painful Compare:
n−1
k−1
(2
g
)
....... ${\displaystyle \textstyle \sum _{k-1}^{n-1}{\binom {2}{g}}}$
which has source code
{{math|{{larger|∑}}{{sup sub|n−1|k−1}}{{larger|(}}{{sup sub|2|g}}{{larger|)}}}} ....... $\textstyle\sum^{n-1}_{k-1}\binom{2}{g}$
On my browser the sigma and parentheses on the left are still too small, and the super/subscript position on the sigma isn't right because of that. Also, the current software often renders things as images even if HTML is trivial. For example ${\displaystyle A\approx B}$ does not know about the &asymp; entity name for ≈, in the "HTML if simple" mode. So we often have to force images to make display within a single paragraph consistent, or we have to hack the wiki source to try to make the HTML display in a decent way. — Carl (CBM · talk) 13:49, 29 November 2011 (UTC)
Things like ≈ should be easily fixed. Your example extends slightly beyond 'simple' though, so it may not be the best example. Edokter (talk) — 14:04, 29 November 2011 (UTC)
The &asymp; entity was in HTML 4.0 in 1998. The deeper trouble is that wherever the line is drawn, there will be paragraphs that straddle it, so half the math gets shown as images while the other half gets shown as HTML. That's an inherent problem with "HTML if simple" and "HTML if possible". The ugly HTML rendering is an artifact of the poor text rendering engines on browsers, which apart from MathML are not intended to deal with complicated symbol positioning. The main benefit of MathJax over MathML is that MathJax runs on many browsers, including IE 6 and up [10], while MathML support is much more limited. — Carl (CBM · talk) 14:09, 29 November 2011 (UTC)

The main issue, beside mobile browsers, will be getting the fallback correct so that users who don't have Javascript will still see images rather than LaTeX source. Other sites like MathOverflow don't have this problem because they don't fall back to images. But the devs are committed to making Mediawiki work acceptably well without Javascript. — Carl (CBM · talk) 12:55, 29 November 2011 (UTC)

'without Javascript' needs to be an option for all users, not just mobile browsers. On a formula-heavy page MathJax is too slow relative to both HTML and images. The latter, although they probably take as long to generate server-side, benefit from being cached on the server and client so except for the editor that adds the formulae they load quickly to instantly. So MathJax should run server-side, perhaps outputting images as SVG and higher quality (anti-aliased) PNG. Users can then choose between these and JavaScript run in the browser.--JohnBlackburnewordsdeeds 13:54, 29 November 2011 (UTC)
I didn't say it right. The developers have a goal that all users can browse the non-mobile site without Javascript enabled.
MathJax is designed to run client side - it simply cannot be run on the server, any more than Twinkle could be run on the server. And it does not generate any images. MathJax directly displays the mathematics using fonts. For most people it uses web fonts, but in extreme cases it falls back on image fonts; in every case it composes the math locally, symbol by symbol, rather than making a "monolithic" image of the entire formula. The reason that it runs locally is that, apart from those that support MathML, browsers do not have the ability to render things nicely themselves, so some other local software is needed to do the actual math rendering.
What the devs are talking about now are giving users three options: show the raw source code, use prerendered monolithic images from the server, or use MathJax locally. — Carl (CBM · talk) 14:00, 29 November 2011 (UTC)
A certainly sensible approach to me. Re: "On a formula-heavy page MathJax is too slow": It is actually quite fast when you select the MathML rendering. Unfortunately, MathML support is rather insufficient in browsers, including Firefox. (Maybe people should vote on Firefox Bugzilla to resolve some long-outstanding MathML bugs, such as the missing support for negative spaces, required for composing symbols.) Nageh (talk) 14:09, 29 November 2011 (UTC)
Server-side MathJax (generating the HTML) is not impossible, but it would require porting it to PHP. I think this option deserves some brainstorming on feasability. Edokter (talk) — 14:13, 29 November 2011 (UTC)
Yes, it could be rewritten in PHP, but then I wouldn't describe it as MathJax anymore - it would be a separate program at that point. Beyond the initial investment of effort and the ongoing maintenance effort (someone would have to watch for MathJax updates and port them all over to the new system), there are also several MathJax features that seem to require local processing. These include the font selection logic (web fonts or image fonts) and the features in the menu that appears when you right-click MathJax formatted math. I use Mathjax sites all the time and I never find the math rendering time to be particularly onerous. — Carl (CBM · talk) 14:21, 29 November 2011 (UTC)
Doing the rendering serverside so its just the html output has been discussed on the MathJax list and its generally been frowned upon. There are lots of issues, I seem to recall things like browser dependancy in the generated code and loosing all the options you get in the right click context menu, which allow things like rescaling all math output.
Good typesetting of maths is a tricky problem, simple solutions like using <sup> just don't work for anything complex where there is fine spacing to get right. --Salix (talk): 17:10, 29 November 2011 (UTC)
If MathJax can output MathML on the server then it could do that with fewer problems about browser support than html and that could be used for browsers which have MathML support but don't have JavaScript enabled. I believe the support of MathML is good enough to justify doing that and it would be a fairly cheap option to implement I'd have thought. There is no need for everything to be perfect and it would get better with more things like Wikipedia using it. Dmcq (talk) 17:39, 29 November 2011 (UTC)
My opinion is that we need to focus on the system that will be used by default for non-logged-in readers. Our MathML article seems to think that MathML support is not very widespread. The main benefit of MathJax is that it works with enough browsers that, in principle, it could be used as the default system. That would be a major improvement over the current state. On the other hand, a system that is only useful for a handful of editors who opt in seems less important. If the devs are willing to put some of their time towards fixing the math system, I'd rather see them aim for the largest impact. — Carl (CBM · talk) 17:54, 29 November 2011 (UTC)
AFAIK Firefox has got the most complete MathML support of all browsers. Yet, it would be inadequate for general usage on Wikipedia because of crucial missing features like the negative spaces I mentioned above (e.g., TeX "\not=" results in "/=" rather than "≠"). There are other issues with MathML I don't recall right now. Nageh (talk) 19:18, 29 November 2011 (UTC)
MathML is part of HTML5 and support is either in or being put into all the main browsers. By the time any of this would be done the support will be there, and if Wikipedia were using it any bugs would be fairly quickly fixed. Dmcq (talk) 23:09, 29 November 2011 (UTC)
Strictly speaking, MathML isn't a part of HTML5 (it has its own spec, for one thing), but HTML5 does allow MathML to be written inline like SVG and encoded PNGs. CRGreathouse (t | c) 23:45, 29 November 2011 (UTC)

### The mathJax feature request on bugzilla

Here's the feature request I put in in almost two months ago:

https://bugzilla.wikimedia.org/show_bug.cgi?id=31406

I'm glad to hear it's moving along. Michael Hardy (talk) 05:15, 30 November 2011 (UTC)