# Wikipedia talk:WikiProject Mathematics/Archive 60

 Archive 55 ← Archive 58 Archive 59 Archive 60 Archive 61 Archive 62 → Archive 65

## Semigroup: independent views requested

It would be helpful to have some independent views at Talk:Semigroup#Section_on_group_of_fractions on the validity and relevance of some material on the group of fractions of a semigroup. Thanks. Quotient group (talk) 20:40, 29 March 2010 (UTC)

## Featured picture candidates part 5

File:Helicatenoid.gif, with some small modifications, was promoted to Featured Picture. There aren't any current nominations for math, though there is a statistics one that is active.--RDBury (talk) 22:29, 29 March 2010 (UTC)

## Beppo-Levi space

The new article titled Beppo-Levi space could use some work. In particular, it's a near-orphan; probably some other articles should link to it. Michael Hardy (talk) 03:15, 30 March 2010 (UTC)

## Laplacian

Does our project have any preference on whether the Laplacian should be written as Δ or ∇2? I have noticed a trend in the past few months to replacing Δ with ∇2 in many articles, and I can't say that I approve. Sławomir Biały (talk) 17:22, 28 March 2010 (UTC)

I haven't done any of such changes but personally I prefer ∇2 for its economy of symbolism, why do you dislike it? Dmcq (talk) 18:06, 28 March 2010 (UTC)
I also prefer ∇2, though I don't feel strongly about it. The 2 emphasizes that the operator is second-order, and Δ is already used to represent the change in the value of a variable. It would be nice if someone could do a survey of some relevant textbooks to see which one is more common. Jim (talk) 18:30, 28 March 2010 (UTC)
I prefer Δ. I'm used to seeing the Laplacian generalized to differential forms, where it takes the form dd* + d*d. (This leads to Hodge theory, of course.) While there are gradients and divergences in that formula, it isn't a gradient followed by a divergence, so I'm reluctant to embrace a notation which suggests that it is. Ozob (talk) 19:50, 28 March 2010 (UTC)
This is not a question of preference, our notation should follow the accepted use. Sławomir, what are the articles where this has happened? Certainly, in PDEs and differential geometry, Δ is standard and ∇2 is rare at best. Besides the reasons mentioned by Ozob, the "usual" Laplacian has a square root, but it's the Dirac operator, not ∇. In vector analysis and some areas of physics the convention may be the opposite. By the way, Δ is both older and uses fewer symbols than ∇2, so it is in fact, more "economical". Arcfrk (talk) 22:39, 28 March 2010 (UTC)
The ones I can find off the top of my head are at partial differential equation, Laplace operator, Zakharov system, and Hartree equation. Obviously, we have a lot of articles that use one convention or the other, but what I am mostly reacting to here is the (apparently) undiscussed migration from one convention to the other. Sławomir Biały (talk) 22:50, 28 March 2010 (UTC)
Yes I go with the convention of not changing the convention that's used in an article if there isn't any good reason to do so. The person who went to the bother of writing an article should have some perks! Dmcq (talk) 12:49, 29 March 2010 (UTC)
To Ozob: Borrowing from Klein–Gordon equation#Gravitational interaction, I think that
${\displaystyle \Delta \psi ={\frac {1}{\sqrt {-g}}}\partial _{\mu }(g^{\mu \nu }{\sqrt {-g}}\partial _{\nu }\psi )=g^{\mu \nu }\partial _{\mu }\partial _{\nu }\psi -g^{\mu \nu }\Gamma ^{\sigma }{}_{\mu \nu }\partial _{\sigma }\psi \,.}$
Is that what you mean? JRSpriggs (talk) 13:01, 30 March 2010 (UTC)
No. See Laplace–Beltrami_operator#Laplace–de Rham operator. This Laplacian acts on differential forms, not functions, and it's div grad plus grad div. For functions, the grad div term drops out, giving the equation you wrote above. I believe that de Rham, Differentiable manifolds, Griffiths and Harris, Principles of Algebraic Geometry, and Demailly, Complex Analytic and Differential Geometry each discuss this in detail. Ozob (talk) 22:58, 30 March 2010 (UTC)

## Semigroup: independent views requested

It would be helpful to have some independent views at Talk:Semigroup#Section_on_group_of_fractions on the validity and relevance of some material on the group of fractions of a semigroup. Thanks. Quotient group (talk) 20:40, 29 March 2010 (UTC)

## Featured picture candidates part 5

File:Helicatenoid.gif, with some small modifications, was promoted to Featured Picture. There aren't any current nominations for math, though there is a statistics one that is active.--RDBury (talk) 22:29, 29 March 2010 (UTC)

## Beppo-Levi space

The new article titled Beppo-Levi space could use some work. In particular, it's a near-orphan; probably some other articles should link to it. Michael Hardy (talk) 03:15, 30 March 2010 (UTC)

## Tagging number articles

User:Notorious4life has recently bulk-tagged almost every number article from 2 (number) to 200 (number) with {{template:examplefarm}}, which says "This article may contain excessive, poor or irrelevant examples. " and adds the articles to Category:Articles with too many examples. I have invited the editor to come here to discuss their concerns about these articles. Gandalf61 (talk) 11:19, 30 March 2010 (UTC)

• Actually, the mathematics examples within those articles are great and should be the focal point in the number articles. However, the number articles go off a terrible tangent of useless examples that are only included because they contain the number, such as "The electric battery-powered Lightning GT sports car, with a full charge, has a range of about 188 miles" being included in the 188 (number) article. Most of the examples listed in the number articles are absolutely terrible. I have brought this issue up before at Wikipedia_talk:WikiProject_Numbers#Too_many_examples on the Numbers WikiProject, which is where my problems rest. At first, the problems were met with agreement by the active projects members (of which I am not involved), but only two of the articles up to the number 200 have been fixed. The Number WikiProject has a vague and unenforced criteria for what constitutes a good example, and I intend to readdress the problems with them. In addition to the lack of inclusion criteria and pathetic examples, every one of those articles is unreferenced, poorly structured, and in need of much work. — №tǒŖïøŭş4lĭfė 11:50, 30 March 2010 (UTC)
If you're referring to 8 and 9, the removal of retired jersey numbers and specific use of the number in sports did not have consensus, although policing the "notable people with jersey number n" sections to limit them is a pain, and the split had no consensus whatsoever. I quite agree with removing numbers with units unless notable in the popular culture (the entries in the former subdisambiguation 55 mph probably deserve notice).
And I would think Wikipedia talk:WikiProject Numbers would be the appropriate place to discuss this. — Arthur Rubin (talk) 12:36, 30 March 2010 (UTC)
not that it really matters, as long as pointers are there. — Arthur Rubin (talk) 12:37, 30 March 2010 (UTC)
Yes, I only thought of Wikipedia talk:WikiProject Numbers after I had already posted here. So I put a pointer there instead. Gandalf61 (talk) 13:30, 30 March 2010 (UTC)
• The tags seem to me inappropriate (the items in question are not "examples"). User:Notorious4life seems to have a fundamental problem with the way WP:WikiProject Numbers set up number articles, which isn't shared by the rest of that project. Each number article typically contains mathematical properties of the number, and a list of (non-mathematical) topics where the number occurs (because most people use numbers in a non-mathematical way, and may be looking up a number because they really want a pointer to some other article). Let's take 60 (number) as an example: it has a list of mathematical properties, uses of "60" in science (e.g. buckminsterfullerene C60 has 60 atoms), discussion of base-60 number systems, uses of 60 in religion, uses in sport, and a miscellaneous list. One or two items might be trimmed, but I'm happy with the article as is. I would agree with removing numbers with units only in the cases where these are approximations (i.e. I would retain 60 as a speed limit, but remove 60 where it is an approximation to e.g. 60.120978). I don't think any large-scale removal should occur, certainly not without broad consensus. -- Radagast3 (talk) 21:57, 30 March 2010 (UTC)

## The final stages of the collapse of civilization...

What is this world coming to? I reverted this edit. Has anyone seen this happen before? Should we put in commented-out warnings in the hundreds of articles that use this locution? Michael Hardy (talk) 00:49, 31 March 2010 (UTC)

The more complete the encyclopedia gets, the higher the ratio of silly edits to reasonable edits. Sooner or later we will have to slowly move towards something like the Citizendium model to keep most of the silliness out. But I guess we still have a few years before it gets really pressing. Hans Adler 01:00, 31 March 2010 (UTC)
I disagree with this comment. Wikipedia was drowning in silliness six or seven years ago. Most of that isn't there any more. Michael Hardy (talk) 11:18, 31 March 2010 (UTC)
Using "an Euler xxx" is more common on Wikipedia than "a Euler xxx" by 227 to 76. Furthermore, it's correct, since Euler is pronounced "oiler." "Corrections" which make things wrong are sadly common. -- Radagast3 (talk) 01:02, 31 March 2010 (UTC)
The edit summary for this says it was via AWB; maybe that tool needs an exceptions table to keep track of things like "Euler". — Carl (CBM · talk) 01:12, 31 March 2010 (UTC)
Good idea. -- Radagast3 (talk) 02:37, 31 March 2010 (UTC)
Speaking of strange edits, here are two of them that replaced "work in (subject)" with "work CONCERNING (subject)" and "(verb) in (year)" with "(verb) DURING (year)": [1], [2]. I didn't want to revert because at least some of the corrections seemed good, yet many were downright silly. Arcfrk (talk) 03:36, 31 March 2010 (UTC)
Go right ahead and revert silly edits! -- Radagast3 (talk) 04:10, 31 March 2010 (UTC)
We may also need to put a comment like that into Probability theory, so that grammar geniuses stop "fixing" die → dice. And on the subject of bots, AWB and other automated tools: they frequently function as weapons of mass destruction. I can mention removals of white space and replacements of html based symbols with equivalent characters: &ge; with ≥ (both changes are invisible and hence useless for the readers, but very annoying for the actual editors who put them there), as well as "spelling fixes" like these: [3], [4] and "clean-ups" like this: [5] (there was a reason why only "riemannian" and "symplectic" were underlined, wouldn't you think so?).
Is there a way to make people sign a damage control agreement before being allowed to use these tools to make the perpetrators at least AWARE of the consequences? Arcfrk (talk) 03:59, 31 March 2010 (UTC)
We may need an exception list in some of these tools. -- Radagast3 (talk) 04:10, 31 March 2010 (UTC)
AWB Typo rule list has been updated for Euler and Euler's. Rjwilmsi 07:28, 31 March 2010 (UTC)

## C rating status

I updated the rating criteria so that the C rating is official. I also updated the maths rating tag so Category:C-Class mathematics articles will populate itself. VeblenBot still needs to be updated but Carl said that won't be hard.

I think issues to consider for the future are the eventual fate of the B-Plus rating, and more generally whether we should maintain separate criteria for WPM ratings. As far as I know this is the only project (other than Statistics which uses ours) that uses it's own rating criteria; the others just link to Wikipedia:Version 1.0 Editorial Team/Assessment. My thinking is that if we are to have are own rating criteria then it should be because there is a consensus here that ours are better, as least for math articles. The current WP 1.0 criteria are (imo) confusing and inconsistent, so coming up with better criteria should be possible, but achieving consensus may prove problematic.--RDBury (talk) 10:26, 31 March 2010 (UTC)

## Superscript slash subscript

Part of Wikipedia:Manual of Style (mathematics) tells us to only write fractions in styles like 1/2 and ${\displaystyle {\tfrac {1}{2}}}$ in mathematics articles. But there was an attempt to change it today to explicitly condone 12 style as well, a style that EmilJ and I have been fighting in some recent changes on Riemann hypothesis. See ongoing discussion at Wikipedia talk:Manual of Style (mathematics)#Fractions. —David Eppstein (talk) 22:29, 31 March 2010 (UTC)

## Discrete Math Category

Why do we have a Category:Discrete mathematics ? Surely this is just as absurd as having a Category:Continuous mathematics containing things like euclidean geometry, sine function, real numbers, Set theory, manifold, Continuous symmetry. And information theory which is currently in the discrete mathematics category could just as easily be in a continuous category. I propose deleting this category. Bethnim (talk) 12:11, 23 March 2010 (UTC)

I suppose there is a point to the effect that combinatorics is a research-oriented classification, while discrete mathematics is more of a pedagogically-oriented classification. Category:Subdivisions of mathematics is the over-category of both, and defines itself as "Fields and other subdivisions of mathematics". Which doesn't rule out such a subcategory, if it is useful for navigation. Charles Matthews (talk) 12:53, 23 March 2010 (UTC)
The collection of things that are included in the Discrete math category is kind of random, though. Maybe it should only have a few categories in it, with the articles all in more specific categories? —David Eppstein (talk) 15:43, 23 March 2010 (UTC)
Apart from things like DIMACS and Discrete Mathematics (journal), that seems a reasonable suggestion. Charles Matthews (talk) 16:18, 23 March 2010 (UTC)
Ok, I cleaned out the category and added a few other categories as subcategories of this one. —David Eppstein (talk) 22:49, 23 March 2010 (UTC)
Nice work. Though I'm not entirely convinced number theory should be in this category. RobHar (talk) 23:38, 23 March 2010 (UTC)
I wasn't sure about that either. I suspect a paper in number theory might not be considered in scope for the journal Discrete Mathematics, for instance. Feel free to take it out if you think it would be better not listed there. But on the other hand, I think some amount of elementary number theoretic sequences, such as the Fibonacci numbers and Catalan numbers, would typically be included in a discrete math curriculum, so if number theory as a whole is not listed then maybe parts of it should be? I tried looking at the one book on my office shelves with "discrete mathematics" as its title (an old one by Ross and Wright) and it includes recurrences, but not really anything else in that direction. On the other hand it includes more linear algebra and abstract algebra than I would have expected. —David Eppstein (talk) 00:06, 24 March 2010 (UTC)
Cool. I think I'll remove number theory, but at least throw in elementary number theory (I might reorganize the number theory category as well). RobHar (talk) 02:11, 24 March 2010 (UTC)
PS: As it stands, "integer sequences" is in "combinatorics" which is in "discrete mathematics", so the numbers you mentioned somewhat inherit the discrete category via their appearance in "integer sequences". RobHar (talk) 02:15, 24 March 2010 (UTC)
I think many who replied did not understand the intention of Bethnim. This is not about whether discrete mathematics is much different from combinatorics (actually, I thought they were synonymous until I read their WP articles) or whether this or that topic should be included. Looking at Special:Contributions/Bethnim for the last day(s), I see what seems an effort to single-handedly wipe the notion of Discrete Mathematics off the Wikipedia (see also the section #Theoretical computer science: The Myths of a Discrete-Continuous Divide and a Pure-Applied Divide above). Sure there are notions that are straddle the discrete/continuous boundary, and not all computers are digital (though quite a few are), but this does not make the discrete/continuous distinction any more invalid than pure/applied mathematics or even mathematics/computer science. Any subdivision of mathematics is debatable, but that does not mean that one may not make a tentative classification. I don't see what's wrong with saying combinatorics is a field of discrete mathematics (the adjective discrete was removed from the lede, as well as the category Discrete Mathematics), even if continuous techniques may at some places be used. I think some moderation would be in place. Marc van Leeuwen (talk) 15:49, 24 March 2010 (UTC)
Marc you are over-reacting. I proposed deleting the category, but if it is deemed a useful category then so be it. As for deleting the adjective discrete from the lede of the combinatorics article, I didn't delete it - I just moved it further along the sentence. It just seemed weird to start of by saying "X is a branch of discrete mathematics" - this is tantamount to saying that all maths is continuous unless stated otherwise. Also every branch of mathematics contains branches of discrete mathematics - it's just that combinatorics is more associated with discrete than others. I was going to insert the word mainly which would give: "branch of mathematics concerning the study of mainly finite or countable discrete structures" but that didn't seem very grammatical. You mention moderation, and that is precisely what I've been doing. Previously the Discrete mathematics article said that "discrete mathematics is the language of theoretical computer science" - a sentence in definite need of moderation. The whole Discrete mathematics article gave the impression that theoretical computer science was only about discrete stuff, as did the main mathematics article. All the main areas of maths consider both discrete and continuous concepts but that's not the impression that the Discrete mathematics article used to give. Bethnim (talk) 21:00, 24 March 2010 (UTC)
It is interesting though why does the term "Discrete mathematics" exist. Is it just a historical accident - because after Newton for the next few centuries continuous mathematics was the dominant theme.
Well, I am definitely convinced of Bethnim's good intentions, but some edits seem a bit overly zealous, and push a particular point of view (that no exclusively discrete fields of mathematics exist). I agree that it is absurd to associate discrete mathematics exclusively with computer science, or to associate computer science exclusively with discrete mathematics. But there are a lot of mathematical and computer science problems that are genuinely discrete (which cannot be studied involving continuous variation of parameters), and I think it is somewhat biased to suggest that every area has discrete as well as continuous aspects; at some point the Discrete mathematics page looked a bit like it was trying to argue at all kinds of places that the notion is pointless. I've removed a claim about continuous graphs that seemed mainly there to provide such an argument, because there was nothing that could help the reader understand what was meant. I'm not saying no meaning can be given to "continuous graph", maybe it is something like the graph on R2 defined by points being at distance 1? Marc van Leeuwen (talk) 12:50, 25 March 2010 (UTC)
I think almost any object can be continuized e.g. continuous graphs (Novel architectures for P2P applications: the continuous-discrete approach). Even continuous proof, infinite proof trees with continuous branching. If a discrete object doesn't have a continuous version it is just because noone has gotten round to continuifying it yet. Bethnim (talk) 18:10, 25 March 2010 (UTC)
My take on this is that "Discrete mathematics" is a term which one will encounter during the course of studies. To ask Wikipedia what it is, and not get an answer because there is a philosophical standpoint that it is not meaningful or helpful would be disappointing.--Matt Westwood 16:29, 3 April 2010 (UTC)
Who said anything about not getting an answer? The answer is given in the discrete mathematics article. The lead paragraph says that discrete mathematics studies discrete objects i.e. that do not vary smoothly like real numbers but have distinct separate values like integers. Further down, the article lists the areas of mathematics and describes which aspects of these subjects are discrete and which aspects are not. None of these areas is only concerned with discrete objects so it is important to describe which aspects of these subjects are discrete and which aspects are not. Bethnim (talk) 19:40, 3 April 2010 (UTC)
Sorry, this was in response to the initial posting: "I propose deleting this category." I am coming down on the side of "anti" deleting this category. I misunderstood the thrust of the argument. But all said and done, the discrete mathematics article is all very well, but all it can do is give a general description of the topic, and give a list with short descriptions of its applicability. Okay as far as it goes but it's necessary to have a category in which one can browse further. And I believe it is advantageous to have such a category. --Matt Westwood 22:22, 3 April 2010 (UTC) —Preceding unsigned comment added by WestwoodMatt (talkcontribs)
To inject my 2c worth, I'm very unhappy with some of the recent edits to Discrete mathematics, which seem to me not to accurately reflect the nature of the subject. I certainly do NOT support deleting the category. -- Radagast3 (talk) 03:08, 4 April 2010 (UTC)

## Cousins?

Our articles on the physicist John Baez and the singer Joan Baez link to each other, each mentioning that they are cousins.

Bernard Osgood Koopman's mother was a cousin of William Fogg Osgood; both were mathematicians. Should they similarly mention and link to each other? Michael Hardy (talk) 21:47, 1 April 2010 (UTC)

If you can source it, and mentioning it doesn't unbalance the article in the direction of too much trivia and too little professional accomplishments, why not? For another example, see Greg Kuperberg and his parents, or for that matter the Bernoulli family. —David Eppstein (talk) 22:56, 1 April 2010 (UTC)

I thought I'd seen it in one of the articles linked to externally. But now I can't find it. But I will eventually, unless someone beats me to it. Michael Hardy (talk) 03:06, 3 April 2010 (UTC)

.... PS: One might also notice that the author of the obituary of William Fogg Osgood that is linked to externally was Bernard Osgood Koopman. Michael Hardy (talk) 03:07, 3 April 2010 (UTC)
• A source is found here. John says, "My uncle Albert Baez showed me lasers, holographs and lots of physics experiments when I was a kid. Though mainly famous for being the father of the folk singer Joan Baez, he is a physicist who started out in optics, ...". Jwesley78 04:04, 3 April 2010 (UTC) Whoops. Sorry, nevermind. :-( I'll now look for an answer to the actual question. (I should learn to read whole comments, and not simply skim!) Jwesley78 04:48, 3 April 2010 (UTC)
You're answering the wrong question. When I wrote that I thought I'd seen it in one of those externally linked articles, I was referring to the two people that this thread is about, not to the Baez's. Michael Hardy (talk) 04:30, 3 April 2010 (UTC)

## favourite occurrence of logarithms

Guys, what's your favourite application/occurrence of logarithms? I'm just working on that article, which does have a few ones, but the more I read on the more crazy things I find, so I thought I should ask for broader input. Jakob.scholbach (talk) 18:20, 25 March 2010 (UTC)

The logarithm on time scales ( Time scale calculus ) Bethnim (talk) 18:32, 25 March 2010 (UTC)
Depending on how much you want to add it might be worth considering splitting the article or outsource parts to "main articles" such as "application of logarithms". At least with 61Kb already the article is getting rather big.--Kmhkmh (talk) 19:11, 25 March 2010 (UTC)
Definitely decibels. Also, the Richter scale. My favorite mathematical application is as the inverse map to the universal cover exp : CC×. The logarithmic derivative is good, but possibly too specialized. Ozob (talk) 23:52, 25 March 2010 (UTC)
Mine's that the bivector that describes the rotation between unit vectors m to n is the very neat log(mn), when calculated in geometric algebra: details at Plane of rotation#Bivectors. It's the generalisation of the log of a complex number including its geometric properties to higher dimensions.--JohnBlackburnewordsdeeds 00:17, 26 March 2010 (UTC)

A few of my favorites:

• Binary search, variants such as Fibonacci search, and their analysis.
• The use of logarithms of complex numbers to transform plane symmetries that involve rotation and scaling (complex multiplication) into symmetries that are purely translational (complex addition).
• Log-log plots.
• The partial sums of the harmonic series (these come up quite frequently in the analysis of probabilistic algorithms such as quicksort, if you're looking for applications that are less purely mathematical).

David Eppstein (talk) 00:36, 26 March 2010 (UTC)

Just to add my exp(log 2)¢, to me the slide rule (already mentioned and depicted) and continuous compounding came to mind, although in both cases one could argue they are as much about the exponential function as about the logarithm. Marc van Leeuwen (talk) 09:03, 4 April 2010 (UTC)

## Navbox in Mathematics

### Old Navbox

This is the current Navbox:

Updated 16:44, 2 April 2010 (UTC)

### Suggestion

Today I propose the following navbox to replace the present one (whose organizational principle escapes me). It has only two lines --- the first for the general public and the second for those with special interests in mathematics. Your comments are welcome. Thanks! Kiefer.Wolfowitz (talk) 18:56, 1 April 2010 (UTC)

I never understand who uses these or what they use them for, so I don't understand on what basis they are to be evaluated. —Dominus (talk) 19:11, 1 April 2010 (UTC)
I'm still not sure what the point of this is. It's still missing a number of elementary topics I mentioned here, but adding them and then others to balance would make it much larger. And more generally readers can and should be able to use inline wikilinks to find most related topics, and the one mathematics that should be in the lede of a maths article to find all others.--JohnBlackburnewordsdeeds 19:27, 1 April 2010 (UTC)

I think both "Navboxes" are fairly useless. I'd prefer that neither one be in the article. Paul August 19:30, 1 April 2010 (UTC)

I agree that the seem somewhat useless. However, if they must be used, then the inclusion and exclusion of topics should be based on some external source. I would suggest starting from the list of branches as defined by "The Princeton Companion to Mathematics", ISBN 9780691118802, rather than some other arbitrary classification. Plastikspork ―Œ(talk) 19:32, 1 April 2010 (UTC)
Expressions of bewilderment are unhelpful---either make suggestions to improve the navbox or argue against having it the first place.
Other editors commented that the current navbox is mixed between advanced and basic topics, and so is confusing. This navbox splits the topics into 2 lines.
The basic section follows the courses that a student would see in basic education and the start of university.
In the more advanced section, the selection of topics roughly follows the MSC2000 hierarchy, with topology moved below and applied mathematics moved after statistics (so that probability and mathematical statistics are neighbors) --- it is certainly not arbitrary. The MSC2010 system was developed also with the German surveying journal, ZBM perhaps, and has been developed over 40 years or so. It is a better guide than the Princeton companion. Kiefer.Wolfowitz (talk) 19:45, 1 April 2010 (UTC)
I am sorry that you found my comment "unhelpful". I cannot make helpful suggestions to improve the navbox when I do not understand its purpose. Nor do I want to argue against having it in the first place, since I do not understand its purpose. I suggest that since many people seem to be puzzled about the same thing, that it would be a good use of your time to try to explain what purpose it is intended to serve and why you think the new one serves that purpose better than the old one. —Dominus (talk) 19:56, 1 April 2010 (UTC)
Wikipedia has a discussion of navboxes and pros/cons.Kiefer.Wolfowitz (talk) 20:04, 1 April 2010 (UTC)
Thanks: My template has statistics for the basic line and mathematical statistics for the advanced line. Yes, I can imagine a neighbor of S. D. Chatterjii (known for his work on martingales in Banach spaces) wanting to know something about the combinatorics of topologies on n-points, about which Chatterjii has also written! More seriously, statistical research on weak convergence of laws (Billingsley, Dudley, etc.) and measurable selections (Hoffman-Jörgensen, etc.) use general topology and descriptive set theory. Kiefer.Wolfowitz (talk) 15:40, 2 April 2010 (UTC)
If you are unwilling to abandon the project, but are still looking for comments, then my comment is: By the criteria you have indicated, I see no particular advantage to either of the navboxes over the other. —Dominus (talk) 20:20, 1 April 2010 (UTC)

I prefer not to split them into advanced/elementary. Doing so requires a certain degree of judgment, so if we do it here people will just keep popping up to complain that we made the wrong choice. Moreover, splitting the topics into elementary and advanced overemphasizes the difference between them. It can be read either as "that basic stuff isn't really math" or "that advanced stuff is too hard, stick with the easier stuff", both of which are unfortunately too common as attitudes. Keeping all the areas together emphasizes the unity more, which I like. So those are two reasons to keep everything in a single list. — Carl (CBM · talk) 20:03, 1 April 2010 (UTC)

Conclusion? What I'm hearing is: The editors dislike the proposed navbox, but don't want to discuss changing the old navbox, which many dislike. Thus the old navbox stands (despites its lack of organization and topics, e.g. "game theory" and "information theory"). Kiefer.Wolfowitz (talk) 13:58, 2 April 2010 (UTC)
I would suggest using the IMU list of fields [6] as a basis for choosing fields for the navbox. I just dislike splitting them into "easy" and "hard". — Carl (CBM · talk) 14:18, 2 April 2010 (UTC)
Regarding IMU: The IMU listing is a definite improvement over the "Princeton Companion" but it was put up for the ICM, and so reflects the interests of the program committee and Fields winners, etc. about what is "hot". Isn't the Mathematical Reviews/ZM Mathematics Subject Classification System (MSC2000) more established, having been developed through decades and having a lot of care in its revision (e.g. asking for comments from professional societies, etc.)? Kiefer.Wolfowitz (talk) 15:33, 2 April 2010 (UTC)
I think that the existing template should be split into two templates. I believe that the basic line would be useful for many articles (e.g. for beginning students in high school or in community college, thinking about courses). I agree that a more advanced template may not be so useful, but I believe that the current one needs revision or deletion. Kiefer.Wolfowitz (talk) 15:36, 2 April 2010 (UTC)
The edit history of the template shows there is a bit of a conflict over whether to include High School topics. I think wikipedia should recognise that topics like trigonometry are a major topic from the perspective of those who have studied school-level maths. Perhaps there should be a separate template called "Common School Mathematics topics" and another one called "Research classification of Main Areas of Mathematics". Bethnim (talk) 14:31, 2 April 2010 (UTC)
I agree with editor Bethnim.Kiefer.Wolfowitz (talk) 15:47, 2 April 2010 (UTC)

I have finally thought of a use for these navboxes, so I feel I'm now in a position to comment on them. It seems to me that these navboxes would go fairly well on articles about major fields of mathematics: Algebra, analysis, geometry, etc. Those articles might also contain navboxes about their specific areas (e.g., algebra might have elementary algebra, linear algebra, abstract algebra, etc.) but the point of this navbox is that it's for someone who wants a taste of all the mathematics that's out there—for instance, the bright 14-year old who knows he or she likes math but has no experience and no assistance. In the past, such kids might have been lucky enough to stumble upon World of Mathematics or perhaps Mathematics: Its content, meaning and methods; ideally the navbox would guide such kids just as the tables of contents of those books guided their readers.

With that in mind, I think that neither the MSC nor the IMU listing is well-suited to the task. They are both classifications of research mathematics. They don't include trigonometry or elementary algebra or axiomatic Euclidean geometry; nobody does research in these anymore. The Princeton Companion to Mathematics's list of branches of mathematics (in Part IV) is, I think, somewhat bizarre and even less suited to our task. I think a good solution might be to take all the fields in the IMU listing and put them together with a list of historical research fields of mathematics (surely trigonometry and elementary algebra were at one time active fields of research). Perhaps there's a good historical work that does that for us. At Talk:List of important publications in mathematics, User:Lesnail mentioned Grattan-Guiness's Landmark Writings in Western Mathematics 1640-1940. Maybe that would be a good start. Ozob (talk) 04:12, 5 April 2010 (UTC)

I had thought of that use case, but it seemed to me that such a user might be better-served if those articles had a simple link to Areas of mathematics instead, so I did not mention it. —Dominus (talk) 13:24, 5 April 2010 (UTC)

## Candidates for translations

Hello. Lately I've creating a few new articles by translating articles from other language editions of Wikipedia (mostly German.) Does anyone know of a list of math articles that English Wikipedia don't have but other editions do? -- Taku (talk) 22:31, 4 April 2010 (UTC)

Usually the English Wikipedia is the most complete. If you can translate from English to German, perhaps you might translate Veblen function. I tried to give them a version from which I had stripped out the words and put most of that material into the formulas, but it seems to have been deleted. They had a red-link to de:Veblen-Hierarchie from their biography of Oswald Veblen. JRSpriggs (talk) 03:20, 5 April 2010 (UTC)
There are a few biographical articles that are in other language editions, but are lacking here (or, like Robert Fricke, are stubs in the English edition). You can search for them by category and check English interwiki link or program a bot to do it for you. Arcfrk (talk) 03:50, 5 April 2010 (UTC)
One article that comes to mind is de:Parametrisierter Algorithmus which has a lot of stuff not present in our Parameterized complexity. --Robin (talk) 04:00, 5 April 2010 (UTC)
To second Arcfrk, there are probably quite a few articles in Category:German mathematicians where information from the German Wikipedia could be imported.--RDBury (talk) 09:06, 5 April 2010 (UTC)

I don't speak German (or French or any other) so I can't enrich other editions with English content. Anyway, apparently no one answered my question (we are typical mathematicians...), so I take it no. I will probably run a bot or something. (That's actually quite easy.) I'm concentrating on biographies since most of stuff in such articles are quite mandane (going to school X; got Ph.D in Y etc.) and thus machine translation works quite well. -- Taku (talk) 11:48, 5 April 2010 (UTC)

I think that it is a bad idea to use machine translation to create (or expand) articles. I would much rather see a redirect to the original article in foreign language Wikipedia. For any kind of translation, there should be a reference to the source (either in the edit summary, or, better, on the talk page). Arcfrk (talk) 01:05, 6 April 2010 (UTC)

### Finite difference coefficients translated

Hi. Today I have created a new article in English; I'm italian and so my English isn't very good... if someone wants to improve my article, it is Finite difference coefficients. -- Superale85 (talk 18:01, 5 April 2010 (UTC)

To Superale85: The table Image:Coeff_der_cent.jpg which is used in the article Finite difference coefficient appears to have an error in it. The section devoted to the second derivative is simply a copy of the section for the first derivative. Of course, it should be different. There may be other errors also. JRSpriggs (talk) 09:05, 6 April 2010 (UTC)

Thanks a lot, now it should be right... you can check if it's all right at this site: http://amath.colorado.edu/faculty/fornberg/Docs/MathComp_88_FD_formulas.pdf. -- Superale85 (talk 10:01, 6 April 2010 (UTC)

The huge jpeg tables that constitute the bulk of the information in the article should be typeset as ordinary html tables. See Help:Table. Sławomir Biały (talk) 12:23, 6 April 2010 (UTC)
Those are images? Yes, they really need to be redone. I'll see what I can do. — Carl (CBM · talk) 12:43, 6 April 2010 (UTC)
Hy Carl, we've done the same job... take a look at it:Coefficienti differenze finite, maybe is better a table like that... -- Superale85 (talk 16:02, 6 April 2010 (UTC) —Preceding unsigned comment added by 79.25.134.191 (talk)
FWIW, I prefer Carl's table. For one thing, the entries in your table are way too huge, for no good reason.—Emil J. 16:30, 6 April 2010 (UTC)
I know... but it's because I use the MATH code (\frac{}{})... someone knows how to put a formula with a smaller font size? -- Superale85 (talk 16:55, 6 April 2010 (UTC)

Hi. I've turned the images in tables, and now it should be all right... I hope so! -- Superale85 (talk 07:00, 7 April 2010 (UTC)

## Hippasus of Metapontum and the square root of 2

In Talk:Square root of 2#Hippasus of Metapontum and the square root of 2 somebody is arguing that Hipassus might have discovered the irrationality of the square root of 2 but didn't prove it. It seems to me they must be trying to apply some funny idea of proof. They have lots of books to quote which I don't have access to but some might be accessible from google, I haven't looked. I guess if they have cites they can stick something in but I wonder what weight there is for such stuff which I consider revisionism. Dmcq (talk) 14:50, 6 April 2010 (UTC)

I am not sure what you mean, because (a) there were innumerable (ha!) mathematical discoveries made throughout the ages that had to wait a few hundred years for the proof: e.g. Dickson remarks in the "History of the theory of numbers", vol 1, V that Fermat "stated he had a proof of" Fermat's little theorem (1640), but Euler was the first to publish a proof (1736) (and further, that the case of base 2 "was known to Chinese as early as 500 B.C." — did they, ahem, discover it?); (b) it is rather the substitution of the modern concept of proof for the earlier meaning of "proof" or "to prove" that appears to be historical revisionism. At any rate, after browsing through the article, a much bigger issue, to me, is the presence of unsourced proofs (or sketches of proofs) of the irrationality of √2, algorithms for rational approximations, etc. If they all belong there — and I am not convinced that that's the case — accurate historical references, with secondary sources, of course, would be both valuable and appropriate. Arcfrk (talk) 04:47, 7 April 2010 (UTC)
One might notice a pattern that p2 ≠ 2 q2 for any nonzero integers p and q which one tries, but not knowing of the Fundamental theorem of arithmetic, one might not be able to convert that to a proof. So it depends on what you know. JRSpriggs (talk) 02:36, 7 April 2010 (UTC)
Fundamental theorem of arithmetic is not needed! It's enough to observe that if p2 is even then so is p. This, I believe, was the idea behind the original Pythagorean proof. Arcfrk (talk) 04:06, 7 April 2010 (UTC)
The difference in this case would simply be whether they argued from the evenness of the numbers or whether they just tried to find a fraction that worked and said we haven't been able to find such a fraction we believe there isn't one. Same with the theorem of Pythagoras, if they just found 3,4,5 seemed to give a right angle that would be one thing, if they made an argument from similarity or one of those diagrams with a square inside a square then that's proof. Our standards are different now in that we require axioms to be very clearly defined but I see no reason to dismiss everything before the twentieth century because it didn't have its axioms and proof schema correct by our standards. What gets me is them arguing they might have discovered irrationality from the pentagram first, once one knows the golden ratio seeing that it is irrational would be easy but it requires quite a large amount of extra machinery before you get that far. I guess it is possible for people who are geometrically inclined but I though the strong geometric inclination only came later. Dmcq (talk) 07:50, 7 April 2010 (UTC)
I think the moral here is that someone needs to do some serious reading through "History of Greek Mathematics" books, and rewrite the section based on what they say. -- Radagast3 (talk) 21:41, 7 April 2010 (UTC)

## Bearing-from-coordinates formula

See Bearing-from-coordinates formula. Is this whole article just a triviality? Michael Hardy (talk) 06:57, 7 April 2010 (UTC)

I believe it is, and have PRODed it. -- Radagast3 (talk) 07:11, 7 April 2010 (UTC)
The same user has given us Gauss' area formula, which has a fantastic diagram, but covers the same subject as Shoelace formula. -- Radagast3 (talk) 07:36, 7 April 2010 (UTC)
Someone should also investigate the merge possibilities of polar formula, although the use of grads rather that degrees, and a diagram whose x and y axes are reversed from the usual conventions makes me question its value. Sławomir Biały (talk) 10:43, 7 April 2010 (UTC)

An example of a book cover, taken from Book:Hadronic Matter

As detailed in last week's Signpost, WildBot has been patrolling Wikipedia-Books and searched for various problems in them, such as books having duplicate articles or containing redirects. WikiProject Wikipedia-Books is in the process of cleaning them up, but help would be appreciated. For this project, the following books have problems:

The problem reports explain in details what exactly are the problems, why they are problems, and how to fix them. This way anyone can fix them even if they aren't familiar with books. If you don't see something that looks like this, then all problems have been fixed. (Please strike articles from this list as the problems get fixed.)

Also, the {{saved book}} template has been updated to allow editors to specify the default covers of books (title, subtitle, cover-image, cover-color), and gives are preview of the default cover on the book's page. An example of such a cover is found on the right. Ideally, all books in Category:Book-Class mathematics pages should have covers.

If you need help with cleaning up a book, help with the {{saved book}} template, or have any questions about books in general, see Help:Books, Wikipedia:Books, and Wikipedia:WikiProject Wikipedia-Books, or ask me on my talk page. Also feel free to join WikiProject Wikipedia-Books, as we need all the help we can get.

This message was delivered by User:EarwigBot, at 00:42, 8 April 2010 (UTC), on behalf of Headbomb. Headbomb probably isn't watching this page, so if you want him to reply here, just leave him a message on his talk page. EarwigBot (owner • talk) 00:42, 8 April 2010 (UTC)

## Missing mathematics topics

I've updated my list of missing mathematics topics - Skysmith (talk) 13:29, 8 April 2010 (UTC)

Where is this list coming from? Just doing a quick random check, many aren't existing red links.--RDBury (talk) 13:59, 8 April 2010 (UTC)
Various offline sources, mostly books and dictionaries. If you feel that some subject does not merit an article, comment on the list page - Skysmith (talk) 14:09, 8 April 2010 (UTC)
This is very useful indeed. I see quite a few of these redlinks can be turned into helpful redirects right away. Sławomir Biały (talk) 14:40, 8 April 2010 (UTC)

## No new articles?

Have we really had two days of no new mathematics articles or is a bot malfunctioning somewhere? —David Eppstein (talk) 03:18, 9 April 2010 (UTC)

Most likely articles are not being tagged as mathematical. -- Radagast3 (talk) 03:25, 9 April 2010 (UTC)
Actually, it probably is a malfunction. I PRODed Bearing-from-coordinates formula, and that should have appeared in the list. -- Radagast3 (talk) 10:59, 9 April 2010 (UTC)

The difficulty is that there are two bots. The current activity page depends on the list of mathematics articles, and that list seems to have not been updated by MathBot since the 6th. Michael Hardy already asked Oleg about it, so hopefully it will be fixed soon. — Carl (CBM · talk) 11:27, 9 April 2010 (UTC)

## Well-formed formula

Comments would be welcome on the phrasing of the lede of Well-formed formula, at Talk:Well-formed_formula#Problems_with_the_lede. — Carl (CBM · talk) 00:10, 10 April 2010 (UTC)

## how spell i

as in i^2 = -1 is it roman i or italic i —Preceding unsigned comment added by 170.170.59.138 (talk) 17:37, 9 April 2010 (UTC)

The article on imaginary numbers uses italic i, which is the convention for displaying variables. You can produce an italic using two single-quotes on each side. (See the source for this post.) Justin W Smith talk/stalk 18:20, 9 April 2010 (UTC)
Alternatively there is ${\displaystyle \imath }$ and its companion ${\displaystyle \jmath }$ which are the specific LaTeX symbols. IMO we should always try to use LaTeX whenever mathematical formulas are being presented. This has probably already been discussed at great length elsewhere. --Matt Westwood 20:12, 10 April 2010 (UTC) —Preceding unsigned comment added by WestwoodMatt (talkcontribs)
The WP:MOSMATH discourages the use of LaTeX to typeset inline formulas, because of a number of issues the most significant of which is that the rendered PNG output often aligns poorly with the text, depending on the browser settings. So I generally disagree that LaTeX should be used whenever mathematical formulas are presented: html is still often preferable. Sławomir Biały (talk) 21:59, 10 April 2010 (UTC)
However there are good reasons to use latex or rather $-tags nevertheless. They are often easier to use for authors, who can stick to latex expressions, they are already familiar with. Also they provide a uniform handling of formulas, which makes it easier to parse for them and modify/improve their display globally, with new (future) rendering engines. You can probably also argue they are even easier to read/parse for humans being familiar with latex (in comparison to many html codes).--Kmhkmh (talk) 05:39, 11 April 2010 (UTC) I agree. Latex is much easier to use/maintain than trying to express such things in HTML. And if an editor needs to embed mathematical notation into the body of a paragraph, and he/she knows latex but is unsure of how to express the formula otherwise, they should definitely use latex. If another editor doesn't like the way it looks, he/she can change it later. Ideally, we could all just use Latex anywhere in an article, and the symbols would display beautifully. Unfortunately, this is not the case. Many browsers will only display the formulas as PNG images. So when used in the middle of a paragraph, the notation looks very clunky. Hopefully within a few years, browsers will all support MathML, and latex will display nicely in-line. Justin W Smith talk/stalk 05:53, 11 April 2010 (UTC) I agree that short comings of the current rendering emgines are an issue. However the "clunkyness" is also a bit in the eye of the beholder. Personally I rather like the png-rendering, since being clunky or not fitting into a text paragraph quite that seamlessly makes it easier for the human eye to parse for formulas. This can be a (slight) advantage if you skim a certain article for a particular formula. I suspect this scenario of readers using WP as a formula lookup is quite common.--Kmhkmh (talk) 06:06, 11 April 2010 (UTC) Interesting perspective. I hadn't thought of it that way. So it's a decision between pragmatism (= Latex) and aestheticism (= HTML). Justin W Smith talk/stalk 06:12, 11 April 2010 (UTC) In any case, the correct LaTeX symbols are ${\displaystyle i\,}$ and ${\displaystyle j\,}$. The characters ${\displaystyle \imath }$ and ${\displaystyle \jmath }$ are dotless version of these letters to be used when combined with another diacritic (such as ${\displaystyle {\hat {\jmath }}}$), they should not be used alone.—Emil J. 14:02, 12 April 2010 (UTC) Wow! I never knew that! Many thanks.--Matt Westwood 18:57, 12 April 2010 (UTC) According to WP:MOSMATH both italic i or (bold) roman i are acceptable. Also since the WP:MOSMATH recommends to use italic for variables, it might makes sense to use roman for (well known) constants to contrast them.--Kmhkmh (talk) 05:52, 11 April 2010 (UTC) There's a caveat about using latex inline. It says, • "Having LaTeX-based formulae in-line which render as PNG under the default user settings, as above, is generally discouraged, for the following reasons..." Justin W Smith talk/stalk 05:55, 11 April 2010 (UTC) Nevermind. This was not really relevant to the current discussion.Justin W Smith talk/stalk 06:00, 11 April 2010 (UTC) WP:MOSMATH does "recommend" italic for i. It says, • On the other hand, for the differential, imaginary unit, and Euler's number, Wikipedia articles usually use an italic font, so one writes... Justin W Smith talk/stalk 06:02, 11 April 2010 (UTC) Not quite, since you only quote half of relevant text. The "full" version is: On the other hand, for the differential, imaginary unit, and Euler's number, Wikipedia articles usually use an italic font, so one writes [...] Some authors prefer to use an upright (Roman) font for dx, and Roman boldface for i. Both forms are correct.--Kmhkmh (talk) 06:11, 11 April 2010 (UTC) You're right; I stopped too quickly. But you may have also... I think the next sentence may be the most important in deciding which to use: • Both forms are correct; what is most important is consistency within an article, with deference to previous editors. Justin W Smith talk/stalk 06:16, 11 April 2010 (UTC) ## Chinese decimals One of the most rapidly developing areas in Decimal. Tkuvho (talk) 17:08, 11 April 2010 (UTC) There seems to be a lot of overlap between the discussion of counting rods, rod calculus, and the similar discussion in Decimal. Maybe the best solution is to merge the discussion to counting rods, with a "Main article: counting rods". Rod numerals is a redirect to counting rods. I have added a bunch of "suggested merge" templates, but I haven't time to do anything else at present. —Dominus (talk) 22:42, 11 April 2010 (UTC) The issue of what constitutes a reliable reference can be discussed at the talkpage. Tkuvho (talk) 09:09, 12 April 2010 (UTC) Something will need to be done about this. The added content is grossly out of proportion to the rest of the article, and also doesn't seem to represent a consensus of scholarly opinion. Rather the section seems unacceptably keen on "building a case" that the Hindu-Arabic numerical system actually originated in China. WP:SYNTH and WP:NPOV both appear to be relevant. Sławomir Biały (talk) 11:17, 12 April 2010 (UTC) Editor Gisling proved to be very cooperative, and removed most of the material that was only backed by chinese sources (and therefore unverifiable as far as most of us are concerned). Tkuvho (talk) 11:25, 12 April 2010 (UTC) The content still seems to be quite skewed, although I am no expert on the history of mathematics, and it remains out of proportion to the rest of the history section. As the Hindu-Arabic numeral system has its own separate article, most of this newly added material should also be farmed out to other more specific articles. Try to get it down to a paragraph or two that summarizes the key ideas. Sławomir Biały (talk) 11:30, 12 April 2010 (UTC) Why not just split it off to Traditional Chinese decimals, then ask WP:CHINA to handle it? 70.29.208.247 (talk) 05:29, 14 April 2010 (UTC) ## Codomain of a random variable Codomain of a random variable: observation space (recently archived) There are several unresolved issues, primarily pedagogical or presentational in my opinion. One is whether a random variable is real-valued, whether the codomain of a random variable is a subset of the real numbers. There is some value in consistency across articles, but that is not the only value. If the answer will be consistently yes (all random variables are real-valued) than we need a general term for those random whatchamacallem that aren't r.variables. --P64 (talk) 19:57, 11 April 2010 (UTC) One more value is: WP should reflect the external world (rather than invent its own, even if consistent and nice, world). I recall (see that recently archived text) that four books that I've looked all treat a random variable as real-valued; and more general objects are called random vectors, random functions and, most generally, random elements (of a given measurable space). Why do otherwise? Maybe other books do it differently; if so, please give us examples. Boris Tsirelson (talk) 20:07, 11 April 2010 (UTC) +1--Kmhkmh (talk) 20:50, 11 April 2010 (UTC) Evidently random element is the proposed general term. It doesn't seem to have a sibling term in the sense random variable and random variate are siblings. Perhaps a value of the function f is a random variate regardless whether the codomain is a subset of R; that is, regardless whether f is a random variable or a more general random element. I have suggested a case for treating random variables as real-valued that does not depend on proving a negative. As long as wikipedia values primarily reflection of the messy external world, who will trouble to impose any restrictive consistency across these articles (as you wish)? Someone who hopes to change that world might do it, or someone happy to extrapolate from the four references. Random variable presently introduces the real-valued special case in section four. (The article doesn't really have anything to say about more general random elements, and the opening sections don't do a good job of explaining random variablehood or elementhood. That's another matter or two.) Random sequence is not about random elements of any kind, after the first two sentences. Instead its subject is algorithmically random sequence, or I would say the algorithmic randomness of sequences, essentially infinite sequences of binary digits. --P64 (talk) 19:40, 12 April 2010 (UTC) Here's the link above, formatted as an internal link: Codomain of a random variable: observation space (recently archived) Michael Hardy (talk) 19:51, 12 April 2010 (UTC) Thanks! WolframMathWorld uses state space for the so-called observation space, i.e. the codomain of a random element, or a random variable in the extended sense. --following J.L. Doob 1996. See "Random Variable" at WolframMathWorld and also their "State Space". Beside the point of discussion, some of you may be interested to read J. Laurie Snell, "A Conversation with Joe Doob". It includes Doob's claim that he and a colleague chose random variable over chance variable, establishing the usage by publisher Wiley (i understand) by tossing a coin. It also includes this, only a minor treasure but that surpasses my threshold here, "It was a shock for probabilists to realize that a function is glorified into a random variable as soon as its domain is assigned a probability distribution with respect to which the function is measurable." --P64 (talk) 22:46, 12 April 2010 (UTC) A function R→R is glorified into a moving one-dimensional particle just by saying that the first R will be called the time and the second one the space. So what? Boris Tsirelson (talk) 05:03, 13 April 2010 (UTC) I think Doob's point is that for most probabilists at the time, this was not obvious! Doob talks quite a lot about the terrible state of probability theory. Here's another relevant quote: In a 1934 class discussion of bivariate normal distributions Hotelling remarked that zero correlation of two jointly normally distributed random variables implied independence, but it was not known whether the random variables of an uncorrelated pair were necessarily independent. Of course he understood me at once when I remarked after class that the interval [0, 2pi] when endowed with Lebesgue measure divided by 2pi is a probability measure space, and that on this space the sine and cosine functions are uncorrelated but not independent random variables. He had not digested the idea that a trigonometric function is a random variable relative to any Borel probability measure on its domain. (Hotelling was apparently a professor of statistics at Columbia.) Ozob (talk) 00:44, 14 April 2010 (UTC) I just found this thread after spending hours clicking through Wikipedia's probability articles trying to find out exactly what an observation space is (after seeing the term in random variable), and (completely missing as far as I can tell) what an observation is (after seeing it elsewhere, that I can't seem to find again, but I mean the thing that is informally described as drawing a sample from a random variable). So I do think the topic is in a pretty murky state right now. Is it even a reasonable question, to ask for a formal and rigorous mathematical definition of "observation"? Maybe I will try to get a textbook. I notice my local bookstore has Renyi's "Foundations of Probability" which looks good--do ppl here recommend it? Thanks. 66.127.52.47 (talk) 01:03, 14 April 2010 (UTC) ## ?????? Urquhart The article titled Urquhart graph begins like this: In computational geometry, the Urquhart graph of a set of points in the plane is But it should say this: In computational geometry, the Urquhart graph of a set of points in the plane, named after ?????? Urquhart, is for some suitable value of ??????. Michael Hardy (talk) 20:31, 14 April 2010 (UTC) Roderick B., apparently [7]. Charles Matthews (talk) 20:56, 14 April 2010 (UTC) I'm skeptical that the subject of this article is sufficiently notable to include. I tried to search for the term, and aside from other work by the same authors found only a survey on proximity graphs by Godfried Toussaint that mentions these graphs briefly. My standards for whether a mathematical object is notable enough to have an article are pretty low, but they involve the object being studied by multiple independent groups of researchers. —David Eppstein (talk) 23:04, 14 April 2010 (UTC) I only found this using the term on GS. However, it seems that there was substantial work by Urquhart and others on the concept before the term "Urquhart graph" was coined. -- Radagast3 (talk) 23:28, 14 April 2010 (UTC) Ok, if you add those earlier references it's probably (barely) enough. —David Eppstein (talk) 23:33, 14 April 2010 (UTC) ## Announcing... WP Math Typography! It is my pleasure to announce a new subproject, WikiProject Mathematics/Typography (or WP:WPMATHTYPE for short)! Lovers of math typography, or anyone who cares about how formulae are written or rendered, please: To kick off, is HTML-rendered TeX (texhtml) too big for you? Do the following all render about the same size for you? They don’t for me, and all four are commonly used. 1+1 1 + 1 ${\displaystyle 1+1}$ ${\displaystyle 1+1\,}$ If you, too, suffer from a too-big texhtml in your life, or just want to join the discussion, put in your 2¢/2c/2p/2¥ at texhtml is too big, and welcome! —Nils von Barth (nbarth) (talk) 08:50, 15 April 2010 (UTC) ## Expert Request Hello the Wiki-smarts ;-). I know this is really not the place, but primary editor is insistent on removing {{Expert-subject|Mathematics}} from an article that only the WP:Mathematics members (Topology, perhaps?) have even half a chance of comprehending. I really don't want to escalate, so would appreciate if one of you could pop along and take a "third-party", educated beyond my abilities look :-) The article is Augmental homology, and to make things really interesting editor has admitted wp:ORN on the Talk Page, but that doesn't mean that it isn't notable...(?) Much appreciated, and apologies for placing request here. (It took a lot, trust me... I feel like I've stumbled into the 6th form room all over again, and expect to be hung upside down on the coat hooks again... just like all these years ago... <sigh>) --Haruth (talk) 11:30, 15 April 2010 (UTC) Goran Fors of Stockholm published an article on augmental homology 28 years ago. The term has not been picked up by other topologists, and the article does not seem to be cited in almost any publication. My conclusion is that (1) the term is a neologism, and an article should not be named after it; and (2) the subject of the page is not sufficiently notable to have a wiki page on it. Of course, if and when there is any evidence of this notion becoming influential, the situation may change. Tkuvho (talk) 11:45, 15 April 2010 (UTC) The author of the article admits that it's WP:OR: I don't think the subject is notable. -- Radagast3 (talk) 11:48, 15 April 2010 (UTC) I don't think the subject os "original research" in the wiki sense. I am not sure where the author admitted this. He may have misunderstood the term (his published paper is certainly original research in the generic sense of the term, and his other edits indicate professional competence in topology). The issue is not OR, but rather notability, it seems to me. Tkuvho (talk) 11:53, 15 April 2010 (UTC) The author says "I am Gofors, who wrote the article "Augmental homology". I invented this homology theory..." and refers to an unpublished paper at arXiv.org. This makes it OR in the Wikipedia sense, as well as a notability issue. I have added a PROD tag to the article. -- Radagast3 (talk) 11:57, 15 April 2010 (UTC) The paper is Fors, Göran: Algebraic topological results on Stanley Reisner rings. Commutative algebra (Trieste, 1992), 69--88, World Sci. Publ., River Edge, NJ, 1994. I found no reference to the arxiv at the discussion page. Where did Gofors mention an arxiv article? The fact that he invented augmental homology does not mean that augmental homology is OR in the wiki sense. Tkuvho (talk) 12:17, 15 April 2010 (UTC) The paper cited in the article Augmental homology is "G. Fors, On the Foundation of Algebraic Topology, arXive 2010." [8] -- Radagast3 (talk) 12:31, 15 April 2010 (UTC) The paper you mention is cited in a different article: Stanley-Reisner ring (binary operations). -- Radagast3 (talk) 12:35, 15 April 2010 (UTC) ## Separate page I would like to see separate articles on the McLaughlin and Suzuki sporadic simple groups. Presently they are just treated under Conway groups. Also I would like to see an article on the Suzuki groups, which are not the same as the aforesaid group. Now there is just a disambiguation page entitled 'Suzuki group.' Scott Tillinghast, Houston TX (talk) 19:45, 13 April 2010 (UTC) See Wikipedia:Splitting. The procedurally correct way would appear to be to add the template {{split2}} to the Conway groups article, and start a discussion on the Talk page there, to gather views. Charles Matthews (talk) 10:38, 14 April 2010 (UTC) The possible split can be discussed at Talk:Conway group#Possible split. -- Radagast3 (talk) 14:24, 16 April 2010 (UTC) ## Augmental homology nominated for deletion You can comment at http://en.wikipedia.org/wiki/Wikipedia:Articles_for_deletion/Augmental_homology Tkuvho (talk) 12:12, 16 April 2010 (UTC) ## Rating how an article stands against the next assessment rung A little time ago I had a (non-mathematical) article assessed by WikiProject Germany. As well as giving a current rating, their assessment template includes a 5-point check for how the article currently stands against the next rating up, and what would need to be fixed for promotion. Is this something that might be worth adding into {{maths rating}} ? Reporting where the article stands against the systematic next-step assessment criteria is probably helpful for assuring ratings consistency. Perhaps more significantly, in my case, being told how close my article was to getting a "B" actually got me to fix it, unlike any of the times when I have just got a "C" without further explanation. Is this an idea that might be worth considering? Jheald (talk) 18:55, 16 April 2010 (UTC) The five point checklist is used in the Wikipedia 1.0 assessment scale for a B rating, the WP 1.0 scale is used by nearly every project. I like this multidimensional approach but seeing as how it's only been a few weeks since we added a C rating it might be a good idea to let the dust settle a bit before embarking on more major changes. Imo both the WP 1.0 criteria and Math criteria could be improved but coming to consensus as to what the changes should be is a slow process. You might be interested to know that the Italian Wikipedia actually uses four ratings for each article, so it might get a good rating on completeness and a medium rating on verifiability. This gives you a lot of information about what needs to be improved but I think it asks a lot from reviewers.--RDBury (talk) 19:32, 16 April 2010 (UTC) It's not just the "B" rating, the WP:Germany template has similar feedback boxes for the other assessment levels too, I think, for the reviewer to indicate how the article is measuring up on each criteria it needs to achieve to make the next level. The WP:Comics project template uses the code too, I think, and probably others. As I wrote, from the point of view of the raters, I believe this is likely to give better consistency and good calibration; and for editors, it actually explains why their work has been rated the way it has, and gives a much more positive focused stimulus as to how to improve it. Does it ask more of reviewers? I'd like to think reviewers would be mentally running a checklist like this anyway. Jheald (talk) 20:03, 16 April 2010 (UTC) I think there are really several issues here. First, the Math project does not use a checklist, it uses its own criteria for B which are somewhat weaker than the WP 1.0 criteria. The WP 1.0 version of B corresponds roughly to our B+ rating but our criteria for B+ don't use a checklist either. Even to get to the point where adding the checklist to the template would make sense the Math criteria would need to be updated. My thinking is that our eventual goal should be to adopt the WP 1.0 criteria which most other projects use, but in order to do that we would need to re-evaluate the existing B+ rated articles and there doesn't seem to be a consensus to do that at the moment. You do have a point in that a simple letter rating doesn't give any clues as to where efforts should be focused. But I'm not convinced though that the rating template should be used for this. There are already a host of cleanup tags that can be used to indicate where the article could be improved and the talk page itself should be used for specific criticisms. The edit comment can also be used to indicate reasons for a rating if it might be questioned. Even if the rating template were to be used, I'm not convinced that the checklist machinery is the best way of doing it. For example, putting an X for grammar and style doesn't tell you which sections have grammatical or style issues. The Todo template seems like it might be useful to plan where to focus editing efforts, but I've never used it myself.--RDBury (talk) 17:24, 17 April 2010 (UTC) I completely agree with Jheald: it would be very, very helpful from the points of view of consistency and calibration to have specific criteria in a form of a checklist next to the quality rating. Rating math articles is a very ad hoc and subjective process. I have rated many articles myself (field, importance, class) and looked at other people's ratings and, even if there had been an implicit agreement on what the criteria should have been, it was not systematically applied, at least for articles below B plus level. I think that part of the reason is that careful evaluation is time consuming, while we had several "drives" to rate the articles, where the average time spent on a single article was under a minute! Also, people who are willing to invest time in this fairly thankless task are not necessarily experts in the subjects of the articles they rate and they frequently don't leave comments for improvement on the "Comments" subpage (or even sign their rating). That is actually a strong argument in favor of clearly displaying the criteria according to which the rating was assigned. On the other hand, let us not overestimate the role of the ratings: they provide an internal mechanism for improving the mathematics coverage, but do they have the desired effect? Also, what happened to the much discussed idea of updating the fields? Arcfrk (talk) 01:15, 18 April 2010 (UTC) I think there is general agreement that some change in the field system would be OK, but no concrete details yet. We should probably open a discussion at Wikipedia talk:WikiProject Mathematics/Wikipedia 1.0 to work out the details, then present them here and see if there is agreement. I have been to busy to really look into it; it seems like something we could complete by in late spring or early summer. I think that overhauling the ratings system would be a lot of work, so I favor either keeping our system, or just adopting the universal system with minor changes, rather than trying to develop a new system from scratch. I agree that a "comments" system for B-class and higher articles would be nice, but it isn't clear that it's the best use of editor time (we're talking about ~1000 articles, which is a lot to look at). In general, I think that the assessment system works best if we don't expect it to be perfect. Individual article ratings will go up or down and will probably settle out about the right place regardless what the rating criteria say. — Carl (CBM · talk) 13:40, 18 April 2010 (UTC) Can I encourage people to look at an example of WikiProject Germany's template in action? See eg Talk:David Hilbert, click 'show' to expand the WP:Germany project template, and then click 'show' again (next to 'B') to show the criteria breakdown. We're not talking about a time-consuming extensive comment system, just a simple and quick pass/fail/not checked rating -- but one which makes so much clearer just why the article is not currently getting a B from WP:Germany. Jheald (talk) 19:33, 18 April 2010 (UTC) ## Nemmers for Tao? Nemmers Prize in Mathematics says that Terence Tao has the 2010 award. The official page at Northwestern is not updated, may not be this weekend. One blog says this is true; do we have any more? Shouldn't go into the Tao article as a rumour. Charles Matthews (talk) 10:40, 17 April 2010 (UTC) It's in Terence Tao#Research and awards with a link to the official announcement. -- Radagast3 (talk) 10:55, 17 April 2010 (UTC) ## Adding references Hello! I just wanted to comment that another "thing to do" that could be added to the table is "Add references for mathematical facts". This is particularly easy to do for those who study mathematics: since the classes usually have some text book which the students should read, the students can add from time to time a reference in the articles about the subjects they are reading. This is somewhat easier than to choose a Wikipedia article first and then search for references for the facts in it... (you don't need to change of book =), just of article...). I've been doing this for a while... ;) It is just an idea... Helder (talk) 19:20, 17 April 2010 (UTC) You may be interested in Wikipedia:WikiProject Unreferenced articles.--RDBury (talk) 23:35, 17 April 2010 (UTC) Sure, good idea. I will add it to the table. — Carl (CBM · talk) 13:31, 18 April 2010 (UTC) If anyone wants to get started on this, the above mentioned Wikipedia:WikiProject Unreferenced articles has information, a how to guide, etc. The following math articles have had unreferenced tags since 2006. (I've already done a bunch of these long outstanding ones but these were tougher than average, at least for me.) • Informal mathematics - I think this requires some background in some softer sciences such as sociology or education to do it justice. See the discussion page for details. • Infinite-period bifurcation - This seems to require some expertise in dynamic systems to make sense of possible sources. Part of the process is to verify that the source actually supports the material in the article and this is hard to do when the terminology is unfamiliar. • EigenTrust - This seems to require knowledge of network security systems. • Georgiy Shilov - Bio articles where possible sources are mostly in foreign languages are tricky as well, so it might be best for someone who speaks Russian to look at this. --RDBury (talk) 14:07, 19 April 2010 (UTC) For Shilov, Russian Mathematical Surveys (in English translation) probably has a long obituary - and it is online (subscription site). Someone whose library subscribes might find this easier than I do (there is basic biographical data in the Russian Wikipedia, but no new web references). Charles Matthews (talk) 14:52, 19 April 2010 (UTC) ## Move discussion at Talk:Seki Kōwa Please come participate in the move discussion at Talk:Seki Kōwa#Move discussion. Thanks! ···日本穣? · 投稿 · Talk to Nihonjoe 18:03, 19 April 2010 (UTC) ## C rating draft Per the consensus mentioned above, I added a draft of criteria for C rating to the Wikipedia:WikiProject Mathematics/Wikipedia 1.0. In the process I tweaked the B rating criteria to make some room by raising the bar a bit. I think this is reasonable because if you look at the Wikipedia 1.0 B criteria, which is used by nearly every other project, their B rating is very close to our B+ rating. I'll allow some time for comments/revisions and then remove the "(draft)" from the criteria. It seems to be that the next step is to update the {{maths rating}} template so it sorts the C rated articles into Category:C-Class mathematics articles. — Preceding unsigned comment added by RDBury (talkcontribs) 08:37, 23 March 2010 Thanks. JRSpriggs (talk) 10:27, 20 April 2010 (UTC) ## List of zero terms I recently came across the list of zero terms (it figures prominently in Category Zero), which to me does not seem to have any use. Without stating its topic, it is a random list of mathematical terms containing "zero". For instance zero divisor is in but nilpotent is out; there is also zerosumfree monoid. I think an article about mathematical "nothingness" in general could be in place (which might even discuss why it should not be left to individual taste whether 0∈N, or whether 00 is defined ;-), but this is not it. I've proposed it for deletion for this reason, but the {{prod}} was anonymously removed, saying that is was a good topic for a list. Being united by choice of terminology only, I find it rather silly, even in comparison to most other articles in the Category Mathematics-related lists. Any ideas? Marc van Leeuwen (talk) 14:13, 19 April 2010 (UTC) Even sillier than 86 references on the parity of zero? There should be some page where zero matrix and zero vector and the number zero are all disambiguated, to counter the overloading of "zero" in mathematics. It need not be this exact page, of course. Charles Matthews (talk) 14:31, 19 April 2010 (UTC) Wow! A former featured article! Hans Adler 14:58, 19 April 2010 (UTC) Not promoted to FA, as far as I can tell, but fully deserving it. If that's an essay, it's an exceptionally well written and well documented essay, an ideal to aspire to among general interest math articles. Arcfrk (talk) 02:44, 20 April 2010 (UTC) Seems to be as useless as Category:Theories and Category:Modules. I see two options: (1) AfD with possibly a lot of drama. (2) Someone has a brilliant idea for a related reasonable topic that we can turn this into or redirect to. Hans Adler 14:58, 19 April 2010 (UTC) Two thirds of elementary teacher candidates thought zero was odd? Eek! Surely that can't be right? Dmcq (talk) 16:18, 19 April 2010 (UTC) That is not quite what the article says. It says about two thirds answered "False" to "Zero is an even number." I guess most of them thought it was neither even nor odd. It's bad but I'm willing to believe it. I would have been less willing to believe that two thirds thought zero was odd. PrimeHunter (talk) 23:00, 19 April 2010 (UTC) I am not at all surprised. Just a couple of days ago, in an article about prospective US math teachers (elementary and middle school), NY Times reported that The study found considerable variation in the math knowledge attained at different American colleges, with students at some scoring, on average, at the level of students in Botswana, the study said. Various other studies reported that as much as 50% of US mathematics teachers cannot correctly solve homework problems assigned to their students. Arcfrk (talk) 02:44, 20 April 2010 (UTC) Not only mathematics. I had a teacher who couldn't spell who set spelling tests - I still remember her trying to convince us of the spelling of "Belguim". —Preceding unsigned comment added by WestwoodMatt (talkcontribs) 18:56, 20 April 2010 (UTC) I've just read the Zero page and I confess to thinking it's not very coherent and could well do with improving. Considering as to how there are so many pages featuring the concept of zero in various contexts, I wonder whether there's room in the world for "project zero". Completely agree on the need to tidy it all up. What's there is excellent, it just needs structuring. --Matt Westwood 20:36, 19 April 2010 (UTC) I agree that list of zero terms is little more than a replication of basic functionality of the search engine. Does the common occurrence of zero in these article names have any significance other than an entirely unexplained historical accident? I think it would be far more useful to have a list of concepts related to or defined in terms of zero (in its general sense as the additive identity). I think I'd call it something like: List of concepts related to zero. Or better, why not just roll these all into a big section in zero? Dcoetzee 06:02, 20 April 2010 (UTC) A list of zero terms seems to me useless, especially as it seems to mix the concepts of structures containing only one element, objects generalising the number zero, and mathematical terms that just happen to contain the word "zero", such as "zerosumfree monoid." Grouping these things together just creates confusion, it seems to me. -- Radagast3 (talk) 07:13, 20 April 2010 (UTC) I'd AfD it, except that that would fill my inbox with negative messages. -- Radagast3 (talk) 07:14, 20 April 2010 (UTC) Since zero (disambiguation) exists, a merge into that page seems adequate. Charles Matthews (talk) 08:32, 20 April 2010 (UTC) Agreed. Also, I note that Zero element is currently just a dab page. It could be expanded into a full article, possibly incorporating some of the content here. -- Radagast3 (talk) 07:07, 21 April 2010 (UTC) ## Discrete Fourier merger Should the nearly orphaned discrete Fourier series get merged into discrete Fourier transform? Michael Hardy (talk) 13:42, 20 April 2010 (UTC) It's a confusing article. If you take a function of discrete time over some interval, force it to be periodic, and then take its Fourier series, what have you got? I think it's what I'd call an exponential sum. I suppose this is a numerical method, in which case it is probably fine to redirect it. Charles Matthews (talk) 16:01, 20 April 2010 (UTC) ## No more visible new articles We have been accustomed to seeing a list of new math-categorized Wikipedia articles every day on this WikiProject's current activities page. That stopped functioning six days ago. Oleg can't fix it because he uses an "external module" to log in to Wikipedia, and it's broken. Whoever maintains it probably doesn't suspect it affects this WikiProject. This situation will persist until it's fixed, and "until it's fixed" is apparently all the information we will ever get about when that will be, until it's fixed. Should we seek to establish a system that doesn't depend for its existence on someone whose identity we don't know and who doesn't know that we exist? Michael Hardy (talk) 19:49, 12 April 2010 (UTC) ... most edits to the list of mathematics articles are done by Oleg's bot, and happen whenever any of the math category tags is added to an article, including new articles bearing those tags, and also including all moves of articles bearing any of those tags. But sometimes someone edits the list by hand. I did a small edit to the list by hand today. And so we see on the current activity page an allegedly new article today---the first in six days. All other new articles created in the past six days have not been brought to our attention. I usually edit these for ordinary sorts of compliance with WP:MOS and WP:MOSMATH, often adding links, and putting links to the new article into other articles, and sometimes I look at the authors edit history and edit some other articles they've done, and mention on this present page any that I encounter along the way that I think need this community's attention. All that's on hold for now. Michael Hardy (talk) 02:24, 13 April 2010 (UTC) Well, Oleg could switch to my bot framework or some other bot framework. It's a question of how long it takes for the other one to be fixed. What happened is that the system admins made a change (to fix a security issue) that broke essentially every bot that logged in to Wikipedia. I found out when I got email from my bot reporting login failures. Fortunately, I had time that day to drop other plans and hack up a patch to VeblenBot; Oleg may not have that luxury. This breaking change was somewhat unusual, so I think that it's best to be patient and give Oleg a chance to fix the issue. — Carl (CBM · talk) 02:40, 13 April 2010 (UTC) So this external module Oleg uses is within Wikipedia? In that case maybe whoever handles it is capable of being aware that there's a problem for us? Michael Hardy (talk) 03:45, 13 April 2010 (UTC) I'm told it's been fixed. We'll see what happens when it's time for the next daily update. Michael Hardy (talk) 17:34, 13 April 2010 (UTC) That's right, the bot got fixed. As mentioned above, the problem was not in mathbot itself, but in a software package mathbot uses to log in. I know too little of the type of programming necessary to fix that kind of problem, so I had to wait until somebody fixes that package. Michael's impatience is understandable, but on the other hand, Wikipedia does not provide ready-made software to run bots. We rely on volunteers to create and maintain such packages. And often times those folks are too busy in real life to attend promptly to issues. Oleg Alexandrov (talk) 20:50, 13 April 2010 (UTC) ....and I did not know for a while that the "external module" involved was actually within Wikipedia. Michael Hardy (talk) 21:31, 13 April 2010 (UTC) The external module that his bot uses isn't within Wikipedia, but the reason that the bot was not working is that Wikipedia changed in a way that broke every bot. No previous warning was possible, because the developers were worried about a security hole being exposed before it was fixed. So unscheduled updates had to be made for AWB and for all the various bots that log in to Wikipedia, because code that used to be prefect no longer works. — Carl (CBM · talk) 22:03, 13 April 2010 (UTC) We're getting new articles, but I'm not entirely convinced that we're seeing all of them. Where are all the mathematical biographies we used to get? For instance, I created a new article Paul Finsler a couple of days ago — why is the bot not picking it up? —David Eppstein (talk) 02:07, 21 April 2010 (UTC) I contacted Oleg about this and it seems to be fixed now. The log at User:Mathbot/Changes to mathlists shows a huge number of changes to the mathematicians list yesterday. — Carl (CBM · talk) 22:03, 22 April 2010 (UTC) Today's "new articles" section on the current activities page, which is now less than one hour old, is much longer than usual, and nearly all of the new items are about individual mathematicians. Michael Hardy (talk) 02:20, 23 April 2010 (UTC) Thanks for the good news. And we should give Oleg a round of applause for maintaining this useful bot. —David Eppstein (talk) 02:57, 23 April 2010 (UTC) ## Lagrange's identity Can someone please have a look at recent changes this article, in particular this change. It seems to be unsupported by the source, and a synthesis based on at best unclear reasoning on the talk page.--JohnBlackburnewordsdeeds 11:36, 23 April 2010 (UTC) Since the Lagrange identity is a defining property of the 7D-cross product, I don't see anything that is not supported. However, the remark about the non-uniqueness of the cross product seems off-topic.-- By the way, the quaternion reference is rather incomplete. Nowhere does it say that the identity follows from the form of the product formula for purely imaginary quaternions.--LutzL (talk) 14:29, 23 April 2010 (UTC) I noticed this too. The relationship with quaternions clearly needs a bit of fleshing out. Sławomir Biały (talk) 17:16, 23 April 2010 (UTC) John, I don't know why you are doing this, because you were the one who argued so strongly for the fact that the relationship in question holds in seven dimensions. You convinced me with numbers, where I was having great difficulty trying to convince myself with algebraic manipulations involving 252 terms. We are all agreed now that the Lagrange identity is a defining property of the 7D-cross product. Hence your revert over at cross product is not in line with your arguments at seven dimensional cross product. The cross product article requires the correction as I have just explained on the cross product talk page. It was a very weak argument on your part to claim that the article is only about the 3D cross product and that we should therefore keep the fact that the relationship also holds in 7D as a secret. Even if it had been only about the 3D cross product, we would still have been obliged to clarify that the Lagrange identity in relation to cross products holds in both 3 and 7 dimensions. If we allow it to only mention the case of 3D, then that will mislead readers, such as myself, into thinking that it only holds in 3D. It was the misleading information in that article and also at Lagrange's identity which caused me to believe that it only held in 3D, and hence caused all the unnecessary trouble over at the seven dimensional cross product page. We need consistency throughout all the related articles. David Tombe (talk) 15:34, 23 April 2010 (UTC) Can someone please also help at Talk:Cross product where David Tombe is trying, for the second time this year, to merge seven dimensional cross product into it.--JohnBlackburnewordsdeeds 08:49, 24 April 2010 (UTC) ## AfD: Future of mathematics Please comment at Wikipedia:Articles for deletion/Future of mathematics. Thankyou. Bethnim (talk) 07:31, 25 April 2010 (UTC) ## NumBlk issue I notice that on Lagrange's identity, someone recently replaced all of the {{NumBlk}} templates with ad hoc formatting because the NumBlk template appears to introduce additional spaces. Here is what I am referring to ${\displaystyle \int x\,dx={\frac {x^{2}}{2}}+C}$ (1) Notice the unusually large gap between the formula and the surrounding text. The code for the above is: {{NumBlk|:|[itex]\int x\,dx = \frac{x^2}{2} +C$|{{EquationRef|1}}}}. Apart from this issue, however, I think the template looks better than the ad hoc version. Is there anyone here knowledgable about tables that could have a look at that template and try to fix it? This issue affects a number of mathematics articles. Sławomir Biały (talk) 23:12, 23 April 2010 (UTC)

It looks like a combination of indenting using <dl> and a table. Both introduce spacing so there is double spacing, the spacing of one or the other needs to be removed somehow. Dmcq (talk) 13:21, 24 April 2010 (UTC)
Regardless of the spacing, I for one prefer the label to be on the left without the dotted line, which is the way I've seen it most of the math books. But with math formulas on Wikipedia there is a limit to what you can expect with respect to aesthetics.--RDBury (talk) 15:17, 24 April 2010 (UTC)
Whereever the number is placed, it should probably be done in a way that does not wrap depending on the geometry of the browser window. In my case, the numbers just look badly when the formula wraps onto the next line. The NumBlk template at least prevents the line wrapping. It would be nice to remove the dashed line from the default in that template, though. (It doesn't even show up in my browser and screen settings.) How do we do that? Sławomir Biały (talk) 16:13, 24 April 2010 (UTC)

────────────────────────────────────────────────────────────────────────────────────────────────────I've found out where the extra line spacing was coming from, and how to fix it: the {{Repeat}} in the {{NumBlk}} is adding non-breakable spaces immediately after the <dl> and <dd> tags, which do the indentation. This User:JohnBlackburne/thinBlk seems to fix it, e.g.

${\displaystyle \int x\,dx={\frac {x^{2}}{2}}+C}$

(2)

The limitation is the version of repeat I've used only goes up to 20, so no more than 20 levels of indentation, but I don't think that's too much of a limitation. It looks OK to me in Safari 4 with the vector skin, does it look OK to everyone else?--JohnBlackburnewordsdeeds 17:12, 24 April 2010 (UTC)

Looks ok to me under OS X in Safari, Camino, Firefox, and Chrome. Curiously, the dashed line is only visible in Camino and Firefox (both in the old template and its replacement), but otherwise the spacing is the same in all four browsers, and much better than the old version with too much space. —David Eppstein (talk) 18:17, 24 April 2010 (UTC)
I didn't know there's meant to be a dotted line ! It makes sense as it was not clear what the extra table in there was for, so now I know what it's for I've fixed my test version so it displays for me, and hopefully for other browsers so it should be visible above. I'm not sure it's needed though, but it may just be that I'm used to the previous version.--JohnBlackburnewordsdeeds 18:46, 24 April 2010 (UTC)
Ok, now I'm seeing your version looking the same in all four browsers, with the dotted line. Whether or not we decide to make it the default to have that line visible, the added consistency seems like another improvement. —David Eppstein (talk) 19:12, 24 April 2010 (UTC)

────────────────────────────────────────────────────────────────────────────────────────────────────OK, I've done the bold thing and replaced {{NumBlk}} with my version. Whether it's better or not it seems it is what's intended, and it can't be left working differently on different browsers. Now it should have changed on all pages using this template, so now's the time to check pages that use it for problems or if there's anything else that should be done while we're looking at it.--JohnBlackburnewordsdeeds 19:37, 24 April 2010 (UTC)

Looks good. Maybe the next thing to consider is removing the default dashed line from the template. That is probably best conducted on Template talk:NumBlk. Sławomir Biały (talk) 20:07, 25 April 2010 (UTC)

## Edward Belaga

In my ignorance, I've never heard of this supposedly distinguished mathematician. The bio is unreferenced (except for publications, of course). I stumbled on the article by searching for occurrences of Acta Informatica in Wikipedia. (Off topic: This isn't the greatest CS journal nowadays; some would say only obscure stuff gets published in it. I was surprised to find that many occurrences, so I clicked on a few. Most citations are from the 70's and a few from the '80s. There was even one Gödel prize paper among them.) Pcap ping 06:24, 25 April 2010 (UTC)

I found a home page, with some difficulty. Charles Matthews (talk) 11:26, 25 April 2010 (UTC)
With a mathscinet h-index of 1 (one, .999...), it is hard to imagine this would survive an AfD. Tkuvho (talk) 11:43, 25 April 2010 (UTC)
MathSciNet does not keep track of citations reliably. The h-index appears to be 3 on Web of Science and 4 on Google Scholar; there is a paper in Doklady with 30 on Google Scholar. But, anyway the criteria of notability do not seem to be numerical (other than measuring "substantial"). Jmath666 (talk) 19:26, 25 April 2010 (UTC)
None of these h-indices give the impression of substantial contributions. The subject's CV is likewise quite unimpressive (no evidence of awards or otherwise significant accomplishments). Sławomir Biały (talk) 19:40, 25 April 2010 (UTC)
I've wp:prodded the article. Pcap ping 14:40, 25 April 2010 (UTC)
Seems a bit harsh, at first sight. He appears to be a CNRS researcher, which in French terms basically means holder of an off tenure-track research position. But his research is apparently known and cited. Charles Matthews (talk) 18:50, 25 April 2010 (UTC)
See also a previous Wikipeda discussion and a web item with further biographical info. Jmath666 (talk) 19:26, 25 April 2010 (UTC)
Is it relevant that much of the bibliography seems to be added by Belaga himself? Jmath666 (talk) 19:35, 25 April 2010 (UTC)

## Perron–Frobenius theorem

Can some people have a look at that page? I've tried to clean it up according to the standards of Wikipedia, but that didn't go well with a recent contributor. Arcfrk (talk) 17:28, 26 April 2010 (UTC)

## Reverting contributions of banned users

Is there a new Wikipedia policy of blanket reversions of old contributions by banned users? I am concerned about this and several related reversions. I wasn't able to find out the reasons for the ban in the first place, it seems to be a unilateral lifetime ban with no prior warnings. Arcfrk (talk) 19:59, 27 April 2010 (UTC)

It will be a sockpuppet case, given the diff. It is not a new policy: it is an old policy that is selectively applied. Usually you should assume such cases involve factors that are not going to be made public. Charles Matthews (talk) 20:05, 27 April 2010 (UTC)
You are however free, at your own discretion, to "adopt" — that is reinstate and take responsibility for — any edits which you deem to be "good". Paul August 20:10, 27 April 2010 (UTC)
Moreover, a short email to the person making the reverts can sometimes get you at least a pointer to the original ban discussion. There are many "banned" users, but very few for whom anyone would bother mass-reverting edits. In this case, I don't know who this user might have been. — Carl (CBM · talk) 20:36, 27 April 2010 (UTC)
This is the same banned user that was discussed at Wikipedia_talk:WikiProject_Mathematics/Archive_57#Strange_edit_summaries_by_Golumbo.
Re Ribet's theorem, Lagelspeil (talk · contribs) is the same banned user; as those edits were so long ago I left them.
-- 01:33, 28 April 2010 (UTC)
Thanks John for providing the link to that discussion. Paul August 01:45, 28 April 2010 (UTC)

## Proposal to change divisor classes infobox to navbox

The infobox-style Template:Divisor classes has become too long for a column list. I propose replacing it with Template:Divisor classes navbox. This has identical content but uses the navbox layout instead of the infobox style, and so would appear at the bottom of articles instead of down the right hand side. See Primitive abundant number for an example of how it appears in an article. I am happy to do all the necessary page edits myself, but just wanted to check here first in case anyone has any objections or suggestions for improving the navbox template. Gandalf61 (talk) 11:25, 24 April 2010 (UTC)

Looks good to me! -- Radagast3 (talk) 12:40, 24 April 2010 (UTC)
Yes, this seems like an improvement to me too. —David Eppstein (talk) 18:19, 24 April 2010 (UTC)

I've re-organised the navbox and added a few more article links. I will roll it out across relevant articles tomorrow unless there are major objections. Gandalf61 (talk) 16:08, 25 April 2010 (UTC)

Looks good to me to. I did something similar in January, replacing Template:N-dimensional space with Template:Dimension topics. I didn't ask anyone's opinion beforehand, though I was prompted to do it on seeing the older template removed by editors objecting to it cluttering up the side of articles.--JohnBlackburnewordsdeeds 17:13, 25 April 2010 (UTC)
The inclusion of File:Lattice of the divisibility of 60.svg in Template:Divisor classes navbox doesn't seem helpful to me but it nearly doubles the height of an already high navbox on my screen. I think the image should go. Otherwise the navbox is an improvement over Template:Divisor classes. PrimeHunter (talk) 23:08, 25 April 2010 (UTC)
Rather than remove the image, I have set the initial state of the navbox to "collapsed", so it takes up less real estate initially. BTW, the new navbox template is now rolled out across all relevant articles, and I have marked the old infobox template as "deprecated" (but I didn't blank it because it is still displayed in historical versions of articles). Gandalf61 (talk) 15:02, 28 April 2010 (UTC)

## Orthogonal analysis

What do we think of the new article titled Orthogonal analysis? Does it fit within the topic of some existing article and if so, should it get merged? It certainly barely hints at the variety of applications of the idea. Michael Hardy (talk) 05:46, 25 April 2010 (UTC)

Merge with Orthogonal functions. Bethnim (talk) 07:28, 25 April 2010 (UTC)
From a quick look a Google books it seems like the term is used in different ways in different fields. There are several books on signal processing, where I assume it's related to Fourier analysis, and some books on statistics, where I assume it has to do with resolving correlated random variables into linear functions of uncorrelated variables. Not really my area of expertise either way. The article itself doesn't seem to be talking about either one of these and it's unreferenced so it's hard to tell. I'd say give the author a day or two to add some references and then prod it as OR.--RDBury (talk) 07:51, 25 April 2010 (UTC)
I went ahead and PRODed the article since there wasn't an movement on correcting the issues.--RDBury (talk) 18:12, 29 April 2010 (UTC)

## Plans for WPMATH bots

There are several bots that update pages for WPMATH.

Bot Maintainer Jobs
Mathbot Oleg Alexandrov Updates list of mathematics articles and list of mathematicians
Jitse's bot Jitse Niesen Updates the current activity page and the list of articles needing attention
VeblenBot CBM Updates the article assessment tables on WP:WPMATH and elsewhere

Many editors here rely on these bots, so that even a short outage is widely noticed.

Oleg Alexandrov, Jitse Niesen, and I are discussing moving these bots to the m:toolserver as a "multi maintainer project". The motivation is to put these bots into a location where it would be easy to add additional maintainers if the existing maintainers are unable to continue for any reason. This is just a logistical rearrangement, and should not cause any change in the behavior of the bots. If you are interested in following or contributing to the discussion about the hosting, it is located in the "JIRA" issue tracking system for toolserver, here. — Carl (CBM · talk) 14:11, 28 April 2010 (UTC)

I think this is an excellent move. CRGreathouse (t | c) 00:33, 30 April 2010 (UTC)