Wikipedia talk:WikiProject Mathematics/Archive/2006/May

"Tone", pronoun use, etc. in math articles
The other day, I left a pretty extensive comment on Talk:Knot theory, in response to two editors who complained about the article's tone. One specific complaint was the use of pronouns and that the article sounded like a teachger giving a lesson. Now, I just noticed that Braid group has been tagged (by someone else) with a "tone" tag, and the talk page mentions for example, that the use of "we" is bad and that it sounds too much like a "math lesson instead of an encyclopedia".

My thought is that while some of the pronoun use could be favorably excised, I am definitely starting to get the feeling (especially after examining the articles in question) that these particular editors do not understand the conventions in mathematical writing, e.g. "We consider blah as doing blah..." is ok. They also may not understand that sometimes a procedural description should be given, e.g. "take such and such and do such and such...". See my long comment linked above. I would like to know what those who normally work on mathematics articles think about all this, so please drop by those pages and make some comments. --C S (Talk) 03:58, 1 May 2006 (UTC)


 * We is pretty much mathematical jargon; one is better for the general reader. Charles Matthews 11:45, 1 May 2006 (UTC)


 * I believe the passive is the preferred thingy. "We consider..." becomes "... is considered". --MarSch 14:08, 1 May 2006 (UTC)
 * But then... "is considered", er, by whom? By a deity? (Igny 15:33, 1 May 2006 (UTC))
 * This reflects a certain diference about using We. In a statement like We can deform a knot in 4D it can easily be rewitten as a knot can be deformed in 4D and the prounoun can easily be dropped. However We consider... are subjective statments and in a paper the we is used to indicate the opinion of the authors. In wikipedia such subjective statements need appropriate qualification most mathematicians consider 4D knots to be very boring. --Salix alba (talk) 19:04, 1 May 2006 (UTC)


 * I've responded where requested; see for details. Passive is not preferred; just the opposite. Overuse of "one" also makes reading drag. Technical writing has a tradition of such conventions, not to its credit. --KSmrqT 19:15, 1 May 2006 (UTC)


 * A MIT style guide says to use "we" in the active voice. I see now that I was mistaken in thinking it too personal, and yes, I did not understand mathematical writing conventions as pointed out by Chan. I will try to not be an ignoramus in the future. --Reader12 03:57, 2 May 2006 (UTC)


 * Well, you live and learn! I tried to carefully explain how the situation appeared to me without being patronizing or rude; I hope you weren't offended.  At any rate, I think it's been a very fruitful discussion thus far with a variety of people voicing their thoughts and it's still ongoing!  --C S (Talk) 08:08, 2 May 2006 (UTC)


 * No, no offense taken. This has been very instructive to me. Thanks! --Reader12 21:40, 2 May 2006 (UTC)


 * I've just come across a great book on Algebraic topology by Allen Hatcher which can be downloaded . To my mind he has a very good writing style, which avoids the problems of overly technical writing, whilst still being technically correct. I fell there is quite a bit which could be learnt by examining how he structures his writing. I think a lot of illustrations help, the sub project /Graphics has reciently been set up to try to improve the illustrations of the maths articles. --Salix alba (talk) 09:21, 2 May 2006 (UTC)

Naming: "fixed-point" vs "fixed point"
Several articles are named inconsistently. I prefer "fixed point". Any opinions? Post here or at Category talk: Fixed points. Staecker 21:18, 1 May 2006 (UTC)
 * It's my experience that "fixed point" is way more common in the literature, so we should stick with that.--Deville (Talk) 22:25, 1 May 2006 (UTC)
 * Not so fast; there's a grammatical distinction. As a noun phrase, we would write the "fixed point" of a recursive function, without the hyphen. But as an adjective, we often write "fixed-point" thingy, with the hyphen. In the case of theorem names, the former applies, as in "Brouwer fixed point theorem". And what about "Kleene fixpoint theorem"? It should redirect. --KSmrqT 22:59, 1 May 2006 (UTC)
 * I don't mind making the distinction, but I don't think I understand as you've stated it. In "Brouwer FP Theorem," it sounds like an adjective phrase to me (modifying "theorem"). Is this an exception? When would the hyphen be appropriate? Something like "fixed-point set"? That sounds like an adjective phrase to me, but I never write it that way myself. Come to think of it, I don't ever use the dash regardless of context. (Except when I have to link to Lefschetz fixed-point theorem) Staecker 23:19, 1 May 2006 (UTC)
 * You want me to explain why punctuation conventions make sense?! I wish. I can say that I would never hyphenate in a situation like "Every rotation has a fixed point." The article on hyphen discusses some common rules. So why not "Brouwer fixed-point theorem"? I suppose because it's a ritual thing, with "theorem" doing the modifying. Or it's an example of the general guideline that hyphens are for clarity, and if we don't need them we don't use them. The still more general guideline is to tread carefully in this territory, and don't rush to accuse anyone of doing it wrong just because their choice is not yours. (But you knew that already, yes?) --KSmrqT 02:47, 2 May 2006 (UTC)
 * My usage would be like KSmrq's. The underlying reason may be that a "fixed-point set" is a set which consists of fixed points (or is a fixed point, if you're doing category theory); but a "fixed point theorem" is a theorem about fixed points: a more distant relationship, analogous to the difference between mathematics and metamathematics. Septentrionalis 18:58, 5 May 2006 (UTC)

Are you sure there's an inconsistency? A fixed-point theorem (with a hyphen) asserts the existence of a fixed point (with no hyphen), and it is completely appropriate to use a hyphen in one case and not in the other, because of the difference in the way the phrase is being used. That is not an inconsistency. Michael Hardy 20:09, 5 May 2006 (UTC)

hyphens generally
By the traditional conventions concerning hyphens,


 * A man-eating shark (with a hyphen) scares people away from beaches, whereas
 * A man eating shark (with no hyphen) is a customer is a seafood restaurant.

The traditional usage is still followed by nearly all newspapers and magazines and in novels, and people are accustomed to seeing it. But many educated people, including many authors of scholarly papers and books no longer follow the traditional rule. I've tended to be conservative about it and I moved the Wikipedia article titled "light emitting diode" (with no hyphen) to light-emitting diode (with a hyphen) and have done the same with various other articles. I think in some cases, the hyphen is a magnificently efficient disambiguation device. Michael Hardy 20:14, 5 May 2006 (UTC)

Nice example, copied from hyphen:


 * semantic changes caused by the placement of hyphens:


 * Disease causing poor nutrition, meaning a disease that causes poor nutrition, and
 * Disease-causing poor nutrition, meaning poor nutrition that causes disease.

Michael Hardy 20:18, 5 May 2006 (UTC)


 * A fixed point theorem is a point theorem that was found to contain an error, which now has been repaired. Lambiam Talk 21:13, 6 May 2006 (UTC)

Blahtex and wikimania
The poster deadline for wikimania is fast approaching. I think it would be really good if we could have some presence there as a step to getting Blahtex integrated into the main encyclopedia sites. Neither User:Dmharvey or myself are able to attend, but posters can be submitted without having a physical presence. Questions: is anyone here planning to go to wikimania Aug 4-6, in Cambridge MA? Anyone happy to spend some time standing next to a Blahtex poster? For those who don't know Blahtex is a extension which converts LaTeX maths into the MathML XML markup which allows for improved rendering of mathematics in MediaWiki with moder browsers. --Salix alba (talk) 10:05, 2 May 2006 (UTC)

Bogus AfD of proof article
Loom91 has been goaded by Melchoir into nominating "Proof that 0.999... equals 1" for deletion, on the grounds that Wikipedia should not contain proofs like this. The archives of sci.math currently show well over a thousand postings related to this topic, which is therefore included in the sci.math FAQ; yet it appears that Wikipedia covers the topic far better. Those who are interested can register an opinion here. Caution: This topic (and perhaps this vote) attracts, um, non-standard thinkers, to put it delicately. (See the talk page archives for examples ad nauseam.) --KSmrqT 10:31, 5 May 2006 (UTC)


 * Yeah, I feel bad about that; sorry, everyone! (In my defense, though, I did try to explain why the AfD would fail, after which I didn't think Loom91 would actually go through with it.) Well, at least it's attracting some fresh constructive attention, and it'll be useful to have on record. Melchoir 20:09, 5 May 2006 (UTC)

By the way, in case anyone hasn't seen it yet, the AfD closed with a keep. Melchoir 22:58, 5 May 2006 (UTC)


 * That's a understatement; it closed with a speedy keep, with overwhelming support and complaints about the nomination as violating WP:POINT. --KSmrqT 22:31, 6 May 2006 (UTC)

Rewrite of Mode (statistics)
I rewrote the article Mode (statistics). Please review and correct errors, rewrite awkward sentences, simplify, embellish, supply sources, etc. It would further be nice to have some illustrations, both for a continuous density function and a histogram. Lambiam Talk 20:40, 5 May 2006 (UTC)

AfD for List of Mathematical Formulas
Should this be kept, deleted, merged, or should there be a category of "mathematical formulas"? (I wonder what the morphisms would be.) Visit Articles for deletion/List of Mathematical Formulas and contribute your two cents. Lambiam Talk 21:04, 6 May 2006 (UTC)


 * As far as I can see, the chemists don't need Category:Formulas. We might not need it either, though. Charles Matthews 19:09, 7 May 2006 (UTC)

WAREL back?
See. I don't read Japanese so I can't tell if the change is correct, but it's exactly the type of change we might expect from WAREL if he came back. --Trovatore 15:24, 10 May 2006 (UTC)
 * OK, I hate machine translation but it has its points. He changed the article to point to a nonexistent article on ja.wiki, called "Commutative field". It's WAREL alright; please block him with all deliberate speed. --Trovatore 15:41, 10 May 2006 (UTC)


 * blocked. -lethe talk [ +] 17:20, 10 May 2006 (UTC)

James Stewart
Just created the page on Stewart, James Stewart (mathematician), your contributions would be most appreciated.--Jersey Devil 09:08, 11 May 2006 (UTC)

TeX font size
There is a discussion at the Village pump that might interest a few people here. —Ruud 01:09, 12 May 2006 (UTC)

Koszul-Tate
Is there anybody here interested in tackling the Koszul-Tate derivation topic listed on the "Articles requested for more than two years"? Thank you. &mdash; RJH 15:45, 12 May 2006 (UTC)

WAREL
is back again at Field (mathematics). --Trovatore 02:39, 13 May 2006 (UTC)
 * . -lethe talk [ +]

Zeration
Can someone please review zeration? Thanks. Samw 03:28, 13 May 2006 (UTC)
 * I'd give it thumbs down, in regard the &Delta; numbers. That is just wrong, even if referenced in the paper. The rest is more-or-less accurate, although I believe it falis WP:N.
 * As for hyperexponentials, my first paper (in 1966) references an earlier paper by Donner and Tarski which discusses hyperexponentials on the ordinal numbers. I doubt the primacy of the 1987 paper.  &mdash; Arthur Rubin |  (talk) 04:29, 13 May 2006 (UTC)


 * Referencing something from 2004 makes it a bit young and possibly fails "established research". Dysprosia 08:44, 13 May 2006 (UTC)


 * Duly sent to AfD, see Articles for deletion/Zeration. -- Jitse Niesen (talk) 08:47, 13 May 2006 (UTC)

Spanish category
I wrote the following on Category talk:Mathematics; copying here.

An anon recently changed the Spanish link to es:Categoría:Matemática from es:Categoría:Matemáticas, or perhaps the other way around. It seems that both categories exist and are populated. Would someone whose Spanish is better than mine like to go tell them? I don't know how they handle these things over there; I think things like cfm are set up language-by-language. --Trovatore 14:54, 13 May 2006 (UTC)
 * It looks like es:Categoría:Matemática was created just today, by one es:Usuario:Ingenioso Hidalgo, who then took it upon himself to go around recatting over a hundred articles, then apparently got tired. Unless this was discussed somewhere this doesn't strike me as good behavior; someone should let them know. I don't know if they have any equivalent to WikiProject Mathematics. --Trovatore 15:21, 13 May 2006 (UTC)
 * On second thought, I suppose someone will notice, as the recats will surely show up on some watchlists. --Trovatore 15:35, 13 May 2006 (UTC)

P-adic numbers
There is a discussion on decimal-style notation for p-adic numbers, and what would be appropriate to use, on the talk page Talk:P-adic number which we would like comments on. I added a section which uses a notation which is unusual but not unprecedented, in the section intended to convey the intuitive idea of a p-adic number. It seems to me the notation I used does that more successfully than any alternative for people used to decimal notation. Gene Ward Smith 21:14, 13 May 2006 (UTC)

Real number
User:Oleg Alexandrov seems to me to be engaging in abusive reverts on this page, to a previous verison which is arguably incorrect mathematically and which removes a lot of new material, material for which he has given no argument for removal. He also says, falsely, that my attempt to satisfy his previous criticims amounted to "writing a one-liner" which seems to prove he hasn't even seriously looked at the version he is reverting from. I think we need other people to weigh in at this point. I am very much opposed to simply allowing it to say the real numbers have a number line and calling that a definition. My proposal to say they have a number line, with no "room" to fit additional numbers in, is an attempt to make the one-line introduction correspond to an actual rigorous definition, which will not be the case if we allow Oleg's revert. Gene Ward Smith 22:32, 13 May 2006 (UTC)


 * Comments at talk:real number are encouraged. My version of things is that Gene is convinced enough that he is right that he is prefers repeatedly reverting to his version to discussing things on the talk page. Oleg Alexandrov (talk) 22:51, 13 May 2006 (UTC)


 * I think you need to take your own advice; your reckless reversion was done without any discussion. Gene Ward Smith 23:28, 13 May 2006 (UTC)


 * Regardless of who did what, there is a discussion running at the talk page now. Please engage yourselves there. --  127 . * . * . 1  23:35, 13 May 2006 (UTC)

Islamic mathematics
User:CltFn has proposed to move Islamic mathematics to Middle-Eastern mathematics. Please comment at the talk page. —Ruud 02:36, 15 May 2006 (UTC)

A typesetting subtlety
See if you can spot the difference between this:


 * $$a+b+c+d\,$$


 * $$+e+f+g+h\,$$

and this:


 * $$a+b+c+d\,$$


 * $${}+e+f+g+h\,$$

without looking at the TeX code, and guess how and&mdash;perhaps more subtly&mdash;why the difference was achieved.

I think perhaps this should be borne in mind in editing math articles. Michael Hardy 02:37, 15 May 2006 (UTC)


 * This is presumably because TeX does not apply its operator spacing rules in the first case, while since you've forced an empty group in the second, it does. Preferrably if you're continuing a sum onto two lines, one would add a \quad of space in the second or add a text indent (via a ":"), instead of relying on empty groups. Dysprosia 03:02, 15 May 2006 (UTC)


 * Sadly, I spotted the difference instantly, and even knew exactly where to look. This has been with TeX for decades, and Knuth explicitly calls attention to it in The TeXbook (ISBN 0201134489, p. 196). You'd never guess he was the type to pay extraordinary attention to detail, now would you? ;-D
 * "An extra ‘{}’ was typed on the second line here so that TeX would know that the ‘+’ is a binary operation."
 * The difference is a consequence of the operator handling rules. --KSmrqT 04:27, 15 May 2006 (UTC)

Personally, I never noticed this until recently. I once asked Donald Knuth why he had issued an infallible pontifical decree about minute details of the design of the lower-case letter delta. He said it's because the design he prescribed was just obviously the right one. Anyway, in non-TeX mathematical notation, I've been something of a stickler about proper spacing with binary operations and binary relations, thinking all the while that there's no need to think about that in TeX, but in cases like this, there is. Michael Hardy 23:55, 15 May 2006 (UTC)


 * Dysprosia: How does a text indent via an initial colon achieve this result? It only adds space to the LEFT of "+". Michael Hardy 23:57, 15 May 2006 (UTC)
 * I wasn't exactly precise in what I was meaning above -- what I meant is that if one wants to continue a sum on two lines, one should add space to the left somehow, instead of keeping both lines of the sum aligned, for example
 * $$a+b+c+d\,$$
 * $${}+e+f+g+h\,$$
 * as opposed to
 * $$a+b+c+d\,$$
 * $${}+e+f+g+h\,$$
 * I probably should have added "and keeping the same indent" to the end of my comment. It's a shame that the TeX system in use here ignores initial spacing via quads and such. Dysprosia 08:46, 16 May 2006 (UTC)
 * I probably should have added "and keeping the same indent" to the end of my comment. It's a shame that the TeX system in use here ignores initial spacing via quads and such. Dysprosia 08:46, 16 May 2006 (UTC)

Math error right on this page?
On this page there is a box telling us that hyperreal numbers, superreal numbers, and surreal numbers are "complex extensions"; in fact, they are all real closed fields. Gene Ward Smith 04:34, 15 May 2006 (UTC)

Zero-eigenvalue bifurcation
Could someone take a look at zero-eigenvalue bifurcation? It is proposed for deletion, but it do find some uses of this term on google scholar. —Ruud 00:17, 16 May 2006 (UTC)


 * The deletion, rather than redirection, seems summary and not necessary. Charles Matthews 11:03, 20 May 2006 (UTC)


 * I agreed with the deletion because I think that the term "zero-eigenvalue bifurcation" is hardly used by itself (in constract to more complicated phenomena like the "double zero-eigenvalue bifurcation", used as a synonym for "Bogdanov-Takens bifurcation"). But if you want to create a redirect, be my guest. -- Jitse Niesen (talk) 13:07, 20 May 2006 (UTC)

p-adic numbers notation
A debate is in progress at Talk:P-adic number about whether p-adic numbers should be written from right to left or from left to right. The article used to use the right-to-left notation, but was recently rewritten with the left-to-right notation. Contributions to the debate from a wider pool of wiki mathematicians would be helpful, to see if we can reach a concensus. Gandalf61 08:21, 16 May 2006 (UTC)


 * Okay, after some discussion on its talk page, I have now changed the p-adic number article to consistently use the right-to-left notation, but with a new section that mentions other alternative notations. Any comments on the partial re-write are welcome at Talk:P-adic number. Gandalf61 09:34, 26 May 2006 (UTC)

Moore closure
I propose to delete the bits about Moore closure in the article Kuratowski closure axioms; see Talk:Kuratowski closure axioms. --Lambiam Talk 09:05, 16 May 2006 (UTC)

Fine topology (suggestion needed for better name)
I have created a new page on fine topology (as in classical potential theory), but as the title "fine topology" already seems to be taken by a page about general topology (i.e. 'finer topology' rather than "THE fine topology"), I have called my page "classical fine topology" - seems like there ought to be a better solution - any ideas? —The preceding unsigned comment was added by Madmath789 (talk • contribs).

(Copied from my talk page, I don't have a good answer to this. Oleg Alexandrov (talk) 23:30, 16 May 2006 (UTC))
 * Call the page Fine topology (potential theory) and use a
 * at the top of Comparison of topologies? Kusma (討論) 23:43, 16 May 2006 (UTC)
 * at the top of Comparison of topologies? Kusma (討論) 23:43, 16 May 2006 (UTC)

Thanks for that suggestion - I have renamed the page. In a similar vein, I am tempted to write 2-3 articles on the subject of 'thin sets' and 'polar sets' (as used in potential theory, subharmonic functions etc.) and find that these terms also link to pages mainly about set theory. Would it be sensible to call my new pages 'thin sets (potential theory)' etc. What do more experienced wikipedians think? Madmath789 10:10, 17 May 2006 (UTC)


 * Nothing links to Fine topology, so it might be better to turn this into a disambiguation page rather than redirect to Comparison of topologies, thereby avoiding an awkward disambiguation phrase in Comparison of topologies. Nothing links to Thin set either. --Lambiam Talk 11:07, 17 May 2006 (UTC)

Idea: when user clicks on an equation wikipedia explains it
Sorry if this is the wrong place / its already been suggested (I searched :-\), please direct me to the right place if here is incorrect (or tell me its not a worthwhile idea if you think so). This is a suggestion that when a equation is displayed (for example the one on this page) the user can click on the equation and is taken to a special page that explains the contents of the equation and what it means.


 * OK, let's try it:


 * $\int_0^\infty 1\,dx.$


 * Weird! What I see is this:


 * UNIQ5f19c7bc44ccc704-math2f6e29f1133d184200000001


 * What I "should" see is this:


 * $$\int_0^\infty 1\,dx.$$


 * When I click on it, it takes me to the right place.


 * Is this browser-dependent? Michael Hardy 01:50, 20 May 2006 (UTC)
 * You are seeing artifacts of one of the intermediate interpretation passes that mediawiki does during math markup. When all goes well (e.g. properly formed or properly messed up math syntax) you'll either see the math, or some nice error note. If something unexpected happens (e.g. math in links, math in image captions, etc) then mediawiki will mysteriously dump out that garbage. Basically, you're causing an error that isn't specifically handled by the markup engine, so it gets confused. It's totally browser-independent.


 * As for the suggestion, I think such a thing would overly burden the database and the authors. It sounds like you're suggesting that a new page be created to explain every equation. That's a lot of new pages to store, and a lot to write. That style of writing probably wouldn't be very popular, since most of us are used to explaining equations in neighboring text. Plus, it would be quite a large programming task to add that functionality into mediawiki. Staecker 02:07, 20 May 2006 (UTC)


 * Ahh no I meant something automatically generated. By definition a mathmatical equation is exact and parsable by a computer. It will be a bit of work by someone to make it function, but I thought I'd put it out there as an idea.
 * In the page I referenced above, the reason for the equation is explained, but at the level of someone who understands equations already, not to someone who has no idea what the $$\sum$$ means. I thought it would make wikipedia more accessible to non maths experts and require the time of one developer (and not the time of every maths editor).
 * See User:RickiRich%5CMath_Example for an example of what I think could be programatically created, and a description of How it could be created without too much fuss. After exams I'll have a go at this if no one else has.
 * --RickiRich 01:01, 22 May 2006 (UTC)


 * I don't think this is a good idea, I doubt it will get used by anybody if it gets implemented, and I doubt the developers will ever bother implementing that. You should at least get some support for this feature before you decide to do anything about it. But again, I don't think this wil lead anywhere. Oleg Alexandrov (talk) 04:07, 22 May 2006 (UTC)


 * What Oleg said. Dysprosia 06:31, 22 May 2006 (UTC)


 * I think it won't work. A significant obstacle is that mathematical symbols can have many different meanings, and a computer just ain't smart enough to distinguish which one you mean. For example, the + symbol could mean addition, or it could mean the span of two vector spaces, or the concatenation of two strings, etc. So much depends on context. (Also you probably wanted a forward slash in the title of that page, not a backslash. See Subpage.) Dmharvey 21:43, 24 May 2006 (UTC)


 * Intriguing idea, but I don't think its right for wikipedia. There have been some development along similar ideas both MathML and OpenMath formats have had some aspect of representing the meaning of an equation rather that its purely visible representation. OpenMath in particular has seen a lot of work with people developing Content Directories which are domain specific collections of mathematical definitions. There has been numerous papers on the subject, but I don't think its gained much acceptance apart from as a means of converting from one computer algebra system to another. In the wikiworld Semantic MediaWiki is a wikipedia extension which allows some form of semantic markup.
 * Why its not right for Wikipedia: basically the wiki concept follows KISS principle (Keep it simple stupid) and this sort of system gets rather complex. Hopefully all the relevant terms should be linked in the text anyway. --Salix alba (talk) 22:17, 24 May 2006 (UTC)

Massive edits foil comparison operation in article history
Sometimes an editor goes thru an article and changes many minor things at once. For example: spelling corrections; deleting unneccessary spaces; replacing & alpha ; with α; etc.. When this is done, the function which shows changes in the history often fails. It may begin matching an old paragraph to the wrong new paragraph and then it never gets back in synch (until one reaches a section header, if that was not changed). Of course, this makes it very difficult to check that the change was done appropriately.

I think that it is probably impractical to correct this bug in the comparison. So I am suggesting that you-all try to avoid this situation in the first place. When you do such massive edits, please first do every other paragraph (to allow the software to get back in synch with an unalterred paragraph). Then do a separate edit to change the remaining paragraphs. Thank you. JRSpriggs 06:06, 20 May 2006 (UTC)


 * I think you'll need to provide a concrete example of this happening. Dysprosia 09:39, 20 May 2006 (UTC)

The most recent occassion on which this happened to me was in the 18 May 2006 edit of Constructible universe by UkPaolo, called clean up +spelling correction using AWB. See http://en.wikipedia.org/w/index.php?title=Constructible_universe&diff=53858793&oldid=53818751 and scroll down to the section named "L is absolute and minimal". JRSpriggs 09:05, 21 May 2006 (UTC)


 * For this example it would have helped if the diff algorithm ignored blank lines, that is, tried to match up the two versions after filtering out the blank lines (which should be re-inserted for the final presentation). I suppose there is a backlog of all kinds of wishes for the developers, and I don't know how important this really is, but it is relatively simple to implement. --Lambiam Talk 18:48, 21 May 2006 (UTC)


 * I think that the problem is more difficult than Lambiam thinks it is. In the section to which I referred, the only blank line was the next to last paragraph.  Yet the mismatching of paragraphs began at the first paragraph in the section.  Apparently the diff-software cannot measure the similarity of the contents of two paragraphs until after it has decided irreversably that they are matching paragraphs.  That matching of paragraphs appears to depend only on whether they are identical, followed by interpolation (guessing) between identical pairs of paragraphs. JRSpriggs 07:12, 22 May 2006 (UTC)
 * Blank lines were removed in the edit following each and every section title. This doesn't show up clearly in the diff, but start an edit on both versions and compare the contents of the edit boxes, and it will be obvious. If then the next paragraph is also modified, the diff algorithm can't line them up. The silly thing in this massive edit is that many of the changes have no substance and consist of replacing two spaces after a full stop by a single space. --Lambiam Talk 10:06, 23 May 2006 (UTC)


 * You may want to mention this on Village pump (technical) or check the bugZilla where there are currently 93 bugs related to the diff. In this case the edit summary gives some clue, the edits were done using the WP:AWB tool, they are mainly minor edits and it would be hard to break this up into smaller edits, by limitations of the software.  --Salix alba (talk) 07:16, 23 May 2006 (UTC)


 * The problem is apparently caused by a feature of AWB, "Apply general fixes", which removes "excess white space" to which the diff algorithm is sensitive (AutoWikiBrowser). --Lambiam Talk 10:15, 23 May 2006 (UTC)

resolve a revert war at dual space
I find myself in a revert war at the article dual space. It's mostly about style; how much information is too much, whether material looks good or fits. this diff shows the difference between the two users preferred revisions. See also this old version for a much longer revision that I reverted. I am pessimistic with how talks on the talk page are going. We seem not to see eye-to-eye. I would like to get some more opinions. -lethe talk [ +] 04:42, 23 May 2006 (UTC)

Compound Poisson process question
Probabilists out there, I wonder if you could answer a question posted at Talk:Compound Poisson process. Oleg Alexandrov (talk) 17:25, 24 May 2006 (UTC)


 * looks right to me. (and the changes i made were mostly cosmetic.) Lunch 19:10, 24 May 2006 (UTC)
 * I added a final line to the moment generating function calculation, which should clarify matters further. The variance result looks OK, by computing them in terms of the moment generating function.  &mdash; Arthur Rubin |  (talk) 20:27, 24 May 2006 (UTC)

Looks OK to me, too. Michael Hardy 21:17, 24 May 2006 (UTC)


 * ... and generally, the nth cumulant of the compound Poisson distribution, following the notation now in the article, is &lambda;t times the n moment of the distribution of the random variable that the article (in its present form) calls Di. This can be shown via the law of total cumulance.  The cases n = 1 and n = 2 are just what now appears in the article. Michael Hardy 21:20, 24 May 2006 (UTC)

Widespread mathematical delusions
I'd like to hear some opinions about the new article Widespread mathematical delusions. At the moment, the article lists only one delusion, and I am not sure what the delusion actually is, but it has something to do with statistical independence. In fact, the article Widespread mathematical delusions criticizes the lead section of statistical independence. Can somebody make sense of the new article?

The user who created the article has also written some articles on eventology, a theory which I haven't heard about. The article on eventology lists ten references, all by the same author, including some papers in good Russian journals so we might want to keep the article even though it violates the Vanity guidelines. -- Jitse Niesen (talk) 05:12, 25 May 2006 (UTC)


 * 0.999... ≠ 1 must be pretty widespread. And misconceptions about infinity are pretty common.  -lethe talk [ +] 06:58, 25 May 2006 (UTC)


 * I can't make much sense out of this rant. The "intuitive" meaning offered in the article Statistical independence appears to me to be an informal way of saying P(B|A) = P(B). Using the standard definition of conditional probability, this means P(A ∩ B)/P(A) = P(B), or P(A ∩ B) = P(A) P(B), in other words: events A and B are independent. Where is the delusion? There is no shortage of delusions, including mathematical ones, and the field of statistics and probability theory is particularly rich, but this doesn't seem to be one of them. Its like having a diatribe against saying that 1 < 2 means that 1 is less than 2, while it means nothing except "1 < 2". To AfD? --Lambiam Talk 11:16, 25 May 2006 (UTC)


 * I find it hard to understand exactly what this guy is ranting about, mainly because of the poor translation of his thoughts (presumably from Russian) into English. His maths seems to be correct, but only seems to show that conditional probability can be different in different situations. If this page is to be kept, it surely needs a different title? (and a lot of work on wording) I cannot believe that this really is a *widespread* delusion Madmath789 11:46, 25 May 2006 (UTC)


 * Whatever else it it is, it is surely OR. Paul August &#9742; 11:51, 25 May 2006 (UTC)


 * The delusion consists in popular attempts to justify or to prove or to deduce the definition of independence of events: P(AB)=P(A)P(B) from other assumptions. Mathematical definitions do not demand proofs, especially in a preamble to encyclopaedic paper on probability theory. The criticism is directed only on style of a preamble. All other sections of paper “Statistical” are quite correct. Thanks for discussion. - Helgus 12:28, 25 May 2006 (UTC)


 * Helgus: I think you misunderstand what the lead section (what you are calling the "preamble") of Statistical independence, is saying. It is not trying to "prove the definition" rather it is simply trying to provide an intuitive understanding of the concept. In any case any criticism of that article belongs at talk:Statistical independence not in some other article.  Paul August &#9742; 15:52, 25 May 2006 (UTC)


 * Probably you are right. Especially it concerns the second section of paper. However the first section without doubts keeps within a well-known encyclopaedic category “Paradoxes in mathematics”. Russian mirror of this paper contains, for example, popular delusions which often meet at discussion on “Fermat's last theorem”, “Parallel lines in Lobachevsky's geometry”, “Events with zero probability”. Can be it is necessary to open a new category “Paradoxes in mathematics” into which this paper could enter? - Helgus 21:58, 25 May 2006 (UTC)


 * Yes AfD unless its moved to a different name and cleaned up to be less like Orignial Research, give it a bit of time though the page is less than a day old.


 * Also the eventology page is now proposed for deletion, although the other sub articles and the category are not. Either it should be all or none and I think AfD might be better than prod in this case. --Salix alba (talk) 12:58, 25 May 2006 (UTC)


 * If the page is to be kept, it should probably be renamed -- "delusions" is not quite neutral, perhaps "misconceptions" would be better. Dysprosia 13:03, 25 May 2006 (UTC)

The eventology pages look suspicious to me. The only reason I created Category:Eventology is too keep them all in one place. I agree that an AfD vote on all of them could be the things to do. Oleg Alexandrov (talk) 15:37, 25 May 2006 (UTC)

It really is OR and a rant. The title reads pretty bad as well, it probably should be deleted.--Jersey Devil 17:37, 25 May 2006 (UTC)

I've removed the prod tag from eventology, If we are to believe the references there, it isn't OR, although it may be non-notable. So I agree with Jitse's, I'm not sure we should delete this. Paul August &#9742; 18:09, 25 May 2006 (UTC)
 * But User:Helgus is Oleg Vorob'ov, the author of 10 out of 11 of the references. Sounds like OR to me. Staecker 02:44, 26 May 2006 (UTC)
 * No, OR means writing about something which has not yet been published elsewhere. Paul August &#9742; 02:48, 26 May 2006 (UTC)
 * You're right- sorry, I confused it with WP:AUTO. Not surefire grounds for deletion, but it gives me the willies. Staecker 02:57, 26 May 2006 (UTC)


 * Yes writing about your own work is problematic. And we should take special notice of such. Paul August &#9742; 17:10, 26 May 2006 (UTC)


 * eventology, but not sub-pages now on AfD. --Salix alba (talk) 10:45, 28 May 2006 (UTC)

Lebesgue spine
Being a newcomer here, I would appreciate some brief advice: Lebesgue spine is listed somewhere as a missing link, but when I look at 'what links here', I only find things like Missing science topics/Maths16. I could write a page about the Lebesgue spine, but would it be any use? Madmath789 20:35, 25 May 2006 (UTC)
 * Sure it would be useful. Paul August &#9742; 02:45, 26 May 2006 (UTC)

Non-negative v. nonnegative
OED lists "non-negative" but Webster's lists "nonnegative". Is this a British/American usage split? I've looked through a few textbooks, but there doesn't seem to be any particular consistency (not all American books use "nonnegative" and not all European ones use "non-negative"). Any opinions? There seems to be a mix among Wikipedia articles (even within a single article) and titles. Thanks. Lunch 22:05, 25 May 2006 (UTC)


 * I use either when the mood strikes me. If there's no standard, what's the difference? Ryan Reich 22:39, 25 May 2006 (UTC)


 * I s'pose I was thinking consistency would make things easier to find, and any source I found was always self-consistent whereas the Wikipedia isn't. And now that I look through the textbooks sitting in front of me, four have "nonnegative" (five American authors) and only one has "non-negative" (two Frenchmen).  Lunch 23:11, 25 May 2006 (UTC)


 * In my experience, in American papers and textbooks "nonnegative" is by far the most common. Older works may use "non-negative" to a greater frequency. --C S (Talk) 01:52, 27 May 2006 (UTC)

Stone-Cech compactification name
Most of the references I've seen have a symbol over the "C", which I can't figure out exactly how to generate. (Also, there seems to be a convention that the "-" should be replaced by an n-dash "–".) &mdash; Arthur Rubin |  (talk) 00:28, 26 May 2006 (UTC)


 * How about this: Čech? Dmharvey 02:51, 26 May 2006 (UTC)
 * When I open an edit window, below the Save page button is a box that says "Insert:", followed by numerous special characters. The character in question is one of them, and clicking on it causes it to be inserted into the edit box. JavaScript must enabled in the browser for this to work. --KSmrqT 03:52, 26 May 2006 (UTC)


 * What a mess. We have Stone-Cech compactification and Stone-Čech compactification, and Čech points to neither, and probably we need Cech as a redirect as well. Dmharvey 02:56, 26 May 2006 (UTC)
 * Hm, apparently the redirect at Stone-Čech compactification is my fault; don't really remember doing it. Stone-Cech compactification should be moved to Stone-Čech compactification, but it won't let me move it because the redirect is to a different place. I'll tag the redir for speedy. --Trovatore 03:05, 26 May 2006 (UTC)
 * OK, fixed now. This time the endash thing came in handy. --Trovatore 03:12, 26 May 2006 (UTC)

How about Štone-Cech compactification? :-) -lethe talk [ +] 04:01, 26 May 2006 (UTC)
 * Added. Hey, you never know. --Trovatore 22:34, 26 May 2006 (UTC)

Maths AfDs
A certain User:Mathguru has AfD'd Quasi-Hopf algebra and Quasi-bialgebra. I think it is notable, but as the author, I may be biased.Blnguyen | Have your say!!! 06:39, 26 May 2006 (UTC)


 * I'm a hair away from closing them both speedy keep. -lethe talk [ +] 10:48, 26 May 2006 (UTC)


 * Too late now ... I closed them. -- Jitse Niesen (talk) 12:00, 26 May 2006 (UTC)

well, mathguru, Afd' the Australian Mathematics Competition as well.Blnguyen | Have your say!!! 08:00, 31 May 2006 (UTC)


 * Also closed as a speedy keep. -- Jitse Niesen (talk) 08:36, 31 May 2006 (UTC)

A query
Does anyone have a reference or proof for Kronecker's lemma? This has been bothering me, mainly in case absolute convergence of &Sigma; xn ought to be included. Charles Matthews 13:07, 26 May 2006 (UTC)


 * I think the statement is true as is stands, but I don't have a reference. Using summation by parts,
 * $$\frac1{b_n}\sum_{k=0}^n b_k x_k = S_n - \frac1{b_n}\sum_{k=0}^{n-1}(b_{k+1} - b_k)S_k,$$
 * where $$S_k$$ are the partial sums of the x's. Pick any epsilon > 0, choose N so that $$S_k$$ is epsilon-close to s for k > N. Then the right hand side is
 * $$S_n - \frac1{b_n}\sum_{k=0}^{N-1}(b_{k+1} - b_k)S_k - \frac1{b_n}\sum_{k=N}^{n-1}(b_{k+1} - b_k)S_k$$
 * $$= S_n - \frac1{b_n}\sum_{k=0}^{N-1}(b_{k+1} - b_k)S_k - \frac1{b_n}\sum_{k=N}^{n-1}(b_{k+1} - b_k)s - \frac1{b_n}\sum_{k=N}^{n-1}(b_{k+1} - b_k)(S_k - s)$$
 * $$= S_n - \frac1{b_n}\sum_{k=0}^{N-1}(b_{k+1} - b_k)S_k - \frac{b_n-b_N}{b_n}s - \frac1{b_n}\sum_{k=N}^{n-1}(b_{k+1} - b_k)(S_k - s)$$
 * Let n go to infinity. The first term goes to s, which cancels with the third term. The second term goes to zero. Since the b sequence is increasing, the last term is bounded by $$\epsilon (b_n - b_N)/b_n \leq \epsilon$$. Dmharvey 13:41, 26 May 2006 (UTC)


 * Now transcribed to that controversial category Category:Article proofs. linas 01:43, 13 June 2006 (UTC)

Indiscriminate collection of information?
Don't pages like this, Derivative (examples), break with WP:NOT?--Jersey Devil 02:32, 27 May 2006 (UTC)


 * I have put it up for afd, your input would be appreciated.--Jersey Devil 02:36, 27 May 2006 (UTC)

Mathematics is Article Improvement Drive collaboration
Ladies and Gentlemen! Did you know that the article Mathematics is the current Article Improvement Drive collaboration? --Lambiam Talk 22:40, 27 May 2006 (UTC)
 * Voted for it on the AID page. One user commented that it is in the top ten most viewed pages on Wikipedia and therefore must be a featured article.--Jersey Devil 23:01, 27 May 2006 (UTC)

Eventology AfD
The article Eventology (by the same author as Widespread mathematical delusions) has been nominated for deletion. --Lambiam Talk 13:21, 28 May 2006 (UTC)

Delusions in probability theory and statistics on AfD
I've nominated the article Delusions in probability theory and statistics (earlier called Widespread mathematical delusions) for deletion. --Lambiam Talk 22:31, 28 May 2006 (UTC)

Disambiguation of sinc function
There are two possible definitions of the sinc function, namely
 * $$\operatorname{sinc} \, x = \frac{\sin x}{x} \quad\mbox{or}\quad \operatorname{sinc} \, x = \frac{\sin \pi x}{\pi x}. $$

One possible way to handle this is to split the article sinc function in two, sinc function (normalized) and sinc function (unnormalized), similar to the usual disambiguation process. We are having a discussion on Talk:Sinc function (unnormalized) whether this is the proper way to go about it, and I'm solliciting others to join. -- Jitse Niesen (talk) 05:21, 31 May 2006 (UTC)

Possible confusion over 'subadditive'
There is an article Subadditive which discusses functions satisfying $$f(x+y)\leq f(x)+f(y)$$, and there is a link to this article from Sigma additivity in the category measure theory. There seems to be a different definition of 'subadditive' (and also 'countably subadditive') in use in measure theory:


 * $$\mu(E \cup F) \leq \mu(E)+\mu(F)$$

(used in developing the theory of 'outer measure'). My question is: do we need a separate page for subadditve set functions, or should we incorporate it into the existing subadditive page? (Or are subadditive set functions not notable and we do not need them?). I might be in a position to write something on the set function version of subadditive (if needed), but would appreciate some views about what might be done - and there are probably others better qualified to write such stuff anyway.Madmath789 11:27, 31 May 2006 (UTC)


 * I think you're right, subadditive (measure theory) deserves its own article. I don't know any measure theory, but I recall there being interesting theorems about set functions which are additive (on finite collections of sets) and countably subadditive. Dmharvey 11:37, 31 May 2006 (UTC)

Be bold! Write stuff, we move and fix later. Charles Matthews 11:46, 31 May 2006 (UTC)

Barry Simon article
The piece on Barry Simon is from a fan, it seems. Important guy for mathematical physics, and this should be better expressed and sourced, and have more technical stuff about the work. Charles Matthews 11:46, 31 May 2006 (UTC)
 * A good example of hagiography I guess. --CSTAR 18:54, 1 June 2006 (UTC)