View source for Wikipedia talk:WikiProject Mathematics/Archive/2006/Jun

{{WikiProject Mathematics archive list}}

==[[E9 (Lie algebra)]]==
My knowledge of Lie algebras is a single course, but this potentially confusing notation was never mentioned. Has anyone else heard of this? [[User:Pmanderson|Septentrionalis]] 18:40, 1 June 2006 (UTC)

:I have never heard of this notation.  I note that my references list the notation as ''E''<sub>8</sub><sup>(1)</sup>.  The subscript here is, as always, the rank. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 18:51, 1 June 2006 (UTC)

== Please review ==

I have extensively revised and cleaned up [[Divisibility rule]], so please take a look and help to improve it more.  As I'm not fully experienced at all the editing tools, I'm sure the formatting and adherence to guidelines and standards could be improved.

I'd like to create a number of other pages related to mental math, so I'd like to get feedback on this one, the first I've heavily edited.  (The current [[mental arithmetic]] has only the most basic, simple of techniques.

[[User:Wroscel|Walt]] 01:59, 2 June 2006 (UTC)

==[[:Category:Billion]] and cousins up for deletion==

See [[Wikipedia:Categories_for_deletion#Category:Thousand]]. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 18:57, 3 June 2006 (UTC)

== [[Poincaré conjecture]] ==

Some Chinese news sources have picked up a story about a recent journal article by Cao and Zhu, experts on the Ricci flow, who have written what they (and the journal editors) claim is a "complete" proof of the geometrization conjecture, by giving more details of Perelman's work.  Slashdot has also picked up on this.  As a consequence, there has been several editors who have insisted on placing mention of Cao and Zhu's paper in the lead section.  I have disagreed (see talk page discussion and also some of my edit summaries for extensive reasons).  Please continue discussion there.  I would also appreciate if people could pop in and check that things don't get out of control.  Thanks.  --[[User:C S|C S]][[User talk:C S| (Talk)]] 02:15, 6 June 2006 (UTC)

== American Institute of Mathematics ==

The article on [[American Institute of Mathematics]] has been [[Wikipedia:Articles for deletion/American Institute of Mathematics|nominated for deletion]] by someone. [[User:R.e.b.|R.e.b.]] 13:02, 6 June 2006 (UTC)

== PlanetMath Exchange project milestone ==

The [[Wikipedia:WikiProject Mathematics/PlanetMath Exchange|PlanetMath Exchange]] project has today reached a new milestone, with 40% of all PlanetMath articles reviewed.

For those of you who have not been following the project, I thought I would take this opportunity to report on the status of the project, and the progress which has been made to date. The purpose of the project is to review all PlanetMath (PM) articles (which are licensed under [[GFDL]]) and to incorporate any appropriate PM content not adequately covered on Wikipedia (WP).

There are over 4800 PM articles listed, of which over 1900 of which have been reviewed so far. Of the reviewed articles, 143 PM articles have been copied to WP, creating entirely new WP articles,  and 121 have been merged into already existing WP articles. Additionally, a further 75 PM articles have been identified as needing to be copied, and 349 needing to be merged.

The project maintains 49 lists of PM articles grouped by topic (e.g. [[Wikipedia:WikiProject Mathematics/PlanetMath Exchange/11-XX Number theory|11 Number theory]], [[Wikipedia:WikiProject Mathematics/PlanetMath Exchange/26-XX Real functions|26 Real functions]], [[Wikipedia:WikiProject Mathematics/PlanetMath Exchange/54-XX General topology|54 General topology]]). The entire list of lists is compiled into a [[Wikipedia:WikiProject Mathematics/PlanetMath Exchange#Table|"Article lists" table]], and statistics are maintained for each topic's list.

19 editors have identified themselves as [[Wikipedia:WikiProject Mathematics/PlanetMath Exchange#Participants|participants]], and 26 have reviewed at least one PM article (see [[Wikipedia:WikiProject Mathematics/PlanetMath Exchange#Editor contributions|Editor contributions]]).

[[User:Oleg Alexandrov|Oleg Alexandrov]], has provided several excellent tools to facilitate the project. He and [[User:Mathbot| Mathbot]] created the original 49 lists (first created in Feb 2005, and updated with new PM articles in March 2006). They also perform daily updates of statistics in the "Article lists", and "Editor contributions" tables. In addition, Oleg has created a convenient [http://www.math.ucla.edu/~aoleg/pm/pm.html tool] to assist in converting a PM article to wiki markup.

I heartily encourage everyone to join the fun.

[[User:Paul August|Paul August]] [[User_talk:Paul August|&#9742;]] 02:06, 8 June 2006 (UTC)

== [[Direct logic]] up for deletion ==

See [[Wikipedia:Articles_for_deletion/Direct_logic]] -Dan 15:36, 8 June 2006 (UTC)

== Another misguided nomination for deletion ==

Please vote at [[Wikipedia:Articles for deletion/American Institute of Mathematics]]. [[User:Michael Hardy|Michael Hardy]] 23:33, 9 June 2006 (UTC)
:Yeah, R.e.b. told us already. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 00:48, 10 June 2006 (UTC)
::I closed that AfD. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 00:54, 10 June 2006 (UTC)

== Functional analyst needed ==

Hi, I left a question regarding the correct statement of the [[Ryll-Nardzewski fixed point theorem]] at [[Talk:Ryll-Nardzewski fixed point theorem]]. Cheers, [[User:AxelBoldt|AxelBoldt]] 04:10, 11 June 2006 (UTC)
:As stated it's wrong. The semigroup is  required to satisfy another property, that it be "distal". Also I don't think it can be used to prove existence of Haar measure on general locally compact groups, although I think for compact groups yes.  I think this is in Rudin's functional analysis book for instance.  Also see Frederic Greanleaf's little book (now horribly outdated) on "Amenable Groups".--[[User:CSTAR|CSTAR]] 12:41, 12 June 2006 (UTC)

== Rewrite  [[Poincaré_conjecture]]? ==

I invite interested parties to make comments at [[Talk:Poincaré_conjecture#Peer_review]].  --[[User:C S|C S]][[User talk:C S| (Talk)]] 12:48, 11 June 2006 (UTC)

== [[Jaques Hadamard]] or [[Jacques Hadamard]]? ==
An anon recently redirected the wikilink in [[Chaos Theory]] from the first to the second.  Is this legitimite?  Are these the same person?  &mdash; [[User:Arthur Rubin|Arthur Rubin]] |  [[User_talk:Arthur_Rubin|(talk)]] 15:30, 11 June 2006 (UTC)

:Yes, same person. Correct spelling is ''Jacques'' [http://www-history.mcs.st-and.ac.uk/~history/Biographies/Hadamard.html]. I have changed the ''Jaques'' page to a redirect and fixed the link in the single remaining article that used the wrong spelling. [[User:Gandalf61|Gandalf61]] 15:53, 11 June 2006 (UTC)

== [[Zipper theorem]] ==

I wanted to {{tl|prod}} this article. But to be sure I thought I'd check. Is this article nonsense or not? I couldn't google the name, but that doesn't always mean anything. [[User:Garion96|Garion96]] [[User_talk:Garion96|<sup>(talk)</sup>]] 00:20, 12 June 2006 (UTC)
:The theorem and its proof in the article are correct. The theorem was not known to me under this or any other name. --[[User:Lambiam|Lambiam]][[User talk:Lambiam|<small><sup>Talk</sup></small>]] 00:53, 12 June 2006 (UTC)
:: Thanks, so I won't {{tl|prod}} it. Anyone here wants to clean that article up? Cause the way it looks now, it's not understandable for the non mathematician reader. Like me. :) [[User:Garion96|Garion96]] [[User_talk:Garion96|<sup>(talk)</sup>]] 12:04, 12 June 2006 (UTC)
:: Hmm, perhaps I should have looked at at the article again. It already is cleaned up. Thanks. [[User:Garion96|Garion96]] [[User_talk:Garion96|<sup>(talk)</sup>]] 12:05, 12 June 2006 (UTC)
::: I think it's a neologism. I think it should be deleted without some evidence of that name having widespread currency. [[User:Dmharvey|Dmharvey]] 12:15, 12 June 2006 (UTC)
::: I've heard it referred to in that way ("zipper theorem"); dunno if that's enough evidence for you.  I also can't think offhand of a place I've seen it in print, though.  I could ask around.  [[User:Lunch|Lunch]] 18:53, 12 June 2006 (UTC)

I'm skeptical that the name is very common.  I can't imagine the theorem would even have a name amongst mathematicians.  So I think the term would only be used in certain kinds of introductory course work.  Google gives no results (off Wikipedia), so nobody that has mentioned it, for example, in a course webpage.  The only place I can think the term may exist is in some textbooks somewhere.  Even in that eventuality, I don't know if it's worth having an article based on that amount of usage.  I guess it does no harm, but I'm also hard-pressed to imagine a situation where we would want to link to it.  --[[User:C S|C S]][[User talk:C S| (Talk)]] 19:18, 12 June 2006 (UTC)

:Merge it into [[Limit of a sequence#Properties]]?  —[[User:Blotwell|Blotwell]] 17:01, 13 June 2006 (UTC)

::I've asked a few people around, and none other than me have heard this result referred to as the zipper theorem.  I guess it's not as popular a term as I thought.  Maybe zipper lemma instead?  ;)  Maybe it'd qualify for a list of some sort of elementary properties of limits; if not, maybe stick it in the article on limits.  BTW, this theorem is true for any metric space, but is it true for non-Hausdorff spaces?  How much can the requirements of the theorem be relaxed?  [[User:Lunch|Lunch]] 21:57, 20 June 2006 (UTC)

::: The exact same proof, translating epsilons into open sets, proves it in every topological space.  This result has about the same significance as, say, the linearity of differentiation, and should probably go in a [[list of limits]] like the [[list of derivatives]]. [[User:Ryan Reich|Ryan Reich]] 22:48, 20 June 2006 (UTC)

::::Sure, a list of limits article would be a good idea.  And I guess you can just replace balls with neighborhoods; I think I was confusing myself with the non-uniqueness of limits in non-Hausdorff spaces.  [[User:Lunch|Lunch]] 23:33, 20 June 2006 (UTC)

:::::Sorry if I was curt with that reply.  I'll be happy to put together a basic [[list of limits]].  Actually, following the model of the [[list of derivatives]], there isn't any need to touch [[zipper theorem]], just link to it from the list.  Unless we really don't like it for some reason. [[User:Ryan Reich|Ryan Reich]] 00:22, 21 June 2006 (UTC)

::::::looks good!  [[User:Lunch|Lunch]] 17:58, 22 June 2006 (UTC)

== integrable systems ==
Over at [[Talk:Constant of motion]], I've been reduced to babling and waving my hands to the effect that a "system of differential equations with constants of motion == integrable system == system with symmetries" and conversely, "non-integrable system == system with no constants of motion".  However, it occurs to me that I know of no grand theorems making this claim. Are there any?  Is this in fact a collection of small results in narrow fields that have accreted into a grand truth? Guidance? How can one make this clear at a college-math level? It doesn't help that the article [[integrable system]] is somewhat foreboding in its current form. [[User:Linas|linas]] 01:30, 13 June 2006 (UTC)

:Maybe I'm being lame? Maybe its just the [[Frobenius theorem]] coupled to the idea that the submanifold has a natural symmetry, ergo by [[Noether's theorem]] has constants of motion? I've never had formal skoolin in this matter. [[User:Linas|linas]] 03:13, 13 June 2006 (UTC)

::I think I'm grasping for [[Liouville's theorem (Hamiltonian)]]. I swear this stuff goes in one ear and out the other. I'm babbling even now. [[User:Linas|linas]] 03:27, 13 June 2006 (UTC)

You make a good point about the current article being somewhat forbidding.  I would go a step further.  I don't think [[integrable system]] should redirect to [[integrability conditions]].  An integrable system usually (?) refers to a [[Hamiltonian system]] with a full set of Poisson-commuting flows.  Naturally, integrability conditions do play a role, but there is more structure a priori in an integrable system.  For the point about conserved quantities for an integrable system, since the Hamiltonian flows commute, there should be loads of conserved quantities.  (As you ask, is there a general theorem here? Does Noether apply? etc).  Hence a system without "enough" conserved quantities will be non-integrable.  I'm not so sure about the converse.  [[User:Silly rabbit|Silly rabbit]] 13:15, 13 June 2006 (UTC)

:Thanks. What I've been reading gives the name '''completely integrable system''' to the case of a full set of commuting Poisson brackets. Your "not being sure about the converse" would imply that there are non-integrable systems with a "full set" of conserved quantities. That certainly sets my mind wandering in wild directions. [[User:Linas|linas]] 23:27, 16 June 2006 (UTC)

:Nice start on [[integrable system]]s.  It certainly has helped me organize some of my own wild wanderings.  I'm clearly not an expert, but it seems to be tricky to give a good definition of an integrable system.  (Ok, so first off, yes I meant what you call completely integrable: which is unarguably a better term ;)  In particular, there are issues of local versus global integrability.  What does global integrability mean anyway?  Do the all the level submanifolds have to be closed?  Do the constants have to be found explicitly, or can they just be given in some implicit sense?  Can a locally completely integrable system have degenerate Poisson brackets on some small dimensional locus, and still have functionally independent integrals?  (Here is the "lack of converse" possibility -- if it exists to begin with.)  [[User:Silly rabbit|Silly rabbit]] 23:37, 17 June 2006 (UTC)

::Thanks. I'd say a Lie group is the prototype for something that is "globally integrable". I don't know of any systems that are "provably integrable" (constants of motion implicitly given), but whose solution is unknown (no explicit form). I suspect one can find level manifolds that are not closed, certainly things like the [[horocycle flow]] ( aka [[Anosov flow]] on tangent space of SL(2,C)) has the flavour of being non-compact but this is an off-the-cuff remark. I believe that the whole area of [[sub-Riemannian geometry]] is permeated with integrable systems that have cuts and isolated singularities and the like. Next, chaotic systems have "regimes" of regular and chaotic motion that's interspersed; the [[KAM torus]] being the famous example, although the easy-to-understand variants are in [[difference equations]]. Then there's all this stuff about [[homoclinic orbit]]s, and stuff like [[Axiom A]], which I dimly understand. Or things I dont:[http://planetmath.org/?op=getobj&from=objects&id=5990 Smale's spectral decomposition theorem]. I'm sort of learning this stuff as I go along.[[User:Linas|linas]] 04:57, 18 June 2006 (UTC)

== Mathematicians for Wikipedia:Version 0.5 Nominations ==

On [[Wikipedia talk:WikiProject Mathematics/Wikipedia 1.0]] there is a request for the most notable mathematicians whos biographies could be included in [[Wikipedia:Version 0.5 Nominations]]. Suggestions for celebratity mathematicians welcome. Possible also assesments of the quality of their article also welcome. --[[User:Salix alba|Salix alba]] ([[User talk:Salix alba|talk]]) 07:45, 15 June 2006 (UTC)
:Thanks to great work by [[User:Lethe|Lethe]] we now have a fairly comprehensive list of the the giants for mathematics on [[Wikipedia:WikiProject Mathematics/Wikipedia 1.0|Mathematics/Wikipedia 1.0]]. A new template [[Template:maths rating]] has also been created together with a set of categories listing the quality and importance of mathematics articles. Mathbot will included these articles in [[Wikipedia:Version 1.0 Editorial Team/Mathematics articles by quality]] on a daily basis. Help is now needed in identifying the important maths articles and assigning then a grade (Feature Article/A/Good Article/B/Start/Stub), which can be done by including the template on the talk page. There are a few biographies which may be suitable for listing as good articles and several other on some key figures which are barely more than stubs and could do with expansion.
:I'm also thinking that the list of mathematicians could make a good article in its own right, either as a section in [[Mathematicians]] or its own article, possible [[Influential mathematicians]]. --[[User:Salix alba|Salix alba]] ([[User talk:Salix alba|talk]]) 09:25, 16 June 2006 (UTC)
:: We already have [[list of mathematicians]], but I guess you are thinking of a selective subset. I don't know if it is worth its own article. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 15:37, 16 June 2006 (UTC)
:Yes I was thinking of a more selective list, probably anotated as well, briefly describing their main acheivments. It could be an interesting way to tell the history of mathematics through the people involved and the new areas of study they started. This sort of presentation, is quite popular in science books aimed at the general reader and might appeal to certain wikipedia readers. --[[User:Salix alba|Salix alba]] ([[User talk:Salix alba|talk]]) 20:20, 16 June 2006 (UTC)
::Well If you want a selective list one place to start would be Bell's ''[[Men of Mathematics]]''. [[User:Paul August|Paul August]] [[User_talk:Paul August|&#9742;]] 20:55, 16 June 2006 (UTC)
::: Might I also suggest the obvious web site, [http://www.gap-system.org/~history/Indexes/HistoryTopics.html MacTutor]? --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 04:53, 17 June 2006 (UTC)

== Probability/Measure theory glossary? ==

Does WP have a glossary that translates the language of [[probability theory]] to [[measure theory]]? I've got a complaint on my talk page that I'm trying to decipher; I don't understand [[Score (statistics)]] and [[Fisher information]], although I suspect I would, if they were restated in terms of measure theory.  The root of this interest is the rather astounding edit [http://en.wikipedia.org/w/index.php?title=Fisher_information&diff=48088906&oldid=48022218 here], which is so remarkable, I abstract it here:
:''Fisher information is a powerful new method for deriving laws governing many aspects of nature and human society. [[B. Roy Frieden]] sets out in detail how Fisher information can ground a great deal of contemporary [[physics|physical theory]], including [[Newtonian mechanics]], [[virial theorem]], [[statistical mechanics]], [[thermodynamics]], [[Maxwell's equations]], [[Lorentz transformation]], [[general relativity]], [[EPR experiment]], [[Schrodinger equation]], [[Klein-Gordon equation]], [[Dirac equation]], [[Rarita-Schwinger equation]], and the fundamental [[physical constants]]. Frieden and coauthors have also used EPI to derive some established principles and new laws of [[biology]], the [[biophysics]] of [[cancer]] growth, [[chemistry]], and [[economics]].''

Surely, the ommission of [[M-theory]] and [[intelligent design]] is just an oversight? [[User:Linas|linas]] 00:38, 17 June 2006 (UTC)

:See [[Talk:B._Roy_Frieden]] for a little bit of discussion and some links to external reviews of Frieden's work.  He has some interesting ideas but, it seems, not quite the revolution he makes out for himself.  The IP address of the edits is assigned to [http:/csc.canterbury.ac.nz Christchurch College of Education] in New Zealand.  Maybe Frieden's been travelling?  [[User:Lunch|Lunch]] 03:49, 17 June 2006 (UTC)

== user mathisreallycool ==

A new user {{user|mathisreallycool}} has made several edits which to my mind betray a fundamental lack of knowledge in certain mathematical topics.  I have reverted several additions by this user, and I want to vet some other things by the user.  For example, the article [[Konfisakhar space]] seems unobjectionable, it's referenced.  However I've never heard of this idea, it's not in any of my texts, nor is it in my EDM2, and frankly, I find the idea of a fractal vector space hard to believe.  Can someone (maybe with access to the book by Schaeffer) verify this concept?  Otherwise, I shall want to AfD is.  And maybe also [http://en.wikipedia.org/w/index.php?title=Semidirect_product&diff=prev&oldid=58863312 this] definition of semidirect products for monoids? -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 07:14, 17 June 2006 (UTC)
: A web search for Igor Konfisakhar suggests the work of a creative student, violating [[WP:NOR]]. The citation of the Schaeffer book is also not quite correct; the second edition ({{ISBN|978-0-387-98726-2}}) has two authors. I have no personal knowledge of the topic or the book, but I share your reservations.
: <small>PS: I've begun using 13-digit [[ISBN]]s, since the official transition is not far off. On online converter is [http://www.isbn.org/converterpub.asp available].</small> --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 10:40, 17 June 2006 (UTC)

::I've listed [[Konfisakhar space]] for deletion. "Professor Igor Konfisakhar" appears to be an undergrad, notable only for being a 3rd place winner in a Putnam prize contest, which is better 'n me but not good enough for this. [[User:Linas|linas]] 03:54, 18 June 2006 (UTC)
::I know Igor Konfisakhar personally (or did), and can confirm that he is (at present) an undergraduate. [[User:Tesseran|Tesseran]] 03:21, 19 July 2006 (UTC)

: The reference work listed is searchable online at Amazon (see [http://www.amazon.com/gp/product/0387987266/102-1711821-3179360?n=283155]). I  find no reference to "fractal" or "Konfisakhar". [[User:Paul August|Paul August]] [[User_talk:Paul August|&#9742;]] 04:35, 18 June 2006 (UTC)

== Problems at Propositional Calculus ==
:(''Copied from my talk page. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 07:51, 17 June 2006 (UTC)'')
JA: Hi, could you help sort out the continuing tangles at [[Propositional calculus]]?  First there was that improper name change last month, and I let it go because the user who did it seemed fairly competent and added some good stuff, but now the word "logic" seems to be inviting anonymous users to take the article out of the [[mathematical logic]] designation and add any sort of half-baked exposition that they can cook up.  I don't know my way around the procedures well enough to keep dealing with sort of stuff.  Much appreciated, [[User:Jon Awbrey|Jon Awbrey]] 05:15, 17 June 2006 (UTC)

:There had been some noise in the past about moving [[propositional calculus]] to [[propositional logic]] or [[classical propositional logic]].  The move to propositional logic was affected by Charles Stewart via [[WP:RM]] last month, then reverted by a history-destroying copy-paste by Jon Awbrey this week.  I reverted the copy-paste (restoring the history), then reverted the proper move (preserving the history), so now we're back where we started.  If the move is to happen, a case will have to be made again.  -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 07:59, 17 June 2006 (UTC)

== Use "iff", not "if", in definitions! ==

Some editors appear to believe that there is a convention which requires the use of "if" in definitions rather than "[[iff]]" (short for "if and only if"). A definition is a proposition which ''equates'' a new term to a compound expression composed of old terms. So using "if" is wrong. One should use "iff" or an equivalent, such as: "if and only if", "is", "is the same as", "means", "is equivalent to", "when and only when", etc.. [[User:JRSpriggs|JRSpriggs]] 08:20, 17 June 2006 (UTC)

:Though you are technically correct, I don't think it's such a problem to use just an "if" in a definition.  It's tedious to always write "if and only if" (and the abbreviation is esoteric), and the full meaning can always be inferred.  Of course to ''require'' "if" in definitions is certainly bad. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 08:29, 17 June 2006 (UTC)
::I am complaining because thrice recently someone has changed "iff" to "if" in a definition. [[User:JRSpriggs|JRSpriggs]] 10:03, 17 June 2006 (UTC)
:::If I saw that happen, I would probably revert. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 10:25, 17 June 2006 (UTC)

:::: Well, "if" is brief, commonly understood, and colloquial; "iff" is brief, ''not'' commonly understood, and precise. What to do? Personal, I dislike "iff", so I either write out "if and only if" or use a phrase like "exactly when". My feeling is that anyone who understands the meaning of "iff" and feels comfortable with it also has enough of that fabled "mathematical maturity" to not misinterpret a definition using "if". I am not aware of a WikiMath guideline, nor a Wikipedia guideline that speaks to this slightly delicate issue involving both accessibility and formal correctness.
:::: A recurring challenge with a multinational pool of editors is melding one's own training and taste with that of others. I cringe whenever I see the word "ditto" in an article, as to me it screams of informality, not suitable for an encyclopedia. I'd love to see both "iff" and "ditto" banned, but I have no sense of how much agreement I would find for that view. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 11:01, 17 June 2006 (UTC)
::::: I would agree with abolishing "ditto" but not with abolishing "iff".  Anyway, I agree with Ryan below.  The precision afforded by the usage "iff" is useful for theorems, but not so much for definitions.  -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 11:18, 17 June 2006 (UTC)

:This doesn't follow any mathematical practice I've ever seen, so why should we insist on it simply because it's technically right?  We don't make policy here, just record it.  Besides, to counter your argument, "iff" is logically absurd in this context since the term to be defined has no prior meaning; whether or not it applies is determined by the text of the definition.  In other words, "only if" is vacuous if the term is unique, and if not, it is erroneous.  Someone reading an "iff" definition for the first time will wonder if they've missed some other discussion of the term, and anyone else will be annoyed because it departs from the usual style.  I agree with lethe, though: any change of one to the other should be reverted.  This is a personal preference. [[User:Ryan Reich|Ryan Reich]] 10:57, 17 June 2006 (UTC)
::We are certainly allowed to make policy here.  What we don't do is invent subject matter for our articles.  So we can't invent terminologies, but we can certainly decide on conventions for our terminologies. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 11:18, 17 June 2006 (UTC)
:::I'd argue more but apparently you agree with me.  My objection to inventing policy in this sort of case is that the choices are not all equally acceptable; it's not like choosing an indentation style for C code, where many different styles all have their widespread adherents.  I've simply never seen "iff" in a definition. [[User:Ryan Reich|Ryan Reich]] 11:30, 17 June 2006 (UTC)
::::I can't quote chapter and verse, but I remember seeing a mathematical style guide recommending "if" in definitions. Personally I prefer "when", to distinguish it from the notion of logical consequence (as in: ''You are in a dilemma when you don't know which way to turn''), although some may decry the temporal connotation. --[[User:Lambiam|Lambiam]][[User talk:Lambiam|<small><sup>Talk</sup></small>]] 12:07, 17 June 2006 (UTC)
::::: I much prefer "if", and that's what I observe as common mathematical practice. [[User:Dmharvey|Dmharvey]] 12:57, 17 June 2006 (UTC)

:<s>I think "if" is somewhat unclear</s>, but I have no problem with "only if", "if and only if", the equivalency arrow (<math>\Leftrightarrow</math>) and other such language. The term "iff" I object strongly to, at least in basic math articles, on the grounds that it is jargon that is unfamiliar to many basic students of mathematics who have not done proofs. But don't take my word for it - I've seen countless edits where amateurs have "corrected" iff to "if". [[User:Deco|Deco]] 13:53, 17 June 2006 (UTC)
::Something unseemingly asymmetrical about accepting "only if" (⇐) and rejecting "if" (⇒).  I must say I do not understand your position. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 14:04, 17 June 2006 (UTC)
:::The words "only if" do not imply "given the sufficient condition that", and it is a myth that "if and only if" is the conjunction of "if" and "only if". It is merely a way of clarifying "if" using the additional qualifier "only if" that only serves to strengthen that "no we don't mean this is just a necessary condition" but in fact an equivalency is intended. If I say "a number is prime only if it has exactly two factors", the intepretation is clear; it does not even suggest that there might be a prime which doesn't have two factors. [[User:Deco|Deco]] 17:23, 17 June 2006 (UTC)
::::Indeed, "only if" implies "given the ''necessary'' condition that", and "if" means "sufficient".  And in mathematics, "if and only if" certainly is their conjunction, at least in a formal context, but since this is a formal phrase that is to be expected.  Using it in an informal context evokes its formal meaning and is just confusing when you start to split hairs about what it ''really'' means, especially given that syntactically, it definitely ''looks'' like the conjunction of "if" and "only if".  Stating "only if" in a definition is redundant, since the term is intended to be deciphered, not encoded: if I see a long string of conditions which happen to have a nice definition but I don't know it, I will not go looking for one until it's necessary; on the other hand, if I see an unfamiliar term I will go looking for its definition.  Putting "only if" in the definition would just mean "whenever you see this term, you can be sure it means this phrase", which is exactly what the process of defining the term means anyway.  Combined with the common-sense reason that people just don't talk like that, I say "only if" should stay out. [[User:Ryan Reich|Ryan Reich]] 18:03, 17 June 2006 (UTC)
:::::Oops, I switched necessary and sufficient, that's not what I meant. I don't object to leaving out "only if" if you find it unclear. <s>I'd like to avoid "if" due to ambiguity if possible</s>, but my main concern is that that we avoid "iff", which people generally assume is a typo if they don't know about it. [[User:Deco|Deco]] 21:01, 19 June 2006 (UTC)

I strongly support the use of "if" in definitions over either "iff" or "if and only if". By the way this has (of course) been discussed before. I will now provide for your reading pleasure this oldie but goldi, this blast from our past:

:(''Start of copied text from talk page archives'')

:Can I raise the question of whether we want [[iff]] in definitions? I don't. I think it's offputting to those not pure-mathematical 'native speakers'. And the idea that it's more rigorous is surely shallow.

:[[User:Charles Matthews|Charles Matthews]] 16:28, 21 Oct 2003 (UTC)

::In the absence of an explicitly-stated convention, I think it's marginally more rigorous than "if". I have occasionally used "if" in a definition and meant "if but not only if", although not on Wikipedia as far as I remember.  I'd suggest that if "iff" is undesirable, the best replacement for the non-specialist reader is "if (and only if)", since the rigorous alternative is to ensure that "if" is never used other than to mean "iff". [[User:Onebyone|Onebyone]] 16:49, 21 Oct 2003 (UTC)

:I don't accept the 'rigour' argument, anyway. Using 'if' there is an implied 'one can assert' in front of mathematical propositions - which no one writes unless in a very careful formal treatment. Those who care about this can imagine it all anyway. Better, I think, just to use normal language: 'an X is a Y with property P'. I haven't checked whether the definitions of legal terms on Wikipedia make a point of this type of care. On the whole I think it's wasted: it's hard to imagine the user who needs it. [[User:Charles Matthews|Charles Matthews]] 17:58, 21 Oct 2003 (UTC)

:: Well, I agree that the pedantry is not worthwhile if it is off-putting for readers. On the other hand, I'll take no part in any kind of global edit to deliberately introduce ambiguity, even if that ambiguity can generally be resolved from context. You say "I think this care is wasted", but I suspect that for most mathematician authors it will require extra care to remember '''not''' to do this rather than extra care to do it! 
:: "An X is a Y with property P" sounds good to me, especially in the standout definition at the top of the article. Nobody writes articles on topics other than maths saying "a person is a '''saint''' if and only if they have been canonised by the Church" or whatever. If there's a more formal section of maths in the article, I do think that "iff" and other jargon words should be used in that section exactly as the author would use them in any mathematical writing.
::[[User:Onebyone|Onebyone]] 10:35, 22 Oct 2003 (UTC)

:So, my understanding is that the Project isn't trying to prescribe, but is looking for some harmonisation. [[User:Charles Matthews|Charles Matthews]] 19:02, 22 Oct 2003 (UTC)

:(''End of copied text'')

[[User:Paul August|Paul August]] [[User_talk:Paul August|&#9742;]] 18:38, 17 June 2006 (UTC)

In regards to Lambiam's comment on a style reference, a popular one is Nick Higham's "Handbook of Writing for the Mathematical Sciences."  On page 20 of the second edition it says:  
:By convention, ''if'' means ''if and only if'' in definitions, so do not write "The graph ''G'' is connected if and only if there is a path from every node in ''G'' to every other node in ''G''."  Write "The graph ''G'' is connected if there is a path from every node in ''G'' to every other node in ''G''" (and note that this definition can be rewritten to omit the symbol ''G'').       
In my own experience, I cannot recall ever seeing "if and only if" in a definition in formal mathematical writing.  Can someone supporting the use of "if and only if" cite a current journal article with this usage or give reference to a style manual that advocates its use?  [[User:Lunch|Lunch]] 20:44, 19 June 2006 (UTC)
:Oh, in definitions. I didn't realise this was regarding ''definitions'' and not ''theorems''. My apologies for my dissent - of course it's redundant in a definition to state that it's an equivalency. I would not use any more verbose language in this case. [[User:Deco|Deco]] 21:03, 19 June 2006 (UTC)

If the consensus is that "iff" may be confusing because some lay-persons do not know what it means and it might be mistaken for a misspelling of "if", then I will not object when other editors change "iff" to "if and only if" or an equivalent. However, I still object to using "if" by itself between the definiendum and the definiens. [[User:JRSpriggs|JRSpriggs]] 03:52, 20 June 2006 (UTC)

===Using a conditional rather than a biconditional in a [[definition]] is wrong===
"Often ... the definition is a statement that expresses a logical equivalence between the definiendum and the definiens." 
When we define a mathematical symbol (constant, function, or relation), the definiendum (symbol defined) is a new word being added to our language; and it has no meaning other than that given to it by the definition. The definition is a postulate which gives meaning to the new word. Since it is not normally our intention to add strength to our set of axioms (as the axioms of ZFC), this must be a [[conservative extension]]. And we should be able to translate any sentence involving the new word into one which omits it and has the same meaning. 
If you put a conditonal ("if") rather than a biconditional ("if and only if") between the definiendum and the definiens, then you are doing one of three things:
* Using "if" to mean "if and only if" when in the context of a definition. This is potentially confusing to the readers. First, they may not realize that "if" is being used for "if and only if". Second, they may learn to read "if" as "if and only if" in other circumstances where it is mistake to do so.
* You are using "if" to mean "if", i.e. you really intend the postulate which is the definition to be a conditional rather than a biconditional. In this case, one could not prove the negation of the new word was ever appropriate. For example, if we defined "measurable cardinal" via "κ is a measurable cardinal if it is an uncountable cardinal with a <κ-additive, non-principal ultrafilter.", then we could not prove that 17 was not a measurable cardinal.
* You are assuming that anything which is not provably true is false. Surely, since [[Gödel's incompleteness theorems]], it is clear that this is not a tenable position. 
In conclusion, definitions should not be conditionals. [[User:JRSpriggs|JRSpriggs]] 03:52, 20 June 2006 (UTC)
:If you were working in a formal logic, you would not be phrasing your definitions as English sentences at all, and this would not be an issue. The use of "if" in definitions is just one of many places that context is conventionally used to establish the meaning of a symbol. If you did want to make a definition that was not biconditional (for some reason) you could simply use more explicit language such as "A implies that B", "A is a sufficient condition such that B", or implication arrows. Finally, I think the language "B if A" should be avoided in theorem statements in favor of "if A, then B" or "Given A, we have B" or "Whenever A holds, it follows that B", or ''something'' a bit less vague; such use would preclude confusion about the meaning of that sentence structure. [[User:Deco|Deco]] 04:18, 20 June 2006 (UTC)


:The "if" in a definition is not a conditional. It's an assignment, like the = sign in C. This is a well-established linguistic convention (and it ''doesn't'' mean "if and only if"; as I said, it's an assignment, and not any sort of proposition at all).
:Moreover I have a strong antipathy to using "iff" in formal writing (in any context, not just definitions). It's acceptable on a blackboard, like "wrt", but it should not appear in articles. --[[User:Trovatore|Trovatore]] 04:27, 20 June 2006 (UTC)

: Agree with Trov on both counts. That being that "if" in deffintions is perfectly acceptable, while "iff" in definitions is a bit iffy. :) [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 04:39, 20 June 2006 (UTC)

: In a context that makes clear we are offering a definition, "if" works for me.
:: We say that a ''foo'' is a ''bar'' if it satisfies ''mumble''.
: In a context which is ''not'' clearly a definition, we must be more careful.
:: … A ''foo'' is a ''bar'' if it satisfies ''mumble''. …
: Can a ''foo'' be a ''bar'' even when it does not satisfy ''mumble''? Here I don't know!
: So now we come to the question of what to write in Wikipedia articles. Often definitions are not highlighted as such, but appear inline in a form that is ambiguous about the intent. I myself would ''never'' use "iff". I ''would'' try to word the statement carefully so that it was clear what I meant. When we write, ''we'' know what we mean, so we don't always see the possible confusion our words may cause a reader. But when we see a potential problem, the better solution is to reword to make our intent clear, not to throw in jargon like "iff". Flag a definition ''as'' a definition, and our readers will thank us. <small>(Well, no. Actually they'll read happily along, never knowing the confusion we spared them. ''Bad'' writing is what gets noticed.)</small> --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 14:33, 20 June 2006 (UTC)

::I guess I am agreeing with Oleg and Trovatore here. I am happy to go along with pretty much all the authors I respect (Rudin, Lang, Halmos, Ahlfors, ...) and NOT use 'iff' or 'if and only if' in a definition. Either would looks stilted and also be more confusing than helpful to less experienced readers. [[User:Madmath789|Madmath789]] 14:47, 20 June 2006 (UTC)

::As KSmrq said "Often definitions are not highlighted as such, but appear inline in a form that is ambiguous about the intent.". For that reason, if no other, we should use language the same way in definitions that we do elsewhere to avoid confusion. [[User:JRSpriggs|JRSpriggs]] 05:43, 21 June 2006 (UTC)

:::When KSmrq said ''In a context that makes clear we are offering a definition'' I took it to mean that a phrase such as ''we say that'' or ''a foo is called bar if'' or ''we define a foo to be a bar if'' is used.  This doesn't mean that '''Definition.''' has to appear in front of the sentence.  By wording the sentence carefully, it can be made clear that a definition is occuring.  If it isn't clear, putting in ''if and only if'' won't make it clear; that will only make it look more like a theorem if it already looked like one.   I agree with several others, by the way, that common usage avoids the phrase ''if and only if'' in a definition.  [[User:CMummert|CMummert]] 12:36, 21 June 2006 (UTC)

:::: We should also make definitions clear by italicising what we are defining. [[User:Dysprosia|Dysprosia]] 12:39, 21 June 2006 (UTC)

::: I can't believe this is still going on.  I've already made all the arguments I think are necessary to oppose "if and only if", but I do have two questions: is there anyone, anywhere, who has become confused due to the use of "if" in definitions?  Would you actually want to ''read'' an article so reeking of pedantic formalism?  Also, to respond to your comment above: a more important consistency principle than internal consistency is external consistency; our articles must follow common English writing practice.  As KSmirq said, it is always possible to set apart definitions from the text (and this would constitute better writing), thus obviating the internal consistency problem, but it is never possible to set apart Wikipedia from the experience of a native English reader. [[User:Ryan Reich|Ryan Reich]] 12:50, 21 June 2006 (UTC)

== Redirects in the [[list of mathematics articles]] ==

Currently we have 12102 articles in the [[list of mathematics articles]]. Out of them, 1070 are redirects (see the [[User:Mathbot/Page5|complete list]]). Redirects get created in several ways

# Plugging in some redlink in the list (not anymore, as all redlinks are removed automatically)
# Merging an article to a bigger article
# Renaming an article.

In my view it is the third which makes for most redirects. 

While redirects are very important, I see no good reason for why they should stay listed in the [[list of mathematics articles]] (I estimate that there are at least 2000 math redirects which are not there). 

I wonder what people think of a big purge, removing all redirects from the [[list of mathematics articles]]. Of course, if at some point a redirect becomes back an article, my [[User:mathbot|bot]] will add it back to the list. Thanks. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 22:37, 17 June 2006 (UTC)

:So if I create a redirect to a math article, but the redirect isn't already a redlink from the list, then it doesn't get added to the list? -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 22:57, 17 June 2006 (UTC)
:: No. The bot adds to the [[list of mathematics articles]] via categories. So, if your redirect is made to be in a math category (which it won't, most of the time), the bot will add it to the list. Otherwise it won't. The primary purpose of [[list of mathematics articles]] is to list articles I think, not redirects, although a separate list of redirects to math articles may be found useful by some people. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 23:55, 17 June 2006 (UTC)

:::Well whatever uses there may be for a list of math redirects, this list cannot serve, since it doesn't contain them all.  Therefore, you have my full endorsement to remove them.  There is simply no reason to have only ''some'' of the math redirects in a list, right? -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 00:00, 18 June 2006 (UTC)

:I'm not sure what purposes the list serves. Take [[Circular arc]], which is currently a redirect to [[Arc (geometry)]], but the concepts are distinguishable and [[Circular arc]] might eventually grow into a separate article. In an ''index'' it would be reasonable to include it. If the purpose is to have a way to visit every maths article to check if its conforms to a new policy, then you'd prefer to skip it. (By the way, it currently is not categorized.) Perhaps math-categorized redirect pages could be listed, but rendered in italics, like with the [http://en.wikipedia.org/w/index.php?title=Special%3AAllpages&from=Mathematical&namespace=0 ''All pages'' search]. (<-This comment was by [[User:Lambiam]] who forgot to sign it. [[User:JRSpriggs|JRSpriggs]] 11:08, 18 June 2006 (UTC))
:: OK then, so if a redirect is important enough, it should be categorized, and then my bot will add it in. About making redirects italic, that is harder to do, as I would need to daily download a lot of articles to see which are redirects. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 16:25, 18 June 2006 (UTC)

Done. The log is at [[User:Mathbot/Changes mathlist]]. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 02:39, 19 June 2006 (UTC)

== MathML / improved TeX support ==

Hi people. For those of you who have been watching developments concerning [[m:blahtex]], MathML support on wikipedia, etc, I'm sure you've noticed nothing much has been happening for a while. Well, for the past few months, Jitse and I have been trying pretty damn hard to push buttons in the background to make things happen, but sadly the core developers simply haven't taken the bait. It seems to be a case of "yeah, it looks interesting, but we've got like 10,000 other things we're trying to do, and we just haven't got around to checking out the code yet...". It seems that wikipedia just doesn't have enough engineer-hours to give us the attention we need to get this going, and there's only so much pushing that Jitse and I can do without becoming annoying pains in the arse.

The status now is that I'm certainly not spending any more time on the code until I have some indication that there's a chance wikipedia is going to use it. And I've had enough of all the promotional "hey everyone isn't blahtex wonderful and y'all should be using it". It's tiring and not really my style. I enjoy writing code, not selling it.

So unless the people who hang out on this page somehow band together and make the developers realise that MathML is something that people want, the project is going to die a serene death. I took the initiative about a year ago, and wrote 13,000 lines of code to prove that it was possible. I'm happy to help out some more, and of course I look forward to the day when there is good mathml support in wikipedia. But someone else needs to take the initiative now, because I'm through.

Anyway, I think I'll go to bed now, make sure I'm bright and fresh to watch Australia defeat Brazil 6-0 tomorrow.

Good luck guys. [[User:Dmharvey|Dmharvey]] 03:57, 18 June 2006 (UTC)

:Perhaps a petition signed by the user community? Which is then passed up to Jimbo? This is an important chunk of code that is being laid at the feet of the sysadmins; surely its something that should be picked up. A few words of caution: (1) although the code may work well for you, sysadmins concerned with high-availability servers have a very very very different view of what it means "to run reliably". You might not have given them warm fuzzies on this issue. (2) The WP servers seem often overloaded, there may be unvoiced concerns about impacting performance. If you think these issues are under control, then a public appeal may be the right route to get attention. If they're wobbly, you might get blown out of the water. [[User:Linas|linas]] 04:18, 18 June 2006 (UTC)
::I've explored the BlahtexWiki and I have to say, I'm quite impressed.  I just have two main concerns for implementing MathML on Wikipedia, if those were fixed, I would gladly push the developers to implement it.
::#''Browser compatability.''  Almost nothing works for me in IE 6.0
::#''Fonts.''  It appears as if you need to download special fonts for MathML to display correctly.  I'm not sure how many people would want to do that.  Also, the radical symbols do not display correctly in Firefox for me.
::I would be glad to push for the implementation of MathML in WP if we can somehow figure something out for those two problems. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|M]][[User:Mets501/EA|<span style="color:green;">e</span>]][[User:Mets501|ts<small>501</small>]] ([[User_talk:mets501|talk]])</span> 04:26, 18 June 2006 (UTC)

::: There is no way around the issue of downloading fonts. As far as I can tell, Firefox often lacks some fonts by default. For IE I think one needs the [[MathPlayer]] extension. 

::: It is no surprise the developers are weary at accepting a huge chunk of outside code, especially there is not really a huge demand for MathML from users. Any ideas of how to convince the developers to take this step would indeed be much appreciated. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 05:14, 18 June 2006 (UTC)

: Thank you, thank you, thank you for all of your work. Having written some mathematical typesetting code myself at one time, I have a feeling for what a challenge it is to do a good job. There are so many subtle issues of fonts and stretching and spacing and symantics and positioning and compatibility and on and on, that only someone who has been in the trenches can really appreciate the magnitude of this endeavor. It really takes a champion, like Roger Sidje on the Mozilla project or David Harvey on BlahTeX.
: I believe I can speak to systems programmers with some credibility, and I would be happy to do so on behalf of BlahTeX. A noisy outcry from Wikipedia's technical writers might also prove influential. Beyond mathematicians, we have physicists, chemists, biologists, and engineers of all stripes, all of whom could benefit.
: The latest word from the STIX Fonts Project is
:: "After reviewing the tasks required for completion of the project, September was established as a revised target for the beta test. The final production release will likely occur in December, but the TeX package may not be ready until January 2007."
: Although the STIX project has not been exemplary in meeting its targets, it does appear that it is real, it is happening, and in a matter of months there will be little excuse to complain about a lack of fonts for MathML.
: I cannot imagine that server load is a realistic concern. Currently MediaWiki converts &lt;math&gt; mkup to images, which requires parsing, pseudo-TeXing, image generation, and then serving the images. Unless BlahTeX is very poorly written indeed, it is unlikely to be ''more'' of a load. All BlahTeX has to do is transcribe TeX syntax to MathML syntax; and bloated as it is, MathML is still much smaller to serve than the equivalent image. Caching may be used currently to amortize the cost of image creation, but there is no good reason the same could not be done for BlahTeX. And, again, storing cached images requires more space than storing cached MathML.
: That leaves the concern of bullet-proofing. For that, we have the empirical argument that the code has been tested against [http://www.blahtex.org/index.php?page=samples every single equation] currently used at Wikipedia, of which there are hundreds of thousands. Yes, a few hundred do not translate; but that's a small matter of manual conversion because they depend on the bastardized TeX currently supported ([[texvc]]). In compensation, future editors will have use of a broader range of TeX features, something [[category theory|arrow-pushers]] will appreciate.
: It occurs to me that if the developers are recalcitrant, perhaps Jimbo Wales might be persuaded. Pressure from the top could then be more effective than pressure from the bottom.
: Thanks again for all the hard work so far. Given Wikipedia's culture of consensus, it seems only fair that others now help shoulder the burden. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 10:33, 18 June 2006 (UTC)

But so what is the next step?  Campaign to get it installed on test.wikipedia.org?  What can we do to help?  Send messages to mediawiki-l?  I notice searching through the archives, that you have previously announced releases of blahtex to that mailing list, and they have never had any response.  Have you ever had any dialogue with anyone from mediawiki development about this code?  Whom do we talk to? -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 10:43, 18 June 2006 (UTC)

----

At the risk of sounding too critical, how difficult would it be to make things work for the current "bastardized TeX"?  The idea of breaking old revisions of articles without it being obvious why that is makes me kind of queasy ...

Is this a major issue?  How do things fail after the change?  Backwards compatibility is something that needs to be addressed, even if it cannot be guaranteed.

Not that I think this is a huge problem, if the scope is that small.

Otherwise, I'm with lethe.  Whom do we talk to, and what's their favourite ice cream flavour (for bribes, you know)?

[[User:RandomP|RandomP]] 11:00, 18 June 2006 (UTC)
:We have a list of all the broken bastardized tex instances.  There are a couple of hundred, which we've slowly been fixing, one at a time.  We would obviously want to finish them off before we went live. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 11:21, 18 June 2006 (UTC)

----

I'd just like to qualify my remarks:  it seems that even today, "history" won't get you anything like the old version of an article, at least when that article uses images from the commons.

I think it would be really cool if someone wrote, essentially, a simulated wayback machine for wikipedia, that went back to the wikicode, images, and math layout ''as they were when the revision was created''.  I thought that's what history was, but apparently, not so.

So that's not an issue either, and can we please have mathml now?

[[User:RandomP|RandomP]] 14:09, 18 June 2006 (UTC)

=== Brief replies to above questions ===

* ''Linas's question about server overload.'' This is a complete non-issue for several reasons, some already mentioned by KSmrq. I haven't done any benchmarking for a while, but here's what I remember. Both blahtex and texvc spend almost all of their time (at least 90%) on PNG generation. Blahtex is somewhat faster at PNGs, maybe 2 or 3 times faster, since I switched to dvipng instead of using imagemagick+dvips. (And Brion Vibber has endorsed the use of dvipng in the past, ask Google for more information.) MediaWiki already has code for caching the images, so this time only gets spent during the first edit, not on subsequent page views or edits. Second, I haven't directly compared the parsing and mathml generation time of blahtex to the parsing time of texvc, but I do know that my desktop machine can generate mathml for the entire wikipedia corpus in about 30 minutes. There's 200,000+ equations in there, so it's not lightning speed, but you ain't gonna overload their servers. And MediaWiki also has code already for caching the mathml, so again that only happens on the first edit. Third, some tests Jitse and I ran a while back suggested that texvc's parsing is unbearably slow on long input data; blahtex on the other hand processes that kind of input really fast.
* ''Linas's point about reliability''. Of course it's got bugs. All software has bugs, especially software that hasn't yet been exposed to the real world. Someone mentioned above that it's been tested against all the input in wikipedia and doesn't pretty darn well, which is a start, but of course that's not the point. The real question is whether it survives a determined adversary with source code access. Well, I don't know, I suppose most likely it's not secure. ''But all software has to start somewhere''. I'm not asking to have the code installed tomorrow and force everyone to use it. Heck, at this stage I'm not even asking for the "minimal interesting configuration", which is that it's only available for registered users who select MathML in their preferences, and that we stick to texvc for all PNG output, and only allow mathml for the equations for which texvc can already generate graphics. All I'm asking for is that ''some core developer gives us more than ten seconds of their time to render an opinion''. If they tell me the code is crap and I'm a chump, that's fine, I can live with that, at least it's an answer. If they tell me I need to rewrite it in COBOL, that's fine, it gives me something to do. If they tell me I need to write a comprehensive test suite, that's great, I can do that. But so far the longest reply I've had from people like Brion Vibber, Tim Starling, etc, is a one-line email from Brion:
:::''It sounds great, but I've not had a chance to look at it yet...''
: He also replied on the mailing list once, here's what he said:
:::''Neat!''
: I understand 100% where he's coming from, but it's still incredibly frustrating.
* ''Mets501's question about fonts''. As KSmrq points out, the STIX fonts project is going to get there eventually, not tomorrow or the next day, but eventually. I believe it will solve all the font problems, because e.g. Firefox will just be able to bundle the fonts in the default installation and it will all Just Work. So for now, no good answer, but eventually, yes.
* ''Mets501's question about browser compatibility''. Short answer: it sucks. Firefox/Mozilla is the best out there in my opinion, and it's not quite good enough yet. (I've heard about your problem with broken radical signs; I believe it's a recent regression.) I think the reason browsers haven't quite made it yet is because there just isn't the content out there yet. Well, we can change that, because if wikipedia switched on mathml support, it would overnight become the largest repository of mathml on the web. (I don't have stats for that, it's just a guess.) And here's something else: when I first mentioned to the firefox people, like roger sidje, that wikipedia was planning mathml support, suddenly a whole raft of mathml-related bugs in firefox got fixed, bugs that had been lying around unattended for 2-3 years. These open-source guys love wikipedia. If we deliver, they will follow. On the other hand, I don't have any illusions about MSIE.
* ''RandomP's question about backward compatibility''. It's a minor problem in my opinion. See http://blahtex.org/errors.html for a complete list, as of March. Maybe that list looks long, but remember it's across 13 languages, and represents about 0.1% of the total. We could fix them all in a few days. And anyway, Jitse's glue software falls back on texvc if blahtex fails, so it's easy to make the problem vanish entirely.
* ''Everyone's question about who to talk to.'' '''I don't know'''. I've run out of ideas and energy. That's why I'm turning the initiative over to all of you. If enough of you make enough noise, and if the powers that be are hearing voices ''other than that of the guy who wrote the program'', maybe something will happen. [[User:Dmharvey|Dmharvey]] 12:28, 18 June 2006 (UTC)

::Caching: As KSmrq suggests, the MathML is cached and hence it needs to be generated only once.
::Backward compatibility: To expand on what David says, the code as currently written uses texvc to generate HTML and PNG and blahtex for generating MathML. If texvc fails, then blahtex will also generate PNG. Therefore, the few formulae that are not understood by blahtex (for instance because they use invalid latex syntax) will still be rendered as PNG, but there won't be any MathML. In other words, just like the present situation. -- [[User:Jitse Niesen|Jitse Niesen]] ([[User talk:Jitse Niesen|talk]]) 13:02, 18 June 2006 (UTC)

=== my email ===
I sent [http://mail.wikipedia.org/pipermail/mediawiki-l/2006-June/013087.html this email] to mediawiki-l just now:
----
From:   lethe at charter dot net<br>
Subject: Blahtex: what's the next step<br>
Date: June 18, 2006 8:08:37 AM CDT<br>
To:   mediawiki-l@Wikimedia.org<br>
<br>

David Harvey and others has been working hard on Blahtex, the next generation in MediaWiki math rendering technology.  Visit http://www.blahtex.org/ for more information and http://wiki.blahtex.org/go/Main_Page for a running demo hosted by Jitse Niesen.<br>
<br>
Harvey suggests that blahtex will afford a significant performance advantage, but the main impetus is the ability to render MathML.  Support for MathML is not widespread at the moment, so the need for Blahtex is not urgent, but it is the future, and we have reason to believe that Wikipedia's adoption could goad browser developers to speed their efforts (the answer to the old chicken and egg of who comes first, browser support or use by web pages could be: Wikipedia comes first).<br>
<br>
It has to happen someday, and today is as good a day as any.  Harvey says the software is ready for the next step, and wants to move forward, but doesn't know whom to talk to in order to make this happen.  I'm writing you to voice my full support for Harvey's and Niesen's efforts, to find out what needs to be done to take the next step towards rolling this software out, and to ask if there is anything I can do to help the developers to get this software ready for deployment.<br>
<br>
Thanks<br>
lethe
----
I was hoping that several others of you would chime in on the mailing list.  If we had a chorus of complaining voices, we would be harder to ignore.  Currently, the developers watching that mailing list have ignored me completely.  What should I do?  Send another, more plaintive, email? -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 11:51, 20 June 2006 (UTC)

:Are you sure this is the right way to go?  I'm not sure about the relation between mediawiki, the software that actually serves wikipedia, and that mailing list.  Is the authoritative version of mediawiki the one serving en:?  Are decisions about changes to that software, beyond bugfixes, made on that mailing list, the meta wiki, wikipedia (en) talk, or where?

:[[User:RandomP|RandomP]] 11:56, 20 June 2006 (UTC)
::The short answer is, I don't know.  Where is the right venue to discuss changes in the software, and who is the right person to talk to?  I don't know.  Does anyone know what is the right course of action to take?  How to we get software changes evaluated and committed?  As for whether en runs the official version, the answer is yes.  They rollout new versions on test.wikipedia.org first, I think.  But then they roll it out for en.wikipedia.org.  Should I email Brion Vibber or Rob Church or something?  I don't want to be a nuisance, but I think Dmharvey's request to get a response from them at least to say "sorry, we can't accept this" is not unreasonable. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 12:20, 20 June 2006 (UTC)

:::Hmm.  This is a problem.  I've looked around for a good place, but the best I've found is the [http://bugzilla.wikimedia.org/ MediaWiki bugzilla], which currently has two bugs [http://bugzilla.wikimedia.org/show_bug.cgi?id=672] [http://bugzilla.wikimedia.org/show_bug.cgi?id=4915] matching blahtex, and I don't think either is what we want. 
:::Can someone create a new feature request there and link to it (I'd also suggest linking back to a Wikipedia page from the new bug, so we can have discussions without all getting out to get accounts on yet another bugzilla)?
:::That might be a first step to, at least, documenting we're trying to get it in through the official channels ...
:::Again, I'm just confused by the whole thing.  There's a wiki, a mailing list, a bugzilla, and apparently an IRC channel, and I still don't know where and if development discussions happen.  However, at least a bugzilla is permanent and will get someone's attention, one would hope ...
:::Can we move the discussion to [[Wikipedia:Blahtex]] or something?  It's of interest to physicists, economists, biologists, etc, too!  (Or should be.)
:::[[User:RandomP|RandomP]] 12:53, 20 June 2006 (UTC)
:::: [[m:Blahtex]] would be a place to have a centralized dicussion, after we sent spam to all the physicist, economist, etc Wikiprojects.  But that would only be necessary if we are completely unable to open up a discussion with developers in one of the developer channels.  If we can do that, then let's just have the discussion there. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 13:02, 20 June 2006 (UTC)
::::: I have submitted a [http://bugzilla.wikimedia.org/show_bug.cgi?id=6383 bug report] and sent [http://mail.wikipedia.org/pipermail/mediawiki-l/2006-June/013129.html another email] to mediawiki-l.  You can vote for the bug at [http://bugzilla.wikimedia.org/votes.cgi?action=show_user&bug_id=6383 this location].  I have no idea what voting for bugs accomplish; I wouldn't be surprised to find out accomplishes nothing.  -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 13:23, 20 June 2006 (UTC)

:::::I'm told that most discussions take place on IRC, but I haven't seen any. There are two relevant mailing lists: mediawiki-l for the software as used on Wikipedia, other Wikimedia sites, and other wikis not related to Wikimedia; and wikitech-l for technical matters (hardware and software) involving Wikimedia (Wikimedia is the foundation running Wikipedia, Wikibooks, Wiktionary, Wikisource etc).  Either list would be appropriate, and I think they mostly have the same readership. Then there is bugzilla, as mentioned by Lethe, and we also have [[Wikipedia:Village pump (technical)]] here. There are also two central wikis, http://meta.wikimedia.org/ which used to contain everything related to the software, and http://www.mediawiki.org/ where the documentation is being brought over to. So it is rather confusing.
:::::I put the items in the order that seems to be best to get the attention of the powers to be (with IRC on top). However, in the end it boils down to an individual developer taking a decision. The concept of ''consensus'' plays rather a small role on that level. 
:::::I'd advise against emailing the developers individually. -- [[User:Jitse Niesen|Jitse Niesen]] ([[User talk:Jitse Niesen|talk]]) 14:02, 20 June 2006 (UTC)
:::::: I guess the response you may get from IRC depends on who's in the room.  I went there first, before anything else, a few days ago as soon as Dmharvey posted his request, and got no biters there.  They suggested I might have better luck on the mailing list.  Perhaps I try IRC again at a busier time. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 14:08, 20 June 2006 (UTC)

===Discussion continued===

I'm not a developer, nor am I Jimbo, but putting myself in their shoes I'd be much more worried about the font issue than about accepting an apparently well-tested huge chunk of outside code. In fact, not being in their shoes this worries me. Many people access Wikipedia from computers they have no control over, and are in no position to download and install fonts for, even if willing to do so. Others may try to and fail. Most wouldn't even try, and miss out on all Wikipedia has to offer that involves formulas. I think it is important to keep blahtex alive, but aim at introduction after the availability of the required fonts has become common. --[[User:Lambiam|Lambiam]][[User talk:Lambiam|<small><sup>Talk</sup></small>]] 13:53, 18 June 2006 (UTC)

:Thus MathML won't be enabled by default.  Only people who know what it is, have capable computers, and want to see it, will see MathML.  When the day comes that every windows, mac, and linux computer has by default MathML able browsers and plenty of fonts, then we can have MathML by default.  But for today, let's have Blahtex which is smarter in all ways.  This is a non-issue. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 14:22, 18 June 2006 (UTC)
::Yes, I agree.  I will help push for this to be implemented as much as I can.  I do think, however, that the default should not be MathML (yet).  Users who sign up for an account should be able to select MathML from the preferences page, but the option should link to a page called [[Wikipedia:MathML]], which would say what MathML is, which browsers support it, and which fonts/whatever is needed for MathML to work.  I would definitely not give up on this project and I hope that it will be implemented soon (I love experimenting on the BlahTeX wiki!) —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|M]][[User:Mets501/EA|<span style="color:green;">e</span>]][[User:Mets501|ts<small>501</small>]] ([[User_talk:mets501|talk]])</span> 16:54, 18 June 2006 (UTC)

::: We've really got to stomp out some myths. The most important fact is that BlahTeX only ''adds'' capability to MediaWiki, it does not force removal or breakage of anything that already works. A complete set of mathematics fonts will be available [[Real Soon Now]] to everyone on every platform with every browser. Don't have the necessary fonts on the computer you happen to be using? ''Not a problem''; stick with the old-fashioned images and HTML hacks. Browser not set up to support MathML? ''Not a problem''; don't ask for MathML. In other words, adoption of MathML is strictly ''voluntary''.
::: So why BlahTeX? Because it offers so much more than [[texvc]], which is old and seriously deficient. BlahTeX handles a broader range of TeX input, including things that are currently a real pain to work around. Even when it generates PNG output, ''not'' MathML, BlahTeX is superior to texvc.
::: And why [[MathML]]? Because it is the future of mathematics on the web, for reasons such as the following.
:::* A text-to-speech processor can read MathML aloud for vision-impaired users, or for ordinary folks who merely want to know how a formula is spoken.
:::* All the fonts and layout of a MathML display can be scaled up or down, just like the rest of the text on a web page, to either zoom in on a detail or zoom out for an overview.
:::* MathML can include arbitrary Unicode characters, something texvc is unlikely ever to do.
:::* A MathML formula is smaller and faster to serve than a PNG.
:::* MathML can allow internal line breaks, while images cannot.
:::* Programs like Mathematica allow cutting and pasting MathML formulae, so an equation can be transfered easily for evaluation or graphing.
:::* MathML has already found favor on technical [[blog]]s, like [http://golem.ph.utexas.edu/string/archives/000843.html#more The String Coffee Table].
:::* Because MathML is built on [[XML]], it can be processed with [[XSLT]] and used across diverse media. In particular, MathML will be much more compatible with print than any fixed-resolution PNG rendering.
:::* One of my favorite benefits is that the contents of a MathML formula are available to search in my browser, whereas a PNG is an opaque monolith.
::: Note that the MathML 2.0 Recommendation from [[W3C]] was released on 2001 February 21, and the 1.0 version dates back to 1998 April 7. That's an eternity ago in web time!
::: But to reiterate: BlahTeX offers considerable benefits even for those who do not choose to view MathML. ''It can't hurt.'' It can only help. Please support its rapid adoption by MediaWiki, in whatever way suits you best. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 19:22, 18 June 2006 (UTC)
:::: I think you should put that in an email to the mailing list.  Perhaps wait until mine shows up and make it a reply so it's all in one thread though.  We want to generate some noise so that it seems like there is a whole rabble of us clamoring for this.  And of course we have to quelch the false assumptions that people will make to justify ''not'' using the software.  -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 19:29, 18 June 2006 (UTC)

:::::Thanks, KSmrq, that's a nice piece of writing. Not for the first time, I admire your writing skills. 
:::::Apparently, the best way to contact the developers is via IRC (#mediawiki on irc.freenode.net). Another thing we haven't done is to contact our colleagues at the other language Wikipedias. I imagine that especially editors writing in a different script than ours would be interested. -- [[User:Jitse Niesen|Jitse Niesen]] ([[User talk:Jitse Niesen|talk]]) 04:23, 19 June 2006 (UTC)
:::::: Hey, KS, I think maybe this nice list of yours should be copied over to [[m:Blahtex]] where it would be the skeleton of a FAQ.  A central repository that we can refer to easily to stop out myths.  What say ye? -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 14:38, 20 June 2006 (UTC)
::::::: If you like it, use it. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 20:14, 20 June 2006 (UTC)
:::::::: Do you think that we should write an email to Jimbo about this?  Do you know how aware he is of BlahTeX?  If we could convince him, it would definitely get implemented. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 20:40, 20 June 2006 (UTC)
::::::::: Let's try to confine our efforts to those people who will actually have a hand in the software direction, which I don't think Jimbo does.  Anyway, the [http://mail.wikipedia.org/pipermail/mediawiki-l/2006-June/013145.html latest correspondence] sounds like Vibber is going to set up Jitse with an SVN account.  We might be in business, so let's wait to hear from Jitse and Dmharvey what happens with that. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 20:47, 20 June 2006 (UTC)

:::::::::: [via edit conflict] Hang on for the moment guys. Brion gave a more positive reply to one of Lethe's recent emails, [http://mail.wikipedia.org/pipermail/mediawiki-l/2006-June/013145.html see here]. Jitse and I will work out what to do with this development, and we'll keep you all posted. [[User:Dmharvey|Dmharvey]] 20:49, 20 June 2006 (UTC)
:::::::::::Yay!  Good luck guys!  Make sure to let us know about any developments. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 13:11, 21 June 2006 (UTC)

=== Some progress has been made ===

See [http://mail.wikipedia.org/pipermail/wikitech-l/2006-June/036480.html here]. I'm not precisely sure about terminology here, but perhaps this makes Jitse a Developer. This is good news, but I don't promise mathml tomorrow. Still some work to do. We'll keep you posted. Thanks guys for your encouragement, and especially lethe for the insistent emails on mediawiki-l :-) [[User:Dmharvey|Dmharvey]] 12:00, 22 June 2006 (UTC)
:Or perhaps he's saying that he's responding to Jitse, and he will be adding the BlahTex extension (because he put in a comma).  Either way, its good. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 12:35, 22 June 2006 (UTC)
::It only makes me a <small>minor developer</small>. The standard tariff is to sacrifice one virgin every full moon as otherwise Bad Things Happen. However, I can also be placated with papers on which I can put my name as co-author. ;) -- [[User:Jitse Niesen|Jitse Niesen]] ([[User talk:Jitse Niesen|talk]]) 13:19, 22 June 2006 (UTC)
::::: Well, I can give away my virgin [[User:mathbot|mathbot]] as a groom to the brand-new bride-to-be [[User:Jitse's bot|Jitse's bot]] (who am I am sure is a she, or otherwise can be made so just by flipping a bit). [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 16:10, 22 June 2006 (UTC)
::: So who is "jitsenielsen" anyway? [[User:Dmharvey|Dmharvey]] 14:11, 22 June 2006 (UTC)
:::: I'm pretty sure Brion Vibber made a spelling error :-) —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 14:30, 22 June 2006 (UTC)

==Request for book recommendations==
Maybe this is not the place for this (I am aware that this is not un all-purpose forum), but here it goes. I intend to order some math books from Amazon, but I'm not sure what to get. As it seems to me that there are some very good mathematicians here, I think you could help me a lot with some recommendations. Now for some background, to understand what I specifically need: I'm an undergraduate math student (though also an economics graduate and working economist) and I pursue math mostly for my own curiosity and because I truly enjoy it (more than economics :D). I need something mainly appropriate for self-learning, so I'm targeting good classic texts on major fields or other good books. I prefer books that don't shy away from advanced/abstract concepts, but preferably give motivation for concepts and some intuitive explanaition/interpretation. Also, I learn the most from books which include examples worked-out in detail and/or solved relevant problems. Also, note that unfortunately cost is an issue, so don't recommend too many books that are only somewhat helpfull (though by all means recommend books that you consider good, even if they are not very popular). Hope that you will have some advice for me... [[User:AdamSmithee|AdamSmithee]] 20:48, 18 June 2006 (UTC)

: A great place to ask this question, which is indisputably appropriate (unlike here, which is apparently disputably so :)) is the sci.math newsgroup.  You can get there through Google groups if you don't already know.  This page is really just for discussing the Wikipedia mathematics project. [[User:Ryan Reich|Ryan Reich]] 20:57, 18 June 2006 (UTC)

::I am sure that we could give a great deal of advice (though some of us will contradict each other!), but we do need a bit more info about your mathematical interests and level: which branches of maths are you most interested in? what sort of level are you at in that level? Perhaps it might be best if you could tell us some maths books that you believe you have mastered, and we could suggest some books that would make a "good next step"? [[User:Madmath789|Madmath789]] 21:02, 18 June 2006 (UTC)

::: Myself, I'm a graduate student and I like algebraic geometry and sometimes number theory.  Or did you mean him? :) [[User:Ryan Reich|Ryan Reich]] 21:42, 18 June 2006 (UTC)

::::LOL! I did mean 'him', but our edits crossed, and I got the indentation wrong :-) (but if you want some suggested reading on algebraic geometry, I can probably oblige :-) ) [[User:Madmath789|Madmath789]] 21:46, 18 June 2006 (UTC)

: The most affordable route is used books, especially if you live in or near a decent university or college. Some of the much older books are easier to learn from, because not so long ago mathematics texts had a bad habit of being horribly written for learning, though packed full of detail for reference. More recently there may have been a corrective swing, so that one can benefit from both a modern viewpoint ''and'' decent pedagogy. But in a field like algebraic geometry, the really old stuff has lots of geometry while the modern stuff has almost none. Depending on your tastes, one may appeal more than the other. Another fact about older books is that often recent books try not to duplicate the work of the early masters, so if you want to get the original insights from the folks who had them you have to step back in time. It reminds me of something that was said about the programming language [[ALGOL]], that it was an improvement on many of its predecessors, and also on many of its successors. Lastly, it is vital to choose books at the right level at the right time, lest an otherwise great book become a doorstop. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 22:39, 18 June 2006 (UTC)

Well, first of all tx for replying! As I said, I know this is not the place (and I'll probably try sci.math, which I didn't know about), but I tried it because I came to trust many of you guys. As for my background and interests: I'm an undergraduate student in math at this time. So far, my exposure was almost entirely to Romanian textbooks, which are very tightly written and unfortunately are generally very good for reference but not for learning (this is somewhat of a characteristic of Romanian academic books). On the other hand, I've read quite a few American graduate level textbooks in economics and I noticed that, generally, they are much better for learning (also, reading some freely available online math books lead me to believe this is also true for math). To give an example, at this time I'm struggling with linear connections and covariant derivative, but my (Romanian) books insist to much on tightely written modern coordinate-free stuff, giving virtually no motivation and no explanation, and I'm having trouble understanding why the stuff is defined that way, what does it mean and what is it good for.

At this moment my interests are rather wide and I just want to get a reasonable background in the main fields. However, I do have a sweet spot for abstract algebra, and I'm interested in probability and statistics (including links to measure theory, numeric analysis etc.) for the aplications to economics. But I'm also very interested in stuff like differential geometry for instance. As an example of one book that I have heard about, and I might get, I know about Jacobson's 'Basic Algebra' (though I don't know how that is), but I have no idea what else is there.

Regarding level, it is hard to say what undergraduate in Romania means compared to other education systems, but it is possibly more advanced than American undergraduate level (?maybe?). [[User:AdamSmithee|AdamSmithee]] 23:25, 18 June 2006 (UTC)

: Hi, I suggest browsing Dover Publications online catalogue (use Google to find, I am lazy :P). They republish a lot of classical and important texts. By rule of thumb, eastern Europe is more advanced in beggining of undergraduate studies. -- <i>'''[[User:127|<span style="color:blue;">127</span>]].[[User_talk:127|<span style="color:orange;">*</span>]].[[Special:Contributions/127|<span style="color:green;">*</span>]].[[Main_Page|<span style="color:red;">1</span>]]'''</i> 01:14, 19 June 2006 (UTC)

==Poussin proof==
I have just had a brief look at the page [[Poussin proof]], and apart from being a short stub, at least half of it seems to be mathematical rubbish. I would like to have a go at making this into a sensible article - but about the Dirichlet divsor problem (the first sentence of the Possin page), as I can't find anything about this elsewhere. If I have missed it, and there really is a page about the Dirichlet divisor problem, plase let me know before I waste too much time ... [[User:Madmath789|Madmath789]] 12:11, 19 June 2006 (UTC) (OK, having read it again, it is not total rubbish, but badly worded.)

== Change of project scope at Wikisource ==

(''I've copied the following from [[Talk:Mathematics]]. &mdash; [[User:Paul August|Paul August]] [[User_talk:Paul August|&#9742;]] 16:56, 19 June 2006 (UTC)'')

I would like to call the communities attention to and personally protest a decision at Wikisource to exclude and delete a significant portion of the material that was part of its original charter.  Prior  to April 29 of this year, [[Wikisource:What is Wikisource?]] listed the following as included material:

"Some things we include are:
*	1.	Source texts previously published by any author
*	2.	Translations of original texts
*	3.	Historical documents of national or international interest
*	4.	Mathematical data, formulas, and tables
*	5.	Statistical source data (such as election results)
*	6.	Bibliographies of authors whose works are in Wikisource
*	7.	Source code (for computers) that is in the public domain or compatible with the GFDL"
	
On that date the project page was changed to explicitly '''exclude:''' 
	
*Mathematical data, formulas, and tables
*Source code (for computers) that is in the public domain or compatible with the GFDL
*Statistical source data (such as election results)

Obviously, this represents a major change in the scope of the project. It is based on a single poll conducted between April 4 and 27, 2006 [[Wikisource:Scriptorium/Archives/2006/04]]. Previous discussions had been held with opposite results [[Wikisource:Wikisource talk:What Wikisource includes]]. A primary reason given for the new change is that the editors participating do not feel competent to maintain this material and have little interest in it. However apparently no effort was made to notify participants in the previous discussions, nor to recruit new editors that might have an interest. Note that there are many active projects pages in mathematics and the sciences where such people might be found.

There was also no discussion of methods for reducing the load on editors, such as locking material after review. In general, reference material does not need or benefit from frequent edits.

I certainly respect the efforts of the regular editors on Wikisource and agree that their views should be shown some deference. However the process they chose is not sufficient. At the very least, I think there needs to be broader community input into such a massive change in the scope of a Wikimedia project. Even if this material is best excluded from Wikisource, I believe it deserves to be part of an encyclopedia and that any material already contributed should be moved elsewhere rather than be deleted. The simplest solution would be to move mathematical and scientific reference material to Wikipedia, where there are large communities to evaluate and protect this information. An argument could be made that mathematical data belongs in Wikicommons because it is, or potentially can be, language neutral. Or perhaps there should be a new Wikireference project.  Computer source code deserves a separate discussion, since there are so many other open source code repositories available.

At this point hundreds of articles have been marked for deletion. See  [[Wikisource:Category:Deletion requests/Reference data]] Some material has apparently aready been deleted. There is nothing left in Category:Mathematics. I would propose that all article deletions on Wikisource based on this change be frozen until a fuller, community-wide discussion can be held.

I have also posted these comments at [[Wikisource:Scriptorium]], where I think the primary discussion should be held.--[[User:ArnoldReinhold|agr]] 16:01, 19 June 2006 (UTC)
--[[User:ArnoldReinhold|agr]] 16:01, 19 June 2006 (UTC)
:This call to arms would look better at [[Wikipedia talk:WikiProject Mathematics]].  It is about mathematics at wikipedia, not about the article [[Mathematics]] on wikipedia. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 16:12, 19 June 2006 (UTC)

(''end of copied text'')
::It was actually my intent to post the here. I just messed up. I am removing the link from the math talk page.--[[User:ArnoldReinhold|agr]] 20:16, 19 June 2006 (UTC)

:: (Cross-posted from Wikisource)I would like to quote my own remarks on opening up this disscusion back on April 3:
:: <blockquote>I realize this has been discussed several times in the past, to the agreement of accepting such material. However, the current state of reference data on Wikisource is unacceptable. The community members who are active on this site have little interest, and in some cases understanding, of the data we have been hosting. Although there have been editors that were adamant that this material should be included here, they have not remained active in the organization nor matainance of it. Much of this material is beyond the active administrators ability to even distinguish vandalism from corrections. Because of this current state of affairs there have been nominations for deletion for some of this data. However I feel we need discuss the larger questions of the place of reference material on Wikisource before we make any deletions. </blockquote>

:: It is disingenuous to suggest we ignored previous discussions or made no efforts to find other solutions short of deletion.  In fact I opened up the discussion back then to put a stop to this material being brought up piecemeal at Proposed Deletions.  In all honesty, at the beginning of the April disscussion I expected that we would arrive at a solution for keeping a portion if not a majority of this material.  No one who was interested in this material bothered to even suggest any alternatives much less volunteer to implement any solutions in over ''2 months'' since then.  As for calling this to the "community's attention", you imply we are trying to hide it or be secretive.  This is false.  I personlaly have left notes on WP talk pages of people showing recent interest, as well as mentioned the decision in passing on foundation-l.  Not to mention the write up done by Pathoschild in Wikisource news during and after disscussion.  The decision was also mentioned on wikisource-l.  The idea that this was "based on a single poll" is also misleading.  It is based on consensus taking into account ideallistic comments made in prior disscussions as well as the pragmatic reality of maintaining this site. (Added Note: Not a single person spoke up for inclusion)  My negative opinions about inviting in the entire Wikimedia community into these sorts of decisions are given in much detail at the foundation-l archives.  The thread begins with this  [http://mail.wikipedia.org/pipermail/foundation-l/2006-May/006982.html post] (Note this thread is not about Wikisource, but deals with the subject of alerting other Wikimedia projects to dissucions of policy changes within one sister project).  I will quote myself from a later email in that thread:

::<blockquote>I think [Ec has] hit the nail on the head with "Good rules support existing practice rather than shape it." The problem with the original suggestion is such advertisement would atract people who have no understanding of existing practice. That is my concern.  I feel anyone familar with existing practice will be aware of policy disscussion through the normal in-project channels.</blockquote>

::The deletions are proceeding slowly and carefully with any wanted info being moved to other sites.  There were no mass deltions on April 29th.  If you can find a home for anything we could not I will restore the pages for your access, please give me a list.  I think the topic of this post is out of line and [agr's] proposal has little merit.  Especially the idea that we should hold this material until and new sister project of "Wikireference" gets off the ground--[[User:BirgitteSB|<span style="color:#f4a460;">Birgitte§β</span>]] ʈ [[User talk:BirgitteSB|<small><span style="color:#778899;">Talk</span></small>]] 18:16, 19 June 2006 (UTC)

:::Added Note.  This disscussion as seen by those unfamilar with Wikisource may be misleading in our [[s:WS:WWI|inclusion policy]].  I just want clarify that if there is an otherwise acceptable publication with apendices of Mathmatical tables, the enitre work including the tables is accepted at Wikisource.  The exclusion only regards standalone data which is not a transcription of an acceptable publication such as [[s:Trinary numbers]].--[[User:BirgitteSB|<span style="color:#f4a460;">Birgitte§β</span>]] ʈ [[User talk:BirgitteSB|<small><span style="color:#778899;">Talk</span></small>]] 18:27, 19 June 2006 (UTC)

Yes, I would like a list of the material that has been deleted. I think it is totally reasonable to expect some notice and time for us to decide what should be kept and where. I get the message that this material is not wanted at Wikisource, but that is no excuse for simply deleting it without informing anyone who might be interested. The fact that no supporter of the material spoke up during the April discussion should have been a clue that there was not adequate notice. --[[User:ArnoldReinhold|agr]] 20:16, 19 June 2006 (UTC)
:I find your topic header both here, and on the [[s:Wikisource:Scriptorium|Scriptorium]], to be inflammatory, inappropriate, and wildly out of place. To quote from our own [[book burning|article]] on book burning: "Burning books is often associated with the Nazi regime." [[User:bookofjude|Jude]] <small>([[User_talk:Bookofjude|talk]])</small> 00:14, 20 June 2006 (UTC)

I certainly was not trying to suggest that anyone is behaving like Nazis and I apologize if the title is too harsh. As I said in my original post, I believe the regular editors at Wikisource are due some deference in their decision making. But I find the wholesale deletion of articles belonging to topics no longer in favor, Mathematics in particular, to be very disturbing. It is one thing to change the scope of a project, another to simply discard material submitted and accepted in good faith.--[[User:ArnoldReinhold|agr]] 00:38, 20 June 2006 (UTC)

:Just to clarify, nothing was deleted because the topic fell out of favor.  I would love to see mathmatical texts added.  We actually have some being worked on now.  Data is being excluded no matter the topic. --[[User:BirgitteSB|<span style="color:#f4a460;">Birgitte§β</span>]] ʈ [[User talk:BirgitteSB|<small><span style="color:#778899;">Talk</span></small>]] 00:58, 20 June 2006 (UTC)
::The entire category of mathematics was wiped out. Absent a list of what was deleted there is no way to tell what might have been of interest.--[[User:ArnoldReinhold|agr]] 11:54, 20 June 2006 (UTC)
:::Of the 1741 pages that have been deleted since April 29, 2006, on Wikisource, and June 18, 2006, 1381 of them were in the main namespace. Of those 1381 deletions, 152 pages contained "efer" or "ref" in the deletion summary. You can find the complete list of them [[User:Bookofjude/Wikisource|here]]. [[User:bookofjude|Jude]] <small>([[User_talk:Bookofjude|talk]])</small> 13:26, 20 June 2006 (UTC)

::::(edit conflict)Categories are currently little used at Wikisoucre (i.e. [[s:Category:Epic poetry]] lists 5 poems, believe me there plenty more), that one is empty does not mean we have nothing on the topic.  I do not know how narrowly you define Mathmatics but some projects currently underway are [[s:A Treatise on Electricity and Magnetism]] (the proofreading of OCR is being done on the image pages); [[s:The New Student's Reference Work#Arithmetic]]; [[s:1911 Encyclopædia Britannica/Infinitesimal Calculus]] These are just a few example of current work.   Most anything listed on this [http://www.hti.umich.edu/cgi/t/text/text-idx?page=browse&c=umhistmath website] would also be a welcome addition as I believe they are all out of copyright.  The topic of Mathmatics has not fallen out of favor! 

::::You are complaining that pages you might have been interested in (if you had a list of them to examine, as you do not seem to know what actually existed) were deleted by people who examined and disscussed them on project's main discusssion page as well as at Proposed Deletions.  This complaint's scope is based on an empty category on a project that does not currently use [http://en.wikisource.org/wiki/Special:Uncategorizedpages categories in an organized fashion.]  This complaintent despite speaking for the inclusion of data at Wikisource in November, never made a single edit towards the maintanence or organization of that material in the '''5 months''' between then and the April disscussion. Despite your strong interest in the deleted data, you refuse to do the legwork on compilng a list of titles for me to restore.  Titles which you did not put up, did not edit and did not add to your watchlist.  I dislike turning this in your direction, but I ''really'' dislike the the misrepresentations being made about what happened at Wikisource.  I will repeat that this topic heading is quite out of line and would appreciate it if you struck it.  I imagine you realize the [[s:Wikisource:Scriptorium/Archives/2006/05#Plan on phasing out reference data|Plan on phasing out reference data]] will procede without interuption, please make any requests for temporary restoration on my talk page.--[[User:BirgitteSB|<span style="color:#f4a460;">Birgitte§β</span>]] ʈ [[User talk:BirgitteSB|<small><span style="color:#778899;">Talk</span></small>]] 14:15, 20 June 2006 (UTC)

To cool things down a bit, I have changed the topic heading here and at scriptorium. [[User:Bookofjude]] has finally provided a list of the material deleted after others told me to search through the logs. That is a big help. I really don't want to make this personal, but I must point out that after the November discussion led to a clear consensus on keeping reference material, I submitted a detailed proposal on what tabular material to include to the discussion page on January 18, 2006. It received no further comment. I think I had every reason to think the matter was settled. --[[User:ArnoldReinhold|agr]] 14:52, 20 June 2006 (UTC)

:Thank you for the alteration.  I sympathize that you believed things were settled, but I have learned that settled doesn't exist on a wiki.--[[User:BirgitteSB|<span style="color:#f4a460;">Birgitte§β</span>]] ʈ [[User talk:BirgitteSB|<small><span style="color:#778899;">Talk</span></small>]] 15:13, 20 June 2006 (UTC)

Although I am a bystander in the debate, though in favour of keeping math tables on wikisource, I would like to remark that I read Wikipedia Signpost regularly and I don't remember any remark about voting about massive deletions of existing material on Wikisource. Considering that fact that Wikisource is not so high profile and people here could be interested in the voting, I think it's a bit unfair. [[User:Samohyl Jan|Samohyl Jan]] 16:47, 20 June 2006 (UTC)

:I read the Signpost regularly as well.  Although they seem to report very well on Wikimedia Foundation issues, I think their coverage of other projects and other languages is quite minimal.  I don't know that I would say it is unfair of them, after all the Signpost a product of the English Wikipedia.  Anyone interested in Wikisource policies should regularly read the [[s:WS:S|Scriptorium]].  There is nothing of importance that is not at least mentioned there.  I think the archives are quite nicely organized as well for those interested.--[[User:BirgitteSB|<span style="color:#f4a460;">Birgitte§β</span>]] ʈ [[User talk:BirgitteSB|<small><span style="color:#778899;">Talk</span></small>]] 17:08, 20 June 2006 (UTC)

===Deleted math articles===
As best I can determine, here is a list of the math-related articles that have been deleted. [[User:BirgitteSB|<span style="color:#f4a460;">Birgitte§β</span>]] has kindly restored them temporarily:

*[[Wikisource:Prime deserts]]  - a fairly short short list of gaps in the primes
*[[Wikisource:Fibonacci numbers 1-500]]    
*[[Wikisource:Mersenne primes]] - up to number 30, 2^132049−1
*[[Wikisource:Phi to 30,000 places]] - There was also an article listing Phi to 20,000 places

Also there were computer source code articles with the following titles:

*[[Wikisource:Fibonacci sequence]]          
*[[Wikisource:Euclidean algorithm]]    
*[[Wikisource:Prime factorization]]    

I'm not sure these have mcuch value. Finally, I believe there were once articles listing pi and e to a million places. These would be easy to reconstruct if anyone wants to make a case for them.

I think a case can be made for moving at least the first two or three articles above to Wikipedia, presumably retitled as "Table of..."  Comments?--[[User:ArnoldReinhold|agr]] 18:35, 20 June 2006 (UTC)

== [[Babylonian mathematics]], [[Ibn al-Banna]] ==

The section [[Babylonian mathematics#Old Babylonian Mathematics (2000-1600 BC)|Old Babylonian Mathematics (2000-1600 BC)]] of this article seems to be a copy of [http://www-history.mcs.st-andrews.ac.uk/HistTopics/Babylonian_mathematics.html this page] (starting with "Perhaps the most amazing aspect of ..."). It's especially funny in sentences like "In our article on Pythagoras's theorem in Babylonian mathematics we examine...", where in reality, no such article exists on Wikipedia. What should be done about it?

On a somewhat related issue, [[User:Chem1]] has created the article [[Ibn al-Banna]] (1256-1321), to whom he attributes the invention of the iterative process <math>x_{n+1} = \frac{1}{2}(x_n + \frac{N}{x_n})</math> for finding the square root of a number - aka the "Babylonian method". This doesn't seem right. -- [[User:Meni Rosenfeld|Meni Rosenfeld]] ([[User Talk:Meni Rosenfeld|talk]]) 14:41, 21 June 2006 (UTC)

:I'll take a shot at a re-writing and wikifying the [[Babylonian mathematics#Old Babylonian Mathematics (2000-1600 BC)|Old Babylonian Mathematics (2000-1600 BC)]] section. [[User:Gandalf61|Gandalf61]] 14:54, 21 June 2006 (UTC)

:I've removed that section from [[Babylonian mathematics]] as well as and following section as possible copyright violations, leaving a notes on the talk page of that article, and the editor who added it. [[User:Paul August|Paul August]] [[User_talk:Paul August|&#9742;]] 15:31, 21 June 2006 (UTC)

::Okay, I've now trimmed, re-written, wikified and re-ordered the offending section. I think it is now sufficiently different from the source to be no longer copyvio, so I have put the re-written version back into the article. [[User:Gandalf61|Gandalf61]] 13:17, 22 June 2006 (UTC)

== Iff in formal writing ==

I would like to propose that all usages of "iff" to mean "if and only if" be replaced by "if and only if", as iff is not a very common abbreviation. Thoughts? (I actually did a bit of this but [[User:Oleg Alexandrov|Oleg Alexandrov]] advised me to ask here &ndash; if there is a consensus for me to remove those edits it will be no problem for me to do it.) —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 20:24, 21 June 2006 (UTC)

:I disagree that iff isn't very common, but I '''support''' removing it in favour of "if and only if", particularly in articles that might be of use to people who aren't expert mathematicians. [[User:RandomP|RandomP]] 20:28, 21 June 2006 (UTC)

:I would say that iff is quite common in textbooks, and I use it all the time, personally, but this ''is'' an encyclopedia, and I believe (quite strongly) that iff should be avoided everywhere (especially in definitions, whether formal or informal!) [[User:Madmath789|Madmath789]] 20:45, 21 June 2006 (UTC)

:: Yeah, iff is a bit of a neologism (which I think fell out of fashion by now :) and should surely be avoided in defintions. Is it a good idea however to just do a mass iff removal from all math articles? Makes me wonder if it is worth the trouble. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 21:05, 21 June 2006 (UTC)
::: It's not really trouble.  It just takes a bit of time, but I'll put the time in if we get enough consensus here to remove it. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 21:08, 21 June 2006 (UTC)
:::: I prefer "if and only if". Life is short, but if your life isn't that short, I say go ahead and change them. Just be careful with articles like [[if and only if]] and [[IFF]]. [[User:Dmharvey|Dmharvey]] 21:14, 21 June 2006 (UTC)
:::: ''(Edit conflict)'' Well it may not be trouble for you to do it, but you have kind of washed out my watchlist.  This is slightly annoying, but tolerable for a good cause.  Is there any precedent for bot flags for people using AWB? -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 21:15, 21 June 2006 (UTC)
::::: No precedent that I know of. I'm sorry about the watchlist, I know what you mean (my watchlist is full of math articles too).  Hopefully I can get it all done today so that only one day's watchlist is screwed up :-) —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 21:18, 21 June 2006 (UTC)
::: If I recall, "iff" is allowed in any Springer book or journal.  It is in the Merriam-Webster dictionary (supposedly).  I think that disqualifies it from being a neologism.  I personally never use it, but I wouldn't impose a moratorium.  Don't you think this is a bit heavy-handed? [[User:Silly rabbit|Silly rabbit]] 21:39, 21 June 2006 (UTC)
:::: It's there.  At least it's in their [http://www.webster.com/dictionary/iff online version], and I predict that iff (heh) it's there, it's either in their print edition, or will be in the next print edition. --[[User:Histrion|Jay (Histrion)]] ([[User talk:Histrion|talk]] • [[Special:Contributions/Histrion|contribs]]) 17:33, 22 June 2006 (UTC)
:I support making this change, with the exception of "iff" used in definitions which should be changed to "if". In fact I think we should expand the [[WP:MSM|Math Manual of Style]] to discourage the use of "iff".[[User:Paul August|Paul August]] [[User_talk:Paul August|&#9742;]] 21:56, 21 June 2006 (UTC)
:: I support editing out all uses of "iff" from Wikipedia, and augmenting the MSM to discourage future use. However, I think a more delicate touch is required. In definitions that are clearly such, change to "if". Elsewhere, it is often better to rewrite the sentence rather than merely changing "iff" to "if and only if". I realize that may be much more labor intensive, and require more insight and judgement on a case-by-case basis, but the alternative could look ugly. Uglier than "iff", I don't know. My practice has been simply to make this kind of change as I encounter instances, and as the mood strikes me. A note in our conventions, a note in the Manual of Style, and widespread awareness among mathematics editors may be enough to stamp out the problem.
:: I also go after a few other issues as I see them. I've mentioned "ditto" previously. Others are the Latin abbreviations "i.e." (''id est'', "that is") and "e.g." (''exempli gratia'', "for example"). Although I know what they mean and am perfectly comfortable with them, I think they pose an unnecessary barrier to many readers; and since the English glosses are perfectly good substitutes, I see no reason to use the abbreviations here. The list goes on, but that's enough for today. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 23:40, 21 June 2006 (UTC)
::: So what is the proper rewrite for "a triangle is right if and only if its sides satisfy ''a''<sup>2</sup> + ''b''<sup>2</sup> = ''c''<sup>2</sup>"? -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 23:49, 21 June 2006 (UTC)
:::: Depends whether you're defining the term "right" or whether it's been defined previously. [[User:Dmharvey|Dmharvey]] 23:55, 21 June 2006 (UTC)
::::: I'm asking KSmrq how to rephrase a theorem whose converse is also true, so assume "right" has been previously defined as, say, "contains a ninety degree angle". -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 01:27, 22 June 2006 (UTC)
:::::: I'd need more context to be sure; good writing doesn't happen one sentence at a time. Since this is a theorem asserting an equivalence, I would not object to "if and only if", and perhaps not feel the need to edit it. However, if I were writing this ''ab initio'' myself, I might choose different language. For example, if I wanted to highlight the assertion I might write
::::::* '''Theorem'''. Let a triangle have side lengths ''a'', ''b'', ''c'', with ''c'' the longest side. Then the following two statements are equivalent:
::::::*# The triangle is a right triangle.
::::::*# ''a''<sup>2</sup> + ''b''<sup>2</sup> = ''c''<sup>2</sup>.
:::::: For an inline statement, but still feeling the double implication is important, I might write
::::::* For any right triangle with sides ''a'', ''b'', ''c'', the sides satisfy ''a''<sup>2</sup>+''b''<sup>2</sup>&nbsp;= ''c''<sup>2</sup>, where ''c'' is the longest side. The converse is also true: any triangle whose sides satisfy the equality is a right triangle.
:::::: But it really depends on the topic, the audience, the assertion, and the context. For example, in a larger context where this is a minor point, and the paragraph in which it appears is building a more important concept, I'd try to keep it as short as possible consistent with clarity. Does that answer your question? --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 12:53, 22 June 2006 (UTC)
::::::: It does answer my question.  But I don't like it.  You want to double the length of the assertion so that you can mention the statement and its converse explicitly?  I would really much rather stick in an "if and only if".  Listing the equivalent conditions is nice when there are three or four equivalent conditions, but rather burdensome for only two.  Therefore I cannot support the idea to revise the MSM to suggest that "if and only if" be avoided (for theorems, that is.  I'm on board avoiding this turn of phrase for definitions though). -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 03:54, 23 June 2006 (UTC)
:::::::: Yes, I described two variations that are longer. But the last thing I said was that in certain contexts I'd prefer to keep it as short as possible, so as not to detract from a larger point.
:::::::: Here's one way to think about it. I have an assertion in mind. It's a nifty little assertion and I quite like it. But my first question is, does it help the article? Is it important either as an end in itself, or as support for a larger goal? Or perhaps as entertainment or enrichment? If it does not help the article, no matter how much I like it I shouldn't use it. OK, I decide it stays. Is it a brief aside, or is it something the reader really should understand? If the latter, then brevity is less important than clarity. Both of the longer versions I offered are predicated on the assumption that each direction of the implication is important for the reader to absorb. If it's that important to say, then spend a few extra words and do it right. If it's not that important to say, then maybe we don't really need it.
:::::::: Prose that packs five major ideas in one paragraph is not reader-friendly. We tolerate it in mathematics texts if we must, but we don't enjoy learning from it. (I'm reminded of a graduate algebraic geometry class that spent the better part of a term covering the first chapter of the text: Hartshorne, {{ISBN|978-0-387-90244-9}}.) That kind of density intimidates mathematics graduate students; surely it is inappropriate for an encyclopedia.
:::::::: As for the MSM, my proposal was to ward off "iff", not "if and only if". --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 23:03, 23 June 2006 (UTC)

:::::OK, since it seems like no one is opposed to changing iff to if and only if, I'm going to continue.  As far as replacing some with just "if", that can be done afterwards. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 01:24, 22 June 2006 (UTC)
:::::: I think that's a misreading. Both [[User:Paul August|Paul August]] and I explicitly objected to making the change in the context of a definition, a view widely supported by others in prior discussion. Is there some reason you can't be careful about that? --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 13:00, 22 June 2006 (UTC)
::::::: Basically, what I've gotten out of this discussion is that nobody objects to changing "iff" to "if and only if" (they ''do'' mean the same thing), but that you both support removing some of the "if and only if"s and making them just "if"s, or removing them altogether and rephrasing definitions.  It will be no harder for you to do that when it says "if and only if" than when it had said just "iff".  If you want to go back and do that, well, all the pages that have "if and only if" are now grouped in my most recent [[Special:Contributions/Mets501|contributions]]. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 13:18, 22 June 2006 (UTC)
:::::::: I also would like to add that through my going through all the "iff"s I came by very few definitions. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 13:21, 22 June 2006 (UTC)
::::::::: I don't think this is a big problem. [[User:Paul August|Paul August]] [[User_talk:Paul August|&#9742;]] 17:54, 22 June 2006 (UTC)
::::::::::I would point out, however, that this is one of the reasons we have a link for [[iff]]; so if someone doesn't understand it, it can be explained.[[User:Pmanderson|Septentrionalis]] 00:15, 2 July 2006 (UTC)

== Fraction refraction. :-) ==

I've never poked my head into the Math WikiProject before, but a few months back I did some work on [[Fraction (mathematics)]] before I had to take a break to tend to both Real Life and my proper job.  Looking around, I can't help feeling there's a lot to be done, and it's not just a matter of the one article:
* If [[Vulgar fraction]] and [[fraction (mathematics)]] are not to be merged, then duplicate material needs to be excised.  If they are to be merged, then let's merge 'em!
* [[Fraction (mathematics)]], while slowly improving, needs cleanup, and needs it badly, but the lengthy material on the arithmetic of fractions really belongs in an article all its own.  Or, for that matter, in a Wikibook, but...
* the Wikibooks material is scant, sometimes incorrect, and things are often hard to find, or can be found in more than one place.  Looking for fraction arithmetic, for instance, I found it under both Algebra/Arithmetic and Applied Math Basics, but not under Beginning Mathematics.  Are Wikibooks out of the scope of this WikiProject?
* Amongst the mess, there's probably more duplicated material about [[Egyptian fraction]]s than there needs to be.

I'd keep going, but another task is calling me from my PC.  I know that fractions might not be a hip'n'trendy subject, but I work as a tutor at a community college and there are a few math topics that come up a lot, and manipulating fractions is one of them. :) I'd be willing to take the lead on this, as long as I have the support of the Project. --[[User:Histrion|Jay (Histrion)]] ([[User talk:Histrion|talk]] • [[Special:Contributions/Histrion|contribs]]) 21:09, 21 June 2006 (UTC)

== New template ==

I just created a new template, {{tl|In sqrt}}.  It basically displays the radical (√) and the the number with an overline.  For example, if you enter <nowiki>{{In sqrt|x}}</nowiki>, it will produce {{radic|x}}. It works great for all CSS capable browsers, otherwise it just displays a radical sign. I was wondering, should we put this in the mathematics manual of style as a recommendation for all inline square roots? —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 01:15, 23 June 2006 (UTC)
::::::::::"it will produce √<span style="text-decoration: overline;">x</span>." <span title="Pronunciation in IPA" class="IPA">[[User:Jimp|J]][[Special:Contributions/Jimp|ɪ]][[User talk:Jimp|m]][[wikt:User:Jimp|p]]</span> 04:26, 31 May 2007 (UTC) 
: ''otherwise it just displays a radical sign''
: So what happens if I enter {{radic|x+2}} in a non-CSS capable browser? Is it going to appear as √x+2? [[User:Dysprosia|Dysprosia]] 01:50, 23 June 2006 (UTC)
::::::::::"if I enter √<span style="text-decoration: overline;">x+2</span>" <span title="Pronunciation in IPA" class="IPA">[[User:Jimp|J]][[Special:Contributions/Jimp|ɪ]][[User talk:Jimp|m]][[wikt:User:Jimp|p]]</span> 04:26, 31 May 2007 (UTC)
::Yes, I think it will.  However, there are so few non-CSS capable broswers that this is not an issue.  Or if people here think it is an issue, then don't use this template for polynomials. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 01:56, 23 June 2006 (UTC)
::: If it's going to fail and effectively look ''incorrect'' for any number of users, then it's not a Good Thing. As KSmrq said, √(x+2) is always correct. [[User:Dysprosia|Dysprosia]] 03:57, 23 June 2006 (UTC)

: I take it the benefit is the [[vinculum]] (overline)? Otherwise, &amp;radic;2 produces &radic;2 just fine.
: I'm leary of this for a few reasons. One is that a browser that doesn't support CSS properly doesn't have a graceful fallback to show the grouping, so readers can't distinguish {{radic|''x''}}+2 from {{radic|''x''+2}}, whereas with &amp;radic;(''x''+2), &radic;(''x''+2), they can. The second problem is that the radical sign doesn't stretch up or down, so that something like {{radic|<sup>''x''</sup>&frasl;<sub>''y''</sub>}} or {{radic|''x''<sup>2</sup>+''y''<sup>2</sup>}} won't look right. It seems I can't write the fraction using the {{tl|fraction}} template, because there is no nesting; still, I suppose this doesn't come up often. But template use incurs extra server overhead; is it worth it?
: My last concern involves the arrival of BlahTeX. Currently the notation <nowiki><math>\sqrt{x^2+y^2}</math></nowiki> produces a PNG, <math>\sqrt{x^2+y^2}</math>. BlahTeX can serve this as MathML that renders beautifully inline. However, this creates a predicament for the template. How should the template adapt? Should it be revised to produce the &lt;math&gt; form, or continue to produce the Unicode/CSS form which is now less attractive for many readers?
: Your thoughts? --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 03:45, 23 June 2006 (UTC)
::::::::::"can't distinguish √<span style="text-decoration: overline;">''x''</span>+2 from √<span style="text-decoration: overline;">''x''+2</span>, ... something like √<span style="text-decoration: overline;"><sup>''x''</sup>&frasl;<sub>''y''</sub></span> or √<span style="text-decoration: overline;">''x''<sup>2</sup>+''y''<sup>2</sup></span> won't look right" <span title="Pronunciation in IPA" class="IPA">[[User:Jimp|J]][[Special:Contributions/Jimp|ɪ]][[User talk:Jimp|m]][[wikt:User:Jimp|p]]</span> 04:26, 31 May 2007 (UTC)
:: On my machine (Firefox on Mac OS) it renders like this: [[Image:SqrtTemplate.png]]. Honestly, if I saw something like that in an article, I would change it to <nowiki><math></nowiki> straight away. I think it looks awful. I looks like "square root of the conjugate of x+2". It's marginally better in Safari. [[User:Dmharvey|Dmharvey]] 11:04, 23 June 2006 (UTC)

::I really dislike the idea.  Sure, presentation is important for Wikipedia, and we all (or at least some of us) are looking forward to seeing a beautiful print version of wikipedia in the library one day (or just a nicer version on a high-resolution display with large fonts).

::However, at least as far as I'm concerned, the real value's in the database being created.  I'm already somewhat skeptical of the guideline to avoid using inline math.  Templates make it even harder to understand what's going on, are limited in their applications, and I'm not sure they'll ever do exactly what you want with screen readers.  Blahtex promises to be a better way out, for now, with MathML salvation on the horizon.

::(I don't think Wikipedia should be using TeX-derived syntax forever, though.  An advanced language that would allow us to specify not only what our formulas should look like, but also what they mean, and allow wikilinked symbols, might be a good idea when MathML has become accepted).

::[[User:RandomP|RandomP]] 12:08, 23 June 2006 (UTC)
:::Thanks everyone for your input. I will stop using the {{tl|In sqrt}} template (it appears as if that's what everyone above thinks), and have removed the changes to the [[square root]] article (the only one which I changed.  Oh god, we need BlahTeX!  It's ''so'' ugly with inline PNG square roots and even uglier with the &radic; sign. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 12:51, 23 June 2006 (UTC)
:::: While we're on the topic, something else I should mention is that blahtex knows how to get the vertical alignment of a PNG equation correct (thanks to dvipng). That is, it aligns the baseline of the equation with the surrounding text. This is not enabled on the demo wiki, because it requires some (minor) changes to mediawiki's database schema, and we don't want to be pushing our luck yet. It is however enabled on the [http://blahtex.org/index.php?page=interactive interactive demo]. Things like inline square roots become a lot less uglier when the baseline is correct, especially if the font size is approximately correct. [[User:Dmharvey|Dmharvey]] 13:20, 23 June 2006 (UTC)
::::: Yes, I forgot to mention baseline issues as one of the advantages of BlahTeX. MathML display, of course, automatically gets it right without clever hacks. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 14:21, 23 June 2006 (UTC)
:::::: Yes, I've experimented more with the interactive demo, and it does render ''much'' better.  How long do you guys think it will be before it's implemented? (or is not quite finished yet?) —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 17:53, 23 June 2006 (UTC)
::::::: Don't know. We're working on it. (In between the real lives that we sometimes pretend to have.) [[User:Dmharvey|Dmharvey]] 18:02, 23 June 2006 (UTC)
:::::::: What, you're not still faking that whole doctoral thing, are you? Or do you mean serious pursuits like sleep and beer? Oh, now I remember; you were planning to spend time celebrating Australia's 6–0 win over Brazil! Ah, well; at least you didn't have to play Ghana. ;-) --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 20:26, 23 June 2006 (UTC)
::::::::::In case the function of the template is changed in the future (which would be a good thing seeing as it's otherwise unwanted) I've made copies of the text which transcludes it and added <code>subst:</code> so that the text as it originally looked will still be able to be read. <span title="Pronunciation in IPA" class="IPA">[[User:Jimp|J]][[Special:Contributions/Jimp|ɪ]][[User talk:Jimp|m]][[wikt:User:Jimp|p]]</span> 04:26, 31 May 2007 (UTC)

== [[:Category:Degenerate forms]] up for deletion ==

[[Wikipedia:Categories for deletion/Log/2006 June 23#Category:Degenerate forms]] [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 01:48, 23 June 2006 (UTC)

==Need third opinion at Operation (mathematics)==

JA: Could use a third opinion at [[Operation (mathematics)]], a page that was created as a gloss on the generic concept but is now being converted into "hwk-helper" with material that either belongs or is pretty much already covered at [[Binary operation]] and other places.

JA: Looking down the road, in both directions, I am seeing here a more generic issue for the WP math community.  For instance, the article in question was categorized as Mathematical Logic, and is now being recategorized as Elementary Mathematics.  I think that there needs to be a standard operating procedure for sorting out and coordinating "tutorial" and "standard" articles.  I notice that the physics folks already have a template for doing this.  Anyway, something to think about.  Thanks, [[User:Jon Awbrey|Jon Awbrey]] 17:56, 23 June 2006 (UTC)

:As the other editor in this dispute, let me summarize my position. "Operation" is an elementary term in mathematics. Someone helping their kid with his or her homework would likely end up at [[Operation (mathematics)]]. The term belongs in [[:Category:Elementary mathematics]]. In editing the article I preserved the full formal definition. The entire article fits on one screen. There is no need in this case (though there certainly may be in others) for "tutorial" and "standard" articles. (I gather by "standard" JA means aimed at specialists.)

:No specialist is harmed by having to skip over a dozen or so lines of introductory material to get to a formal definition. If there were a need for a specialized page for the mathematical logic community (and I fail to see why since they are using the ordinary meaning), a proper name for such an article might be "Operation (mathematical logic)." According to Wikipedia policy [[WP:NAME]]: "Generally, article naming should give priority to what the majority of English speakers would most easily recognize..." 

:I agree with JA that a broader discussion would be helpful. I have no problem with highly technical articles that treat their subject rigorously, but where it is possible to do so introductory sections should be included that speak to a wider audience. I have tried to do this in several places and I consider it some of my best work. See [[homotopy groups of spheres]] for example. Wikipedia should try to demystify math, not obfuscate it. --[[User:ArnoldReinhold|agr]] 17:28, 23 June 2006 (UTC)

:: My personal opinion that the article requires a general definition as well as examples. In this version, the examples are nicely covered in introduction (one more example: operations on [[set]]s and [[function]]s, ''which I have just added''). Operations in math logic is just one of the examples, and I think that elementary mathematics is more appropriate. ([[User:Igny|Igny]] 19:10, 23 June 2006 (UTC))

::In this specific case I see no reason not to combine an elementary treatment with one for the specialist. And let's be honest, a specialist has no need to look up such basic stuff, so actually general understandability is more important. One thing that is not made clear and may be confusing, is that there is no clear distinction in mathematics between the meanings of [[function (mathematics)|function]], [[operation (mathematics)|operation]], and [[operator]]. For example, the article [[Operation (mathematics)]] now mentions [[square root]] as an example of a [[unary operation]], while the article [[Square root]] itself only mentions "[[function (mathematics)|function]]". It is largely a matter of historical convention when which term is used. --[[User:Lambiam|Lambiam]][[User talk:Lambiam|<small><sup>Talk</sup></small>]] 19:26, 23 June 2006 (UTC)

JA: This is like ''deja vu'' of discussions that we had on Function and Relation, and so I'd rather focus on the generic problem, as I'm fresh out of ergs to be caring about this stuff unless others do.  I created this article because of a recurring need in other articles — check the "what links here" page — for a quick gloss to a suitably general concept of k-adic operations.  And now anybody chasing those links is likely to skip the whole darn thing before getting past the TOC.  What we have now is two articles whose front ends are devoted to [[Binary operations]], and so it seems like the whole thing is better dealt with by way of a 1-liner up top like:  <nowiki>{{for|an introductory treatment|Binary operation}}</nowiki>.  [[User:Jon Awbrey|Jon Awbrey]] 19:48, 23 June 2006 (UTC)
:First of all, the present intro to [[operation (mathematics)]] does not just deal with binary operations. It also describes unary operations. The common mathematical use of the word "operation" includes both.  The binary operation page is not that elementary and goes off to discuss groups, monoids and the like, as it should. The unary operation page devotes a lot of its space to computer programming operations.  So there is a need for the current version of "operation." This is an encyclopedia, not a glossary, and specialists can put up with a little intro material. Regarding "what links here," I came to this article in the first place when I was editing [[exponentiation]] and wanted to link the word "operation.' What I found when I looked there was totally inappropriate. I suspect other editors of elementary articles have come to the same conclusion. 

:As for the [[relation (mathematics)]] article, it already has a long introductory section. It would take very little editing to make its intro beginner friendly, eliminating the need for an initial redirection. Basically defer the jargon for sentence or two. And that I think is the broader issue here. Where it is possible to do so, editors should be able to add short introductions to articles that make them more accessible to non specialists, without a big battle each time.  Long tutorials deserve their own article, of course. But an average reader landing on a basic mathematical topic should get an initial explanation they can understand before being redirected.--[[User:ArnoldReinhold|agr]] 21:44, 23 June 2006 (UTC)

::I suggest creating [[operation (elementary mathematics)]], [[function (elementary mathematics)]] and [[relation (elementary mathematics)]] which would have content aimed at the primary-school/secondary-school/high-school  level. This might solve the edit-warring over these articles. [[User:Linas|linas]] 00:19, 2 July 2006 (UTC)

== Span.texhtml ==

Please see my proposal [[MediaWiki talk:Monobook.css#Span.texhtml|here]]. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 22:20, 23 June 2006 (UTC)
:Doesn't anyone want to comment?  It's very relevent to all math pages on Wikipedia. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 23:49, 24 June 2006 (UTC)
:: We've seen it before. There's little enthusiasm for a global stylesheet change for two reasons (at least).
::# For an inline formula using &lt;math&gt; tags that happens to force a PNG, the "x" will appear in a serif font, which is also the way it appears in most displayed equations (since the typical display is a PNG); consistency in this case dictates that the HTML should use a serif font as well.
::# Anyone who really cares about using a sans-serif font can do so using using their personal stylesheet, just like the users you noted.
:: No matter which choice is taken, so long as the monobook body text uses sans-serif and TeX PNGs use serif, we have a conflict. Nor is that the end of it; look at the difference in other characters, such as Greek symbols and operators.
:: This conflict is unlikely to end with the release of the STIX fonts, as suggested by the following statement:
::: “Most of the glyphs in the STIX Fonts have been designed in Times-compatible style. Times was first designed under Stanley Morison's direction by Victor Lardent at The London Times in 1932. Many variations of this design have been produced since the original.
::: “In addition to Times-compatible glyphs, some portions of the STIX Fonts include other design styles such as sans serif, monospace, Fraktur, Script, and calligraphic.”
:: Thrilling; all of the extra styles ''except'' sans serif are essential for TeX. So get used to serif mathematics; it looks to be with us for a long time to come. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 00:27, 25 June 2006 (UTC)
::: How about "<code>span.texhtml {font-size=14px}</code>"? That will at least get it to be the same line height as the sans serif.
:::: Will it? For which OS, browser, fonts, and settings? This kind of hair-pulling madness is a tiny fraction of the issues [[User:Dmharvey|Dmharvey]] and [[User:Jitse Niesen|Jitse Niesen]] have been wrestling with over in [[m:BlahTeX|BlahTeX]]-land. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 22:38, 25 June 2006 (UTC)

== he's baaaacccckkkkk..... "made it clear" ==

[http://en.wikipedia.org/w/index.php?title=Special:Contributions&target=218.133.184.53] [[User:Dmharvey|Dmharvey]] 18:35, 24 June 2006 (UTC)

:He never seems to tire, does he? Blocked again... -- [[User:Fropuff|Fropuff]] 05:35, 25 June 2006 (UTC)

:In defense of our clarificator, there is an apparent contradiction between the [[Real number]] article, in which "a [presumably meaning ''any'' here] real number can be given by an infinite [[decimal representation]]", and the article [[Decimal representation]], which has: "Every real number except zero has a unique infinite decimal representation" (which is true the way things are defined locally). Instead of blocking, it might be better to smooth away the contradiction. --[[User:Lambiam|Lambiam]][[User talk:Lambiam|<small><sup>Talk</sup></small>]] 10:00, 25 June 2006 (UTC)
::I just removed that section in "decimal representation". It was probably also put there by WAREL and missed by others. [[User:JRSpriggs|JRSpriggs]] 11:00, 25 June 2006 (UTC)
:::Actually, if you read that paragraph again, you will notice that it is correct. Every positive real number has exactly one decimal expansion which doesn't end with all 0's, and one decimal expansion which doesn't end with all 9's (usually, these two are the same). That paragraph emphasized the first of these - which looks unusual, so I don't object to the removal. -- [[User:Meni Rosenfeld|Meni Rosenfeld]] ([[User Talk:Meni Rosenfeld|talk]]) 18:05, 26 June 2006 (UTC)
::::The first sentence of the removed paragraph said was "Every real number except zero has a unique infinite decimal representation, that is, one in which not all of its digits become zero after a while. ". Although the subordinate clause tries to rescue it, the main clause is false. Some real numbers have more than one infinite decimal representation. It is senseless to discriminate against a terminal string of zeros in favor of a terminal string of nines. If anything, I would do it the other way around. [[User:JRSpriggs|JRSpriggs]] 10:22, 27 June 2006 (UTC)
:::The subordinate clause clarifies what was the meaning of "decimal expansion" in the main clause. The main clause would have been false on its own - but it is accompanied by the subordinate clause to form a whole sentence - a correct one. It is the same as saying "every real number ''a'' has a unique cube root, that is, a real number ''b'' such that ''b''<sup>3</sup> = ''a''". The first part could have been seen as false on its own, if we see it in the context of complex numbers - but the second part clarifies that we are only concerned with real numbers. Not much point in arguing about this, though - I do agree that ther article is better off without that section. -- [[User:Meni Rosenfeld|Meni Rosenfeld]] ([[User Talk:Meni Rosenfeld|talk]]) 10:35, 27 June 2006 (UTC)

It is more like saying "Every positive real number has a unique square root, i.e. a negative number which when multiplied by itself gives the positive number.". He is treating the abnormal case as the normal. [[User:JRSpriggs|JRSpriggs]] 11:01, 27 June 2006 (UTC)
::That is something I certainly agree with. -- [[User:Meni Rosenfeld|Meni Rosenfeld]] ([[User Talk:Meni Rosenfeld|talk]]) 11:28, 27 June 2006 (UTC)
:::I would agree with all this, but I have to say that I do recall situations in proofs, where it is more convenient to use the version of a real number which ends in a string of 9's (it means that every strictly positive real has a non-terminating decimal representation) - but in this instance, I agree that he is advocating the 'abnormal'. [[User:Madmath789|Madmath789]] 11:48, 27 June 2006 (UTC)

:Here is an attempt to say something that is (a) true, and (b) not a manifent consequence of what is already in the article:
::Every non-negative real number has an infinite decimal representation. It is unique, except for those positive real numbers that also have a finite decimal representation: these have two infinite representations. For example, the number 5/4 = 1.25 has the two infinite decimal representations 1.24999… and 1.25000….
:Is it worth adding this? --[[User:Lambiam|Lambiam]][[User talk:Lambiam|<small><sup>Talk</sup></small>]] 17:23, 28 June 2006 (UTC)
::If you do add it, add it to the existing section "Multiple decimal representations" rather than making a new section. [[User:JRSpriggs|JRSpriggs]] 04:55, 29 June 2006 (UTC)

==Request from non-mathematician==

When I do "random article" I occasionally come across mathematical formulae (and sometimes with general science books etc). It would be useful for those of us who are not mathematically informed if there was a "basic explanation" as to use and purpose.

See the examples I put on [[Wikipedia:Requests for expansion]] for what I mean. [[User:Jackiespeel|Jackiespeel]] 16:54, 26 June 2006 (UTC)

:In reference to [[boolean-valued function]], [[boolean domain]], and [[finitary boolean function]].  Those are pretty short stubs.  They need lots of work (or perhaps even to be merged somewhere).  In response to your general query: yes, I will try to make every math article I write have explanations, examples, context, and everything else that makes for brilliant writing.  Sometimes a stub is better than nothing though. -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 17:37, 26 June 2006 (UTC)

On the request for expansion page, you wrote:
:Finitary boolean function, Boolean domain and Boolean-valued function and some of the links thereof - can someone give an explanation in "ordinary English" as to what these functions are. I can see that they are complex mathematical functions - but "what are they"? Perhaps a brief standard text could be added. "This mathematical function is used in xxx, and does yyy." (add more detail as required) Jackiespeel 23:14, 24 June 2006 (UTC)
The article "finitary boolean function" describes a simple generalization of a boolean function.  There's not much else to write.  Perhaps that article needs to be merged into the "boolean-valued function" article.  The article "boolean domain" is just a definition, and is already marked as a stub.  The article "boolean-valued function" gives what you ask for: it describes the function and gives several fields where it's used.  Could you explain why that doesn't meet what you want?  [[User:Lunch|Lunch]] 18:32, 26 June 2006 (UTC)

:[[Finitary boolean function]] is not a generalization but a specialization of boolean function. The situation is a bit messy. There is also the article [[Boolean function]], which never defines what a boolean function is. Is there a difference between the concepts of "boolean function" and "boolean-valued function"? What is sorely missing here are examples. There is further an article [[Logical connective]], which treats operators like AND and NOR, the redirect page [[Boolean operator]] redirecting to [[Logical connective]], and the redirect pages [[Boolean operation]], [[Logical operator]] and [[Logical operation]], which instead redirect to [[Boolean function]]. --[[User:Lambiam|Lambiam]][[User talk:Lambiam|<small><sup>Talk</sup></small>]] 20:03, 26 June 2006 (UTC)

== Conventions in graph theory : strongly regular graph ==

I was busy trying to make a [[Strongly regular graph]] separate article, and I was wondering : what will we agree on the conventions.

Graph theory can really be annoying when you really want to do it right.  For instance my syllabus agreed on not including disconnected graphs and their complements, which in turn implied <math>v-1>k>\mu>0</math>.

The spectrum also changes when you allow disconnectedness: the degree of disconnected graphs becomes an eigenvalue with more than dimension one.

What is your opinion?

[[User:Evilbu|Evilbu]] 18:22, 26 June 2006 (UTC)

:My advice would be to have a look at the other [[graph theory]] articles to see if their conventions seem reasonable, and try to follow those if so. You can of course use your own conventions too &mdash; the most important part right now is to write the article; we can discuss your conventions later. Just be sure to explain what your conventions are in the article. - [[User:Gauge|Gauge]] 02:39, 28 June 2006 (UTC)

:: Research first, write afterwards. Halmos, a widely respected mathematics author, says:
::: "A good, consistent notation can be a tremendous help… Bad notation can make good exposition bad and bad exposition worse; ad hoc decisions about notation, made mid-sentence in the heat of composition, are almost certain to result in bad notation."
:: ''Try'' to conform to standard conventions. But especially, ''be explicit'' about what conventions you choose; don't leave the reader guessing. This is ''essential'' within Wikipedia, where readers and editors come from different disciplines, different schools, different continents, and different levels of experience.
:: Graph theory is mathematics applied to many tasks, and the conventions that are helpful for one may be an impediment for another. Since we cannot know why someone is reading an article, we cannot assume that for their purposes all graphs are connected. However, it is fair to introduce a discussion by saying something like, "Here we restrict attention to connected graphs." That's not only good for the reader, it also makes it easier for another editor to come along, see the restriction, and expand the coverage.
:: You will find this done throughout the mathematics articles. In fact, it can help to start an article that includes both introductory material for a general audience as well as much more abstract material for an advanced audience. First give the accessible and common cases to build intuition, then later remove restrictions.
:: Specifically with regard to [[strongly regular graph]] (and note: don't capitalize the first word just because it's linked!), nothing in the definition of regular graph implies or depends on having a connected graph. If some of the results you want to state only apply with that restriction, say so.
:: A fine point of TeX usage is that it is incorrect to write
::: <math> srg(v,k,\lambda,\mu) . \,\!</math>
:: TeX typesets this as if ''s'', ''r'', and ''g'' are three single-letter variables being multiplied. I mention this here instead of on the article talk page because it's a common mistake. Instead, try
::: <math> \operatorname{srg}(v,k,\lambda,\mu) . \,\!</math>
:: The special notation here, "\operatorname{srg}", does several good things; use it. This is not highlighted at [[Help:Formula]], but many other helpful suggestions are; read it. Especially note the trick (which I've used here) to force displayed equations to use a [[PNG]] image (which is large and uniform) instead of an approximation in [[HTML]].
:: I'll also use this opportunity to point out that since there is no reason to capitalize the first letter of a link, there is also no reason to write, say, "<nowiki>[[Adjacency matrix|adjacency matrix]]</nowiki>" instead of merely "<nowiki>[[adjacency matrix]]</nowiki>". The MediaWiki software also performs other background magic, such as simplifying plurals like "<nowiki>[[complete graph]]s</nowiki>", which comes out looking like "[[complete graph]]s". Something that often proves handy in mathematics articles is that trailing parentheses in a link, needed for disambiguation, can be automatically removed by using the "pipe" character, "|". Thus we can write "<nowiki>[[graph (mathematics)|]]s</nowiki>" to get the word "graphs" with a disambiguated link, like this: "[[graph (mathematics)|graph]]s". --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 04:27, 28 June 2006 (UTC)

Okay, well first of all, I checked my syllabus and found that followig THOSE conditions works out eventually.  But I don't want to get into any trouble with my own University for copying very explicitly.  The problem is that the University of Ghent is such a big 'player' in the field of incidence geometry, that a lot on the internet (and that is assuming you find something) comes from their sites
I bet you also disapprove then of my pg(s,t,\alpha) notation in the [[partial geometry]] article?
I read that Formula page and even applied one of the guidelines on [[Paley graph]].  
But I am totally confused with HTML/Tex/PNG, especially since I was instructed very recently to switch my Preferences to 'Always render PNG'.
[[User:Evilbu|Evilbu]] 13:09, 28 June 2006 (UTC)
: Explicit copying is a bad idea anyway, because this is an encyclopedia, and written for a much wider audience. It's not enough that ''you'' understand what you write, or that a university lecturer understands; the goal is that anyone in the world with an interest in the topic (and sufficient background or determination to learn) can understand. We have a [[WP:MSM|mathematics style manual]] that is helpful. Much more could be said. My personal guidelines remind me to try to include, among other things,
:* intuition
:* examples
:* counterexamples
:* connections
:* pictures
:* humor
: Although it is helpful to have an article that is little more than a definition or theorem, it is much ''more'' helpful to explain in what area of study the definition is used, why it may be useful or plausible, and to show it in action either directly or with links. And since this is an encyclopædia, we also like to cite at least one academic source (something more reliable and permanent than lecture notes or online course material).
: Looking at the [[partial geometry]] article, I see again the need to use "\operatorname{pg}" instead of "pg", but I also see two other problems. (And, again, I discuss this here for the benefit of everyone, not just one editor and one article.) The first sentence looks like this:
:* "An [[incidence structure]] ''S=(P,B,I)'' is a ([[finite]]) partial geometry …"
:* "<nowiki>An [[incidence structure]] ''S=(P,B,I)'' is a ([[finite]]) partial geometry …</nowiki>"
: The italics are misused; only the variables should be italicized, not the equality and not the parentheses. While we're at it, we'd like the equation to have a little breathing room but not a bad line break. Here's a way to do all that.
:* "An [[incidence structure]], ''S''&nbsp;= (''P'',''B'',''I''), is a ([[finite]]) partial geometry …"
:* "<nowiki>An [[incidence structure]], ''S''&amp;nbsp;= (''P'',''B'',''I''), is a ([[finite]]) partial geometry …</nowiki>"
: The wiki markup is a nuisance, and we eagerly look to the day when [[m:BlahTeX|BlahTeX]] will rescue us; but, for now, that's it.
: The second issue has to do with your HTML/TeX/PNG confusion. The sad fact is that mathematics markup ''is'' confusing. Again we look to BlahTeX, which will simplify this as well. Switching your preferences affects you alone; most of your readers will not be using the "PNG always" preference. For example, I don't. Many of us do not like to see big PNG images jutting out in our inline text. We do our best to confine the PNG to displayed equations, and there we ''always'' want to see it.
: This leads to a highly annoying dual writing technique: hard-to-edit wiki notation for inline, and TeX notation for display. Either way, we're taking a leisurely stroll through a minefield. We have a diversity of philosophies about what we're comfortable with inline, with some people using TeX whenever they need a special character and others (including me — see [[User:KSmrq/Chars|here]]) using [[Unicode]]; but we have a broad consensus that "built-up" material such as "{a \over b}" is undesirable inline. So this is a second thing you should fix in the [[partial geometry]] article.
: I find that TeX (or [[LaTeX]]) has many subtleties that the average mathematics writer overlooks; the typesetting of operator names is but one of them. For example, not many people know the correct way in TeX to write the colon in ''f'':&nbsp;'''R'''<sup>2</sup>&nbsp;→&nbsp;'''R'''. (Use "\colon" instead of ":" to get the right spacing; try it!) However, our current situation is even worse, because Wikipedia depends, not on genuine TeX, but on a lame partial imitation, [[texvc]]. Again we look to BlahTeX for eventual relief!
: I appreciate that there is a lot to learn about writing mathematics for Wikipedia, and I hope you will not be discouraged. We're here to help, and eventually we'll have new software to help as well. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 19:22, 28 June 2006 (UTC)

==Bots and automatic Unicode conversion==
I noticed [[User:Bluebot]] is automatically converting HTML entities to Unicode on various articles. See e.g. [http://en.wikipedia.org/w/index.php?title=Direct_sum_of_groups&diff=52121124&oldid=42345382]. Does anyone have an opinion on whether such conversion is desirable in mathematics articles? Would it hinder possible future efforts to automatically switch to MathML? - [[User:Gauge|Gauge]] 05:55, 28 June 2006 (UTC)
:First of all, MathML only affects math written in <code>&lt;math></code> tags, and unicodifying only takes place outside <code>&lt;math></code> tags, so it would have no effect of MathML.  As far as being desireable, it makes it easier to read the article in edit mode, especially for newbies who are not used to used to HTML entities. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 12:44, 28 June 2006 (UTC)
:::I know the automatic conversion of Blahtex would only apply to math tags; I was thinking instead of possible future efforts to convert inline HTML being used for math into MathML (using blahtex with math tags), once it is widely supported by browsers (likely several years off, but worth discussing now). What if different bots use different Unicode symbols for the same HTML entities? - [[User:Gauge|Gauge]] 18:38, 28 June 2006 (UTC)
::It makes a little more difficult to edit the article, especially with HTML entities such as & nbsp; , but it's probably a good thing. &mdash; [[User:Arthur Rubin|Arthur Rubin]] |  [[User_talk:Arthur_Rubin|(talk)]] 17:25, 28 June 2006 (UTC)

::: Converting Unicode to MathML should be just as easy as converting HTML to MathML I think, so &amp;int; --> \int and &int; --> \int should not be that different. I would be opposed however on such bots (or worse, semiautomatic editors) doing mass unicodification very often, they just obscure watchlists with no good purpose. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 19:02, 28 June 2006 (UTC)

: Somewhere we've had this discussion before. My recollection is that many editors objected to replacing an HTML named entity with Unicode because the HTML name and the TeX name were the same, making consistency easy. That objection does not apply to numerical entities, but those are so unpopular that we rarely see them. MathML can cope with ''any'' Unicode (UTF-8) character for a symbol; in fact, it knows special things to do with [http://www.w3.org/TR/MathML2/byalpha.html many more] than are supported in TeX. I don't recall exactly how BlahTeX copes, but it either can or will do better than [[texvc]], at least for passing things on to MathML. My personal preference at the moment is to stop the bot, on the grounds of previous rejection and of TeX (not BlahTeX) incompatibility. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 19:38, 28 June 2006 (UTC)
::On a different note, will we deprecate HTML math formulas with the arrival of BlahTeX? —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 20:19, 28 June 2006 (UTC)

::: I think not. Not in the immediate future.
::: To address KSmrq's question: currently blahtex does ''not'' allow non-ASCII characters in math mode material, on the grounds that people would abuse it, and it would lead to the database becoming horribly incompatible with standard tools. People should be using the TeX commands instead. It ''does'' allow arbitrary non-ASCII in text mode, which gets passed through to the MathML <nowiki><mtext></nowiki> element. I suppose this could lead to the same sort of abuse (like <code><nowiki><math>\text{∫}_0^1</math></nowiki></code> -- yuck!). It might become desirable to limit the characters that could be used in text mode (e.g. extended latin, and other scripts like japanese, chinese, klingon, etc). [[User:Dmharvey|Dmharvey]] 20:49, 28 June 2006 (UTC)
:::: Why wouldn't we deprecate HTML math formulas, though?  If we put it in <code>&lt;math></code> tags, then BlahTeX will render it as HTML, anyway. So there seems to be no reason why we should keep using math formulas written in HTML.  In fact, I'm not quite sure why we use inline HTML now for things like variables or "flat" equations that would render (in <code>&lt;math></code> tags) now as HTML now anyway with texvc. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 01:13, 29 June 2006 (UTC)
:::::The main reason to use HTML now instead of texvc for inline stuff is that the texvc conversion of TeX to HTML on "simple formulas" is so pitiful. Blahtex would generate MathML output for math tags for people who want it, but I think it still falls back to the old texvc HTML conversion for people not using MathML. Also, there are certain things that texvc will tend to encode as PNG rather than HTML (any sort of spacing, for example), so one might be forced to use HTML for the desired result anyway. - [[User:Gauge|Gauge]] 19:59, 29 June 2006 (UTC)

In response to KSmrq's comment about prior discussions involving unicode in mathematics article, on this page, there have been at least three:

:*[[Wikipedia talk:WikiProject Mathematics/Archive8#Unicode in math articles|Unicode in math articles]] (Sep 24 2005)
:*[[Wikipedia talk:WikiProject Mathematics/Archive8#Mathematical characters usage|Mathematical characters usage]] (Oct 18 2005)
:*[[Wikipedia talk:WikiProject Mathematics/Archive11#IE compatibility|IE compatibility]] (Mar 28 2006)

[[User:Paul August|Paul August]] [[User_talk:Paul August|&#9742;]] 21:37, 28 June 2006 (UTC)

:Thanks Paul. I found this quote by [[User:Dysprosia|Dysprosia]] that I thought was worth repeating here:
::''The difference is that the Unicode alpha is just another character in the text, like "t", or "q". The HTML entity is the string "&amp;alpha;". All good computer systems should support ASCII, and the HTML entity consists of only ASCII characters, so no matter if you use a computer that supports Unicode or if you don't, the string will be unchanged. However, some browsers that don't support Unicode simply ignore the Unicode characters, so if someone edits with one of those browsers, it will look like all the Unicode characters in the article have suddenly disappeared. If the browser chooses to render "&alpha;" with a Unicode character, that's fine, but it doesn't mean that that Unicode character is somehow equivalent to the HTML entity -- they aren't. Hope that explains things a bit better...''
:I think this is reason enough to discourage proactively converting HTML entities to Unicode. Let the browser decide which symbol to use instead of forcing a particular Unicode symbol. Also, what is the state of screen reader support for Unicode as of about 5 years ago?  It seems reasonable to give handicapped users some time to upgrade their software if Unicode is going to be proactively deployed. I don't mind if people use Unicode in articles, but they shouldn't be converting HTML entities to Unicode wholesale without some discussion. - [[User:Gauge|Gauge]] 22:53, 29 June 2006 (UTC)

== \mathscr anyone? ==

Are people interested in having the \mathscr command available? (Provided by \usepackage{mathrsfs}.) Here's what it looks like:

[[Image:Mathscr-vs-mathcal.png]]

The top one is \mathscr, the bottom is \mathcal (which is what we have now). I've noticed that \mathscr (or something similar) is quite popular in certain fields. I've noticed it especially in functional analysis.

There wouldn't be any difference in MathML because MathML only defines a single "mathvariant=script".

Opinions welcome. [[User:Dmharvey|Dmharvey]] 19:25, 28 June 2006 (UTC)

: It's also popular in algebraic geometry, for denoting sheaves and sheaf-y versions of various things like functors.  I've once or twice wished I could use it.  It's not essential, but I guess I would say that I'm interested in having it. [[User:Ryan Reich|Ryan Reich]] 21:11, 28 June 2006 (UTC)

::Do we get one or the other, or can we have both? Personally, I find \mathcal very useful at times, and wouldn't want to lose it. If we can have \mathscr for those that want it, without losing \mathcal, then that would be great. [[User:Madmath789|Madmath789]] 21:21, 28 June 2006 (UTC)

::: You get to have both. Unless you're viewing with MathML, in which case they look the same. This would only become a problem in articles that use the same letter in the two fonts to mean different things. It would be possible to disable MathML for \mathscr if that's what people wanted, in which case it would fall back on PNGs. [[User:Dmharvey|Dmharvey]] 21:50, 28 June 2006 (UTC)

:::: MathML is only part of the obstruction. Unicode itself has no font variation facility to handle this (that I know of). There is a code point for "B" (U+0042) and "b" (U+0062), and for "Б" (U+0411) and "б" (U+0431), and for "ב" (U+05d1), and for "&#x1d505; (U1d505) and "&#x1d51f;" (U1d51f), and for "&#x1d539; (U1d539) and "&#x1d553;" (U1d553), and for "&#x212C;" (U+212c) and "&#x1d4b7;" (U1d4b7). The idea seems that be that these variations of "B" are in separate alphabets (Latin, Cyrillic, Hebrew, Fraktur, double-struck, and script), not separate fonts. (The difference between uppercase and lowercase is an anomaly, retained for historical reasons even though it's somewhat inconsistent.) So an argument would have to be made to the Unicode committee that there is an essential semantic difference between the calligraphic alphabet and the script alphabet. I'm guessing it would be a hard sell; we all know mathematicians have a boundless appetite for new alphabets and new characters. (We need this alphabet for the space, and that one for the structure over the space, and the other one for the mapping of the structure over the space, and so on.) I think we already have enough distinctions to tough it out if we must! In fact, any author who wants to make a semantic or type distinction between script and calligraphy is already unkind to readers. For those who are still not persuaded, MathML accepts [[CSS]] styling, so it's possible to use a Latin code point and ask for a different font-family. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 01:18, 29 June 2006 (UTC)

::::: All very true. In fact, there are a few more: for example there's also &#x1d5a1; (U1d5a1) which is "MATHEMATICAL SANS-SERIF CAPITAL B" ([http://www.w3.org/TR/2003/REC-MathML2-20031021/sans-serif.html]). Interestingly, the reference glyphs for script letters given on the mathml site ([http://www.w3.org/TR/2003/REC-MathML2-20031021/isomscr.html]) appear to be the same as the \mathscr above, even though the fonts that I got from the Mozilla site render more like \mathcal. I wonder what the STIX ones will look like. [[User:Dmharvey|Dmharvey]] 01:42, 29 June 2006 (UTC)

Is anyone aware of any sources that use ''both'' a mathscr-like font and a mathcal-like font, with different semantics? There's a thread on the www-math mailing list discussing this now. If anyone could build a case, we might well get two different font variants in MathML 3.0 (which is on the drawing board). [[User:Dmharvey|Dmharvey]] 18:39, 5 July 2006 (UTC)

== he he he ==

You know how we all put something like "\,\!" at the end of <nowiki><math></nowiki> blocks to force the output as PNG? Well I was just doing some database work and happened to be trying things out on the [[:he:|hebrew wikipedia]], and discovered that they all put "\ " at the '''beginning''' of the equation! (e.g. [http://he.wikipedia.org/w/index.php?title=סכום_ישר&action=edit]) Or is it the end of the equation? I don't even know... the <nowiki></math></nowiki> comes before the <nowiki><math></nowiki>... [[User:Dmharvey|Dmharvey]] 22:02, 28 June 2006 (UTC)
:The LaTeX equation itself runs from left to right. In this equation the "<code>\ </code>" is at the beginning. If we think of the eqn as an atom in a right-to-left context, then to the reader the blank space ''appears to appear'' to the left of and therefore ''after'' the atom (instead of being part of the atom). --[[User:Lambiam|Lambiam]][[User talk:Lambiam|<small><sup>Talk</sup></small>]] 22:50, 28 June 2006 (UTC)

== interesting statistics ==

More database work.... last time I checked around the beginning of March, the 13 largest wikipedias had 208,000 distinct equations altogether. Now (as of about mid-June) there are about 289,000. That works out at about a 10% growth rate per month. Pretty amazing. [[User:Dmharvey|Dmharvey]] 02:06, 29 June 2006 (UTC)

: You should write a paper about it.  When it gets published, I can write a Wikipedia article about the paper. [[User:Ryan Reich|Ryan Reich]] 02:53, 29 June 2006 (UTC)
::And make sure in the Wikipedia article that you use more formulas :-) —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 03:15, 29 June 2006 (UTC)

== Help wanted ==

The "[[proof that 0.999... equals 1]]" article is once more under attack — from the inside. And for the ''n-''th time, [[User:Melchoir|Melchoir]] is involved. I'm sick of dealing with him and (now) [[User:Supadawg|Supadawg]]. If anyone is interested, please get involved in whatever way you see fit. As for me, it's come down to a revert war or walking away.

Some of you may be aware I completely stopped editing Wikipedia articles awhile back, except for really minor things like typos. I confined my contributions to talk pages, because I had no more stomach for seeing articles obstinately trashed by editors with inadequate subject knowledge, horrible writing skills, and no social skills. That worked for me, though not so well for the articles I abandoned. In the current instance, I can't see wasting more time debating with someone who pretends a proof using [[Dedekind cut]]s and the [[Archimedean property]] is original research, and who doesn't see a problem in beginning a sentence with a decimal point, but who knows exactly how the article should be rewritten.

However, if ''you'' long for abuse or have a desperate yearning to save the world (or both!), here's your opportunity. You'll need to act quickly, for the Mongol hordes are invading as we speak. They have already insisted that an article devoted to a proof should not be so named, nor should state that in the opening sentence. ("It's unencyclopedic!") Next on their agenda is a complete rewrite. It boggles the mind.

OK, so saving this article probably won't save the world. Still, I'll bet it gets more page views than the [[snake lemma]] and the [[hairy ball theorem]] put together (no disrespect intended). Please stop by the [[talk:proof that 0.999... equals 1|talk page]], or help revert. ([http://en.wikipedia.org/w/index.php?title=Proof_that_0.999..._equals_1&oldid=59718286 This version] works for me, tolerably.)

Just for fun:
: Question at job interview: "What is one third plus two thirds?"
:* Mathematician: "It's one."
:* Engineer (using calculator): "It's 0.999… ."
:* Accountant (winking slyly): "What do you want it to be?"

Thanks, all. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 06:42, 29 June 2006 (UTC)

:I must say that I find the article unconvincing, also in its earlier incarnations. Surely, it is intended for people who, in a Zeno-like way, feel queasy with the identity. Most of what is in there is completely above their heads. If I was not mathematically educated, and I saw something that needed so many different proofs for its validity to be demonstrated, I would start to doubt the claim made! Can't we just have two proofs:
:#A solid one from first principles, basically saying (sketch): (1) '''By definition''', 0.999... stands for the limit of the sequence 0.9, 0.99, 0.999, ... (2) That limit is, '''by definition''' of limit, equal to one when the elements of the sequence |0.9-1|, |0.99-1|, |0.999-1|, ... eventually become less than any positive number ε you care to state. (3) And indeed, it does: if the decimal representation of 1/ε has ''n'' digits before the decimal point, then the ''n''+1st and subsequent elements are all less than ε.  
:#The informal argument: 10''x'' = 9.999...; subtract ''x'' giving 9''x'' = 9.000... and therefore ''x'' = 1.000..., remarking that this, in fact, informally presents an actually valid mathematical argument.
:More is not always better. --[[User:Lambiam|Lambiam]][[User talk:Lambiam|<small><sup>Talk</sup></small>]] 09:23, 29 June 2006 (UTC)
::First of all, thanks for your imput Lambiam, but I'm afraid that's a no (from me at least).  It doesn't ''need'' so many proofs to prove its validity.  The many proofs are to present alternate methods of prooving this "theorem".  Any one of those proofs would serve to prove that 0.999…=0.
::Second, KSmrq, I think that you're actions were not appropriate above. We don't have a consensus yet either way, and you're already assembling a revert army, or so it seems from your statement above.  Also you did not provide a link to the infinite geometric series proof, and only to your version of the article, without the proof.  If we do achieve consensus to delete the section, I will let it be deleted (although personally I would rather it stay &ndash; perhaps you remember [http://en.wikipedia.org/w/index.php?title=Proof_that_0.999..._equals_1&diff=46459662&oldid=46457161 when I added the proof] on April 1 of this year, and you [http://en.wikipedia.org/w/index.php?title=Proof_that_0.999..._equals_1&diff=next&oldid=46460377 swiftly removed it]), but until we have that consensus, it will stay in the article. —<span style="font: small-caps 14px times; color: red;">[[User:Mets501|Mets<small>501</small>]] ([[User_talk:mets501|talk]])</span> 13:00, 29 June 2006 (UTC)

::: Please direct all follow-ups to the article [[talk:proof that 0.999... equals 1|talk page]]. They will properly be associated with the article history, and won't annoy the vast majority of mathematicians who ''don't'' long for abuse. Thanks. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 15:44, 29 June 2006 (UTC)

I'm happy to join the corps of reverters for that article, but I cannot in good conscience revert to the version you link, which is buried behind over a hundred edits already.  The best I can do is add the article to my watchlist and revert future changes.  -[[User:Lethe/sig|lethe]] <sup>[[User talk:Lethe/sig|talk]] [{{fullurl:User talk:Lethe|action=edit&section=new}} +]</sup> 15:37, 29 June 2006 (UTC)
: Not a problem. I had a hard time picking through all the debris to find a good target, with all the additions and reversions that have been happening lately, so I went back further to be safe. Thanks for anything you feel comfortable doing to help. --[[User:KSmrq|KSmrq]]<sup>[[User talk:KSmrq|T]]</sup> 15:44, 29 June 2006 (UTC)

== Redirect question ==

Is there a way to have a redirect focus the point on a specific section of the article?  Specifically, I have in mind the redirect from [[Koszul connection]] to covariant derivative, which reads
: # REDIRECT [[[[covariant derivative#Koszul connection]]]]
If you follow the link explicitly, by clicking the above link, then the point focuses on the relevant section.  But if you follow the link [[Koszul connection]], then you are taken to [[covariant derivative]] without the change in focus.  Any thoughts or advice?  [[User:Silly rabbit|Silly rabbit]] 17:32, 29 June 2006 (UTC)

: See [[Help:Link#Redirects_with_section_links]].  I recall reading a different document that explicitly said that they had no intention of ever allowing section links within redirects, but I don't know where that went (the "Help" is not always very much help here; they make it very hard to find the detailed manual and I always forget how). [[User:Ryan Reich|Ryan Reich]] 18:05, 29 June 2006 (UTC)

: Hehehe... I just found some related results, and was about to come here and answer my own question: [[Meta:Help:Redirect#A redirect to an anchor]] and [[bugzilla:218]].  It's kind of annoying that this seems to be impossible.  Any stylistic pointers on how to handle a merger of this sort? [[User:Silly rabbit|Silly rabbit]] 18:13, 29 June 2006 (UTC)

:: Redirect to the top of the page.  If the article is well-written then the appropriate section header will be in the TOC and clearly visible (i.e. the preamble won't take up much space).  If not, well-rewrite it.  In any case, if you have a page that used to link to [[Koszul connection]], you could just put a pipe in that link and avoid the redirect entirely. [[User:Ryan Reich|Ryan Reich]] 18:45, 29 June 2006 (UTC)

== Split of [[List of mathematicians]] ==

Sorry if I startled you, the WikiProject, but I boldly separated the List of Mathematicians article into eight smaller articles. Prior to this, the article was giant: it ranked in the Top 50 on [[Special:Longpages]]. Seeing as this is problematic, since not all of our users have the patience to load a page that is hundreds of kilobytes in size, I took the liberty to divide it into smaller pieces. I'm sorry if it's unacceptable to the WikiProject, but I was doing what I felt was good for the list. —[[User:Messedrocker|<small>THIS IS</small> M<small>ESSED</small>]][[Image:R with umlaut.png]][[User:Messedrocker|<small>OCKER</small>]] <small>[[User talk:Messedrocker|(TALK)]]</small> 02:50, 30 June 2006 (UTC)
: Relax. :) As I told you on your talk page, the big problem is that you did not realize a bot is used to update that page, and it will just happily overwrite your changes, or worse, will get confused by it and then the page will be messed up. 

: The list of mathematicians is 164 kilobytes. Time to split? Should it be split modeling the [[list of mathematics articles]], that is, separate lists for each letter, or should there be a grouping into bigger lists, say A-C, D-F, etc.? [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 02:55, 30 June 2006 (UTC)

::Yes a split seems a good idea. I would go for one list per letter. I can't really see an an advantage of A-C lists etc. I suspect most people who use the list will be looking for a specific person and so it will be easy enough for them to click on a specific letter. Further, the number of mathematicians per letter is already quite long for about half the letters. --[[User:Salix alba|Salix alba]] ([[User talk:Salix alba|talk]]) 08:41, 1 July 2006 (UTC)
::: I thought of the same thing. I will work on it when I find time. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 16:56, 1 July 2006 (UTC)
:::: Done. [[User:Oleg Alexandrov|Oleg Alexandrov]] ([[User talk:Oleg Alexandrov|talk]]) 03:52, 15 July 2006 (UTC)

== [[Geostatistics]] ==
This article is extremely POV, particularly considering the open criticism of Geostatistics within the main page. I was hoping that someone with more experience could build some equations and expand on the evolution of geostatistics. Considering how widely geostatistics is used for the natural sciences, environmental planning, climate studies, oceanic studies, military analysis, urban planning, and [[Geographic Information Systems]], this topic warrants some attention from math experts. [[User:Bohunk|SCmurky]] 03:56, 30 June 2006 (UTC)

:JanWMerks is at it again.  He's been editing [[geostatistics]], [[semivariance]], [[spatial dependence]], [[variogram]], [[sampling variogram]], [[kriging]], [[junk science]], [[consensus science]], [[Tolstoy syndrome]], and [[Bre-X]]; I may have missed some. He's been admonished in the past for his crusading; see his [[User_talk:JanWMerks|talk page]] and his list of [[Special:Contributions/JanWMerks|"contributions"]]. It might be nice if more people added these pages to their watch lists to undo his edits.  (BTW, SCmurky, why did you delete my previous comment?)  [[User:Lunch|Lunch]] 17:50, 30 June 2006 (UTC)

::Maybe it is time to take more serious action [[Wikipedia:Resolving disputes]] posibly a request for mediation. --[[User:Salix alba|Salix alba]] ([[User talk:Salix alba|talk]]) 20:03, 30 June 2006 (UTC)