Wikipedia talk:WikiProject Mathematics/Archive/2012/Jul

Merge Invariant interval and Line element
The merge banners have been up for a while. I agree with merging because there is not much point in Invariant interval and is easily contained within spacetime or (my rewrite of) Line element. If there are no objections - I will merge. F = q(E+v×B) ⇄ ∑ici 22:21, 27 June 2012 (UTC)


 * Well, no response: these will be merged now. F = q(E+v×B) ⇄ ∑ici 15:40, 2 July 2012 (UTC)

sorry, but I'm very annoyed
I tried to build up the article Diophantine approximation starting two weeks ago (See its diff-history.) Until then it was a "dead" article no activity on a stub level (called start for politness or motivation I think). After I structured and put MUCH contents to give an overview suddenly User:D.Lazard sprang in action. He must "destroy" the things I want to build up and my thoughts how to present the topic consistently. Look at its talk-page about his justification and reasoning. Apparently he has insufficient knowledge (he doesn't know how to build up this topic he had self wrote) but could judge the importance of certain contributions by mathematicans to this subject. :-( I have waited two weeks now to see whether he is able to learn and improve the article back (or others spring in action). But it seems he is unwilling to check the material what is missing or he has deleted. :-( I withdraw from further contribution to this article and also to Mathematics in general if this is allowed/okay on wikipedia-en, you need really no experts. We(or should I say You?) will never get high quality level of contents. I will look what has happened after 1 week and then decide whether I support wikipedia-en seriously with my knowledge again. Regards, Achim1999 (talk) 20:04, 28 June 2012 (UTC)
 * , fwiw. I see that when you picked up on the article, it was about 9300 bytes, and now it's 21,209 bytes. Looking through the history, it's clear that you added most of that; well done & thanks. Without doing an edit by edit trawl through, it seems to me that you have been mostly successful in building up the article, and that what issues there are are surely on the margins. I don't see a 12,209 byte edit war going on. Reading the talk page, it does seem to me that you are getting emotional and being somewhat uncivil. So, your frustration comes through very loud and clear; but it's counterproductive. I earnestly suggest that you focus on staying very very calm, and discussing issue by issue with DL. It's almost certain that both of you are acting in good faith; if you avoid personalising the discussion there's a fair probability you'll make headway. --Tagishsimon (talk) 20:18, 28 June 2012 (UTC)
 * Sorry, you miss the point. I dislike an revision-war, thus no happend, in contrast I with-draw and now after 2 weeks looked what has happend. I will surely not teach and discuss with a person who has too less knowledge (and highly probable know this!) but whom I must/should convince. Sorry, I will not waste again my time with such people! I wonder that people (you?) here judge firstly on "uncivil"/"impolite" than on content/information and this only surficically. Bye. :-( Achim1999 (talk) 20:27, 28 June 2012 (UTC)
 * No, I entirely see your point. You know more than him/her, he/she should just stand out of the damned way. And yes, look at what happened: the vast majority of your changes are still there. Cataclysmic. What you seem not to be able to see, from your exulted position, is that he or she may in fact have valid points to make, despite being an intelectual pygmy; and indeed your diagnosis of DL's enfeebled mental prowess with respect to yours may in fact be incorrect. Until you see that those are fundamental problems in your approach, there really can be little progress beyond you flouncing off and wikipedia sinking slowly into the mire. We can only wait and hope. --Tagishsimon (talk) 20:38, 28 June 2012 (UTC)
 * This is ridiculous. Achim1999 behaved terribly impolite in several German WP discussions and now tries the same here. Back to mathematics: His style is to write “It may be remarked that, instead of the factor b2, a weight-factor of a2 could have been used; this would have led to effectively the same properties and insights about rational approximation.” without either showing that this is clear or giving a reference. Achim1999: why don't you make this point clear now? Thank you. -- KurtSchwitters (talk) 21:06, 28 June 2012 (UTC)
 * From what I can tell, whether Achim1999 and.or D.Lazard are sufficiently mathematically knowledgeable is a sideline. The problem is that the command of English of the former is insufficient to be able to make coherent sense. --Matt Westwood 05:24, 29 June 2012 (UTC)
 * Agreed, Achim1999's command of written English is not perfect, and his first drtafts of material can be difficult to understand. This difficulty could be overcome if he were willing to work collaboratively with other editors who could re-draft his contributions. Unfortunately, his abrasive style - as shown in his interactions with D.Lazard - makes this unlikely. It is this combination of imperfect English and confrontational interaction style that is the problem here, IMO. Gandalf61 (talk) 08:41, 29 June 2012 (UTC)

I want not enter in a discussion about who is the greatest mathematician nor about Achim1099 aggressive style. Let just recall that he has had his disruptive behavior also in Golden ratio and Line (geometry).

IMO Diophantine approximation needs further attention by memberships of the project. Before Achim1999's edit, it was a stub. Achim has introduced in it a number of relevant results, but also a number of sentences that can not reasonably be understood, a number of assertions that are pure WP:OR and, at least, one mathematical mistake (recently corrected). Moreover, the structure he gave to the article does not give a due weight to Thue-Siegel-Roth theorem. In particular he emphasizes on the use of 1/b2 to measure the approximation, when other exponents are at least as important (1/b2+ε for Thue-Siegel-Roth theorem).

I have resolved some of these issues, but a lot of work is yet needed, that I am not willing to do alone. Two points are behind my knowledge: I mention applications to Diophantine equations in the lead but I am not able to be more explicit. I believe that there are other applications (to ergodic theory?), but I have not enough information to put anything in the article.

D.Lazard (talk) 09:55, 29 June 2012 (UTC)


 * Not commenting on the behavioral issues, the edits to line (geometry) and Diophantine approximation over the past weeks have been net improvements. It would be ideal if Lazard and Achim could collaborate amicably, since jointly they benefit the project more than either does individually. I would be sorry to see Achim leave the project over this issue.  Sławomir Biały  (talk) 13:55, 29 June 2012 (UTC)
 * Contrarily that I have said above, I have further edited Diophantine approximation. Although I am misplaced to judge, I find decent the present version. I hope you will enjoy to read it. However there is yet many things to do in order to have a good article, in particular in the end of the article (from section "Kintchin" on). D.Lazard (talk) 17:47, 2 July 2012 (UTC)

History of Math books
This may already be common knowledge, but a fellow librarian drew my attention to the AMS's History of Mathematics: A Century of Mathematics in America set which they have made available free online -- could be a useful resource for referencing some of the history of math/mathematician articles! -- phoebe / (talk to me) 17:35, 2 July 2012 (UTC)

Recent edits from 32.173.153.198: are they vandalism
The recent edits to mathematics pages by 32.173.153.198 are puzzling. They introduce some subtle errors; most of them have already been reverted. I'd like to assume good faith here, but I think it's important to watch any further edits from that address. Jowa fan (talk) 02:08, 2 July 2012 (UTC)
 * See also 24.18.247.140; I can't see any way to interpret the comments by those two editors, presently at WT:Vandalism as stating that he/she will vandalize unless Wikipedia can find a structural way to prevent it. (And they have now all been reverted.)  — Arthur Rubin  (talk) 04:20, 2 July 2012 (UTC)
 * Subtle this. "It is good to put mistakes in encyclopedias because that will encourage people to love their offspring." Dangerous madness that, worse even than (puke) religion. There is a structural way to stop such behaviour: block the IP address as soon as it happens. --Matt Westwood 05:11, 2 July 2012 (UTC)
 * Obvious troll is obvious.  Sławomir Biały  (talk) 13:44, 2 July 2012 (UTC)

Check the edit I just reverted on Fundamental theorem of arithmetic by some guy calling himself Shrohaneinstein. I don't know if it's vandalism or stupidity, nor do I know if it's 32.173.153.198 or 24.18.247.140. - Virginia-American (talk) 13:09, 2 July 2012 (UTC)
 * No, not anything like the IP edits; much more likely someone who thinks they understand more than they do. (It reads like a sort of typical proof by someone who doesn't really understand what proofs are yet.) -- JBL (talk) 14:08, 2 July 2012 (UTC)
 * Similarly incoherent job done by that same user on Linear congruence theorem which might also need attention. These are the first 2 edits by that user, so I suppose one ought to be gentle. --Matt Westwood 18:02, 2 July 2012 (UTC)
 * And likewise on trapezoid: http://en.wikipedia.org/w/index.php?title=Trapezoid&diff=prev&oldid=500455066. Obviously a well-intentioned person, but with not a lot of competence to back up the intentions :(.  JBL (talk) 19:40, 3 July 2012 (UTC)
 * I reverted that. The result is obvious.  It doesn't require a cryptic "proof".   Sławomir Biały  (talk) 19:53, 3 July 2012 (UTC)

Fernando Revilla
The new article Fernando Revilla has the interesting sentence "In this lecture [by Fernando Revilla], it is proven that dynamic processes assocciated with natural number characterize the Goldbach's conjecture, a characterization which is lost in an instant of time, obtaining a temporal singularity." This suggests that the article may need some attention. -- Jitse Niesen (talk) 09:25, 2 July 2012 (UTC)


 * Full name Fernando Revilla Jiménez, created by User:Ferejim who has only made this article and added an external link to Revilla's website to Goldbach's conjecture. Looks like an obvious WP:AUTOBIO. PrimeHunter (talk) 10:23, 2 July 2012 (UTC)
 * That sentence looks like WP:FRINGE flakiness to me. When I saw that this had been prodded I tried searching for his pubs in Google scholar but I saw very few citations, so I suspect he doesn't pass WP:PROF and I'm inclined to leave the prod in place. —David Eppstein (talk) 20:51, 3 July 2012 (UTC)

Motor variable
What is that article? Should it be trimmed and the non-obvious parts moved to bicomplex number. I know the article is old, but is there any evidence the term is actually used? I would rather not propose a merge tag before I understand what it is. — Arthur Rubin (talk) 15:53, 2 July 2012 (UTC)


 * As far as I can tell, at least some of the article concerns analytic functions of split complex numbers. Presumably this is what the article should be about, although most of it is written in a very obscure way.   Sławomir Biały  (talk) 17:10, 2 July 2012 (UTC)


 * Surely "motor variable" is merely an archaic term for split-complex number? If so, the article should be replaced with a redirect after seeing whether anything should be merged.  I imagine the only mention of this term thereof should be under the history section there, which I note is already the case.  — Quondum☏ 20:33, 3 July 2012 (UTC)

Proposed GA collaboration
I was browsing WP:VITAL, and saw that Area is only start class. Would anyone be interested in collaborating to get this most important mathematical article up to GA status?-- Gilderien Chat&#124;List of good deeds 19:08, 1 July 2012 (UTC)
 * Ok, it has been re-assessed as B-class, any suggestions on improvements for GA?-- Gilderien Chat&#124;List of good deeds 11:18, 5 July 2012 (UTC)

help requested on merge
Hi, I'm cleaning a backlog of old merge proposals, and one of the oldest was for this article: Talk:Gödel–Gentzen_negative_translation which was proposed to be merged with Glivenko's_theorem and renamed to Double-negation translation. The consensus was to merge, so I closed the discussion and asked the involved editors to perform the merge because my math skills are too rusty to safely do this merge; since they may no longer be active, I'm also asking here if someone who understands the math can do the merge correctly. Thanks. --KarlB (talk) 13:01, 4 July 2012 (UTC)
 * now ✅.

Hodge Dual
I've been struggling with trying to understand the Hodge dual article for a while. To be honest, I didn't get anything from it at all. I found an on-line text that explained it in a, to me at least, much more natural way. (It actually motivated the definition!) I've added a section to the article: Hodge_dual, to hopefully add that extra clarity which I found useful. But I'm no expert and would appreciate it if someone could take a look at it. Cheers. — Fly by Night  ( talk )  18:31, 1 July 2012 (UTC)


 * Hi, have you looked at some of the posts at math.stackexchange, in particular this one? If it doesn't address your question, I'd like to encourage you to ask your own there, because I would like to see what answers appear. Rschwieb (talk) 17:47, 2 July 2012 (UTC)


 * It seems bizarre to me that someone would understand the Hodge dual as one questioner at stackexchange claims to do, and yet not understand the much simpler concept of dual space. Or have I missed something? JRSpriggs (talk) 07:43, 3 July 2012 (UTC)


 * When the dual space is identified with the vector space through a metric, as for example in geometric algebra where the dual space is not even mentioned, it seems reasonable that someone might understand the Hodge dual without understanding the concept of the dual space. Those with familiarity of GA might prefer to study the Clifford dual and move from there to the Hodge dual.  Lounesto (2001, footnote p39) indicates a subtle distinction between the two in the context of GA.  I also find the Hodge dual article difficult to follow properly.  — Quondum☏ 15:55, 3 July 2012 (UTC)


 * @JRSpriggs With the diversity of experience out there, it's highly unsurprising that someone has a viewpoint different from the one you described. Rschwieb (talk) 17:00, 3 July 2012 (UTC)


 * On going through the definition in the article, it seems to me that there is a confusion between k-vectors and k-forms (or at least that the two terms are being used interchangably). This may have contributed to the problem, and should be fixed in the article. In particular, the new explanation does not seem to make this mistake, but my impression is that any reference to dual spaces can be avoided. I think anything further should be on the talk page. — Quondum☏ 18:59, 3 July 2012 (UTC)


 * @Rschwieb &mdash; You seem to have misunderstood my question. I was asking for someone to review the new section that I had added. The point was that the article had been insufficient to help me understand the idea, and I had to do elsewhere. — Fly by Night  ( talk )  12:36, 4 July 2012 (UTC)

Relying on Hodge dual which says
 * $$d\omega=\frac{\partial f}{\partial x}dx+\frac{\partial f}{\partial y}dy+\frac{\partial f}{\partial z}dz \,,$$

it seems to me that the coefficients are the components of a covariant vector and thus dx, dy, and dz are the basis of a covector space (the dual space of the tangent space (vectors) of the manifold at the relevant event). So it seems to me that the W of Hodge dual should be a covector space rather than a vector space. JRSpriggs (talk) 13:59, 4 July 2012 (UTC)


 * The W is any vector space. What you term "covector spaces" are examples of vector spaces. — Fly by Night  ( talk )  15:23, 4 July 2012 (UTC)


 * I agree.  Sławomir Biały  (talk) 15:27, 4 July 2012 (UTC)


 * With whom? — Fly by Night  ( talk )  23:18, 4 July 2012 (UTC)
 * With you. Sławomir Biały  (talk) 00:27, 5 July 2012 (UTC)
 * @FlyByNight Sorry yes, I mistook what you wrote as a request for more information. What was the online text you found on the topic, by the way? Rschwieb (talk) 23:34, 4 July 2012 (UTC)


 * To Fly by Night: Of course, all these spaces of covectors and tensors of various types are vector spaces in an abstract sense. However, you should realize that the context here is based on the Tangent space at an point on a manifold; that is THE "vector space". Its dual space (the Cotangent space) is called THE "covector space" (although it is also a vector space). Tensor products of these spaces are called such rather than referring to them as merely vector spaces.
 * When speaking in the context of components and indices as at Ricci calculus, the vectors in THE vector space are also called "contravariant vectors" because their components change contrary to changes in the basis vectors of THE vector space. The covectors in THE covector space are also called "covariant vectors" because their components vary in the same direction as the the basis vectors of THE vector space. (Bear in mind that a change in the basis of THE vector space induces a change in the basis of THE covector space and their various tensor products.) JRSpriggs (talk) 04:48, 5 July 2012 (UTC)
 * But the article isn't about the Ricci calculus, it's about the Hodge dual. This applies to any vector space.  Sławomir Biały  (talk) 11:16, 5 July 2012 (UTC)

I can't shake the feeling that the added explanation refers to dual spaces unnecessarily. Tevian Dray (1999) The Hodge Dual Operator has a very similar "abstract definition" (at least its symbol choice overlaps), and it makes no use of the dual space (not counting the metric) thoughout the paper. To avoid confusion, I too agree that the Hodge dual applies to any vector space (with a nondegenerate symmetric bilinear form). — Quondum☏ 06:27, 5 July 2012 (UTC)
 * I think some of the confusion stems from the fact that "dual" has several meanings in mathematics. To me this page would be clearer if it avoided any mention of the dual of a vector space.  I'm not convinced that the "explanation" section actually helps, sorry to say. Jowa fan (talk) 07:17, 5 July 2012 (UTC)


 * @Jowa fan: The explanation is guaranteed to help some people. I know it helped me. I couldn't make head nor tail of the article as it was. Using the dual seemed much more natural and comprehensible to me. The page Quondum links to is the think I found that really helped me. — Fly by Night  ( talk )  12:26, 5 July 2012 (UTC)


 * @Quondum: Dray uses the dual just like I have. The only difference is that he doesn't explicitly name, or denote, any of the duals. You'll see that he mentions linear functions on spaces a few times. — Fly by Night  ( talk )  15:27, 5 July 2012 (UTC)


 * I retract what I said just above about no reference to the dual space in the paper. In the example Fly by Night has correctly made explicit the implicit fact in the paper that the "real-valued function on a vector space W" belongs to the dual space.
 * How spooky: Fly by Night, I had not read your response before I posted this retraction. I presume it was one of those copyedit phenomena, where your post occurred between my reading it and clicking edit, and I failed notice the changed text in the edit window. Nice to see such similarity in what we said. — Quondum☏ 17:49, 5 July 2012 (UTC)
 * For understandability, I prefer the current "formal definition" though (and I invite comment, especially from Fly by Night), as it can be related to the following. The preferred unit n-vector can be decomposed into a (wedge product of) a unit k-vector and its unit "orthogonal" Hodge dual (up to a sign, and orthogonal in the sense that all the vectors in their decompositions are orthogonal).  Require linearity (and the correct sign ignored here), and this defines the Hodge dual.  So, in a sense, The Hodge dual is the "bit of an n-vector missing from" the k-vector.  — Quondum☏ 15:45, 5 July 2012 (UTC)


 * I really like your last sentence! I agree that the formal definition should stay; I'm in no way challenging that. That's why I created a new section with the aim of explaining the definition in context. I really like Dray's explanation because, instead of simply presenting a definition in abstract isolation, it gives some motivation and explanation for the definition. I realise that it might be superfluous for those that already know and understand the Hodge dual, but I think it's really helpful for those that don't. Maybe we should blend the two sections together. Start with, something similar, to what's in the Explanation section and build up to the abstract definition? — Fly by Night  ( talk )  17:40, 5 July 2012 (UTC)


 * The impression that I get from Dray is that the "explanation" is actually a fully fledged alternative definition, preferred by some authors. It has the advantage that it is largely by construction, and thus does not need an existence proof in addition to the definition.  Perhaps it should be presented in the article as such, rather than as a motivation.
 * On the "missing bit of the n-vector", this would need some development; it is very hazily stated here. Where this may be clearest is given by Lounesto for GA, who states in effect (I presume his 3D statement generalizes) that $${\star x}=\tilde{x} \omega^{-1}$$.  It would be nice to be able to draw on this simplicity for general metric vector spaces.  — Quondum☏ 08:38, 6 July 2012 (UTC)

A few more eyes needed on Fano plane
An editor has been repeatedly adding a very poorly conceived section to Fano plane; I've tried to engage User:Nicolae-boicu on the talk page on how to improve the section to make it acceptable, but the editor is being evasive. (Also, someone interested in this sort of procedural detail could probably find a WP:3RR violation there somewhere.) --JBL (talk) 13:10, 5 July 2012 (UTC)


 * Hello, I am here Joel, trying to do my best. Just believe me, I cannot explain in several hours the Theory of Species and the techology of labeling structures. Neither the Fano article is the right place to do this. Also, I ask you to take a more constructive position; accept it as it is, Fano" = X.Klein and to work toward it and not against it. Thank you  Nicolae-boicu (talk) 15:58, 5 July 2012 (UTC)

Fano plane as labeled structure

 * Fano" = X.Klein

Since two points determine a line, after labeling any two points in the Fano plane another point is settled. The relabeling liberty for the rest of the four remaining points is described by the Klein Group. The Maple permutation group for Fano plane is 7T5.

The e.g.f. is
 * $$\int \int x.6.{x^4 \over 4!} = 30.{x^7 \over 7!}$$

hence there are 30 ways to label the plane. Here 6 represents the six distinct ways of labeling the affine (Klein) corresponding plane.


 * here is the section that has been erased several time. I would compare this section with a Java program. The Java program requiers JRE to run. Without JRE a Java program is only an obscure text. The "JRE" of labeling is the Theory of Species, see Combinatorial species, that I will not explain inside my section. Nicolae-boicu (talk) 16:33, 5 July 2012 (UTC)


 * Please answer these questions, Nicolae-boicu.
 * 1) what does Fano" = X.Klein mean? Is there a reference for it?
 * 2) I'm assuming egf stands for "exponentional generating function." What function is being generated? Why is it an integral rather than a sum? References?
 * Thanks - Virginia-American (talk) 14:48, 6 July 2012 (UTC)


 * You're a bit late to the party (Nicolae has already been blocked for edit-warring) but the mathematics of what's written is fine, it's just a claim of marginal interest and seems to be designed to be impenetrable. The claim is a claim about exponential generating functions for labelings; "X" is the variable, "." is multiplication, and " " " is a second derivative.  It has to do with the theory of combinatorial species.  Why anyone would use this language to express the simple facts that there are 30 distinct labelings and that after one line has been labeled, the group of symmetries of the remaining labelings is the Klein group, is something of a mystery.  --JBL (talk) 15:05, 6 July 2012 (UTC)

Five of seven points answered
Dear Ed, I have already answered to 5/7 "accusations" points. It remains the below two ones. Please be careful and read the talk before clicking an irreversible button. Thank you.

• it is poorly formatted (e.g., the use of "." instead of "\cdot" for multiplication in LaTeX, the unexplained bold text) • the language could use polishing

Nicolae-boicu (talk) 21:29, 5 July 2012 (UTC)

Just out of curiosity: where is this cryptic notation (Fano"=X.Klein etc) used? It's certainly not notable enough to be used in articles to explain things. Rschwieb (talk) 11:50, 6 July 2012 (UTC)


 * It's the language of combinatorial species -- it's a kind of categorical-type approach to enumerative combinatorics. While it is definitely used in the combinatorics literature, I would say that it has not widely caught on; in my (admittedly not vast) experience, Bill Cherowitzo's response at Talk:Fano plane is common.  It's not clear to me what would make a person want to use that notation without mentioning that it's the notation being used, nor why a person would prefer to use that notation than to use the corresponding English sentence when dealing with a single, concrete, finite example.  --JBL (talk) 13:08, 6 July 2012 (UTC)


 * As a guess, it's so as to appear clever. If you speak in a language which is deliberately obscure, and understood only by a few, then everyone will gasp in awe and hold you in high esteem. (Not.) I've encountered such soi-disant mathematicians before, and one of their techniques is deliberately to replace simple English with gnomic symbology, and equally deliberately remove all reference to its interpretation on the grounds that "If you need to be told what the symbols mean, you're not advanced enough to understand the truth that is being communicated." I think there's some sort of attempt to make mathematics the basis for a secret cabal of some kind, with multiple levels of initiation, to which I would respond as Belbo in "Foucault's Pendulum": "Ma gavte la nata." --Matt Westwood 16:52, 6 July 2012 (UTC)
 * You are right ! If someone would ask me to choose between the Latin and the language of Species, I would recommend him Latin : there are much much more to read in Latin. The species Theory ends with the syntethic aposteriori description of several multiply transitive groups. As I alse said before, the text is like a Java program, it requiers a JRE software, that is, in this case, some material distributed in one book and several articles. In that context, the text makes a lot of sense. There are not too many "initiated" of this cabalistic language; they are mainly boomers that are aging and they started to pass by. I think it would be a loos for mathematics if the art of writing or reading species equations will die with them. Nicolae-boicu (talk) 16:51, 7 July 2012 (UTC)

Good news
I continued to work on my section following the expressed requierements. I have now a new form that I cannot imagine how to improve without kidnapp the subject. Thank you all for remarks and your time. The actual variant is on my page. Dear Matt, the argument regarding the redundancy is on my talk user page.Nicolae-boicu (talk) 16:11, 7 July 2012 (UTC)


 * Sorry, I won't be reading it. Life's too short. --Matt Westwood 16:54, 7 July 2012 (UTC)

It's OK, I didn't wrote it for you. Thanks for your comment, after all, you help me to get a better picture. Nicolae-boicu (talk) 16:59, 7 July 2012 (UTC)

Edits by user:Nbarth
Watching edits on Hilbert's Nullstellensatz, I have reverted edits by user:Nbarth, which were out of context and not directly related to the subject of the article. Looking on the article which were linked to by these edits, it appeared that the same user has also inserted inappropriate material in Commuting matrices and Spectral theory. I have reverted, or in some cases rewritten, these edits. There may be other articles that have been similarly edited by the same editor in a way that may be viewed as some kind of subtle vandalism. Attention of the project members is thus needed. I may add that I'll be away from the net for two weeks, and I will not be able to follow the question. D.Lazard (talk) 13:31, 6 July 2012 (UTC)


 * I've also noticed in the past that Barth's edits can tend to go off in directions not related to the subject of the article. I think he's trying to grow the Wikipedia graph by interconnecting different mathematical ideas.  However, even if ideas tend to be linked from time to time in the real world, that doesn't mean that they should be so linked in encyclopedia articles about the topics.  We should try to encapsulate topics.  That said, I don't think there was any harm done per se in Barth's edits.  I certainly wouldn't consider them to be vandalism.  Sławomir Biały  (talk) 18:39, 7 July 2012 (UTC)

Forum of Mathematics on AfD
Forum of Mathematics, an article about two new journals published by Cambridge University Press, has been nominated for deletion. Here's its first paragraph:
 * Forum of Mathematics, Pi and Forum of Mathematics, Sigma are open-access peer-reviewed journals for mathematics licensed under creative commons which will be open to submissions from 1st October 2012 for initial publishing on 1st January 2013, published by Cambridge University Press. It is currently intended to be funded by an author-pays model with fee-waivers for those that can't afford the fees, and no fees at all for any author for the journals' first three years.  Fields Medalists Terrence Tao and Tim Gowers are among the editors.  Gowers is the mathematician whose blog post led to the Cost of Knowledge boycott of commercial publisher Elsevier.
 * Forum of Mathematics, Pi and Forum of Mathematics, Sigma are open-access peer-reviewed journals for mathematics licensed under creative commons which will be open to submissions from 1st October 2012 for initial publishing on 1st January 2013, published by Cambridge University Press. It is currently intended to be funded by an author-pays model with fee-waivers for those that can't afford the fees, and no fees at all for any author for the journals' first three years.  Fields Medalists Terrence Tao and Tim Gowers are among the editors.  Gowers is the mathematician whose blog post led to the Cost of Knowledge boycott of commercial publisher Elsevier.

An argument is that as a new journal it has not yet had time to achieve notability. Another is that it's getting mentioned in the new media in connection with the boycott and with the broader purposes of that movement and is therefore notable for other reasons.

Opine at this page. Michael Hardy (talk) 19:45, 7 July 2012 (UTC)

Cox–Zucker machine
The article titled Cox–Zucker machine suddenly showed up in our "new articles" list although it's several years old and hasn't been edited since June 30th of this year.

It is an orphan i.e. no other articles link to it.

Here's most of the article:
 * The Cox–Zucker machine is an algorithm created by David A. Cox and Steven Zucker. This algorithm determines if a given set of sections provides a basis (up to torsion) for the Mordell–Weil group of an elliptic surface E → S where S is isomorphic to the projective line.
 * The algorithm was first published in the 1979 paper "Intersection numbers of sections of elliptic surfaces" by Cox and Zucker and it was later named the "Cox–Zucker machine" by Charles Schwartz in 1984.
 * The algorithm was first published in the 1979 paper "Intersection numbers of sections of elliptic surfaces" by Cox and Zucker and it was later named the "Cox–Zucker machine" by Charles Schwartz in 1984.

Two tasks: Michael Hardy (talk) 18:17, 8 July 2012 (UTC)
 * Improve the article.
 * Link to it from appropriate other articles.


 * Am I the only one who noticed the funny title? Maybe we should try to get this in shape for an April 1 DYK...   Sławomir Biały  (talk) 18:22, 8 July 2012 (UTC)
 * How do you pronounce the vowel in the second surname? It's a German name.  In German, it would be something like "tsooker" (rhymes with "hooker"). Michael Hardy (talk) 19:15, 8 July 2012 (UTC)
 * Steven Zucker's surname is pronounced in a way that rhymes with "shucker".  Sławomir Biały  (talk) 19:37, 8 July 2012 (UTC)

Assistance request - quick check on Wikipedia talk:Articles for creation/Nagao's theorem
Hiyas there Wikiproject Mathematics,

A new editor recently submitted a new article trough article's for creation on Nagao's theorem. The article itself looks fine, but mathematics is most definitely not a subject that i am to knowledgeable about, which means i have some difficulty reviewing it. On a sidenote i would mention that we did receive some bogus math article's as of late so i wondered if someone could glance over it and check two things:


 * If what is written sounds decent and logical.
 * If the article isn't a duplicate of some other topic.

If you are familiar with the article's for creation area, feel free to handle the entire page. If not, I'll happily take care of those matters. Also - Thanks in advance for the assistance! Excirial ( Contact me, Contribs ) 19:14, 9 July 2012 (UTC)


 * I'm not familiar with the process. Go ahead and create it, though.  It's a worthy article, and there are some edits I would like to make.   Sławomir Biały  (talk) 19:31, 9 July 2012 (UTC)


 * Thanks for the quick check - the article has been created and is now available at Nagao's theorem for your editing and reading pleasure. Excirial ( Contact me, Contribs ) 19:54, 9 July 2012 (UTC)

Wikipedia talk:Articles for creation/Penrose square root law
I just came across another mathematics article, so i fear i have to ask the same as i did above. If anyone could glance over it I'd be grateful. Excirial ( Contact me, Contribs ) 21:05, 9 July 2012 (UTC)
 * I did some editing of it and then noticed there's a notice saying not to edit it while that notice appears. My edits move it into something approximating compliance with WP:MOS and WP:MOSMATH, starting with the fact that the first sentence should be a complete sentence rather than a dictionary-style definition, and the title phrase should be set in bold at its first appearance. Michael Hardy (talk) 21:58, 9 July 2012 (UTC)
 * Thanks Michael, got to admit i am rather impressed with Wikiproject Mathematics response times to questions such as these two. As a sidenote; the message you saw was my own "Being reviewed" template which i added to ensure that people were aware that someone was looking into the article (Even if that someone - me - was just asking for other people's assistance over here)  Excirial ( Contact me, Contribs ) 23:07, 9 July 2012 (UTC)

Wikipedia talk:Articles for creation/Peripheral subgroup
A lot of mathematics related article's lately - at this rate i fear i am going to have to resort to asking assistance on a regular basis. The above article is another submission, and on first glance it looks very decent for a new article. Anyone spare a moment to confirm this? Thanks in advance, as usual. Excirial ( Contact me, Contribs ) 18:21, 11 July 2012 (UTC)

F=q(E+v^B) exposed as puppet master
Please see Wikipedia talk:WikiProject Physics. As suggested there by Christopher Thomas, I am also notifying this project. JRSpriggs (talk) 06:39, 11 July 2012 (UTC)
 * Though the title here makes the situation seem resolved with no doubt, let's let a little more time pass and look at the evidence another time before we write F=... off for sure. Rschwieb (talk) 13:18, 11 July 2012 (UTC)

Whitehead Professorship
We are informed that:
 * Martin Bridson is the Whitehead Professor of Pure Mathematics at Magdalen College, University of Oxford.

Is this professorship named after Alfred North Whitehead, or J. H. C. Whitehead, or someone else? The article about A. N. Whitehead doesn't mention his having a professorship named after him. Can the information be added to the articles with appropriate links among them? Michael Hardy (talk) 18:31, 13 July 2012 (UTC)

GA review
The GA review of the 136th most viewed mathematics article is open for comment.-- Gilderien Chat&#124;List of good deeds 18:24, 15 July 2012 (UTC)

Use of "notion" vs. "concept"
I notice the use of the term notion in a number of articles where I would have used the term concept. The former seems to have semantics of vagueness associated with it, apparently corroborated by several dictionary definitions, whereas the latter seems more appropriate for use in the mathematical context where the thing described is usually precise. Would there be any objections to me replacing notion with concept in articles when this seems to apply? — Quondum☏ 15:33, 15 July 2012 (UTC)


 * To me, notion suggests a proposition (sentence) while concept could refer to a term (noun phrase). JRSpriggs (talk) 16:07, 15 July 2012 (UTC)


 * Excellent point. One would thus expect to see a distinction in the grammar: the notion that ... and the concept of .... I concur. — Quondum☏ 17:05, 15 July 2012 (UTC)

The terms notion and concept are synonymous. However, the preferred term among those who study them formally is "concept". Greg Bard (talk) 18:30, 15 July 2012 (UTC)

I don't think that the distinction is particularly important in the vast majority of our articles. For example, if I write about the notion of Lebesgue measure or the concept of Lebesgue measure I mean the same thing in either case, and if there is any philosophical distinction it will not matter for the subject of Lebesgue measure. I don't see a reason to go through replacing one with the other just for the sake of it. &mdash; Carl (CBM · talk) 18:35, 15 July 2012 (UTC)
 * This probably arose because of some squabble over whether "concept" or "conceit" should be used in a particular place, and in order to defuse the situation whereby the protagonists were about to start beating each other over the head with their teddy-bears, someone suggested to replace it with "notion". I think that was earlier today, but I lose track of time, and I have no idea where. My own view is to use the word "concept", as "conceit" has emotional overtones and "notion" smacks of imprecision. --Matt Westwood 23:40, 15 July 2012 (UTC)


 * Okay, this general perception was what I was trying to gauge. My own perception is that the use of notion as a direct synonym for concept is moderately recent and regional.  If this sense has gained enough mainstream global usage, its use in WP would be reasonable.  And as Carl says: it is not actually important (there is no ambiguity), and wholesale replacement for its own sake is not warranted.  I may still be unable to resist replacing it in text I'm copyediting for other reasons, when it feels particularly out of place to me.  — Quondum☏ 05:30, 16 July 2012 (UTC)


 * A classical subject of dissertation for French agregation of philosophy was "the notion of concept and the concept of notion". I do not remember if it was an actual subject or a joke. D.Lazard (talk) 08:46, 16 July 2012 (UTC)

dominant functor
Dominant functor is a orphaned article (i.e. no others link to it) and lacks references. It's also very very short. Do what you can. Michael Hardy (talk) 20:06, 15 July 2012 (UTC)


 * Category theory is out of my area, but it seems to me that the key word "retract" should not be linked to deformation retract (a topological concept). Perhaps it should link to retract (category theory). Although even then, I do not know how the objects in category D can be considered as morphisms (which such a retract is supposed to be).
 * In any case, I suspect that the "dominant functor" concept is supposed to be similar to a cofinal function. JRSpriggs (talk) 05:59, 16 July 2012 (UTC)


 * Presumably what is intended here is the definition of  Here a retract is defined as the target of a split epimorphism: B is a retract if e:A → B, s:B → A with e epi and e.s = 1B.  In other words, a retract is the object at the end of a retraction.  Single-sentence definitions like the article in question should probably be in Glossary of category theory.  Spectral sequence (talk) 12:15, 16 July 2012 (UTC)

clarification in Böttcher equation
The article titled Böttcher equation begins like this:
 * The Böttcher equation is a functional equation F(h) = Fn, where h is an analytic function with a superattracting fixed point a, which means that
 * $$ h(z)=a+c(z-a)^n+O((z-a)^{n+1}), \quad z\to a $$
 * with n &ge; 2.
 * $$ h(z)=a+c(z-a)^n+O((z-a)^{n+1}), \quad z\to a $$
 * with n &ge; 2.
 * with n &ge; 2.

I don't know if Fn means n-fold composition of functions, or n-fold multiplication of the value of the function. Also, if it's supposed to be evaluated at the same point h, it wouldn't hurt to be clear about that, and if it's not, then what is meant is not clear. Then it says "where h is an analytic function with[ . . . etc . . . ]". Does that mean for every analytic function with that property, or for some analytic function with that property, or does it mean for some special analytic function with that property? Does "with n &ge; 0" mean for some n &ge; 0 (so that as long as there is some such value of n, this is an instance of the Böttcher equation, or for every n &ge; 0, or what? Michael Hardy (talk) 18:31, 17 July 2012 (UTC)


 * This is just a guess, so you would have to check the sources to be sure, but I think the conclusion means
 * $$F(h(z)) = (F(z))^{n} \,$$
 * for all z. In words, ordinary multiplication, not composition.
 * For every n≥2, for every analytic h satisfying the hypothesis, there is an analytic F satisfying the conclusion. JRSpriggs (talk) 11:29, 18 July 2012 (UTC)


 * Since the article says F(a)=0, composition does not make sense (since a≠0 in general).
 * However, it occurs to me that just using the constant function 0 for F would work. Being thus trivial, this is unlikely to be right. I think that the intention is for
 * $$F(z) = c^{1 \over n - 1} (z - a) + O ( (z - a)^2 ), \quad z\to a \,.$$
 * JRSpriggs (talk) 11:44, 18 July 2012 (UTC)


 * The fifth result for my Google search of "Böttcher equation" was this article:  This reference makes it clear that you start with an analytic function h with an n-fold zero at zero [the wiki article considers the trivial variation h(z-a)+a] and look for a function F such that F(h(z)) = F(z)n where the RHS is indeed the n-th power of F(z).  In fact the reference observes that if n is fixed by the condition on h having an n-fold zero at zero, then the only value of k in an equation F(h(z)) = F(z)k that gives an interesting result is k=n.  Spectral sequence (talk) 13:59, 18 July 2012 (UTC)

Property of equivalence in gaussian primes
Property of equivalence in gaussian primes has been around for most of a year, but with a bad category that prevented it from showing up in our new article lists. It needs either a lot of help, or deletion, I'm not sure which. Please do what you can. —David Eppstein (talk) 23:40, 17 July 2012 (UTC)
 * I looked at it and did a few edits and moved it to Equivalence of Gaussian prime numbers. It's one of the worst-written articles I've seen in a while.  I might have cleaned it up quite a lot more if I were sure I understood what it says. Michael Hardy (talk) 04:15, 18 July 2012 (UTC)
 * Indeed. "equivalence" is never defined or used. - Virginia-American (talk) 10:55, 18 July 2012 (UTC)

Probably makes sense to discuss with the author? (At least as far as the goal is to understand what the article is about.) I note that s/he failed twice to get this through Articles for Creation, without apparently improving it in the process. --JBL (talk) 12:46, 18 July 2012 (UTC)
 * Surely the discussion should take place at the article talk page? I have commented there and notified the author, which strangely nobody else has done yet.  Spectral sequence (talk) 13:33, 18 July 2012 (UTC)
 * Without noticing this discussion I noticed the article myself on the daily new maths articles update, and also being unable to identify any notable or even comprehensible content nominated it for deletion.-- JohnBlackburne wordsdeeds 17:37, 19 July 2012 (UTC)

Merge help: Club filter
There is a slow-moving discussion at Talk:Club filter involving a series of merges. I was hoping some math folks could head over there and continue the discussion, and merge the article, as I know nothing of these topics. Thanks, Ego White Tray (talk) 03:39, 19 July 2012 (UTC)


 * I terminated the merger. JRSpriggs (talk) 14:53, 19 July 2012 (UTC)

ambiguity of "any"
Another reminder of the hazards of the word "any". This is from a new article titled Tsen rank:
 * We say that F is a Ti-field if any such system, of degrees d1, ..., dm has a common non-zero solution whenever[...etc...]
 * We say that F is a Ti-field if any such system, of degrees d1, ..., dm has a common non-zero solution whenever[...etc...]

Does this mean "[...]if there is any system of degrees that has a common non-zero solution whenever[...etc...]", or does it mean "[...]if it is the case that _any_ such system, no matter which one, has a common non-zero solution whenever[...etc...]"? A reasonable person might read it either way. In the first case, changing "any" to "some" would resolve the ambiguity; in the second case, changing "any" to "every" would do it. "Any" is sometimes a hazardous word. I've changed it to "every" in the article. Michael Hardy (talk) 20:23, 15 July 2012 (UTC)


 * This seems to me to be a grammatical parsing ambiguity rather than any ambiguity of the word. Not being familiar with the context, I can't judge this instance, but my suggestion would be to try to solve this type of problem by using grammatically unambiguous sentence structures.  Simply replacing the word does not technically resolve the grammatical ambiguity.  — Quondum☏ 05:09, 16 July 2012 (UTC)
 * I disagree. In mathematical usage, "... any X has property P" can mean either "for all X, P is true" or "there exists an X such that P is true".  Changing "any" to "every" removes the ambiguity: the first meaning is indicated.  For the case under discussion, this seems to be the only interpretation that makes sense. (I'm not a specialist in this area, but it seems clear that if the other interpretation is followed then every field would have Tsen rank zero.)  Jowa fan (talk) 05:33, 16 July 2012 (UTC)
 * Nicely explained. I stand corrected. — Quondum☏ 06:35, 16 July 2012 (UTC)
 * If the whole sentence just says "Any A is B", I would take it to mean "every". But if it says "If any A is B, then...", then it could reasonably be construed as meaning "If there is any A that is B, then...", which would be the same as "If there is some A that is B".  So in that case it's ambiguous. Michael Hardy (talk) 23:05, 16 July 2012 (UTC)

Free logic
The quantifier "any" lacks existence claims.

("Any" is often used where free-logic pussyfooting is not intended, and where "every" or "some" should have been specified. Thus Halmos thinks that "any" should be avoided by mathematicians writing it gooder.)

Jaakko Hintikka has a nice article on "any" and ordinary English.

I forget whether Charles Sanders Peirce and his students considered free logical quantification. I think Mitchell has a paper on quantification in the 1878 Johns Hopkins Studies. Kiefer .Wolfowitz  17:13, 24 July 2012 (UTC)

Nomination for deletion of Template:Ring structures
Template:Ring structures has been nominated for deletion. You are invited to comment on the discussion at the template's entry on the Templates for discussion page. DH85868993 (talk) 11:07, 21 July 2012 (UTC)

Mizar system external links discussion
Members of the Mathematics WikiProject are cordially invited to chime-in in the on-going discussion of the pro and con of placing Mizar system external deep links on mathematical articles. Yaniv256 (talk) 16:19, 24 July 2012 (UTC)

Andreas Griewank
Professor Griewank is one of the principal architects of automatic differentiation, a co-founder of the theory of partially separable functions (the usage of which is an important part of the success of AMPL's modeling language and the large-scale optimization packages Lancelot and Galahad), an initiate of the mysteries of semi-analytic geometry, and an amateur guitarist:



His would be an interesting biography.

Thanks! Kiefer .Wolfowitz  17:04, 24 July 2012 (UTC)
 * CV on Homepage. --LutzL (talk) 18:10, 24 July 2012 (UTC)

Another drive-by deletion
Help! We're getting another drive-by deletion being pushed bynon-physicists of a physics topic. Categories for discussion/Log/2012 July 13. To express my frustration: the drive-by deletion process brings out the very worst in wikipedia behavior, and creates a huge amount of damage (remember the deletion of Category:Proof, carefully nurtured for years, here, and shot dead with only three votes?) Please help get these hooligans under control. linas (talk) 01:35, 21 July 2012 (UTC)


 * At least some ongoing/old CfDs are listed at WikiProject Mathematics/Current activity. But it is not clear how any given category is counted as part of the project. There may be several layers of bots involved, which I can't follow. Melcombe (talk) 07:38, 25 July 2012 (UTC)

Indefinite logarithm at AfD
The article Indefinite logarithm has been nominated for deletion. Discussion is at Articles for deletion/Indefinite logarithm. --Lambiam 23:15, 25 July 2012 (UTC)

MathJax working
It looks like the bug fixes in MathJax implementation are now working so we can have less than signs $$x<y$$ and matrices $$\begin{pmatrix}1 & 0\\0 & 1\end{pmatrix}$$.--Salix (talk): 07:03, 26 July 2012 (UTC)
 * Good news! I'm trying the switch from Nageh's version to the built in support. So far it seems a little slower to render but no appearance glitches. —David Eppstein (talk) 07:39, 26 July 2012 (UTC)
 * Yep seems good. I just had a look at Help:Math and there are a few square boxes instead of characters for special characters and when doing \limsup and \liminf but the Nageh version does the same. Overall I'm very pleased and will use the system version of MathJax as default. Dmcq (talk) 08:36, 26 July 2012 (UTC)
 * Well it all depends on what renderer I've switch on. Seemingly that was with the SVG one. With the HTML-CSS they all come out okay though the special characters are half the size. And with MathML it warns me not all the features are supported by the browser. It's a hard choice, I think I'll try the HTML-CSS for a while. Dmcq (talk) 09:01, 26 July 2012 (UTC)
 * MathJax is excellent, but expensive. Sadly, nobody cares about such cheapie as class="texhtml", the font in which should match MathJax's one. Incnis Mrsi (talk) 09:05, 26 July 2012 (UTC)
 * You get that automatically if you use math and there's some ancillary templates that go with it e.g. mvar to just format a variable quickly. However some people here have a very strong dislike of serif font in the middle of non-serif. Not that MathJax will satisfy them immediately. There's also a couple of gotchas like having to put 1= in if one uses equal signs so it is another language again. As for me I'll be putting less effort into trying to use the math tempate in future and will use more even if it is a little slower. Dmcq (talk) 11:43, 26 July 2012 (UTC)
 * Maybe we do not understand each other. I see $x$ or $x_{1}$ markedly different from MathJax equivalents ($$x_1$$). I suppose, although not completely sure, than this can be cheaply fixed by altering texhtml's font-family to those used by MathJax. I hope, sysops just are not aware about the problem. But if someone is aware, but deliberately keeps a substandard appearance of math, then it is definitely an unfair trick to mount a prejudice against "texhtml" typesetting. Incnis Mrsi (talk) 13:07, 26 July 2012 (UTC)
 * You need italics as in $x_{1}$ which gives $x_{1}$. I think it is fairly close but it depends on what method MathJax uses for rendering and your browser. By the way MathJax uses the STIX fonts and MathJax will run a bit faster if you install them instead of using web fonts. I guess texhtml could put the STIX fonts as the first ones to check for but they are close enough to the usual Times one  for most purposes I believe, possibly the size needs to be tweaked slightly as currently it is set to match the old png render program. Dmcq (talk) 19:17, 26 July 2012 (UTC)
 * It was just a typo in $x_{1}$, sorry. Incnis Mrsi (talk) 09:17, 27 July 2012 (UTC)
 * The font of the template could be made compatible with MathJax by adding the CSS rule span.texhtml { font-family: MathJax_Math, serif; } . You can try this in your skin.css and if we are happy with it roll it out to MediaWiki:Common.css or ask a dev to change skins/common/shared.css. I'm not sure quite how the MathJax_Math font is loaded so the font might only change if MathJax is enabled.--Salix (talk): 06:29, 27 July 2012 (UTC)
 * Thanks for explanations, Salix. I have MathJax's fonts locally. I will be completely satisfied if "texhtml" had to switch to MathJax's fonts if these fonts are currently available in the browser. So, do you recommend to proceed with and not wait for further conclusions in this discussion? Incnis Mrsi (talk) 09:17, 27 July 2012 (UTC)
 * P.S. apart of the problem of font-family, there is another problem with font-size in &lt;sup>s and &lt;sub>s. I'm afraid that, due to CSS limitation, the best solution is to supersede that explicit HTML elements by ssups and ssubs respectively, such as $x$. Yeah, it is another language again, Dmcq is right. Incnis Mrsi (talk) 10:09, 27 July 2012 (UTC)
 * After yet some meditation I realized that, since class="texhtml" is defined in templates, not by the engine itself, it would be unwise to request changes to MediaWiki. So, I started small. Incnis Mrsi (talk) 11:30, 27 July 2012 (UTC)
 * Should we also ask for "font-size:larger" to be added. At least for me the following two match x $$x$$. (across multiple display settings). Not sure if this is true for all configurations of browsers/system. TR 12:36, 27 July 2012 (UTC)
 * I agree. Even in a browser without font-family:MathJax_Math this produces a serif text which does not looks too large . Incnis Mrsi (talk) 12:53, 27 July 2012 (UTC)
 * Just checked IE8 and Opera, neither of which actually pick up the mathjax font.TR 12:42, 27 July 2012 (UTC)
 * Did you install these fonts locally? It is useful also for the MathJax proper. Incnis Mrsi (talk) 12:53, 27 July 2012 (UTC)
 * Now I am in doubt again. Should font-size be better placed to math rather than to CSS? Incnis Mrsi (talk) 13:20, 27 July 2012 (UTC)
 * No, because then it cannot be customized by user CSS.—Emil J. 13:28, 27 July 2012 (UTC)
 * I see no difference between increasing font-size in CSS and doing the same in all &lt;span>s which use the class. Both are subject to user customization. Actually, there are two templates, &#123;{math}} and bigmath. What do you propose: To merge (effectively) these two presentations? Or to make &#123;{bigmath}} even larger? Incnis Mrsi (talk) 13:43, 27 July 2012 (UTC)
 * What (I think) Emil was getting at, is that if it is conrtolled through the CSS a user/reader can specify a custom css style which changes the way math output looks. So, for example, if you detest seeing a serif font inline, you can load your own css style that set the texhtml class to a sans-serif font. As a user, you cannot load a custom version of a template.TR 15:33, 27 July 2012 (UTC)

With a bit of messing around the closes set of styles I've managed to come to is Using those styles in skin.css the following two are virtually indistinguishable.
 * $$-3 \sin(x_{2 i})+\ e^{3t}$$ MathJax
 * $−3 sin( x _{2 i })+e^{3 t }$ Using

MathJax uses a different font for variables, MathJax_Math, than for other content, MathJax_Main, and slightly different sizes 123% as opposed to 118%. The code is dynamically generated so it might be different in other browsers.--Salix (talk): 21:34, 27 July 2012 (UTC)

havel
what happened to V. J. Havel (see too: S. L. Hakimi) - --Rovnet (talk) 16:35, 27 July 2012 (UTC) (w:es)
 * It was deleted by WP:PROD in March with the rationale "Poorly-sourced BLP with questionable notability". I can undelete it for you, if you want. —David Eppstein (talk) 17:08, 27 July 2012 (UTC)

I've un-deleted it for now. I'll try to notify interested parties. Michael Hardy (talk) 17:16, 27 July 2012 (UTC)


 * I was the one who proposed the article for deletion. I'm not a mathematician, but at the time I found it frustrating that there was next-to-no information about the person. Havel still appears to fail WP:BLP1E and the WP:GNG, but if the article was fixed, a date of birth mentioned, and some external links offered to confirm any notability, of course I wouldn't mind if the article stayed. Jared Preston (talk) 18:42, 27 July 2012 (UTC)
 * He also appears to fail WP:PROF. Although I think unprodding was the right thing to do, unless more evidence comes up I'd support deletion in an AfD. —David Eppstein (talk) 22:29, 27 July 2012 (UTC)
 * There is also Václav Havel, a famous Czech writer who is not the same person.  Sławomir Biały  (talk) 18:55, 27 July 2012 (UTC)

thx. --Rovnet (talk) 04:33, 28 July 2012 (UTC)

MAJOR merger!!
What a mess! Arabic numerals and Hindu–Arabic numeral system (with an en-dash, not a hyphen) are two separate articles, and Hindu-Arabic numeral system (with a hyphen) does not redirect to Hindu–Arabic numeral system (with an en-dash) but to Arabic numerals, and Arabic numeral system does not redirect to Arabic numerals but to Hindu–Arabic numeral system.

Welcome to the earliest days of Wikipedia. In 2002 and 2003 this would be expected. Michael Hardy (talk) 16:29, 28 July 2012 (UTC)

Not-so-major merger
Is there any reason why Hurwitz quaternion order and Hurwitz quaternion should be distinct article which don't even link to each other? Deltahedron (talk) 17:16, 28 July 2012 (UTC)
 * The first one was linked to the second one through a redirect. I have replaced it by a direct link. However the subjects are distinct: the first article consider a subalgebra in a quaternion algebra, while the second one consider only usual quaternions. As a non specialist of non commutative algebra, I have the impression that both articles concern the integral elements in a quaternion algebra, but none of the articles make clear if the notion of integer element make sense here. I have no opinion about a merger or not. D.Lazard (talk) 19:57, 28 July 2012 (UTC)

Udita fractional operator
The article Udita fractional operator is at AfD. Please comment there. Sławomir Biały (talk) 13:56, 28 July 2012 (UTC)


 * In related news, more eyes would be appreciated on Fractional calculus and Erdelyi–Kober operator, where a gang of SPAs are POV-pushing to include mention of the so-called "Udita fractional operator". Sławomir Biały  (talk) 17:05, 29 July 2012 (UTC)


 * These three SPA, namely MathProff, MathBuddy and Uditanalin lock like sockpuppetts. Can someone investigate this? D.Lazard (talk) 09:37, 30 July 2012 (UTC)

Holomorphic function
If I recall correctly, a function $$f : \Complex \to \Complex$$ is holomorphic in a neighbourhood of $$z_0$$ if $$(\operatorname{d}\! f/\operatorname{d}\! \overline{z})(z_0) = 0$$. There is no mention of this in the article. I'm assuming that this is a well known fact. Should we add something to the article? — Fly by Night  ( talk )  21:33, 29 July 2012 (UTC)


 * It is not sufficient that the Wirtinger derivative vanish at $$z_0$$, rather it should be zero in a neighborhood. Vanishing of the Wirtinger derivative is equivalent to the Cauchy-Riemann equations (and is mentioned in that article).   Sławomir Biały  (talk) 22:31, 29 July 2012 (UTC)

Elementary Algebra GA candidate
If anyone is interested, I've recently made what I consider to be a number of improvements throughout the article on Elementary algebra, and submitted it as a Good Article nominee (see the article Talk page template for details). --Iantresman (talk) 16:29, 30 July 2012 (UTC)