Wikipedia talk:WikiProject Mathematics

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Cone

Must a cone have a circular cross-section? The article Cone initially says that it must, but other statements sprinkled throughout seem not to assume this, or seem unnecessarily vague if it is true. I raised this on the talk page a while ago, but no takers. Does anyone here have a view? 86.128.3.252 (talk) 18:40, 22 January 2014 (UTC)

The article asserted in the first sentence that the cross section is "typically" circular; this means "often" or "in the most common cases" and is perfectly consistent with the rest of the article. I've now substituted the phrase "frequently, but not necessarily," which hopefully is clearer (but I do not object if someone has a better phrasing). --JBL (talk) 19:37, 22 January 2014 (UTC)

The statement that you have changed refers to the base, not a general cross-section. I'm talking about the statement in the next paragraph where it says "such that there is a circular cross section". A cone can have a circular cross-section but be lopped off at an angle such that the base is not circular. The wording "a circular cross-section" seems to be designed to accommodate this case. My question is whether a cone has to have a circular cross-section, not whether the base has to be circular. 86.128.3.252 (talk) 20:14, 22 January 2014 (UTC)

The cross-sections parallel to the base are all necessarily of the same shape as the base. Now that I've read the full lead ( ;) ) I agree with you; I have removed the (uncited) statements that the cross-sections need to be circular. --JBL (talk) 20:34, 22 January 2014 (UTC)

Thanks, I should have mentioned this though, which says that a cone does have to have a circular cross-section. Is that source wrong? 86.128.3.252 (talk) 20:50, 22 January 2014 (UTC)

As with many things, there are different meanings of the same word; often, "cone" means "circular cone," but our article (as you note) is written about a more general class of objects, so the lead paragraph should match it. As you can probably tell, I have not carefully gone over the article or anything; perhaps the lead (and/or the rest of the article) should give more emphasis to the circular case, since this is (in geometry) the most common one, but the word "cone" is also widely used in the more general sense. --JBL (talk) 21:00, 22 January 2014 (UTC)

Right, the word may be used differently by different people, but our article should give the mathematically correct definition (and explain as necessary if it going to extend this to a kind of layman's definition). Normally I would assume that the MathWorld site was mathematically correct, but maybe not in this case ... 86.128.3.252 (talk) 21:16, 22 January 2014 (UTC)

(edit conflict) As far as I remember, a cone with a conic section as basis has always a circular cross-section. Nevertheless I do not remember of a simple proof of that fact. On the other hand, a cone with another curve as basis does not have any circular cross-section.

This article has another issue: depending on the context, "cone" may have various meanings, all mathematically correct, which should be disambiguated in the lead: a cone may be the solid or the surface delimited by the basis and the vertex. It may have a circular basis or have any curve as basis. It may be the surface generated by the rays sharing the same endpoint and cutting a curve. It may be the surface obtained by prolongating these rays into lines. It may also be the union of any set of rays (or lines) sharing a fixed endpoint (or point). All these notions are commonly called "cone" in mathematical texts, and only the context allows to disambiguate. Thus a WP:DABCONCEPT section seems to be needed here.D.Lazard (talk) 21:33, 22 January 2014 (UTC)

Note that the Cone (disambiguation) DAB page already exists and is accessible from a hatnote at the top of the Cone page. DABCONCEPT pages are useful when there is no one dominant usage of the title. But cone, as the geometric object, seems dominant to me. --Mark viking (talk) 22:14, 22 January 2014 (UTC)

Perhaps it's just me, but I thought the base of a cone did not have to even be two dimensional, e.g. the code of a point is a line segment, the cone of a line segment is a triangle, the cone of an n-simplex is an (n+1)-simplex. Has anyone else seen that usage or did I make it up? --RDBury (talk) 03:35, 23 January 2014 (UTC)

What you describe sounds like a cone of a topological space, described at Cone (topology). --Mark viking (talk) 03:52, 23 January 2014 (UTC)

I've seen that usage. Michael Hardy (talk) 04:25, 23 January 2014 (UTC)

• Thanks, the article is less of a muddle now that the statements requiring a circular cross-section have been removed. I spotted later in the article "The center of mass of a conic solid of uniform density lies one-quarter of the way from the center of the base to the vertex, on the straight line joining the two." This statement could do with tightening up with regard to cones whose bases have no obvious "center" -- either to exclude those cases if they are more complicated, or to refer to the "center of mass" of the base if that method always works. 81.159.106.14 (talk) 14:36, 23 January 2014 (UTC)

Feedback request: VisualEditor special character inserter

The developers are working on a character inserter for WP:VisualEditor. Their focus at the moment is on about 50 Wikipedias that have complex language requirements, like Welsh (but not like Chinese, which is a different kind of complexity). There is a special character inserter tool in VisualEditor now. They would like to know what you think about this tool, especially if you speak languages other than English—and mathematics isn't exactly what they had in mind (because an extensive TeX-based formula editor is the main way to deal with mathematics), but it does provide access to some mathematics symbols. So if you are interested in trying it out, please do so, and then let them know what you think of their choices for math symbols. The steps are easy:

• If you haven't already opted-in, then opt-in to VisualEditor by going to Special:Preferences#mw-prefsection-betafeatures and choosing "VisualEditor". (While you're there, you might want to enable mathematics formulas, too.) Save your preferences.
• Edit any article or your user page in VisualEditor. See the mw:Help:VisualEditor/User guide for information on how to use VisualEditor.

The “insert” pulldown on the task bar of VisualEditor will lead you to the ‘⧼visualeditor-specialcharacterinspector-title⧽’ tool.

This is the ⧼visualeditor-specialcharacterinspector-title⧽ inserter. Your feedback on this tool is particularly important.

To let the developers know what you think, please leave them a message with your comments at the feedback thread on Mediawiki.org or here at the English Wikipedia at Wikipedia:VisualEditor/Feedback. It is really important that the developers hear from as many editors and as diverse as set of uses as possible. Thank you, Whatamidoing (WMF) (talk) 00:10, 23 January 2014 (UTC)

Distance from a point to a line and Perpendicular distance

These two articles have been around for a while and except for a few sentences in the lead of the second, their content is pretty much the same (or could easily be made so). It seems to me that a merge is in order. The question is which way should the merge go? I am not happy with either possibility, which is why I am bringing the subject up here. The distance from a point to a line article consists of several different proofs of the same 2-dimensional formula. This article was considered for deletion not too long ago, and several of you argued to keep it (but it doesn't look like anyone has seriously worked on it). I fixed a couple of proofs that had gotten garbled, but to improve the page I think we need to generalize the topic rather than provide more and better proofs of this simple formula. The Perpendicular distance article provides yet another proof of the 2-dimensional formula, and then states and proves a generalization to a formula for the distance between a point and a flat. This article has no references and no diagrams. Neither article contains a calculus based proof (or any other type of proof) that the shortest distance is along a perpendicular (but it is clearly assumed in each article). I think that at least the 2-dimensional proof would not be too far off the level of these articles. I also think that "perpendicular distance" is just a terrible title. My ideal solution would be to merge both articles into a new article, Distance from a point to a flat, but that title would not resonate well with the level of the readers of this article. I am looking for comments, suggestions, etc. Thanks. Bill Cherowitzo (talk) 18:28, 25 January 2014 (UTC)

I converted perpendicular distance into a set-index article listing four other articles (including the point-line distance one) on specific types of perpendicular distance. —David Eppstein (talk) 21:38, 25 January 2014 (UTC)

Thanks, I can work within that framework, but it still leaves open the issue of the weakness of the point-line distance article. There must be something we can do besides pile on proof after proof of the same result. Bill Cherowitzo (talk) 18:55, 26 January 2014 (UTC)

Topology of uniform convergence

Topology of uniform convergence until minutes ago redirected to Polar topology. Someone created a new article titled Topologies of Uniform Convergence, with all those capital letters and the plural, and I moved it to Topology of uniform convergence, deleting the redirect in the process. So now we have

• Topology of uniform convergence, and
• Polar topology.

So:

• Should these get merged?

I'm not sure. The article Topology of uniform convergence deals with the case where the dual pair is (X, X') (i.e. with Y = X' in the polar topology article). So depending on what kind of presentation the reader is looking for, they might want one page but not the other.Mgkrupa (talk) 17:57, 30 January 2014 (UTC)

Also, thank you for your improvements on the article. Mgkrupa (talk) 18:14, 30 January 2014 (UTC)

• What work should be done on the new article, which is longer than the old one? I am not comfortable with the intro paragraph, since the first sentence doesn't even mention the term topology of uniform convergence. Michael Hardy (talk) 04:51, 27 January 2014 (UTC)

Polar topology is a better title, since "topology of uniform convergence" usually means something else. Sławomir Biały (talk) 12:11, 27 January 2014 (UTC)

I think that Polar topology is not the better title since the article topology of uniform convergence describes topologies, such as on the spaces L(X, Y), that are NOT polar topologies. These topologies are all known as topologies of uniform convergence. Also, you said that ""topology of uniform convergence" usually means something else", what do you mean by that? Mgkrupa (talk) 15:08, 28 January 2014 (UTC)

See the disambiguation page uniform topology. Sławomir Biały (talk) 16:52, 28 January 2014 (UTC)

Also, you're right that these don't seem to be called polar topologies in the literature. The standard term seems to be just the ${\mathfrak {S}}$-topology (see Bourbaki, Espaces vectoriels topologiques, III.§3). Sławomir Biały (talk) 00:41, 29 January 2014 (UTC)

From the page Uniform topology I see that one of the links is for Polar topologies, which this article covers, and the other two are for uniform convergence of real-valued (which this article also covers) or metric space-valued functions (which it doesn't cover) and finally for uniform spaces. In terms of sending people to the most general notion of uniform convergence the article "Topology of uniform convergence" should then just be a link to uniform spaces, or a dis-ambiguity link (although I think that this would just confuse anyone who doesn't already know what uniform convergence means and is simply trying to learn the basic notions). What if we were to call this article "Topology of uniform convergence of vector-valued functions"? A long name but also the most accurate.Mgkrupa (talk) 17:45, 30 January 2014 (UTC)

Pollock's conjecture(s)

I'm proposing a merge of the "tetrahedral" and "octahedral" conjectures into a single article. Any comments? (I only noticed this because one of them was added as a "See also" to Fermat polygonal number theorem, where I'm sure it should go.) — Arthur Rubin (talk) 21:20, 27 January 2014 (UTC)

In general I favor separate articles for separate topics, but in this case the topics are so similar, and what little there is to be said about them also so similar, that I agree that a merge makes sense. —David Eppstein (talk) 21:26, 27 January 2014 (UTC)

Working copy at User:Arthur Rubin/Pollock's conjectures. The only difference is that the Mathworld article "Pollock's Conjecture" points only to the tetrahedral conjecture, while "Octahedral Number" has mentions the octahedral conjecture. — Arthur Rubin (talk) 22:25, 28 January 2014 (UTC)

spelling of "l'Hopital's rule"

With this edit, a user has recently changed the text from explaining the difference as an "alternative spelling" to a "misspelling." This switches the tone from prescriptive to proscriptive, and so it deserves some attention. The previous version seems safer, if valid. Anyone know enough about French or math history to be able to verify it is an alternative spelling? Thanks Rschwieb (talk) 14:09, 28 January 2014 (UTC)

From Guillaume de l'Hôpital#Notes: "In the 17th and 18th centuries, the name was commonly spelled "l'Hospital", and he himself spelled his name that way. However, French spellings have been altered: the silent 's' has been removed and replaced with the circumflex over the preceding vowel. The former spelling is still used in English where there is no circumflex." Wikipedia is not a reliable source, but it does match my knowledge about French spelling, and makes sense. No such user (talk) 14:45, 28 January 2014 (UTC)

I agree. In French, the circumflex is (almost) always used for replacing a silent "s". The spelling "l'Hospital" is attested by the titles of two references of fr:Guillaume François Antoine, marquis de L'Hôpital and two external links of the same article. In fact, it appears that the correct spelling is "de l'Hospital", and that the other spellings are only common misspellings. Omitting the "de" is similar as talking about "Gaulle" instead of de Gaulle. However, "l'Hôpital rule" is a translation of the French "règle de l'Hôpital", and "règle de de l'Hôpital" is not so euphonic. D.Lazard (talk) 15:36, 28 January 2014 (UTC)

I don't think the spelling with a circumflex is an error. Some editions of his book appeared with this spelling. Tkuvho (talk) 15:49, 28 January 2014 (UTC)

Authors aren't known for misspelling their own names, so presumably this proves beyond any doubt that L'Hôpital's rule was in fact due to Bernoulli! Sławomir Biały (talk) 16:23, 28 January 2014 (UTC)

To editor Tkuvho: This depends if one accepts the modernization of the spelling for old people names. Thus "l'Hôpital" could be correct for the rule but not for the mathematician. Similarly, we have Vieta's formulas and François Viète (here, it is not modernization, but translation in another language). D.Lazard (talk) 16:50, 28 January 2014 (UTC)

Fontenelle's Éloge de M. le marquis de L'hopital (cited at the French page you linked) must have been one of the first to make the mistake of spelling it without an "s". Tkuvho (talk) 17:11, 28 January 2014 (UTC)

Thanks for all of the knowledgeable and prompt help. Rschwieb (talk) 15:26, 29 January 2014 (UTC)

AfC submission (Deep learning)

Wikipedia talk:Articles for creation/Deep learning. FoCuSandLeArN (talk) 13:41, 29 January 2014 (UTC)

There is already a deep learning article, apparently identical to the submission. Ozob (talk) 14:19, 29 January 2014 (UTC)

I (manually, as the script won't install until at least I close the browser) declined the submission, for that reason. The editor who requested the AfC submission replaced the mainspace article with his modified version. The question of whether this is a matter for WP:MATH is unclear, but I think this section should be considered closed. — Arthur Rubin (talk) 16:51, 29 January 2014 (UTC)

Mathematics and art

Mathematics and art asserts as factual many discredited fringe theories e.g. about the use of the golden ratio in Greek and Egyptian aesthetics. I tried a modest {{dubious}} tag, only to have the edit reverted and a (bad) source for these claims added. Any suggestions for a process that can get this cleaned up? —David Eppstein (talk) 01:27, 30 January 2014 (UTC)

The dubious tag is understandable--that's a pretty ambiguous sentence. It looks like Chiswick tried to be helpful by adding two references, which you don't like. He probably thought he answered your call for references and (along with the refs in the, e.g., Parthenon section) removed the dubious tag. I've worked with him on a symmetry article and he seems a reasonable fellow--why not discuss it with him on the article's talk page? --Mark viking (talk) 01:53, 30 January 2014 (UTC)

There are more citations in Mathematics_and_art#Parthenon. The only statement questioning the use of the golden ration does not have a citation yet. RockMagnetist (talk) 03:17, 30 January 2014 (UTC)

The various subsections of Golden_ratio#Applications_and_observations contain a bunch of useful references for someone interested in rewriting the article more skeptically. --JBL (talk) 04:10, 30 January 2014 (UTC)

Intersection

This has recently been created, with the disambiguation page previously at this location moved to Intersection (disambiguation). The problem is I don't think the mathematical term is the primary topic: if anything the common usage of the word is when talking about road intersections (or listening to your sat-nav read them off to you), but probably being a common English word used in many ways and fields its best without a primary topic, as before.

At the same time the new article at Intersection doesn't seem to be on a distinct topic: it's mostly on geometric intersection, but includes some set theory and possibly other areas, leading to a very confusing introduction, some even more confusing links, and little else. The problem is the different mathematical uses have little in common, except for being different interpretations of the word in different fields. But that does not make for a good article topic.--JohnBlackburne^words_deeds 02:21, 30 January 2014 (UTC)

A road intersection is a 2-D intersection. Intersections in (Euclidean) geometry, algebraic geometry, and set theory derived from one common idea. What namely “does not make for a good article topic”, this WP:CONCEPTDAB? Okay, make the intersection (geometry) article first, and then we’ll discuss the merit of the “most general article”. I think, most people here will agree that intersection (Euclidean geometry) shall not consider differentially-geometric aspects. Imagine one wants to know what is an intersection of a line and a quadric in a projective plane. These are generally curves, but the article on curves hardly considers the question of intersections. These are submanifolds, but the reader hasn’t necessarily know this word. If s/he come to my stub, s/he will obtain some minimal idea how to approach the problem. If s/he come to the original dab, it will be a puzzle. Where to go: intersection (Euclidean geometry) (formerly “intersection point”)? It misses the line at infinity. Intersection (set theory)? S/he will not learn anything new about the problem in question. Intersection theory? The reader will get a huge charge of general nonsense. Whereas for a reader who looks for something about Euclidean geometry there is little difference between “my article” and a conventional dab page.

“Even more confusing links” – which namely? “Little else” – yes, the house is just started. I think one should say about dimensions, as well as relationship between intersection of submanifolds and the orientation structure (what is expressed with the intersection number for dim_intersection = 0, but in more general case). Incnis Mrsi (talk) 08:59, 31 January 2014 (UTC)

I agree with Incnis Mrsi that the situation was confusing. However, IMO, his solution is not the best one. In fact, in mathematics, there is only one concept of intersection, the set theoretical one. I agree that, in incidence geometry, lines and planes are not considered as sets, but they are intuitively. And, in incidence geometry, one may consider the set of the points that are incident to a line; this allows to consider the intersection of two lines as a set theoretical intersection. Therefore I suggest the following

• Rename intersection (set theory) as intersection (mathematics) (I have just noted that the latter is already a redirect to the former)
• Add to Intersection (mathematics) a section "Intersection in geometry" with template {{main|Intersection (geometry)}}
• Rename Intersection (Euclidean geometry) as Intersection (geometry) and add it a section about projective geometry (a motivation of projective geometry is to solve intersection problems)
• Add to Intersection (geometry)#See also links to Intersection theory and Intersection number
• Move back intersection (disambiguation) and replace the existing math. entries by a single link to intersection (mathematics)

D.Lazard (talk) 11:08, 31 January 2014 (UTC)

I do not agree with Daniel that “there is only one concept of intersection, the set-theoretical one”. Set-theoretically there is no difference between an intersection proper and a tangential point (note another red link), but geometrically and algebraically there is. Also look at the picture please: set-theoretically there is a set of two points, geometrically there are simply two intersections, algebraic-geometrically there is a 0-manifold consisting of two components with different signs, provided the line, the circle, and the plane all are oriented. Why not explain it in one article, indeed? Also, what is now intersection (Euclidean geometry) is not a suitable candidate for converting to intersection (geometry). It is a typical enumerative article like the current revision of rotation (mathematics) (see talk:Rotation group for further development) and, unfortunately, many other Wikipedia articles, not mathematical only, that need to be conceptual instead of enumerative. Incnis Mrsi (talk) 15:07, 31 January 2014 (UTC)

I certainly edited Intersection (mathematics) (edit | talk | history | links | watch | logs) to redirect it to intersection (I even remember how I entered {{R from extra disambig}}). Apparently there was a browser glitch and the edit wasn’t saved. BTW, the fr:Intersection (mathématiques) article is IMHO too poor to borrow something really usable from it. Incnis Mrsi (talk) 16:28, 31 January 2014 (UTC)

@Incnis Mrsi: When you write the the circle and the line of the picture have "two intersections" you are correct with respect to the non-mathematical meaning of "intersection" (road intersection), but you are not mathematically correct: the common mathematical terminology is that the circle and the line have two points of intersection, or two intersection points, or also that their intersection consists in two points. All these formulations are standard ways to talk about set intersections. Also it is clear that when the sets that are intersected have an extra structure, their intersection has also an extra structure. If I follow you argument, we should have an article for the intersection of vector spaces (the set intersection of two subspaces is a subspace), for ideals, and so on. Here, we have that the intersection of two algebraic varieties is an algebraic set, which, on your example, is not irreducible and has two components consisting of isolated points. Similarly a tangential point, aka tangent point, is a point of the (set) intersection that has a specific extra structure (the two curves or varieties or manifolds are tangent at that point). I do not see in your post any argument against merging Intersection and Intersection (set theory) into a single article called Intersection (mathematics). However, I see many reasons to use such a merger to improve both articles. D.Lazard (talk) 17:34, 31 January 2014 (UTC)

A good point about an additional structure. The only disagreement is about the precedence: I do not think the set theory should be qualified as the only formalism for intersection in mathematics. It is the standard one, certainly, but not an unique, and definitely not historically an original one (see below). Incnis Mrsi (talk) 19:28, 31 January 2014 (UTC)

(edit conflict)I agree with most of that: I think Intersection (geometry) is better than Intersection (Euclidean geometry); if that means adding some non-Euclidian geometry then do so, it's a good and natural extension of Euclidian geometry. I obviously agree with moving the DAB page back to Intersection. But I don't think it or the set theoretic use of intersection is the main mathematical use, I'd say that the geometric usage is as important. Looking at Intersection (Euclidean geometry) and Intersection (set theory) both are significant areas. So I'd change Intersection (mathematics) to redirect to the DAB page, i.e. Intersection. Apart from that any see-also links and {{main}} type links can be added as makes sense to clarify connections and help readers find articles.--JohnBlackburne^words_deeds 17:47, 31 January 2014 (UTC)

John, do not ignore my question, please. Which of my links are confusing? Of course my solution is not the best possible, but what namely did I do wrongly? Incnis Mrsi (talk) 19:28, 31 January 2014 (UTC)

I mentioned projective plane only as an easily accessible geometry that isn’t Euclidean. There are numerous other alternatives to the Euclidean space: pseudo-Euclidean spaces, for example, or just the affine geometry where words “circle” and “perpendicular” are meaningless. Incnis Mrsi (talk) 22:41, 31 January 2014 (UTC)

The primary usage of the word "intersect" in my opinion is to cut, in the geometrical sense. This is consistent with the Latin origin of the term, and the current English vernacular (as in the intersection of two streets). The set theoretic meaning if the term was not even introduced until the 20th century (or possibly the late 19th century, the OED puts it at 1909). I'm not sure what this implies for an article on the topic. Sławomir Biały (talk) 17:40, 31 January 2014 (UTC)

A bit of support from an unexpected source. But I think we have two distinct (although related) questions: the fate of the new stub (as well as of intersection (mathematics) that I failed to redirect because of a glitch), and the primary topic of the title Intersection (edit | talk | history | links | watch | logs). I do not have a highly competent opinion about the latter and IMHO it should be discussed at talk:Intersection (disambiguation) because it can possibly escalate to an RfC or otherwise attract an attention of non-mathematical disambiguators. Incnis Mrsi (talk) 19:28, 31 January 2014 (UTC)

If an RfC's needed it could be created here; RfCs can be started anywhere, including user pages. But I don't think one's needed; we're not yet reached that point. As for the fate of the current Intersection there's no need for it: Intersection (Euclidean geometry) and Intersection (set theory) are two distinct topics. If there's need to connect them that can be done using appropriate text and links in both articles, and both should be linked from the disambiguation page. But they're not both sub-topics of a more general "mathematical intersection" topic.--JohnBlackburne^words_deeds 19:58, 31 January 2014 (UTC)

John, you catch from the discussion only things convenient to you, and dodge my question about your own claim the second time. Nobody tries to refute that “Intersection (Euclidean geometry)” and “Intersection (set theory)” are distinct. The discussion deals with following problems:

1. There is no article “intersection (geometry)” (virtually all participants).
2. The “new intersection” topic can be merged with “intersection (set theory)” to “intersection (mathematics)” (D.Lazard).
3. The “intersection (Euclidean geometry)” has an inappropriate content and structure to be simply expanded to “intersection (geometry)” (Incnis Mrsi).
4. “Intersection (geometry)” is historically the primary meaning, and the set-theoretical interpretation of intersection was popularized only in 20th century (Sławomir Biały).

You did not comment on any of these 4 points in a reasonable way, only reiterate some of things you said from the beginning: one should not bother to improve or save anything of it, [because] Incnis Mrsi wrote this crap. Incnis Mrsi (talk) 22:41, 31 January 2014 (UTC)

Since there is discussion over what "intersection" truly means, mathematically, I would like to point out that most intersections can be interpreted as fiber products in an appropriate category. This is true of sets, vector spaces, ideals, schemes, and so on. But the primary meaning of "intersection" is not "a kind of fiber product", and the primary article on intersections should not introduce it as such. Ozob (talk) 02:00, 1 February 2014 (UTC)

Just a hint: Please have a look to the German WIKI on intersection = Schnitt. --Ag2gaeh (talk) 10:57, 1 February 2014 (UTC)

The German is less directly analogous, since "Schnitt" is already part of the German vernacular and literally means "cut" (as a noun, at least, as in "ein Schnitt von Rindfleisch"—"a cut of beef"), whereas in English intersection is an old loan word from Latin that would have been used exclusively in a scientific setting before its adoption into the language. This is reflected in the relative rarity of the word "intersection" in modern day-to-day English (with the exception of referring to day-to-day things that are actually geometric intersections, like streets). A better comparison for de:Schnitt would be the English disambiguation page cut. Sławomir Biały (talk) 13:41, 1 February 2014 (UTC)

Sorry, I only had the mathematical part of the German page in mind and did not think about the "intersection" of a knife and a beef. --Ag2gaeh (talk) 10:45, 2 February 2014 (UTC)

Wikipedia talk:Articles for creation/Phan Sequence

Hello, mathematicians! Last chance to read this old Afc draft before it disappears for lack of reliable sources. —Anne Delong (talk) 15:11, 30 January 2014 (UTC)

There is no chance that reliable sources exist for this sequence. --JBL (talk) 16:49, 30 January 2014 (UTC)

Yes, I thought so. Thanks. —Anne Delong (talk) 21:41, 30 January 2014 (UTC)

Wikipedia talk:Articles for creation/Stability of Boolean networks

Dear math experts: Here's another old abandoned Afc submission that's about to be deleted. Is this a notable topic, and should the article be kept? —Anne Delong (talk) 18:10, 30 January 2014 (UTC)

Delete it. Ozob (talk) 02:02, 31 January 2014 (UTC)

The stability of a Boolean network is one of the most important properties of the dynamics of such a network. The article gives a poorly described criterion for stability in NK models with no significant intro or background. Our Boolean network article could use more material on dynamics, but this article is unfortunately not it. I would recommend passing on this one. --Mark viking (talk) 03:02, 31 January 2014 (UTC)

If the AfC is kept, then the material can be used to supplement the existing articles. Is this reason enough to keep it for a few months?

Sorry I wasn't clear--I don't think the prose is salvageable and refs are pretty easy to find on this topic, so I don't see the utility in saving any of it. Thanks, --Mark viking (talk) 20:04, 31 January 2014 (UTC)

Thanks for taking the time to check this out. —Anne Delong (talk) 03:55, 3 February 2014 (UTC)

AfC submission

Wikipedia talk:Articles for creation/K-trivial sets. Regards, FoCuSandLeArN (talk) 00:03, 4 February 2014 (UTC)

Also Wikipedia talk:Articles for creation/One-Shot Deviation Principle. Thank you, FoCuSandLeArN (talk) 01:08, 6 February 2014 (UTC)

EOM links

Spinningspark (talk · contribs · deleted contribs · logs · filter log · block user · block log) has been reverting the addition of EOM links en masse. I don't really have strong opinions about this, but I generally find the EOM to be a rather useful supplement to our own treatment of mathematical topics. At least some of the removed links are of a high quality (actually the first I noticed at Korn's inequality.) What does the project think about these edits? Should they be reverted? Sławomir Biały (talk) 16:31, 4 February 2014 (UTC)

I reverted them en masse because they had been inserted en masse. I am not particularly objecting to the site, I don't really know anything about the site one way or the other. However, the IP that has been inserting the links has been doing nothing else besides inserting them. That is spamming, regardless of the quality of the links. No justification was offered for inserting them in the edit summary, and I noted that many had been added as references without adding anything to the text. Since references are supposed to be there to support the text then that in itself looks spammy. As to their quality as external links, if editors think they are adding something that is not covered in the article then I'm fine with that, but it would be preferable that, if the material pointed to is suitable for Wikipedia, it should be added to Wikipedia and use the site as a ref instead of an EL. There are sometimes reasons material cannot be added to Wikipedia and an EL is justified on those grounds, but I'm not seeing anything here that fits in that category. SpinningSpark 16:59, 4 February 2014 (UTC)

To be sure, I don't question your reasons for removing the links, but I do think that in many cases these links are a valuable supplement to the article and that seems worth some consideration. Sławomir Biały (talk) 17:24, 4 February 2014 (UTC)

I'm fine with you just reverting me on the ones you think are useful. SpinningSpark 18:02, 4 February 2014 (UTC)

I'm not a fan of addition/revert em masse either way. However disagree with an overly literal application of particular line in WP:EL here, that is only adding it if it really offers information not being contained in the article yet. I rather treat it (and to degree links to MathWorld, MacTuror and PlanetMath as well) as "standard" link as long as the EL is rather small and empty. In a way similar to linking the IMDB in movie related articles. The reason for that being twofold. For short article EOM, MathWorld and MacTutor can also be considered as "general" sources/sources outside of footnotes. In such that cases a placing under references might be more appropriate, but since they are links some editors place them under EL. The other reason is simply, that I consider it as beneficial to readers to offer links to alternative encyclopedic representations of math content.--Kmhkmh (talk) 15:39, 7 February 2014 (UTC)

"Octagonal"

The usage of Octagonal (edit | talk | history | protect | delete | links | watch | logs | views) is under discussion, see talk:Octagonal -- 70.50.148.248 (talk) 07:48, 5 February 2014 (UTC)

Cyclic sieving

I've created a new, painfully stubby, article titled cyclic sieving. So work on it. Or, in other words, have fun. Michael Hardy (talk) 05:36, 6 February 2014 (UTC)

I think it would benefit greatly from one or two examples. JRSpriggs (talk) 06:19, 6 February 2014 (UTC)

So far only two articles link to it, so that's another thing to work on. Michael Hardy (talk) 20:07, 6 February 2014 (UTC)

Problem with multiline equations

The Spherical trigonometry article has several bits of LaTeX that Failed to parse, for example the displayed equation in the Spherical trigonometry#Polar triangles section. My guess is that the alignat and align environments are not being handled. I went to the Wikimedia page Help:Displaying a formula and found that the align and alignat environments seem to be supported, but also generate a Failed to parse error on the page. A bug report at the wikimedia bugzilla suggests that these environments might be supported in MathJax, but not texvc. Is this a bug that others see? Thanks, --Mark viking (talk) 23:46, 6 February 2014 (UTC)

align should work with texvc. I just looked at a place I recently edited a formula with align, Triple product#Using geometric algebra, which I'm sure was working then, and it's now broken. The parser is complaining about 'aligned' not align, so is doing some sort of substitution, but I don't know if this is something it normally does. But I'm sure this was working two weeks ago: I was only editing that section, there's only one formula, and I would have used preview when editing it. I've tested MathJax before but haven't had it enabled for several months.--JohnBlackburne^words_deeds 00:01, 7 February 2014 (UTC)

I've asked about this issue at Wikipedia:Village pump (technical)#Math aligned environments failing to parse. Maybe an answer will magically appear there... Melchoir (talk) 02:08, 7 February 2014 (UTC)

Thanks John, for verifying the problem, and thanks Melchoir, for submitting to the technical village pump. --Mark viking (talk) 03:29, 7 February 2014 (UTC)

There is a similar problem at Noether's theorem‎. Unfortunately, some people are trying to fix the problem by editing the source, not realizing that it is the software's interpretation of the source which is at fault. JRSpriggs (talk) 07:57, 7 February 2014 (UTC)

I ran into the problem as well, all multline formulas using \begin{align} ... \end{align} seem to be affected (see here Help:Displaying_a_formula, scroll through the page). However some special symbols seem to have a rendering issue as well (see en:Hilfe:TeX, scroll through the page)--Kmhkmh (talk) 11:38, 7 February 2014 (UTC)

As far as I can see, it seems to work again for me. -- Jitse Niesen (talk) 12:05, 7 February 2014 (UTC)

I'm having the same problem and unfortunately it's leading to people (mostly from anonymous IPs) removing important formatting. The issue with aligned formulas should have critical priority: it needs to be fixed as soon as possible. The servers were offline at some point yesterday, and I assume that this was related. Sławomir Biały (talk) 12:25, 7 February 2014 (UTC)

This remains broken for me. Seconding the urgency of this; the longer this takes, the more reverting we will have to do later. --Rhombus (talk) 13:07, 7 February 2014 (UTC)

I discovered that it has to do with the maths preferences; MathJax works fine (at least for me) while PNG gives problems. It is still not fixed; sorry for falsely suggesting it is working again. The relevant bug seems to be bugzilla:60997 bugzilla:61012. -- Jitse Niesen (talk) 13:27, 7 February 2014 (UTC)

Problem still present. Isn't there a way to post a warning about this issue? Just to avoid people editing all sorts of math articles, escalating problems. This section in this talk page isn't all that easily found, even when looked for:) This is a serious issue after all. I think it should be posted somewhere central that it's known and is a server-side problem. --Loudandras (talk) 19:21, 7 February 2014 (UTC)

Displayed equations are centered?

I recently edited Talk:Transitive relation, and found that displayed equations are centered. I use MathJax, so my view may not be typical, but there could be a problem here.

$aRb\land bRc\rightarrow aRc$

Yep, it's a problem here, also. — Arthur Rubin (talk) 17:07, 7 February 2014 (UTC)