Wikipedia talk:WikiProject Mathematics/Archive/2015/Oct

Proofs, revisited

An editor, SergeyLiflandsky, has been adding proofs to articles on convergence tests. I don't think they add anything of interest to anyone who should be using Wikipedia, but I'd like a second opinion. Articles are:

1. Matrix norm

   Including a proof of a relationship between two matrix norms which follows almost immediately from other results in the article. The (induced) (2,2)-norm is the same as the (Schatten) ∞-norm (noted in the induced norm section) which is bounded by the (Schatten) 2-norm (results from properties of the vector norm) which is the same as the entrywise (2,2)-norm (noted in the entrywise norm section).) I copied the result into the induced-norm section, but I'm not sure it belongs there.

2. Weierstrass M-test

   Including a second proof.

3. Uniform convergence

   Including the proof that a uniform limit of continuous functions in the "Applications to continuity" section. This one might be sufficiently interesting if no other proofs are in the article, as it uses a typical method. However, I believe the proof outline, referring to above as the "epsilon/3" trick, is sufficient. Also, as noted on the talk page, the proof is correct. As an additional note, it doesn't belong in the "Applications" section.

1. Ratio test

   Includes a proof of Kummer's test; but the proof follows from an immediate combination of the results above.

— Arthur Rubin (talk) 17:51, 29 September 2015 (UTC)

I agree with removing the proof from the article uniform convergence, since we summarize that with the "epsilon/3" trick, which suffices.

I don't entirely agree with their removal from ratio test and Weierstrass M-test. In the case of the ratio test, the proof of Kummer's test is valuable to the reader because it gives some meaning to the otherwise very mysterious auxiliary series $\zeta _{n}$. So I would strongly prefer that proof be included. Also, it is not clear to me that Kummer's test follows from the other results (the article asserts that they are all special cases of Kummer's test, suggesting that it is rather the other way around). If that's true, it could be made clearer.

For the Weierstrass M-test, I think the "other proof" that was deleted is much more natural. Prove the uniform Cauchy criterion and use that to establish uniform convergence of the series. That's probably a matter of taste, but I think it's good to have both proofs included. It also gives a good way to work in a link to the Cauchy criterion, and the test itself is given some more tangible meaning as a result. So I think there is definite encyclopedic value in having that. Sławomir
Biały 20:08, 29 September 2015 (UTC)

Arthur here really want to emphasize how brilliant he is and how everything is so obvious to him, but seems unable to understand some obvious things that follow form common sense. He also fails to understand the value of method of the proof. In the proof of Kummer's test the method is emphasized while the proofs above look like tricks. — Preceding unsigned comment added by SergeyLiflandsky (talk • contribs)

1. For matrix norm, I now doubt even the relationship is appropriate, except in a spin-off article relationship between matrix norms. The "proof" that the induced 2,2 norm is less than the elementwise 2-norm is much simpler the way I put it;

   The induced 2,2 norm is equal to the spectral &infty; norm (interesting result, already in the article)

   The spectral &infty; norm is dominated by the spectral 2-norm (follows from properties of vector norms)

   The spectral 2-norm is equal to the elementwise 2-norm (interesting, but already in the article)

2. For Weierstrass M-test, I replaced the proof with the newly added one, and cleaned it up a little. The last step that any "uniformly Cauchy sequence" uniformly converges needs to be added, though. I5 follows from completeness, but not immediately.
3. For ratio test, I can see the point that the proof is not precisely a combination of proofs already in the article, but, if that proof is included, others should be removed.
4. For uniform convergence, after studying the article, I'm sure the proof should not be there. A proof is in uniform limit theorem; I haven't checked whether they are the same proof, and whether possibly a reformmated version of SergeyLiflandsky's proof should replace that one. The proof definitely should not be in the "Applications" section of uniform convergence, and almost certainly should not be in uniform convergence at all.

May I suggest that SergeyLiflandsky's suggestions would likely be appropriate in Wikibooks, and certainly in Wikiversity (if that's still open; there had been an attempt to shut it down.)

— Arthur Rubin (talk) 10:20, 30 September 2015 (UTC)

Only about uniform convergence (the rest can be worked out in the same way, as a textbook might say). Do we really need the article uniform limit theorem? The statement is probably usefully included in the main uniform convergence. I think the proof (that the uniform limit of a sequence of cont func is cont) belongs to the article. It's a very good way to understand the concept of uniform convergence, which can be esoteric to calculus students. I myself learned uniform convergence at the same time as I tried to understand the proof. It would especially be useful to point out exactly how the proof fails if the uniform convergence is weakened to point-wise convergence. The proof that is currently given at uniform limit theorem is correct but not a good one. It's much better to give a more accessible proof (say for real-valued functions on an open interval). The extension to a more general case (say values are in a metric space) is entirely mechanical; we should just say an extension is mechanical and there is no need to give a proof of the general case. -- Taku (talk) 03:19, 5 October 2015 (UTC)

While we're speaking of proofs ...

Category:Articles containing proofs is neither fish nor fowl. It is classified as a maintenance category, but it is not clear what maintenance it enables. It is a hidden category, but is linked from List of mathematical proofs and List of mathematics categories in article space, and it is a subcategory of Category:Mathematical proofs instead of a Wikiproject category. Maintenance categories are mainly for use by maintenance projects, and the categorization guidelines state that articles should be kept out of such categories wherever possible (usually the talk pages are added instead). Generally articles end up in maintenance categories because they are put there by maintenance tags; but the articles in this category are added by hand.

So – does this category serve any maintenance purpose? If so, is there a better way to handle it? I would suggest, at a minimum, relocating it in Wikiproject space and removing mentions of it in article space. RockMagnetist(talk) 23:16, 4 October 2015 (UTC)

At one point it was decided that most proofs in most articles were unencyclopedic. The category is a maintenance category because the articles that had these proofs needed to have them removed, which is essentially a kind of maintenance. I believe it is still the consensus that most proofs that would be included in a textbook or a paper are not sufficiently notable to warrant inclusion in an encyclopedia. However, for the reasons you give, I'm not sure that the category is being handled properly. I agree that it would be good to move it to Wikiproject space and to put talk pages into the category instead of articles. Ozob (talk) 00:13, 5 October 2015 (UTC)

Ultimately, Wikipedia is what the editors want it to be. We (the editors) certainly don't want errors or other inaccuracies in the articles, but I'm not sure if the proofs are equally something that needs to be actively removed. It is probably a stretch to apply the notability criterion to the proofs since the criterion is mainly a mechanism to keep away articles on nobodies and other non-notable sports teams, bands, etc. The notability criterion does not and should not apply to calculations. The proofs should be treated similarly. Some routine proofs are probably not illuminating just as any routine computations are boring. But the decision should be made case-by-case.

Oh, about the category in question: the corollary of what I said is that there is no need for a category like that since an article doesn't mean anything from the maintainance point of view. -- Taku (talk) 00:53, 5 October 2015 (UTC)

The discussion surrounding proofs in Wikipedia articles is as old as Wikipedia itself, see Wikipedia talk:WikiProject Mathematics/Proofs. As far as I can see there's no consensus on whether a consensus ever was reached in this discussion, so to speak. – Tobias Bergemann (talk) 07:42, 6 October 2015 (UTC)

AfC submission 04/10

See Draft:Spectral Correlation Density. Thank you, FoCuS contribs; talk to me! 01:00, 5 October 2015 (UTC)

• Also Draft:Geometric set. FoCuS contribs; talk to me! 17:12, 9 October 2015 (UTC)

Group theory terminology

• Group theory terminology (edit | talk | history | protect | delete | links | watch | logs | views)

On 8 October 2015 this was moved from Glossary of group theory. It has now been nominated for deletion. Johnuniq (talk) 02:31, 10 October 2015 (UTC)

Can we just merge it with group theory? -- Taku (talk) 03:38, 10 October 2015 (UTC)

Draft at AFC needs help

Please help review Draft:Geometric set. If you do not know how to, or don't wish to do a full AFC review, please post your comments on the draft's talk page. Roger (Dodger67) (talk) 09:29, 13 October 2015 (UTC)

Complex affine space → complex coordinate space

Please comment regarding the proposed move at Talk:Complex_affine_space#Requested_move_13_October_2015. Sławomir
Biały 14:17, 13 October 2015 (UTC)

Template:Isaac Newton

I seem to have bitten off a bit more than I can chew in creating {{Isaac Newton}}. Are there any experts on the relevant subjects that could help to sensibly organize the template.--TonyTheTiger (T / C / WP:FOUR / WP:CHICAGO / WP:WAWARD) 17:59, 9 October 2015 (UTC)

• I have cobbled together what I can for this template. It would help to have eyes on it. It would likely benefit from rearranging by an expert.--TonyTheTiger (T / C / WP:FOUR / WP:CHICAGO / WP:WAWARD) 19:16, 13 October 2015 (UTC)

Dihedral angle

Can some persons more knowledge than me have a look at Dihedral angle? I did some edits but it needs attention of a proper geometer , the article is a bit a mix of the same angle in mathematics, computing, chemistry and biology. and the math/ geometry bit is underdevelopped. (the main formula looks to be comming from a computing manual , not from a proper math book) WillemienH (talk) 11:00, 14 October 2015 (UTC)

Flowchart on wiki

This isn't precisely mathematics, but I figured that this group would know: Is there a way to create a flowchart on wiki? Or a set of templates that mimics it?

I want to be able to create some decision trees for a few templates. They would say things like this:

Should you use this template?

• Is there currently a problem with neutrality in this article?
  • No: Then don't use it.
  • Yes: Then see the next question.
• Is the neutrality problem caused by an editor with a COI?
  • No: Then don't use this one. Use plain old {{POV}} instead.
  • Yes: Then see the next question.
• Could you easily fix the problem yourself?
  • Yes: Then just fix it, and don't use the template.
  • No: Then take both of these two steps:
    1. Add the template to the article.
    2. Leave a note on the talk page that describes the neutrality problem.

This isn't very complicated as flowcharts go, but I don't know of any way to draw this on wiki. Does anyone have any ideas for me? WhatamIdoing (talk) 23:29, 8 October 2015 (UTC)

Mediawiki has a number of extensions that allow for creation of flowcharts and diagrams: FlowchartWiki, Dia, and PlantUML, but I don't know if any of these are implemented in Wikipedia's version of mediawiki. --Mark viking (talk) 04:37, 9 October 2015 (UTC)

Use Special:Version to see what extensions are installed. Re the proposal, there is a flowchart at WP:BOLD, revert, discuss cycle#General overview but I don't think it is very helpful—the flowchart was constructed off-wiki then uploaded as an SVG image. The text in the OP is probably as good as it gets. Johnuniq (talk) 05:59, 10 October 2015 (UTC)

Thanks for the replies. None of those extensions are installed here. I would like to avoid creating a static image, but I suppose that it's an option. WhatamIdoing (talk) 17:49, 14 October 2015 (UTC)

Sylvester matrix and User:Akritas2/Modified resultant

Dear mathematicians: Would "Modified resultant" be a useful redirect to the Sylvester matrix article? If so, can someone add a mention of the term in that article? Or is this a valid topic on its own that should be moved to Draft space? It's pretty stale and will soon be deleted under db-g13.—Anne Delong (talk) 11:21, 14 October 2015 (UTC)

I agree to delete the draft. The term "modified resultant" seems WP:OR. As far as I know, it appears literally only in the unique reference of the draft, which is a recent article (2014). Certainly some authors have written things like "we modify the definition of the resultant as follows ...", but "modified resultant" alone has no meaning for the specialists of the resultant. Note also the WP:COI: the author of the draft is one of the authors of the unique cited article. D.Lazard (talk) 13:15, 14 October 2015 (UTC)

Thanks, D.Lazard. If no one edits in during the next week, it should be eligible for db-g13 and I will delete it then.—Anne Delong (talk) 08:20, 16 October 2015 (UTC)

New contributor needs help

A new Wikipedian has repeatedly tried to submit a draft to AFC User:Artyom M. Grigoryan/sandbox/Paired Transform and Fast Fourier Transform but it has been declined repeatedly per WP:NOTJOURNAL - we're at a stalemate. I believe this editor could become a productive contributor but clearly needs help to understand that WP does not simply republish academic articles. BTW his native language appears to Russian, so communicating in that language might help his understanding. Roger (Dodger67) (talk) 11:37, 20 October 2015 (UTC)

Well, a message is send to him. Boris Tsirelson (talk) 18:15, 20 October 2015 (UTC)

Disruption at complex affine space

See WP:DISRUPTSIGNS for context. It is clear disruption to tag an article, and obvious tendentious editing to claim that one editor against four is a "tie". Whoever changed the title of this section obviously can't be bothered to pay attention.

User:TakuyaMurata is disruptively adding a "POV" tag, because he personally appears to disagree with sources like Marcel Berger's "Geometry", Armand Borel's "Linear algebraic groups", Nicolas Bourbaki's "Elements of mathematics", H.S.M. Coxeter's "Introduction to geometry" and "Projective geometry", W.V.D. Hodge and Dan Pedoe's "Methods of algebraic geometry", J S Milne's "Algebraic geometry", and even some of the sources that he himself brought to the discussion. As far as I can tell, any source that does not agree exactly with what appears in Robin Hartshorne's textbook "algebraic geometry" is immediately dubbed "nonstandard" and therefore less relevant to the subject of what a "complex affine space" is (see this revision that is being held up as the epitome of standard).

The kicker is this: Takuya wants to redefine "affine space" to mean the n-fold Cartesian product of a field with itself, equipped with the n coordinate projections, and linear structure. He even went so far as to say that the complex affine n-space carried a canonical Hermitian inner product (and was very insistent for awhile on that point). In other words, for Takuya an "affine space" means the same thing as a coordinate space. It's clear to everyone (except Takuya) that this is a very idiosyncratic view that does not reflect standard terminology. Now, I've bent over backwards to try to accommodate this perspective in the article complex affine space, at least without saying something that is actually wrong. But Takuya insists on restoring the "POV" tag, apparently because he believes that the article should be rewritten from this very weird perspective.

I'm not sure what to do. It's very clear to me that Takuya is simply wrong about the primary use of the term "affine space" in mathematics. But he insists that the primary use should be determined apparently by a single textbook in algebraic geometry that he happens to like. Sławomir
Biały 00:55, 22 October 2015 (UTC)

I am far not expert in algebraic geometry, but anyway, I'd formulate the position of Takuya as follows:

"In algebraic geometry, 'complex affine space' is Cⁿ. (Up to isomorphisms, of course... never mind... all depends on the context.)"

He insists that (some) sources are intentionally vague about "up to what?" and therefore Wikipedia must be equally vague. Boris Tsirelson (talk) 06:51, 22 October 2015 (UTC)

I'm not an expert either; I just wanted to follow the sources and apparently I'm not allowed. Just to be clear; I think the definition depends on a context (say Zariski topology or classical topology). But apparently Wikipedia needs to exist outside the reality ($\mathbb {C} ^{n}$ doesn't have inner product); anyway, I don't understandl this stuff... -- Taku (talk) 07:04, 22 October 2015 (UTC)

No problem with the two topologies; both are invariant under the affine group, thus, both are well-defined on an affine space. There are still other topologies; for example, the fine topology from the potential theory. Still affine invariant. The affine space is, by definition, an algebraic structure (unlike, say, a topological vector space). But the inner product is not affine invariant, of course. When you speak about "embedding of C^m into Cⁿ" (you really did), do you mean the embedding must preserve the inner product, or not? Who knows? The question is: whether the group of automorphisms of an affine space is the affine group (shifts and linear transformations), or rather, depends on the context. Boris Tsirelson (talk) 08:37, 22 October 2015 (UTC)

Sorry, of course, the "affine structure" is unrelated to the topology. Just to be on the record, I'm not debating anything about the definition of an "affine space" as in affine space. When I say "complex affine space", I'm not thinking of any affine space in the sense; I simply meant $\mathbb {C} ^{n}$ and then the topology matters. As for the embedding, again it depends on the context; if we are talking about the embedding of schemes, then it doesn't preserve the inner product since the inner product is not a part of the scheme structure.

All I'm saying that some people (especially algebraic geometers) use the "complex affine space" to mean $\mathbb {C} ^{n}$ (whatever that means). Unfortunate? Perhaps. -- Taku (talk) 08:48, 22 October 2015 (UTC)

A quick Google search turns out many instances (when people are not thinking of any affine structure); e.g., [1]. The key point is that they use "complex affine space" instead of "complex coordinate space". Anyway, I'm tired and I'm not going to press the issue. -- Taku (talk) 09:14, 22 October 2015 (UTC)

Well, if so, this fact could be mentioned in the article (I think so); but as a side remark about an abuse of language, not instead of the "official" definition. Boris Tsirelson (talk) 10:52, 22 October 2015 (UTC)

• "I just wanted to follow the sources": I'm sorry, but this is definitely not what Takuya has been doing. I presented a list of six or seven very standard sources in different areas of geometry and algebra, which Takuya has been doing his best to dismiss. As far as I can tell, there is only one "source" that Takuya has tried to follow, and that is a single textbook in algebraic geometry. In fact, one of the sources that Takuya presented as the new "standard" in algebraic geometry (Vakil's notes), does not support his position at all. (That defines complex affine space as $Spec\mathbb {C} [x_{1},\dots ,x_{n}]$, not $\mathbb {C} ^{n}$.) Yet he persists in arguing that this is literally the same thing as $\mathbb {C} ^{n}$, presumably because of his own confirmation bias.
• In particular, I have directed you to the standard textbook by Hodge and Pedoe, which really should have stopped all argument. They give an extremely clear account of what "affine" means in algebraic geometry, and it is clear how this relates to the standard meaning of the term in "classical" geometry. An affine space is a projective space with a fixed hyperplane "at infinity". In fact, it's really only from this point of view that the adjective "affine" makes sense as it's used nowadays in algebraic geometry. However, apparently instead of bothering to see what they had to say about it, you just wrote off the source as not "contemporary", because you "can't follow their presentations". In fact, I strongly suspect that you haven't even looked to see what they say. Well, you lose the right to claim that you are trying to "follow the sources".
• Regarding the link [2]: I don't see why this is inconsistent with the view in the current article. But we should be clear, $\mathbb {C} ^{n}$ as an affine space is something different from $\mathbb {C} ^{n}$ as a set or $\mathbb {C} ^{n}$ as a topological space, or $\mathbb {C} ^{n}$ as an inner product space. Takuya has systematically failed to appreciate this, despite being asked to clarify his position on multiple occasions.
• "I simply meant $\mathbb {C} ^{n}$ and then the topology matters." Great! But you haven't said what $\mathbb {C} ^{n}$ is. At one point you said that it was a set. At another point you said it was an inner product space. At another point, you agreed that it was an affine space. Now you're saying it's a topological space. All of these are extra things, that are not built into the set $\mathbb {C} ^{n}$. For example, a topology is a collection $\tau$ of subsets satisfying certain axioms. An inner product is a particular kind of complex-valued function. The structure of a vector space is given by a pair of functions, called addition and scalar multiplication, satisfying certain axioms. These are all extra. When someone writes $\mathbb {C} ^{n}$, they may mean some of these things and not others. For example, I have never seen anyone besides you, even in the most egregious language abuse, refer to an inner product on the affine space $\mathbb {C} ^{n}$. By and large, when a geometry refers to the affine space $\mathbb {C} ^{n}$, they mean $\mathbb {C} ^{n}$ with its natural affine structure. (They don't mean it as a linear space, an inner product space, etc.) This is exactly what the article currently does. Yet you insist that there is a POV dispute, but have failed to articulate any clear position.
• In fact, Takuya is the one who is adding the tag, yet admits at Talk:Complex affine space: "But apparently the issue is something else; I don't know what it is myself." Surely, if there is a dispute, the responsibility lies solely with the one adding the tag to clarify what "the issue" is. If there is no issue, there is no reason to add a tag in the first place.
• "Well, if so, this fact could be mentioned in the article": The article already does mention this. Twice. Once in the lead, and once in the section on coordinates. Sławomir
  Biały 11:20, 22 October 2015 (UTC)

My 3cts:

• A complex affine space is an affine space where the underlying vector space is modeled over the complex numbers. An affine space is a triple $(A,V,-)$ where $A$ is a set of points, $V$ is a vector space and $-\colon A\times A\to V$ is a subtraction map which maps two points to the corresponding difference vector (satisfying a few axioms).
• The standard example of a complex affine space is $(\mathbb {C} ^{n},\mathbb {C} ^{n},-)$ where $-$ is the component-wise subtraction of n-tuples. Of course, there are many more examples of such spaces, also infinite-dimensional ones. For example, given a complex vector space $V$, any nonzero linear functional $l\colon V\to \mathbb {C}$ and any complex number $c\in \mathbb {C}$ define a complex affine space $(l^{-1}(c),l^{-1}(0),-)$ with $-$ as vector subtraction.
• That being said, the bulk of the current article Complex affine space is not specific to complex affine spaces but applies to affine spaces over any field (just replace $\mathbb {C}$ by $F$). The article should focus on the special properties of complex affine spaces as defined.

Best wishes, --Quartl (talk) 14:33, 22 October 2015 (UTC)

No objections here. But there is a certain party that seems to believe that a "complex affine space" refers to something that is very different from an affine space that is complex. This party instead believed that a "complex affine space" was defined to be the space of n-tuples of complex numbers, together with n canonically-defined coordinate functions, and a hermitian structure. The reason the current article dwells on affine spaces in general is because this party did not seem to believe that a complex affine space is just an affine space that is complex, and insisted on [this revision as encompassing the "standard" definition of "complex affine space". I'm pretty sure that definition bears very little resemblance to what you've just given (which I would call the standard definition of "complex affine space" as the term would be understood by virtually all practising mathematicians with even a passing familiarity with geometry). Sławomir
Biały 15:36, 22 October 2015 (UTC)

I agree with Biały and others. However there is more to say. From the discussion in Talk:complex affine space, it appears that Taku's concern is about the notion of affine space in algebraic geometry. This discussion appears here because the complexes are an algebraically closed and some people (it seems that Taku is among them) believe wrongly that only algebraic geometry over algebraically closed fields is interesting. Thus the question is "what is an affine space in algebraic geometry?", and this discussion concern also Affine space (algebraic geometry) (an article that has no talk page).

It appears from the whole discussion in Talk:complex affine space that Taku has two theses that are both OR. The first thesis appears explicitly in taku's posts. It is that "affine space" has not the same meaning in algebraic geometry and in usual geometry. IMO this is wrong and the article Affine space (algebraic geometry) should be merged into a section "In algebraic geometry" of Affine space.

The second thesis, less explicit, but rather clear, is that algebraic geometry is scheme theory, and that everything in algebraic geometry must be rewritten in terms of schemes. Corollary: he has edited Affine space (algebraic geometry) for inserting there an OR definition of an affine space in terms of schemes. Unfortunately for him, he forgot that affine spaces have much less automorphisms as affine spaces than as algebraic varieties. This confusion led him to write that every variety that is isomorphic to an affine space is an affine space. In simpler words, a parabola is a line, because they are isomorphic as algebraic varieties! This opinion that algebraic geometry is scheme theory is not only error prone as in this example; it is also the cause that many articles of algebraic geometry are unnecessary too technical. D.Lazard (talk) 21:08, 22 October 2015 (UTC)

Issues with the math notation software

$a\equiv 5{\bmod {3}}\,$

$a\operatorname {giraffe} b\,$

$a\operatorname {giraffe} (b)\,$

$a{\mathbin {??}}b\,$

\operatorname{giraffe} seems to be functioning properly, including a bit of space to the left and right in its first occurrence above and to the left in its second. I seem to recall the spacing was formerly not working correctly.

However, the first line above uses \bmod, which should behave like a binary operation symbol. These behave as follows:

$3+5\,$

$+5\,$

The point is there is some space to the left and right when "+" is used as a binary operator and no such space to the right when it's used as a unary operator as in "+5". \bmod doesn't seem to have proper spacing.

The line with the two question marks is coded as follows:

a \mathbin{??} b \,

Since \mathbin is supposed to make something behave like a binary operation symbol, there should be spacing, as in 3 + 5. That's not working.

Who attends to bugs in this kind of thing? Would such a person be reading this page? Or should I go straight to bugzilla? Michael Hardy (talk) 19:14, 25 October 2015 (UTC)

Probably straight to https://phabricator.wikimedia.org/ — I don't think the devs normally follow this page. But there appears to be more than one bug here. Your bmod example has no spacing around the mod in the default "PNG images" rendering mode for math, but looks ok when I change to "MathML with SVG or PNG fallback" (which I think uses the SVG fallback for me since I'm using Chrome). Your ?? example has no spacing around the ?? for both rendering modes. I verified that the actual LaTeX rendering of this example does put spaces around it. Incidentally, there is something wrong with \mathrel, too.

a+b — $a+b$

a\mathbin{+}b — $a{\mathbin {+}}b$

a\mathrel{+}b — $a{\mathrel {+}}b$

In LaTeX, these three look almost the same, but the mathrel one has very subtly wider spacing. Here (with the SVG fallback view) the ones with the explicit mathbin and mathrel have no spacing. —David Eppstein (talk) 19:46, 25 October 2015 (UTC)

Are we collecting misbehaviors of the WP math rendering system anywhere? Because here's another one. The input

\frac{1}{4} \left\lfloor\frac{n}{2}\right\rfloor\left\lfloor\frac{n-1}{2}\right\rfloor\left\lfloor\frac{n-2}{2}\right\rfloor\left\lfloor\frac{n-3}{2}\right\rfloor,

produces

${\frac {1}{4}}\left\lfloor {\frac {n}{2}}\right\rfloor \left\lfloor {\frac {n-1}{2}}\right\rfloor \left\lfloor {\frac {n-2}{2}}\right\rfloor \left\lfloor {\frac {n-3}{2}}\right\rfloor ,$

in which (in my viewing, using SVG fallback in Chrome) the first fraction's floor brackets are much smaller than the other ones. They are all the same size in LaTeX, or in the default bitmap view, or for that matter on other sites that use MathJax for their rendering. The workaround in this case is to use explicit sizing \biggl and \biggr instead of \left and \right. —David Eppstein (talk) 05:30, 26 October 2015 (UTC)

suggested move gradian -> gon (angle)

I submitted an page move request for renaming gradian to Gon (angle) or Gon (angle measurement)), gon is the ISO unit (ISO 80000-3#Units of angle. Join the discussion at Talk:Gradian#Requested move 27 October 2015. I don't really care anyway, but it is a bit do we adhere to ISO standards. WillemienH (talk) 08:36, 27 October 2015 (UTC)

Comment on Draft:Geometric set

Your comments on Draft:Geometric set are welcomed. Please use Preferences → Gadgets → Yet Another AFC Helper Script, or use {{afc comment|your comment here}} directly in the draft. -- Sam Sailor ^Talk! 11:12, 27 October 2015 (UTC)

Binomial

Please, look at, and comment the requested move at Talk:Binomial (polynomial)‎‎#Requested move 27 October 2015 — D.Lazard (talk) 14:42, 27 October 2015 (UTC)

Depressing a polynomial article

Do people think that there is enough information available and/or enough notability(?) to have an article on Depressing a polynomial?— Preceding unsigned comment added by ‎Naraht (talk • contribs)

As "depressing a polynomial" is commonly called Tschirnhaus transformation (although there are other Tschirnhaus transformations), it would be better to expand Tschirnhaus transformation to include this and to create only a redirect. D.Lazard (talk) 20:05, 27 October 2015 (UTC)

I add my vote that this is an article worth expanding. It is not very useful in its present form. Sławomir
Biały 23:34, 27 October 2015 (UTC)

Also, I note the mathematical definition in Wiktionary is incorrect...Naraht (talk) 02:11, 28 October 2015 (UTC)

Created new article - British statistician Roger Thatcher

I've created a new article on the British statistician Roger Thatcher.

Additional input for further research collaboration and secondary sources would be appreciated at the article's talk page, at Talk:Roger Thatcher.

Thank you,

— Cirt (talk) 05:12, 30 October 2015 (UTC)

Comment on draft at User:Mjirina/sandbox

Your comments on User:Mjirina/sandbox are welcomed. Please use Preferences → Gadgets → Yet Another AFC Helper Script, or use {{afc comment|your comment here}} directly in the draft. -- Sam Sailor ^Talk! 09:10, 29 October 2015 (UTC)

Tagged for speedy deletion as a copyright violation. —David Eppstein (talk) 05:49, 30 October 2015 (UTC)

problem with the math-rating template ?

I noticed that when in the math rating template Template:Maths rating I follow the link generated by the field=basic part I get forwarded to the (almost) empty page Wikipedia:WikiProject Mathematics/Wikipedia 1.0/Basics cI am not sure where to link it to Wikipedia:WikiProject Mathematics/Wikipedia 1.0/Fields or Wikipedia:WikiProject Mathematics/Wikipedia 1.0/Fields#basic seem good candidates , or maybe we could add more content to Wikipedia:WikiProject Mathematics/Wikipedia 1.0/Basics any ideas on this? (lets first discuss this before we get edit wars about it, although I would not even know how to edit this complicated template) WillemienH (talk) 12:30, 31 October 2015 (UTC)

A link to Category:Mathematics articles related to basic mathematics might be useful.--Salix alba (talk): 14:37, 31 October 2015 (UTC)