Wikipedia talk:WikiProject Mathematics

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Can someone create a very simple graph in Maple?

It was pointed out to me that the graph File:Champernowne_constant_logscale.svg used in Champernowne constant has a mistake: the dots corresponding to the 41-st digit is out of place (it should be at height 10^{2504}. Not sure how that happened! :/ Anyway, at the moment I don't have access to Maple, so it would be nice if someone could re-do the graph (the code should be just a couple of lines, one could also take the data from here). Notice that being the misplaced point much bigger than in the graph, this means that the graph is going to be really flat, I guess it's OK, but another option is to leave that point out of the graph (mentioning it in the caption), or to go for a double logarithmic scale.--Sandrobt (talk) 23:12, 10 May 2016 (UTC)

Chow group and Chow ring

We have a new article titled Chow group of a stack. In the first sentence, it links to Chow group, which redirects to Chow ring. Should it be left that way, or should Chow group perhaps be a disambiguation page, or should we leave Chow group intact as a redirect while also putting a hatnote atop Chow ring telling the reader that Chow group of a stack exists, or should something else be done? Michael Hardy (talk) 20:20, 14 May 2016 (UTC)

I've been thinking this awhile: I think we should rename Chow ring to Chow group. Given the materials there, the latter name looks more appropriate. -- Taku (talk) 21:45, 14 May 2016 (UTC)

Based on your comments I'd have gone ahead and clicked on the "move" button but for this: The first sentence and maybe somewhat more of the first paragraph should get somewhat rephrased if the name is to be changed. Michael Hardy (talk) 23:18, 14 May 2016 (UTC)

The move and the necessary rewriting of the intro have been done by User:Ozob. Thanks! -- Taku (talk) 02:13, 16 May 2016 (UTC)

(To give context for the new article, given an algebraic variety/scheme X, you can define its Chow group of X, which is like homology but uses rational equivalence. If X is smooth, you can define multiplication (intersection product), giving it a ring structure and the result is called the Chow ring of X. It is probably not too important whether th article is called Chow group or Chow ring, since they are the same in the smooth context. Now, you want to extend the definition to stacks, which is straightforward over Q at least for Deligne–Mumford stack but becomes more tricky in general; i.e., one should probably not define it as simply the group of the rational equivalence classes. It is known that a DM stack with the resolution property is an (essentially) global quotient stack and so one can (in fact should ?) use equivariant Chow group in such a case. Given this background, I thought it makes sense to have a separate article, since this type of technicalities would be distracting.) -- Taku (talk) 21:52, 14 May 2016 (UTC)

I agree that Chow group is a better name. One defines individual Chow groups first (the definition is quite elementary), and then, with effort, one shows that there is a ring structure (the intersection product; depending upon how generally one wants this to be defined, this is either fairly simple or quite involved).

Oddly enough, the article mostly omits the relation to motivic cohomology, and Bloch's higher Chow groups aren't mentioned at all. That's quite a gap. Ozob (talk) 01:28, 15 May 2016 (UTC)

I've moved the page to Chow group. Ozob (talk) 18:38, 15 May 2016 (UTC)

(See above). If I'm reading the same article, I think it mentions both motivic cohomology and higher Chow group; I think the POV adopted there is that higher Chow groups are special cases of motivic homology; I don't know "how valid" this idea is. Is really so in the non-smooth cases for instance? Maybe "philosophically true"? (smooth is needed to compare with motivic cohomology). What I want for my Chrismas is motivic homology of a stack, but maybe that's too much :) -- Taku (talk) 02:13, 16 May 2016 (UTC)

(Can't stop thinking) If I remember correctly, the main difference between Bloch's higher Chow group and motivic homology is that the former relies on Bloch's moving lemma (which was controversial initially) and the latter doesn't (it uses a sheaf with transfer.) Maybe this stuff is only of historical nature. -- Taku (talk) 06:03, 16 May 2016 (UTC)

The relevant question is not how the two constructions are performed, but what they're trying to accomplish. It is generally agreed that there is a universal cohomology theory, namely the category of mixed motives. Cohomology in this category, known as motivic cohomology, is a powerful invariant. While there are several definitions of categories of mixed motives in the literature, none of them have yet been proven to behave entirely as expected. Motivic cohomology, on the other hand, has had usable foundations since Bloch. It was well-known to experts that the weight-graded pieces of algebraic K-theory captured the rational part of the motivic cohomology groups, but that's not quite the same. Bloch's groups simply worked. Bloch's construction yielded, for varieties smooth and quasi-projective over a ground field, the true motivic cohomology groups.

But they were not a panacea. If pressed for specifics, however, experts will admit that just as in the topological case, in general one has to distinguish between homology and cohomology and between compact supports and not; and in order to study the relative situation (a family of varieties over P¹ or a variety over Spec Z) one actually wants a derived category and the usual six operations. Bloch's groups did not do any of this. Voevodsky's derived category of mixed motives comes much closer. Voevodsky constructed a triangulated category in which one can find homology and cohomology with and without compact supports. If I recall correctly, at least in some cases this triangulated category is known to admit the six operations. So it is an enormous technical improvement on what Bloch did, though it came at the cost of introducing additional technique from homotopy theory. Nevertheless, it is still trying to capture the same information; despite all the new ideas, it's still aimed at the same purpose. And Bloch's definitions are still useful (even if one is willing to simply treat Voevodsky's theory as a black box) because they can be used to make direct geometric computations in some situations, whereas in Voevodsky's setup everything is defined indirectly. Ozob (talk) 13:04, 16 May 2016 (UTC)

Mathematicians biographies on the drafts name space

Is there any that should be moved to the main space? Grogamoco (talk) 12:31, 15 May 2016 (UTC)

I do not know about that, but I suggest that Draft:Niggonometry be deleted as a probable hoax and intended to be offensive. JRSpriggs (talk) 14:28, 15 May 2016 (UTC)

Speedied. Cheers! bd2412 T 14:59, 15 May 2016 (UTC)

"Niggonometry" referred to "the well known 20th century mathematician CJH". When you clicked on it, you saw the article on the 19th-century English novelist Charles Dickens. If everything else in the article were not enough to conclude it's a hoax, look at that. Michael Hardy (talk) 18:17, 18 May 2016 (UTC)

Related to the same editor, is the new Fluctuation spectra (a) comprehensibly about an actual topic, and (b) not a copyvio. Sławomir Biały (talk) 23:24, 15 May 2016 (UTC)

In there I did see a draft for Boris Levin. I recognized the name as that of a well-known Soviet functional analyst. I added some references to the draft, then it was re-reviewed and moved to main-space. Nsk92 (talk) 16:09, 15 May 2016 (UTC)

What about Draft:Spyros Alexakis? He has won a respectable prize (at least I think it is), but Google Scholar citations count is very low. 187.107.38.174 (talk) 18:06, 15 May 2016 (UTC)

Actually, citations count is not so low, it's just that Google Scholar did not find some of his papers the way I made the search the first time... But, still, by citation count alone it can't be accepted, but maybe because of the prize it can. I don't know. 187.107.38.174 (talk) 18:14, 15 May 2016 (UTC)

Classical decomposition at AFD

• Additive state decomposition (AfD discussion)

You might want to weigh in on what to do, here. Uncle G (talk) 21:09, 15 May 2016 (UTC)

This article is a complete orphan, i.e. no other pages link to it. Michael Hardy (talk) 18:23, 18 May 2016 (UTC)

List of Laplace transforms

The article List of Laplace transforms was recently forked out of Laplace transform. Is this really necessary and helpful to likely readers of Laplace transform? Please comment at Talk:Laplace transform#List of Laplace transforms. Sławomir Biały (talk) 12:40, 17 May 2016 (UTC)

Function theory

The page titled function theory redirected to function (mathematics). I had followed a link to that name from a new biographical article on a mathematician, in which I suspected the term has the first sense listed below. So I changed it to a disambiguation page, as follows:

See:

• Complex analysis, the study of holomorphic functions of a complex variable. Especially in works written during the 19th century and the first half of the 20th century, the term function theory often has this sense.
• Function (mathematics)

This disambiguation page lists mathematics articles associated with the same title.

Quite possibly this could benefit from more eyeballs. Michael Hardy (talk) 17:44, 18 May 2016 (UTC)

Milne-Thompson method for finding an analytic function

If anyone knows anything about the Milne-Thompson method for finding an analytic function, such as (1) whether the article ought to exist, or (2) what more it should say, or (3) references to cite, etc., then there it is. (I found it badly in need of copy-editing and did some of that, but probably more of that can be done.) Note: "Milne-Thompson" is a hyphenated name of one person, _not_ two names; hence it is properly a hyphen rather than an en-dash. Michael Hardy (talk) 19:06, 21 May 2016 (UTC)

I don't know the answers to your questions, but it's about holomorphic functions, not analytic ones, so I changed the title to Milne-Thompson method for finding a holomorphic function. Ozob (talk) 19:16, 21 May 2016 (UTC)

It seems that the correct spelling of the name is "Milne-Thomson", with no p, so I've moved the page (again) to Milne-Thomson method for finding a holomorphic function. Ozob (talk) 02:02, 22 May 2016 (UTC)

John von Neumann GA review

John von Neumann is being reviewed as a potential Good Article. Please participate in the review at Talk:John von Neumann/GA1. —David Eppstein (talk) 16:52, 25 May 2016 (UTC)

I nominated the article under Military History because we're the ones who polished the article to bring it to GA, as part of a broader effort on Manhattan Project people, and our project is a multi-disciplinary one. Assistance is welcome. Hawkeye7 (talk) 22:03, 25 May 2016 (UTC)

The article has now passed its GA review. If WP-Mathematics has an A class Review process, it can nominated. Hawkeye7 (talk) 22:25, 28 May 2016 (UTC)

I think the WPM A-class process is defunct. —David Eppstein (talk) 22:52, 28 May 2016 (UTC)

Oh. It has nowhere to go then. I could nominate it for A class at MilHist, but there doesn't seem much point. Hawkeye7 (talk) 01:11, 29 May 2016 (UTC)

Користувач:Перевод

Could someone who knows more about these things have a look at this? Obviously this title is incorrect... --Randykitty (talk) 10:49, 27 May 2016 (UTC)

"Differential geometry of curves" is meant. Boris Tsirelson (talk) 10:59, 27 May 2016 (UTC)

No, that is "Диференціальна геометрія кривих" that means "differential geometry of curves". By the way, looking on the history, it appears that the article is a (very bad) translation of the Russian WP article on the subject (probably an automatic translation). I have no idea of the meaning of the title. IMO this translation does not add anything useful to the content of Differential geometry of curves. Therefore, I suggest deletion. D.Lazard (talk) 11:12, 27 May 2016 (UTC)

(e/c) Differential geometry of curves already exists. There does not seem to be anything there that is not already covered in our existing article, apart from some material on curvature which is already covered in the curvature article. Moreover, the mistitled article looks like the result of a bad machine translation. I don't think anyone would lose sleep if this article were just deleted. I will add a prod tag, but feel free to remove it as per the usual WP:PROD rules. Sławomir Biały (talk) 11:14, 27 May 2016 (UTC)

Matrix decomposition into clans

Is there any content worth saving in Matrix decomposition into clans? —David Eppstein (talk) 05:28, 28 May 2016 (UTC)

On one hand, the author talks of solving linear systems over rings and monoids. We have an article Linear equation over a ring that covers some of the basics. But rather than a general monoid, what the author really seems to be discussing is a solution technique for solving a system of linear Diophantine equations over nonnegative integers, nonnegative integers being a simple type of monoid. For this, we already have Diophantine equation#System of linear Diophantine equations. The section doesn't discuss the nonnegative constraint, but there exists other papers out there, such as [1], which treat this common case in integer programming. The author's papers, while interesting, don't seem to have generated any secondary commentary or citations. Hence this work is non-notable and I don't think it would be of due weight to include it in Diophantine equation#System of linear Diophantine equations. In short, no content worth saving. --Mark viking (talk) 18:40, 29 May 2016 (UTC)

Ok, thanks; I've prodded it. Another of the same editor's contributions, about another piece of research by the same author (who is likely the same person as the editor) is also prodded: see Zaitsev neighborhood. —David Eppstein (talk) 19:21, 29 May 2016 (UTC)

Garden of Eden (cellular automaton)

I'm having a disagreement with an anonymous editor over the preferred level of technicality and redundancy in the lead section and lead sentence of Garden of Eden (cellular automaton). Third opinions welcome; see article history for alternative versions and Talk:Garden of Eden (cellular automaton) for discussion. —David Eppstein (talk) 23:54, 29 May 2016 (UTC)

Advanced calculus

I occasionally see the phrase "advanced calculus". Sometimes it seems to mean introductory real analysis (e.g., sequences, continuity, what distinguishes the reals from the rationals) and sometimes it seems to mean topics in calculus that are usually introduced later rather than earlier in a sequence of calculus courses (e.g., trig substitution, multivariate calculus). Right now, Advanced calculus is a red link. What should we do with it? My first thought is to redirect it to Real analysis. —Kodiologist (t) 15:59, 30 May 2016 (UTC)

I think this terminology is more social than mathematical. I don't know in other countries, but here in Brazil, calculus courses are very different from analysis courses. In calculus one is more interested in the theorems and intuitions than in their rigorous algebraic, topological, number theoretic, etc... justifications. Maybe Advanced calculus could be a redirect to Calculus on manifolds? 189.6.194.219 (talk) 16:20, 30 May 2016 (UTC)