Wikipedia talk:WikiProject Mathematics/Archive/2019/Dec

Q-Gaussian (Second Opinion Needed)

Hello, I am an AfC reviewer and recently (some time ago) I denied Draft: Q-Gaussian due to an article on Q-Gaussian already existing. However, today, the editor who created the article posted on my talk page saying that the two deals with different subjects. So can someone who has familiarity with math/stats take a look at this and see if they do talk about different things? Thanks, Taewangkorea (talk) 17:22, 2 December 2019 (UTC)

@Taewangkorea: Based on the journal sources, the topic discussed in the draft seems to be more appropriately called "q-Gaussian process" or "q-deformation of the Gaussian distribution" (see for instance, 1, 2 3). — MarkH₂₁^talk 17:52, 2 December 2019 (UTC)

Naming is a mess in the q-analog space. We already have q-Gaussian distribution and Gaussian q-distribution; both of these are finite dimensional, so I'd favor "q-Gaussian process" as a good name indicating its multivariate infinitude. Beyond the name change, the draft looks to be in good shape. --{{u|Mark viking}} {Talk} 20:00, 2 December 2019 (UTC)

Can someone help me with my draft?

I am working on the draft Draft:Markov constant (Diophantine approximation). It was declined 10 days ago, and I changed (quite a lot of) wording. However, I asked something else at the Teahouse and the people still think my article is too technical. So can anyone kindly help me to improve my draft? 數神 (talk) 06:09, 2 December 2019 (UTC) Can anyone help me fix any issues (if there really are) and/or review it for me (if possible)? 數神 (talk) 06:16, 2 December 2019 (UTC)

It seems the issue is more of "context" than "technical"; it's ok to cover a technical topic in Wikipedia but it is not ok to assume the context of the topic is immediately clear to every single reader of Wikipedia. "In Diophantine approximation theory," is not a good way to establish the context; thus, I have changed to "In number theory, specifically in Diophantine...". With this change, I think the draft can be moved to mainspace. -- Taku (talk) 07:49, 2 December 2019 (UTC)

Unless there is an objection, I will be moving it to mainspace within the next 24 hours. -- Taku (talk) 08:22, 2 December 2019 (UTC)

It's already been submitted for review. You should wait for the review and/or discuss with AngusWOOF, who was the reviewer for the last failed submissions, and see if they have any further input. — MarkH₂₁^talk 08:28, 2 December 2019 (UTC)

Ok. I will wait then. -- Taku (talk) 09:04, 2 December 2019 (UTC)

Thanks for your advice. 數神 (talk) 10:17, 2 December 2019 (UTC)

Taku, is it good to go from a technical standpoint? AngusWOOF (bark • sniff) 17:14, 2 December 2019 (UTC)

@AngusWOOF: Not a number theorist, but it looked appropriate to me as far as technical validity is concerned. --JBL (talk) 20:26, 2 December 2019 (UTC)

Thanks, I moved it to mainspace as Markov constant. Please help fill in its WP box on talk. AngusWOOF (bark • sniff) 20:29, 2 December 2019 (UTC)

Proposed merger of Fraïssé's theorem and Age (model theory)

Hi all, @Zaunlen: and I are proposing to merge the articles Fraïssé's theorem and Age (model theory) into one, due to their similar scope, brevity and overlap in content. We'd appreciate any participation in the discussion here. Cheers, --Jordan Mitchell Barrett (talk) 05:22, 3 December 2019 (UTC)

Beginner unsure of how to proceed

I am interested in writing an article on Mirror Descent, but I have never written or edited an article on wikipedia before. I have a draft of the article on my personal machine. Additionally I am unsure whether or not this material is better suited to the computer science wikiproject, since this is my background. I'm a little overwhelmed & I would appreciate any advice or pointers to resources. What is the typical pipeline for joining and participating in established wikiprojects - i.e. this one or one of the CS ones. Should I copy my draft into my sandbox and ask for reviewers before publishing? Thanks - Orange3xchicken (talk) 18:38, 4 December 2019 (UTC)

Hello and welcome, Orange3xchicken! Participation in WikiProjects is a very informal process: Anyone can post a comment on the talk page for one, without having to put your name on a list or anything like that. In order to get a feel for how Wikipedia editing works, I recommend making contributions to existing pages first. That way, you can grow comfortable with editing before tackling something big. But if you have a draft already written, you're welcome to copy it into your sandbox and ask for feedback here or at Wikipedia talk:WikiProject Computer science. For general advice, see Help:Your first article. XOR'easter (talk) 18:52, 4 December 2019 (UTC)

Welcome! There is by no means a formal requirement that you first put your draft in the sandbox. Feel free to directly edit the articles you want! Jakob.scholbach (talk) 19:38, 4 December 2019 (UTC)

Thank you everyone. I appreciate the pointers. - Orange3xchicken (talk) —Preceding undated comment added 20:30, 4 December 2019 (UTC)

Good luck and happy editing! XOR'easter (talk) 22:17, 4 December 2019 (UTC)

Separate article?

I want to know whether the section Proth prime of Proth number can become an independent article. I read the list for requested articles and the entry Payam number (in number theory) is just not notable enough; instead, it fits in such an article called “Proth prime”. The question is, is “Proth prime” notable itself? Please help me. I found a few sources on this in the original article, but JUST a few. Please help me. 數神, the Lord of Math (Prove me wrong; My contributions to the world in numbers) 10:55, 5 December 2019 (UTC)

• Personally, I think that Proth prime should not be made into a new article. It's not as though Proth number is a long article that would require sections to be spun out. And, since the Proth primes are a subset of the Proth numbers it also makes organisational sense to describe them in a subsection of the parent article. Reyk _YO! 11:01, 5 December 2019 (UTC)
  • The thing is, there are more things about Proth primes besides those listed in the article. Proth numbers aren't of that great importance by itself; Proth primes are (in my opinion) more significant than Proth numbers. How about I write up a draft and let someone have a look? 數神, the Lord of Math (Prove me wrong; My contributions to the world in numbers) 14:19, 5 December 2019 (UTC)
    • There is clearly not enough content to merit two articles. If you think the primes are the important ones, follow the Mersenne model, where Mersenne numbers is a redirect to Mersenne prime. --JBL (talk) 17:54, 5 December 2019 (UTC)

Well- I'm just gonna write it up first. The current content in the Proth number article is certainly not enough. But Proth primes have something related to it, and should be included as its subsections, and (I think) it will look strange if I put them in the entry Proth number. So how about I write it up first, and someone decide to see if it can be merged or an independent article. 數神, the Lord of Math (Prove me wrong; My contributions to the world in numbers) 23:56, 5 December 2019 (UTC)

Absolutely. Once the content is written it will be easier to decide whether to treat the Proth primes as a subset of Proth numbers, or Proth numbers as a superset of the more important primes. Reyk _YO! 08:59, 6 December 2019 (UTC)

Reyk The draft is completed. Would you like to have a look? If it is accepted, would you also indicate if the article Proth numbers should become a redirect to Draft:Proth prime (after necessary minor modifications). 數神, the Lord of Math (Prove me wrong; My contributions to the world in numbers) 11:06, 6 December 2019 (UTC)

I have gone ahead and merged what remained in the pointless article Proth number into Proth prime. Someone who understands how attribution works on Wikipedia should consider whether anything important has been lost in this process: much of the content that is now at Proth prime was copied directly from the last version of Proth number. --JBL (talk) 21:19, 7 December 2019 (UTC)

I think the {{R from merge}} tag already in place is sufficient. —David Eppstein (talk) 21:27, 7 December 2019 (UTC)

{{R from merge}} is at the source. Attribution is required at the target where people see the copied content. I have made a dummy edit [1] with attribution per Wikipedia:Copying within Wikipedia. @數神: Please make such edit summaries when you copy content, also when it's to a draft. PrimeHunter (talk) 22:57, 7 December 2019 (UTC)

Probability

Our article titled Probability begins with this:

Probability is a measure quantifying the likelihood that events will occur.

That's a really bad opening sentence. Probably I'll come back to it soon, but maybe others can improve this before that. Michael Hardy (talk) 17:31, 5 December 2019 (UTC)

I looked up some google book references here, here, and here, and all of agreed in some form or another. They either said probability was hard to define or skipped straight to mathematical definitions, and they defined probability as (respectively):

1."the proportion (or percentage) of favorable possibilities

2. a measure where the measure of the entire set of outcomes is 1

3. "the probability P(A) of the event A is defined as the fraction of outcomes in which A occurs"

None of these are especially nice for opening sentences. Maybe we could do something like this:

Probability is a numerical way of describing how common or likely a given event is.

or

Probability is a numerical way of describing how common or likely a given event is out of all possible outcomes.

or

The probability of an event is the proportion of all possible outcomes in which that event occurs.

or

Probability is a number describing how often an event occurs. More specifically, given a group of possible outcomes, the probability of an event is the proportion of outcomes where that event occurs.

I'm not really attached to any of these, but I thought I'd put in my 2 cents.Brirush (talk) 21:11, 5 December 2019 (UTC)

All these suggestions are too technical. I suggest to simply add "intuitively" at the beginning, that is Intuitively, probability is a measure quantifying the likelihood that events will occur. D.Lazard (talk) 21:31, 5 December 2019 (UTC)

Moreover, two interpretations of probability are described in that article, while phrases of Brirush support only the first of them; and Lazard's phrase supports both. (I do not like the second, but the fact is that many others do.) Boris Tsirelson (talk) 22:26, 5 December 2019 (UTC)

I think the problem is that likelihood has a technical meaning, which we don't want to invoke here. Better would be ...how likely it is that.... --Trovatore (talk) 22:34, 5 December 2019 (UTC)

I concur with Trovatore's point: "how likely it is that" is better here than "likelihood". XOR'easter (talk) 00:04, 6 December 2019 (UTC)

On reflection, the future tense is also a bit problematic here. At least from some points of view, it's meaningful to speak of the probability of events in the past, if you don't know which one actually happened. Maybe just present-tense "how likely it is that events occur", which can be read as time-neutral. --Trovatore (talk) 00:15, 6 December 2019 (UTC)

I do not think "intuitively" is correct at all. I quite liked Brirush's first version Probability is a numerical way of describing how common or likely a given event is. (I do not understand how this is supposed to be more technical than what exists, nor why it does not cover both senses of probability in the article.) --JBL (talk) 01:39, 6 December 2019 (UTC)

I agree, with minor modification to Probability is a numerical description of how common or likely a given event is. — MarkH₂₁^talk 03:13, 6 December 2019 (UTC)

Nice. Boris Tsirelson (talk) 09:35, 6 December 2019 (UTC)

I like that idea, too. What about Probability is a numerical description of how common, likely or plausible a given event is? XOR'easter (talk) 15:00, 6 December 2019 (UTC)

I don't think I'd start with "common", actually. In fact I might leave it out altogether. --Trovatore (talk) 19:12, 6 December 2019 (UTC)

... because ... ? -JBL (talk) 19:23, 6 December 2019 (UTC)

Well, basically because it's wrong. "Common" sounds like a measure from descriptive statistics, not from probability. Like saying a certain thing happened 5 times out of 10 trials; therefore its probability is by definition 50%. That's so obviously incorrect that I could only see it as a strawman version of frequentism by someone trying to refute it in a not-very-sophisticated way. I'm not a frequentist, but I think frequentism has to be more nuanced than that, or no one would accept it at all. --Trovatore (talk) 21:32, 6 December 2019 (UTC)

So you don't think it's correct to say that probability is the right language to answer the question, ``How common are straight flushes in poker?" That seems ... idiosyncratic. Not as much as JRSpriggs' suggestion below that the first sentence of the article should be ``Probability is an undefinable primitive that cannot be explained in terms of any simpler concepts" (I joke, I joke) but still. (Anyone is welcome to respond to this, but I should be clear that Probability is not even on my watchlist and I'm not planning in getting involved in any discussion about this that takes place on its talk page.) --JBL (talk) 21:42, 6 December 2019 (UTC)

If I'm taking the word "common" literally, no, I don't think probability is the right answer to that question. How "common" they are can be answered only by looking at all the poker hands in the world (or maybe in a time interval under discussion) as they actually occurred, and seeing what fraction of them were straight flushes. That's a different question from asking the probability that an individual hand will be a straight flush. --Trovatore (talk) 19:49, 7 December 2019 (UTC)

I think probability is an undefinable primitive. You may be able to give people an idea of what it is by examples, but it cannot be explained by any simpler concepts. If that is not sufficiently apparent from the attempts to define it classically, then consider that to be strictly correct one would need to define it in a quantum mechanical way as something like the trace of the product of the probability density matrix of the observer and a projection matrix representing the event in question. But then what are these things? No one knows. We can only postulate their existence. JRSpriggs (talk) 20:33, 6 December 2019 (UTC)

A point is an undefinable primitive in elementary geometry, but you could not say so to children on the first geometry class. Boris Tsirelson (talk) 21:46, 6 December 2019 (UTC)

The definitions that speak of how common or frequent an event is ignore things like "The probability that the mass of the planet Saturn is between [this amount] and [this amount] is 0.85." That is a different way of using the mathematics of probability than the one that says the probability of getting a "1" when a "fair" die is thrown is 1/6. The question of when to use which point of view involves things other than mathematics, including the problem of inductive scientific inference. Michael Hardy (talk) 18:33, 8 December 2019 (UTC)

Then, "frequent or likely"? Boris Tsirelson (talk) 19:53, 8 December 2019 (UTC)

Michael Hardy's point is more or less why I suggested adding "plausible" to the mix. I'm not committed to that choice of term, though I do think we need something like it there. XOR'easter (talk) 20:37, 8 December 2019 (UTC)

Honestly I think the best word is "likely", all by itself. I don't think frequentists should have anything to object to here. They may have a different understanding of what "likely" means than Bayesians or other schools do, but they should still agree that probability quantifies how likely something is, as should everyone else.

The elaborations like "common" or "frequent" or "plausible" can be handled lower down, as a lead-in to interpretations. --Trovatore (talk) 00:07, 9 December 2019 (UTC)

Change an article's name?

First off, I'm sorry if this isn't the correct place to ask this. I haven't contributed to Wikipedia yet except for the most minor of changes. Here is my problem:

In all sources cited in the article Natural number object, this concept is called a natural numbers object (which also makes more sense, since the object is not meant to represent a natural number in an arbitrary category, but the set of natural numbers itself). Still the article coherently uses the variation of the name lacking the plural. Of course one can change every instance of this in the text itself, but would it be possible to change the name of the article to the correct spelling? — Preceding unsigned comment added by Gnampfissimo (talk • contribs) 16:23, 9 December 2019 (UTC)

@Gnampfissimo: I was about to tell you to just go ahead and move the page yourself (see H:MOVE for instructions), when I realized you're not auto-confirmed yet, so it won't let you. I've gone ahead and done the move and will let you take care of updating the text in the article if you wish. –Deacon Vorbis (carbon • videos) 16:46, 9 December 2019 (UTC)

Should the pi symbol be italicized?

Perhaps this is a perennial discussion here, but if someone in the know could weigh in regarding this template editing request, I would be grateful. – Jonesey95 (talk) 17:20, 9 December 2019 (UTC)

Hypersphere and n-sphere

Is there a meaningful distinction between the subjects of these two articles? --JBL (talk) 16:14, 7 December 2019 (UTC)

It seems that at Hypersphere, it's making the point that a hypersphere refers to the specific codimension-one embedding of a sphere rather than to the sphere itself, but I don't know how standard this distinction via terminology is. Most of the material at N-sphere is already treating this context, such as discussion of the volume, etc. So I guess the question is: do we want separate articles for properties that are dependent on the specific embedding versus those that aren't? Meh, I lean toward not, but I can see the argument for doing so I guess. –Deacon Vorbis (carbon • videos) 16:40, 7 December 2019 (UTC)

I agree. A hypersphere is a specific embedding (or example) of an n-sphere. The Hypersphere article has almost no content of value. The content, that it does have, can easily be merged into n-sphere. That plan would get my vote. Mgnbar (talk) 17:10, 7 December 2019 (UTC)

Ok, I will put it on my to-do list (if no one else gets there first). --JBL (talk) 03:11, 10 December 2019 (UTC)

Rash of wikilinks to mathematics

I have noticed a bunch of edits to niche mathematical articles from IPv6 addresses, presumably the same editor. The edits are mostly adding wikilinks, and a lot of them seem reasonable. What I'm a bit concerned about is that many of them add a wikilink to mathematics in the lead sentence.

My view, which of course others may have their own opinions about, is that it is inappropriate to link extremely general articles from extremely technical, specific ones. Links in an early sentence giving context should go "one level up" in generality, not all the way to the root article for the field. My rationale is that an editor who has arrived of her own volition at a highly technical mathematical article already knows that it's about mathematics, and is unlikely at that point to want to read our most general article on math.

The IPv6 addresses keep changing, and I doubt that an editor doing this sort of general gnomery goes back to check the subsequent history of the article, so I have no reliable way to contact the editor to express my concern.

Suggestions welcome. --Trovatore (talk) 19:56, 12 December 2019 (UTC)

I think they should all be reverted. Mathematics is a commonly understood term of the kind described in WP:OVERLINKING. —David Eppstein (talk) 20:03, 12 December 2019 (UTC)

While I appreciate their enthusiasm for gnoming, I agree, this is a clear case of overlinking of a commonly understood term--everyone with the education needed to read Wikipedia articles is going to know what mathematics is. Revert them. I am less sure on how to reach out to the editor. I have posted notices on IP talk pages before, but have no evidence that they were ever read. --{{u|Mark viking}} {Talk} 20:12, 12 December 2019 (UTC)

GraphBLAS Article - Review and Improvements Requested

Hello WikiProject Mathematics! I'm one of the authors of the draft article on GraphBLAS. It's akin to the BLAS, but for graph algorithms and operations in the language of linear algebra. It's been stuck in the review queue for a while, so I was wondering if I could recruit some help in 1) Improving the article and/or 2) Getting it approved and out of draft. Thank you so much for your help! --ScottKolo (talk) 21:11, 13 December 2019 (UTC)

Matrix multipliction, German Wikipedia and Manual of Style

Members of this WikiProject may be interesed in what I have posted at Talk:Matrix multiplication#German article and Manual of Style.

The short version is that I think that the article could be greatly improved by looking at the German Wikipedia and MOS:MATH.

I suspect this may also be true of many other maths articles.

Yaris678 (talk) 22:12, 15 December 2019 (UTC)

Update: merger of Age (model theory) and Fraïssé's theorem

I didn't get any feedback on the merger, so I went ahead and created the merged article as a draft, and submitted it for review. Please find the new article at Draft:Fraïssé limit. --Jordan Mitchell Barrett (talk) 23:04, 15 December 2019 (UTC)

Apeirogon

"In geometry, an apeirogon ... is a generalized polygon with a countably infinite number of sides.[1] It can be considered as the limit of an n-sided polygon as n approaches infinity. The interior of a linear apeirogon can be defined by a direction order of vertices, and defining half the plane as the interior." (Apeirogon, the lead). Do you understand this? I do not. Does it mean that apeirogon is a polygon whose number of sides is the apeironumber? Should this number be mentioned in the "Infinity" article? Boris Tsirelson (talk) 06:16, 19 December 2019 (UTC)

I think this means that you pick an ordering of the vertices “in a direction” (and probably assuming that there is no local max/min in the ordering along the line, i.e. if one adjacent vertex is larger then the other is smaller). This would divide the plane that these points implicitly lie on. Pick one of the halves to be the interior. The number of sides is always $\aleph _{0}$. — MarkH₂₁^talk 06:35, 19 December 2019 (UTC)

Maybe. But then I bother about List of two-dimensional geometric shapes#Polygons with specific numbers of sides; there the last item (added recently) is: "Apeirogon - (as close as possible to) infinite sides". Boris Tsirelson (talk) 06:43, 19 December 2019 (UTC)

Our polygon/polyhedra/polytope articles are riddled by original research, sloppy definitions, big galleries of not-very-relevant images, bad sourcing, and big repeated chunks of off-topic general-purpose text masking the lack of material specific to each individual example, and I think this article is part of that pattern. Occasionally I try taking a machete to some of them but they keep growing back. In any case, it should not be our task to try to work out for ourselves a way of making sense of this material. It should be backed up by reliable sources (and by reliable I include the requirement that they make sense mathematically, and are not just equally-sloppy picturebooks of pretty tessellations) or it should be cut. —David Eppstein (talk) 07:04, 19 December 2019 (UTC)

Hmmm. I'd say, the problem is, a mixture of mathematics and recreational mathematics (namely, recreational geometry). Being a general-purpose (rather than mathematical) encyclopedia we probably must reflect both; and I doubt that they are well-separated (in the sources, I mean). Boris Tsirelson (talk) 07:20, 19 December 2019 (UTC)

Taking a look at the sources, some of these don't even mention the topic or just mention them in passing.

• Grunbaum's article only said regular polygons in the Euclidean 3-space E³ are of one of the following types: (i) convex polygons; (ii) star polygons; (iii) the apeirogon; (iv) zig-zag polygons; (v) skew polygons (prismatic and antiprismatic) (vi) helical polygons.
• Coxeter's book Regular polytopes mentions them once; p.45 says: If S is a translation we have the limiting case where p becomes infinite: a sequence of equal segments of one line, the apeirogon (here S is a group acting on a point).
• Johnson's book Geometries and symmetries only mentions them once as well: A regular apeirogon is either a partition of the Euclidean line E¹ into infinitely many equal-length segments or an infinite polygon inscribed in a horocycle or in the absolute circle of the hyperbolic plane. A regular pseudogon is a partition of the hyperbolic line H¹ into segments of length 2λ.

So none of the given sources support almost any of the content in the article. A quick search for articles also suggests that there is very little published mathematical literature on the subject beyond the basic definition given in the three passages above. — MarkH₂₁^talk 08:23, 19 December 2019 (UTC)

I've cleaned up the article using actual sources; it seems that Skew apeirogon is similarly problematic (besides a lot of other recreational geometry articles). — MarkH₂₁^talk 08:51, 19 December 2019 (UTC)

I see; nice. I also changed "List of two-dimensional geometric shapes" accordingly. Just by the way, one more source: Wolfram. Boris Tsirelson (talk) 10:01, 19 December 2019 (UTC)

Thanks. Here's another related few articles if anyone can do some more cleaning up. It seems that none of the sources actually use "apeiro-" to describe these objects: Skew apeirohedron, Apeirogonal prism, Apeirogonal antiprism. All of the literature that I could find just use the word "polygon" or "infinite polygon" (or "polyhedra", etc.) instead. — MarkH₂₁^talk 11:55, 19 December 2019 (UTC)

Substing Pi template

For anyone interested, I'm proposing to subst: all current uses of {{Pi}}. Please see Template talk:Pi#Substing all uses for more information or if you have any comments. Thanks, –Deacon Vorbis (carbon • videos) 15:54, 19 December 2019 (UTC)

Recamán's sequence

In Recamán's sequence, the section on computational complexity says that it is $O(n^{2})$ and gives a reference. This is because the program uses an inefficient way to tell if a term has appeared before. Otherwise it is $O(n)$, but I don't have a reference for that. Does anyone know of a reference?

Secondly, how could 10²³⁰ terms be calculated? Bubba73 ^{You talkin' to me?} 01:25, 14 December 2019 (UTC)

It's worse than that. It says that it's $O(n^{2})$ per term, which would imply $O(n^{3})$ for the first $n$ terms. But it's very easy to get constant time per term (in expectation, in a model of computation allowing hashing) or $O(\log n)$ per term (using binary search trees if you don't like hashing). Probably even simpler would be to just use a bitvector but then for efficiency you'd need to prove that the sequence grows only linearly. I don't know a reference, unfortunately. —David Eppstein (talk) 01:32, 14 December 2019 (UTC)

David Eppstein, You can get $O(\log n)$ operations per term, but each operation takes $O(\log n)$ time, yielding $O((\log n)^{2})$ time per term. We still need a reference. — Arthur Rubin (talk) 16:44, 14 December 2019 (UTC)

Are you counting bit operations maybe? Or thinking about Turing machines? Because the standard model for algorithm analysis is the unit cost model RAM in which each operation takes O(1) time (there are no bignums here). Anyway, I agree, we need a reference. If I made a blog post about it I suppose it would count under the "recognized expert" clause of WP:SPS but that seems kind of sleazy. I'd rather find a real publication to refer to. —David Eppstein (talk) 17:56, 14 December 2019 (UTC)

In similar cases (of results that are easy to prove with standard mathematical knowledge, but for which I do not know any reliable reference), I use to provide a proof in a collapsed box. I know that this not follows formally WP:Verifiability, but, in mathematics, an explicit proof is often easier to verify than a link to a source that may contain a difficult-to-verify proof. Therefore, I think that such situations are cases for WP:IAR. Clearly, it is better to have also a citation, and a tag {{cn}} is recommended. D.Lazard (talk) 18:59, 14 December 2019 (UTC)

I was thinking that computational complexity makes little sense if we don't make bignums cost $O(\log n)$, certainly if we go up to 10²³⁰, but I'll defer to the literature. — Arthur Rubin (talk) 18:43, 15 December 2019 (UTC)

If we believe the 10²³⁰ result, it's obviously generating the sequence in sublinear time, so the time-per-item bounds are not relevant for it. For algorithms that generate one item at a time, bignums are not needed, as we cannot reasonably get past 2^64. —David Eppstein (talk) 18:50, 15 December 2019 (UTC)

I hadn't read the comments to the reference about complexity, but they discuss it in the comments. Bubba73 ^{You talkin' to me?} 19:12, 14 December 2019 (UTC)

My preference would be to just remove the section on complexity unless/until we have a published source on it. The worst case analysis discussed above doesn't really tell the whole story because the repetitive nature of the sequence suggests that the first $n$ terms can be computed (implicitly) in sublinear time, maybe ${\tilde {O}}({\sqrt {n}})$ if the remark about run-length encoding in the comments of https://mathlesstraveled.com/2016/06/12/the-recaman-sequence/ is to be believed. But this is all too tenuous to report as fact in a Wikipedia article. —David Eppstein (talk) 19:30, 14 December 2019 (UTC)

I see your point. However, big-O is an upper bound, so it is correct. It just isn't the best upper bound. Bubba73 ^{You talkin' to me?} 19:48, 14 December 2019 (UTC)

Well, but with that reasoning the $O(n^{2})$ per term bound of the current article is correct too. —David Eppstein (talk) 20:28, 14 December 2019 (UTC)

I made a blog post anyway, not because I have any intention of adding it to the article myself (I don't) but because I was curious: [2]. —David Eppstein (talk) 08:29, 20 December 2019 (UTC)

I am very puzzled seeing this discussion. What could it mean at all, to calculate 10²³⁰ terms of whatever? Say, just of the sequence 1,2,3,...? Am I very naive? It seems to me, to calculate something means at least to do some physical process (related to it). But all I know about our physical universe convince me that 10²³⁰ physical processes is beyond anything we can imagine (the more so, fulfill). Unless, of course, a quantum computation is meant... I assume it is not (otherwise I have other bunch of questions). Boris Tsirelson (talk) 11:30, 20 December 2019 (UTC) Consult Orders of magnitude (length), Orders of magnitude (time) and consider $\textstyle {\frac {(10^{27}\,\mathrm {m} )^{3}(10^{15}\,\mathrm {s} )}{(10^{-24}\,\mathrm {m} )^{3}(10^{-24}\,\mathrm {s} )}}=10^{192}\ll 10^{230}.$ Boris Tsirelson (talk) 19:21, 20 December 2019 (UTC)

I think the appropriate analogy is hashlife, which can compute the evolution of patterns in Conway's Game of Life for simple-enough patterns out to numbers of steps significantly larger than the number of machine instructions it uses to do so. It doesn't explicitly represent each step but it can tell you what the pattern looks like after 10²³⁰ steps (or however many). Similarly, here, to produce the plots linked on OEIS and to justify the claim that 852655 does not appear, we would need to be able to find values at specific points on the sequence (or at least to sample from its values) and to find the deep drops where it returns to already-covered ground and fills in gaps. The algorithm outlined at the end of my post, for instance, could do all that and would take time only proportional to the square root of the number of terms it generates. It could plausibly reach as many as 10²³ steps. But I don't see how to get that extra zero in the exponent, and I'm guessing it might be a typo. —David Eppstein (talk) 19:39, 20 December 2019 (UTC)

Ah, well. More generally, one can (sometimes) find a (finite, even short) proof of a claim about a lot (or even infinitely many) steps of a process. But such activity is usually not called "calculation of a lot (or even infinitely many) steps" (be the proof computer-assisted or not). Boris Tsirelson (talk) 20:09, 20 December 2019 (UTC)

Request for help at DYK

Hi, the article Semisimple representation is nominated at DYK for the main page, but reviewers are having difficulty verifying it because of a lot of advanced math in it. If anyone from this project could look over the article and weigh in here it would be really appreciated. Kingsif (talk) 17:18, 21 December 2019 (UTC)

How precisely

I posted the following at the Bertrand paradox (probability) article this morning, after finding what I believe to be a violation of one or more WP guidelines/policies. Because the observation fits a much broader pattern in the Wikiproject Maths area, where proofs, arguments, and other presentations routinely appear without source, I decided to present the same content here, to stimulate a broader (if ultimately futile) discussion. There, I wrote:

How precisely are the six unsourced distribution graphs and the unsourced closing paragraph of the "Bertrand's formulation of the problem" section not violations of WP:OR and WP:VERIFY? I understand, for the erudition of its members, that Wikiproject Mathematics is given great latitude. But is this not egregious, to ignore and present our own research on the matter (presuming we are not reproducing that of another, and so plagiarising)?

I would note in addition to the legalistic argument—that we are a confederation held together by a commonly agreed upon set of rules, and so only as strong, in the end, as we are willing to adhere to them—there is a very practical argument in favour of presentation from source rather than ones original research or formulation of an argument. It is, that original work is overly dependent on the author, and that at an encyclopedia managed on a volunteer basis, such a dependence is impractical. Every editor/reader query, "What was meant by... ?" is either managed by a trip to the source cited, or by a post-and-wait episode for the author (or their supporters) to reply to. The former is our way, the latter is not, and is an entirely impractical way for this encyclopedia to be maintained.

Following this with a request for an eventual reply. I ask the same here. Cheers, and happy holiday. 2601:246:C700:9B0:E5E5:B1AE:733F:DB51 (talk) 16:35, 24 December 2019 (UTC)

This seems like an overdramatic way to address a simple issue. If you see unsourced content, you of course may tag it with an appropriate tag like CN (within reasonable limits). If you see content that you think is also dubious or likely to be OR, you of course may remove it (though, editing unregistered as an IP, this is rather likely to result in you having to explain yourself to somewhat clueless reviewers of recent edits, even if you use an explanatory edit summary). None of this requires any pseudo-philosophical handwringing. --JBL (talk) 17:44, 24 December 2019 (UTC)

(edit conflict):WP:OR says "Even if you're sure something is true, it must be verifiable before you can add it", and WP:VERIFY says "The prohibition against OR means that all material added to articles must be attributable to a reliable, published source, even if not actually attributed." I am not a specialist of the subject, but it seems clear that everything in this article can be found in some of numerous soures that have discussed the subject of the article. Maybe, the six exact plotted figures cannot be found in the cited sources, but WP:CALC says "Routine calculations do not count as original research, provided there is consensus among editors that the result of the calculation is obvious, correct, and a meaningful reflection of the sources." As plotting a distribution of probability is a routine method for studying probabilities, and there are many software available for such computations, WP:CALC applies. The closing paragraph is not explicitly sourced, but is a immediate consequence of the preceding discussion. So I do not see any Wikipedia rule that is broken here. D.Lazard (talk) 17:48, 24 December 2019 (UTC)

Centered pentachoric number

See Talk:Centered pentachoric number#What number is this?; I'd like help determining if this unsourced out-of-the-way article belongs in Wikipedia or in {{figurate numbers}}, where I ran across it. — Arthur Rubin (talk) 20:04, 21 December 2019 (UTC)

A related question: Is this article referenced within Wikipedia other than through {{figurate numbers}} or related templates? I would guess not.... — Arthur Rubin (talk) 23:45, 25 December 2019 (UTC)

I did a quick test by temporarily removing it from {{Figurate numbers}} and {{Classes of natural numbers}}, and it looks like those account for all of the links to it. XOR'easter (talk) 21:30, 26 December 2019 (UTC)

Default English for mathematics articles

This comes primarily from the discussions over at Talk:Equaliser (mathematics), but ought to apply more generally to mathematics articles on WIkipedia. Is there a default English variant for mathematics articles, whether it is American English, British English, or otherwise, or does it not matter? If there isn't, should there be one for consistency reasons? 73.168.5.183 (talk) 05:11, 27 December 2019 (UTC)

There is no special rule for WP:ENGVAR for mathematics. It is the same as for other non-mathematical topics. If a mathematical topic has some strong connection to one English variant or another (as for instance the Mathematical Tripos does with UK English and the William Lowell Putnam Mathematical Competition does with US English) then it should be in that variant. Otherwise, if it was in a consistent variant, it should be left in that variant. —David Eppstein (talk) 06:49, 27 December 2019 (UTC)

Graph coloring

A COI user has been edit-warring to add a huge and grandiosely-worded section on a new, non-notable, and uncited heuristic in a dubious journal to our article on graph coloring. It could help for more project editors to pay attention to the article. —David Eppstein (talk) 18:28, 28 December 2019 (UTC)

Thanks for calling attention to this. The language is quite promotional indeed: novel, reset this "state of the art", subtle, etc. It reads like the overselling in a failed grant proposal. It is, perhaps unsurprisingly, a copyvio. XOR'easter (talk) 18:49, 28 December 2019 (UTC)

Moving Jacobson-Morosow theorem to Jacobson–Morozov theorem

Can someone (with the necessary rights / experience) help out and perform this move, please? Thanks, Jakob.scholbach (talk) 21:33, 29 December 2019 (UTC)

I have made a move request at Wikipedia:Requested moves/Technical requests; it seems an *old* redirect cannot be moved over (an interesting factoid I learned today). —- Taku (talk) 22:04, 29 December 2019 (UTC)

Done. —- Taku (talk) 22:29, 29 December 2019 (UTC)

Citing Collatz book in P vs. NP and Riemann hypothesis?

Does anyone have access to the Lagarias book to check the appropriateness of these two edits? --JBL (talk) 03:04, 10 December 2019 (UTC)

@Joel B. Lewis: I haven’t checked the original source, but his quotes in this very recent Quanta article are more or less to that effect regarding the Collatz conjecture, and I wouldn’t be surprised if he wrote something similar for RH as well in his book. — MarkH₂₁^talk 02:26, 13 December 2019 (UTC)

@MarkH21: To make my concern precise: I am worried that an off-hand comparison (between Collatz and other questions) is being misrepresented in those two edits, and in particular that a characterization that Lagarias applies to Collatz might be being inappropriately extended. But I don't have the source to check. --JBL (talk) 03:10, 13 December 2019 (UTC)

@Gorrri: perhaps you can address my concerns? What is the full Lagarias quote? —JBL (talk) 13:59, 15 December 2019 (UTC)

I suspect somebody was trying to make fun of the quote and decided to play a little prank with it. While probably true, it’s quite obvious that the quote is from the Collatz conjecture article (even the reference’s title is the 3x+1 problem). --37KZ (talk) 17:16, 30 December 2019 (UTC)