Wikipedia talk:WikiProject Mathematics/Archive/2021/Feb

MOS:MATH says that <math display=block> must be used instead of a colon for displaying a formula. Having testing this, it appears that this provides a bad result: the vertical space before and after the formula is much larger than with a colon. This is definitely confusing as suggesting that the formula is a paragraph by itself, even when the formula is in the middle of a sentence. So, I think that this recommendation must be removed until this bug will be fixed. (I do not know how to submit a bug report for such a case, and submitting a bug report would be more efficient if supported by a consensus.)

By the way, if one want that editors use <math display=block>, this must be added to "Math and logic" menu. D.Lazard (talk) 11:47, 2 February 2021 (UTC)

I agree the spaces give a wrong impression (and also look ugly). Jakob.scholbach (talk) 12:19, 2 February 2021 (UTC)

Can you give an example where you think it looks bad? I have used it in various articles, and have never noticed such an issue. —JBL (talk) 12:46, 2 February 2021 (UTC)

I wonder if there is some confusion here in which someone is mistaking <math display=block> for <blockquote>. I would agree that the latter puts too much space above and below the displayed line. Michael Hardy (talk) 02:18, 4 February 2021 (UTC)

I wonder if someone is comparing <math display=block> to colon-math with blank lines above and below the math, and not noticing that with <math display=block> it makes a difference whether there is a paragraph break before or after the display. If you want to use <math display=block> within a paragraph of text, and make it look like it is a displayed math block within that paragraph, you need to not format it as its own separate paragraph. —David Eppstein (talk) 04:24, 4 February 2021 (UTC)

Trying out all the options. A blank line before a colon-math

${\displaystyle E=mc^{2}}$

Using a blank line after colon-math

${\displaystyle E=mc^{2}}$

Using blank line before and after colon-math

${\displaystyle E=mc^{2}}$

Using blank line before display=block

$${\displaystyle E=mc^{2}}$$ Using blank line after display=block $${\displaystyle E=mc^{2}}$$

Using blank line before and after display=block

$${\displaystyle E=mc^{2}}$$

On my machine, google chrome on a Chromebook, and MathML with SVG or PNG fallback, I can see no difference in the indentation of any of these. There might be a bug here but we would need to see a reproducible example. p.s. When quoting code examples its good to wrap them in <nowiki>...</nowiki> tags to prevent the parser from trying to interpret the tag. The {{tag}} template is handy for this as well. --Salix alba (talk): 06:55, 4 February 2021 (UTC)

• It's not the indentation but the vertical spacing around them. And I don't think it's actually a bug, but more a level of control that's not available with the colons. For me, Chrome on OS X, the blank lines are visible as extra space in the math display block versions, but not the colon math versions. Did you also notice that if you place $${\displaystyle {\text{an equation}}}$$ in the middle of an bulleted item list, it is properly double-indented, and your bulleted paragraph continues with the correct indentation afterwards? —David Eppstein (talk) 07:06, 4 February 2021 (UTC)

Here is an example taken from the lead of Change of basis that I have recently edited, firstly with a colon,

${\displaystyle \mathbf {x} _{\mathrm {old} }=\mathbf {A} \,\mathbf {x} _{\mathrm {new} },}$

followed with the same with "display = block" $${\displaystyle \mathbf {x} _{\mathrm {old} }=\mathbf {A} \,\mathbf {x} _{\mathrm {new} },}$$ In both case, there are no blank lines in the source before or after the displayed formula. As the formula is inside a sentence, the extra vertical space before the formula with "display=block" is definitively a bug. Surprisingly, there is no visible extra vertical space after the formula, although there was one when I edited the article (smaller than the extra space before the formula). Possibly, the implementation of "display=block" has been modified since the opening of this thread. D.Lazard (talk) 08:25, 4 February 2021 (UTC)

It looks like the spacing in the second example is controlled by the style sheets in MediaWiki:Common.css. In particular

/* Make <math display="block"> be left aligned with one space indent for 
 * compatibility with style conventions
 */
.mwe-math-fallback-image-display,
.mwe-math-mathml-display {
	margin-left: 1.6em !important;
	margin-top: 0.6em;
	margin-bottom: 0.6em;
}

Reducing the amount of space with margin-top: 0.4em; should give similar spacing. We can do this locally, anyone with the appropriate admin bit can do it. It would be better if people add this to their Special:MyPage/common.css so we can properly test in first before making it live.

It highly unlikely the implementation has changed, as it takes months to get the smallest change through code review. This bit of the CSS was added by me in 2015 and has not been changed since. --Salix alba (talk): 13:15, 4 February 2021 (UTC)

As a guess, the CSS is targeting the child elements of the actual sibling element, which is <div class="mwe-math-element">. This margin is probably not being collapsed, hence, irregular spacing relative to what would be available with <p>. (Regardless, I do not really understand why we're targeting the two classes rather than the parent.) --Izno (talk) 00:56, 5 February 2021 (UTC)

	Sandbox Organiser A place to help you organise your work

Hi all

I've been working on a tool for the past few months that you may find useful. Wikipedia:Sandbox organiser is a set of tools to help you better organise your draft articles and other pages in your userspace. It also includes areas to keep your to do lists, bookmarks, list of tools. You can customise your sandbox organiser to add new features and sections. Once created you can access it simply by clicking the sandbox link at the top of the page. You can create and then customise your own sandbox organiser just by clicking the button on the page. All ideas for improvements and other versions would be really appreciated.

Huge thanks to PrimeHunter and NavinoEvans for their work on the technical parts, without them it wouldn't have happened.

Hope its helpful

John Cummings (talk) 11:31, 6 February 2021 (UTC)

I think it's okay to merged it into Kiyoshi Oka. Oka's coherence theorem may also be included.--SilverMatsu (talk) 05:00, 12 February 2021 (UTC)

I wouldn't merge them. In both cases, I trust R.e.b.'s judgement about which topics should have separate articles, even if those articles were left in a very stubby state. —David Eppstein (talk) 05:15, 12 February 2021 (UTC)

I would agree that Oka's coherence theorem is important enough as a foundation result in its field (complex geometry and algebraic geometry) to warrant its own page, even if it is currently a stub. Kiyoshi Oka is a reasonably significant figure also, as one of the big early Japanese geometers, so should also obviously warrant their own page, so I would say don't merge those two. I can't speak with any confidence about Oka's lemma.Tazerenix (talk) 05:34, 12 February 2021 (UTC)

Thank you for your reply. I agree that Oka's coherence theorem is a separate page. However, it seems that Oka's lemma may be written on the pseudoconvex domain or the Levi's problem page. Currently, Levi problem is redirected to the Stein manifold, which seems more like Grauert's proof than Oka's proof. thanks!--SilverMatsu (talk) 06:05, 12 February 2021 (UTC)

I found three more sources in MathSciNet with "Oka's lemma" in the title (all about this specific lemma; there's another paper on a different Oka lemma). I think it clearly passes WP:GNG as an independently notable topic. —David Eppstein (talk) 06:34, 12 February 2021 (UTC)

Thank you for your reply. As for Oka's coherence theorem, it would be nice if I could prove it, but I think I'll probably have to wait 70 years from 1978. The content of the current Oka's lemma is a bit questionable, given that Levi pseudoconvex and Levi's problems are redirects. The current content semms like a pseudoconvex domain. In some cases, the content of Oka's lemma is defined as pseudoconvex. but, called Oka Pseudoconvex has a different meaning ...--SilverMatsu (talk) 07:30, 12 February 2021 (UTC)

Apparently, there are two more theorems called Oka's coherence theorem.^{[coherence 1]} To mention this, we need the following Oka's^{[coherence 2][coherence 3]} and Cartan ^{[coherence 4]} paper. As for the ideal sheaf, Cartan also submits proofs independently, so it seems that this theorem cannot be merged on Kiyoshi Oka page. Special thanks to David Eppstein and Tazerenix for their advice. I would like to hear your opinion on adding these two coherence theorems to the page. thanks!--SilverMatsu (talk) 12:03, 13 February 2021 (UTC)

This looks like bad numerology, and it's entirely relying on primary sources because everyone apart from these few authors realizes it's not useful. Is there a good reason to keep this article? --mfb (talk) 22:23, 11 February 2021 (UTC)

Looks like 100% crankery to me. If it's notable enough for people to have written about the fact that it's crankery, then obviously such sources should be included; if not, AfD seems like a good option to me. --JBL (talk) 22:44, 11 February 2021 (UTC)

I'm not finding anything except a passing mention in an essay by I. J. Good about how, yes, you can screw around with numbers and get other numbers that look meaningful. I don't think that warrants an article. The biographies linked from combinatorial hierarchy also need attention. XOR'easter (talk) 14:00, 12 February 2021 (UTC)

All the work of H. Pierre Noyes uses "personal interview" as reference, great. That's arguably worse than Noyes writing his own article, we get all the issues of a person describing themselves plus the issue of having no reference that could be checked. All the work of Ted Bastin is completely unreferenced. --mfb (talk) 15:51, 12 February 2021 (UTC)

I'm really doubtful that Ted Bastin qualifies as wiki-notable. Nothing I'm turning up would count for passing WP:PROF or WP:AUTHOR; the best source is the Times obit that would only get partway to WP:GNG and that seems to have swallowed some fan remarks uncritically. For example, it mentions the original home of Rupert Sheldrake's work on morphic resonance without saying that Sheldrake's "work" is rank pseudoscience. And it says, The link between quantum physics and information theory, in a broad sense, has grown stronger in recent years, as computer scientists investigate the possibility of quantum physics providing a new basis for computer hardware and, simultaneously, quantum physicists investigate the information basis of their subject. But there is little recognition in recent research of the origin of the latter idea in the pioneering work of Bastin and others. The "and others" does a lot of work there: Bastin himself isn't even a marginal figure in the history of quantum foundations and quantum information. XOR'easter (talk) 17:41, 12 February 2021 (UTC)

H. Pierre Noyes, Ted Bastin, Clive W. Kilmister and H. Dean Brown were all started and largely written by the same user. Brown looks okay, Kilmister is probably relevant but the article doesn't do a good job making that clear. --mfb (talk) 21:55, 15 February 2021 (UTC)

Wikipedia:Articles for deletion/Combinatorial hierarchy --mfb (talk) 21:36, 15 February 2021 (UTC)

deletion discussion

Female programmer, co-creator of moldyn method. Yo, we all need to come out for this one, especially if you're in the computational community in phy sci, bigly. Already posted on super- science wp's forum, and several sub-forums as well. It's not certain enough, and too close for my liking. Ema--or (talk) 02:26, 12 February 2021 (UTC)

Sorries all round for my non-NPOV canvas! Ema--or (talk) 21:14, 15 February 2021 (UTC)

Hi, just an issue to discuss. Just wanted to name an issue, which I asked for consultation on, but was not able to get any thing on before the end of discussion. There is the issue of my inconsistencies on Mansigh btw main space and other-space, particularly afd- and Wp project-space, although it is particularly a matter for subjective interpretation. I’d like to end by again apologising for any trouble and thanking anyone who offered any opinion or contribution to the chat, as well as for the space and audience in a place such as this. Bye, ‘til next time. Ema--or (talk) 18:28, 18 February 2021 (UTC)

I don't know where to write a consultation about the article being drafted, so I chose it here. I was wondering if I could create a talk page for the draft space. I think that the harmonic series is related to Draft:Division by infinity. This series diverges to infinity, but in the Basel problem it converges to ${\displaystyle {\frac {\pi ^{2}}{6}}}$. It seems that this series can be regarded as adding the number divided by infinity from the middle of the sequence, but the calculation result is different. I may have overlooked the boundary between infinity and finite. thanks!--SilverMatsu (talk) 12:52, 7 February 2021 (UTC)

The harmonic series and the Basel series are completely different series! —JBL (talk) 13:34, 7 February 2021 (UTC)

Thank you for your reply. Oops, it was a bit (quite?) strange, as it semms like a Hazel problem in harmonic series in my context. I wrote it with the intention of comparing numbers divided by infinity, but for example, the sum of the reciprocals of prime numbers does not converge, but this may be a problem of the spacing between terms rather than the size of each term.--SilverMatsu (talk) 04:47, 8 February 2021 (UTC)

Can you help convince me that an article entitled "Division by infinity" is needed? Would you also make separate articles entitled "Infinity plus zero" and "Infinity divided by infinity" and "Infinity times zero", etc.? It is quite different from the situation with Division by zero, which is about attempting to apply an arithmetic operation to actual numbers, something that students initially expect to be able to do.

As for the content of the article, about half of the sentences right now seem like pseudo-math, without a precise mathematical meaning. Is there a published article or book that has an exposition similar to the one you are presenting? Ebony Jackson (talk) 08:37, 8 February 2021 (UTC)

Thank you for your reply. Sory, I don't have any helpful literature. In this article, I seems that the meaning of infinity in elementary arithmetic was a monotonically increasing sequence of real numbers. And this article seemed to try to explain what the numbers calculated by Division by infinity are. I tried to compare the example of the calculation result, but I didn't have a concrete idea of ​​how to edit it to improve the article. I tried to help with this article, but it's not working. thanks!--SilverMatsu (talk) 10:57, 8 February 2021 (UTC)

Ebony Jackson makes important points. If you choose to continue to develop this draft, my advice is to (A) locate Wikipedia:Reliable sources and then (B) summarize those sources. I mean, don't wait until later to find sources. Because if you can't find sources, or if your text doesn't reflect those sources, then your work might come across as Wikipedia:Original research, which will not be accepted into the encyclopedia. Best wishes. Mgnbar (talk) 13:14, 8 February 2021 (UTC)

That draft started as a student's class project; I happened across it and took a few stabs at making it into an article but never got far enough that I considered it mainspace-ready. If anyone would like to try, the Beyond Infinity book listed at the end might be a decent place to start. XOR'easter (talk) 14:59, 8 February 2021 (UTC)

XOR'easter thank you for the advice. I will search for references. In the references I have now (I don't have Beyond Infinity) , I can provide related examples, but I am not writing from the perspective of dividing by infinity, so I will continue to search for references. thanks!--SilverMatsu (talk) 13:15, 9 February 2021 (UTC)

I am still skeptical that an article on "Division by infinity" should exist at all. I would suggest that you spend your valuable time elsewhere! Ebony Jackson (talk) 18:47, 9 February 2021 (UTC)

I am also skeptical. But if there are many reliable sources that talk about this concept, saying non-trivial things that aren't covered elsewhere in Wikipedia, then maybe this article should exist. In other words, I think that that part of the discussion also hinges on reliable sources. Mgnbar (talk) 19:17, 9 February 2021 (UTC)

I would be surprised if there were lots of high-quality reliable sources calling out "division by infinity" as a separate topic. You can divide by infinity in some contexts, certainly; the most common is probably the Riemann sphere, which doesn't actually seem to be mentioned in the draft as it stands. --Trovatore (talk) 19:36, 9 February 2021 (UTC)

Mgnbar Thank you for the advice. I would like to lower the priority of this article in my to-do list. If this article can exist as a separate article, I've come to think that references will naturally come together while improving other articles. Thank you for taking your time. --SilverMatsu (talk) 07:03, 10 February 2021 (UTC)

Why not post the article? Looks ready to me.... Ema--or (talk) 02:45, 12 February 2021 (UTC) Still waiting, huh? Ema--or (talk) 22:10, 18 February 2021 (UTC)

Are you interested in writing ${\displaystyle {\frac {a}{\infty }}=0}$ (a is a finite real constant number) as follows? ${\displaystyle x_{n}={\frac {a}{n}},\ \{{}^{\forall }\varepsilon >0,\;{}^{\exists }N\in \mathbb {N} \;\mathrm {s.t.} \;{}^{\forall }n\in \mathbb {N} \;(n>N\Rightarrow |x_{n}-0|<\varepsilon )\}}$ It may overlap with the content of (ε, δ)-definition of limit article ...--SilverMatsu (talk) 03:18, 14 February 2021 (UTC)