View source for User talk:Rgdboer

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To facilitate current discussion an archive has been established to clear this page for 2017.[[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 02:40, 22 December 2016 (UTC)

== Undoing edits ==

Hey, there!

I see that you undid all of my edits from last night on [[Protein combining]] without entering any information as to why. Please refrain from doing that. Let me know if you have any questions.

Thanks!

--[[User:SaletteAndrews|SaletteAndrews]] ([[User talk:SaletteAndrews|talk]]) 20:47, 13 January 2017 (UTC)
:The article is very controversial, with dietitians versus biochemists. My contributions to the article ceased in January 2017. However, recently two sources for [[Liebig's law of the minimum#Protein nutrition]] have been provided, and these support the biochemists. [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 03:04, 5 September 2022 (UTC)

== Laurence Clancy ==

Hello Rgdboer. I was delighted to see you started a new article on [[Laurence Joseph Clancy]]! I started an article on the same person in about 2008 but after a few months it was listed for deletion and, despite my best efforts, the listing was successful. You can read the deletion debate at [[Wikipedia:Articles for deletion/Laurence Clancy]]. This will show the sort of argument people brought to bear to have "my article" deleted in 2008, and the sort of argument we need to be able to combat in 2017.

You may wish to ask an Admin to retrieve my 2008 article in order to see what it said, and what citations were supplied. Either way, I am happy to contribute to your new article to make it as robust as possible so it can withstand any future deletion debate.

I continue to cite Clancy in most of the aerodynamics articles I work on, so I am very glad Wikipedia again has some information about him. Best wishes, [[User:Dolphin51|<span style="color:green;">''Dolphin''</span>]] ''([[User talk:Dolphin51|<span style="color:blue;">t</span>]])'' 03:42, 16 January 2017 (UTC)

PS: I have asked an Admin to send me the text of my 2008 article; see my [https://en.wikipedia.org/w/index.php?title=User_talk:RHaworth&diff=prev&oldid=760620221 diff]. Let me know if you want a copy. [[User:Dolphin51|<span style="color:green;">''Dolphin''</span>]] ''([[User talk:Dolphin51|<span style="color:blue;">t</span>]])'' 02:41, 18 January 2017 (UTC)

PPS: [[User:RHaworth]] has restored the 2008 edits to the history of [[Laurence Joseph Clancy]]. Earlier versions can be seen by selecting them in the history of the current article. [[User:Dolphin51|<span style="color:green;">''Dolphin''</span>]] ''([[User talk:Dolphin51|<span style="color:blue;">t</span>]])'' 04:04, 19 January 2017 (UTC)

== I was going to be eliminating those subheader titles that you changed, but thanks! ==

The way that the section in [[Spacetime]] was going, I was going to delete the subheaders, but thanks! I've always appreciated your contributions! [[User:Stigmatella aurantiaca|Stigmatella aurantiaca]] ([[User talk:Stigmatella aurantiaca|talk]]) 23:13, 24 March 2017 (UTC)

== Liebmann (1905) ==

You wrote in [[Möbius_transformation#Lorentz_transformation]], that Liebmann (1905) noted the isomorphism between Lorentz group and Möbius group. However, the [https://archive.org/details/nichteuklidisch00liebgoog 1905 edition] of his "Nichteuklidische Geometrie" does not contain (as far as I can see) any discussion of the Lorentz group (in the [https://archive.org/details/nichteuklidische00liebuoft 1923 edition] there is a little bit). I think a better source is [[s:Translation:On bodies that are to be designated as "rigid"|Herglotz (1909)]], who pointed out that ''"Lorentz transformations definitely correspond to [[hyperbolic motion]]s in <math>R_3</math>"'', transforming the unit sphere into itself (p. 407). Using Klein's classification of hyperbolic motions, Herglotz separated the one-parameter Lorentz transformations into loxodromic group, hyperbolic group, elliptic group, and parabolic group (p. 408).  --[[User:D.H|D.H]] ([[User talk:D.H|talk]]) 11:30, 28 June 2017 (UTC)
:Thank you for the notes and links on this fascinating topic. Given that special relativity is a branch of linear algebra (with physical content), the alignment of the [[Riemann sphere]] with the [[celestial sphere]] accomplishes the Möbius-Lorentz group correspondence. Liebmann was cited because Coxeter mentioned him, but now it seems Herglotz is more appropriate. These century-old sources show that Penrose was a late-comer to this topic. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 23:22, 28 June 2017 (UTC)

I've now included a description of the formulas of Fricke & Klein (1897) and Herglotz (1909) in [[Spherical_wave_transformation#Conformal_group_isomorphic_to_Lorentz_group]]. Regarding Liebmann (1905), on pp. 52ff. he discussed the relation between hyperbolic motions and "Kreisverwandtschaften" (Möbius transformations), obtaining and extending some results of Fricke & Klein (without citing them). In the third edition of his book from 1923 (on p. 143), Liebmann mentioned the relationship between Lorentz transformations and motions of the hyperbolic plane using Weierstrass coordinates. --[[User:D.H|D.H]] ([[User talk:D.H|talk]]) 11:59, 20 July 2017 (UTC)

:The following relevant reference has flaws:
:* Remi Langevin (2015) ''Integral Geometry from Buffon to Geometers of Today'', chapter 18 "Integral geometry of Lorentz spaces", page 147, [[Société mathématique de France]] {{ISBN|978-2-85629-822-0}}
:The misprint in the description of P<sub>z</sub> (third line from bottom of page) has <math>\mathcal{L}(x,z) = 1 </math> where it should be <math>\mathcal{L}(x,z) = 0 . </math> This orthogonality property is given at the outset, but omits to mention [[hyperbolic orthogonality]] as the non-perpendicular meaning in this case. The use of Möbius name is overly broad, being invoked for SO(1,1) and the term ''Mob'' used instead of ''Lorentz group'' as is standard. Langevin's effort to sketch the Mobius-Lorentz group isomorphism is a gloss, not a proof. [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 01:37, 25 December 2017 (UTC) — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 01:46, 25 December 2017 (UTC)

You may be interested in
*[[Homersham Cox (mathematician)#Work on non-Euclidean geometry]] or
*[[Gustav von Escherich#Work on hyperbolic geometry]],
as well as in the recent additions to
*[[History of Lorentz transformations]]
with a bunch of many other authors having historical variants of Lorentz transformations via Weierstrass coordinates, or via Cayley absolute, or via Cayley-Hermite transformation, or via Quaternions etc. (PS: Liebmann did indeed have the Lorentz transformations in 1905, which I initially overlooked). --[[User:D.H|D.H]] ([[User talk:D.H|talk]]) 21:44, 22 March 2018 (UTC)

:The Mobius group has parabolic elements but the Lorentz group does not. I have begun to doubt the group isomorphism. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 03:16, 22 April 2019 (UTC)

== Unblock ==

Requested text:
{{unblock-auto reviewed|2=<nowiki>Autoblocked because your IP address was recently used by "Theskyisblue". The reason given for Theskyisblue's block is: "Abusing multiple accounts: Please see: [[Wikipedia:Sockpuppet investigatio...</nowiki>|3=NinjaRobotPirate|4=7862298|reason=Using university IP accessible to student body, puppeteer is not me|accept=It looks like collateral damage.  I've unblocked you.  Let me know if you have further trouble. [[User:NinjaRobotPirate|NinjaRobotPirate]] ([[User talk:NinjaRobotPirate|talk]]) 03:33, 1 October 2017 (UTC)}}
Thank you. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 02:42, 1 October 2017 (UTC)

== [[History of logarithms]] ==

R, [https://en.wikipedia.org/w/index.php?title=History_of_logarithms&oldid=692341332 this version] you wrote has a story similar to the one we just fixed at [[Napierian logarithm]].  The ref 13 doesn't appear to support what's said about this.  Care to weight in on where to take this?  [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 02:33, 13 May 2018 (UTC)
:Please correct. That text was copied from Logarithm when History of logarithms was begun. November 24, 2015, the Logarithm article was seen to be too long, with much historic material. The namespace "History of logarithm" had a redirect to Logarithm, so text was moved to reduce Logarithm and begin an independent article. The prehistory of [[natural logarithm]] includes the story of Napier, but my efforts have been expended on [[A. A. de Sarasa]] and [[Gregoire de Saint-Vincent]]. While mathematics resists the notion of paradigm shifts, the invention of logarithms was revolutionary for productivity and setting up calculus. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 21:27, 14 May 2018 (UTC)

== Relational view on functions ==

I just came here to express my wish/hope that you do not bother my use of [[Function (mathematics)#Relational approach|your idea]] for these edits. Besides your unlucky use of a (typoed?) link, I shared D.Lazard's view of the original place not really being an optimal one. I expect that the new place and the reduced content might find grace in the eyes of the lords. It is beyond me to invite you to possibly add contents, according to your ideas (composition as another example?), but at least I want to say thanks for the trigger. [[User:Purgy Purgatorio|Purgy]] ([[User talk:Purgy Purgatorio|talk]]) 11:04, 7 September 2018 (UTC)
:You’re welcome Purgy! Thank you for moving the material higher up the article. Editing on an frequently-viewed article is adventurous! But of course, ''relation'' is prior to ''function''. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 02:19, 8 September 2018 (UTC)

== Kutta condition ==

Hi Rgdboer. We are under siege at [[Talk:Kutta condition#"An aircraft with a wing with a smoothly rounded trailing edge would generate little or no lift."]]. If you are able to comment that would be appreciated. Regards. [[User:Dolphin51|<i style="color: green;">''Dolphin''</i>]] ''([[User talk:Dolphin51|<span style="color: blue;">t</span>]])'' 13:21, 7 October 2018 (UTC)
:A figure from [[flow separation]] was used to comment on [[lift (force)]] and use of [[potential flow]]. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 02:14, 9 October 2018 (UTC)

:Many thanks for your contribution. I have commented on the Talk page.

:I’m sure you are aware that potential flow is based on the assumption of zero viscosity, whereas flow separation occurs because of viscosity, so I find mention of both in the same sentence to be challenging. [[User:Dolphin51|<i style="color: green;">''Dolphin''</i>]] ''([[User talk:Dolphin51|<span style="color: blue;">t</span>]])'' 12:25, 9 October 2018 (UTC)

== Relevance? ==

In reading the list of Hotel Fires ([[List of hotel fires in the United States]]), I was struck by the abrupt introduction of what appeared to me as an irrelevant detail. I see that you added that detail on 2013 January 18‎ at 18:32, yet I don't see why. 

It may be true that Lucius W. Nieman had become editor of a paper, but what does that particular detail have to do with Hotel Fires in general? I could see that that part could be rephrased to give similar info but without reference to Mr Nieman: A local newspaper (The Daily Journal) told the "appalling... 

The fact that he had become the editor a few weeks prior to the fire leads to a belief that he was somehow responsible for the article about the fire, yet there is no clear connection nor even a clear indication of when that article was published. The rest of that paragraph, referencing the other newspapers in town doesn't seem to be relevant either.

Could you please readdress that article and see if the details can be either tied in to the topic or removed?

Thanks!  [[User:Westley Turner|WesT]] ([[User talk:Westley Turner|talk]]) 18:00, 31 December 2018 (UTC)
:The contribution has been re-written and moved to its section. The article has grown over six years, and that particular fire was recalled in a 1913 reference detailing other deaths on the Hotel's block. Nieman exploited the tragedy in his newspaper for gain, as noted by Scott Cutlip. In 2013 contributions to [[public relations]] and [[history of public relations]] led to the Cutlip observation. Thank you for calling attention to the Newhall house fire; the accent now is on the "death block" rather than media exploitation. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 00:28, 1 January 2019 (UTC)

==Asking for clarification in an old entry==

In [[Split-quaternion]], when you created it in Feb 2007, there is something like this:

{|class="wikitable"
|-
|where u* = w - x i and v* = y - z i (complex conjugates of u and v), represents q in the ring of matricies in the sense that multiplication of coquaternions behaves the same way as the matrix multiplication. For example, the determinant of this matrix u u* - v v* = q q* ; the appearance of this minus sign where there is a plus in H leads to the alternative name split-quaternion for a coquaternion. Historically coquaternions preceeded Cayley's matrix algebra; coquaternions (along with quaternions and tessarines) evoked the broader linear algebra.
|}

What do you mean by "H", I wonder.

[[User:用户名永远已存在|用户名永远已存在]] ([[User talk:用户名永远已存在|talk]]) 19:47, 2 June 2019 (UTC)
:Convention uses ℍ to designate [[quaternion]]s, like ℂ for [[complex number]]s and ℝ for [[real number]]s. Will edit to clarify. Thank you for noticing. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 21:52, 2 June 2019 (UTC)

==Use of INTDAB for disambiguation, August 23, 2019==

An automated process has detected that when you recently edited [[Murphy]], you added a link pointing to the disambiguation page [[Alex Murphy]] ([//dispenser.info.tm/~dispenser/cgi-bin/dablinks.py/Murphy check to confirm]&nbsp;|&nbsp;[//dispenser.info.tm/~dispenser/cgi-bin/dab_solver.py/Murphy?client=notify fix with Dab solver]). 

([[User:DPL bot|Opt-out instructions]].) --[[User:DPL bot|DPL bot]] ([[User talk:DPL bot|talk]]) 07:42, 23 August 2019 (UTC)
:Usually these notifications are deleted once the disambiguation has been made. In this case it can be left to show the bot's failure to comprehend that the Alex Murphy page should be on the Murphy page even when there are several people called Alex Murphy. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 20:53, 23 August 2019 (UTC)
:Standard approach to this situation is described at [[WP:INTDAB]], a Project convention. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 21:48, 28 August 2019 (UTC)

== Conformal symmetry ==
Hello [[User:Rgdboer|Rgdboer]]. The purpose of my edit on [[conformal symmetry]] that you just reverted was to start bringing some order to the noodle soup of articles on [[conformal symmetry]], [[conformal map]], [[conformal geometry]], [[conformal group]]. There is much duplicated material there, and in my opinion we need one or two articles instead of four. What do you think? [[User:Sylvain Ribault|Sylvain Ribault]] ([[User talk:Sylvain Ribault|talk]]) 07:41, 9 October 2019 (UTC)
:Noodle soup is a metaphor, hardly applicable. Why contract the Project ? A challenge in the topic is finding sources that acknowledge that [[hyperbolic angle]] is an invariant of Lorentz transformations. That fact makes conformal physics much more involved than the [[inversive geometry]] that started the subject. In this project Physics and Mathematics are largely merged (not for [[compactification]]), so sources can conflict due to silos in academia. Please refer to [[split-complex number]] and [[linear fractional transformation]] for mathematical understanding. As for the soup, sip slowly from the bowl edge as it’s very hot. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 22:46, 9 October 2019 (UTC)

== Respond to edit on talk page ==

You undid two of my edits on [[Template: number systems]] without responding to my comments on the talk page. I think it's worth grouping the planar numbers together. Also, where are the dual-complex numbers listed as a hypercomplex system? They aren't listed anywhere. As such, I'm reversing the edit. --[[User:Svennik|Svennik]] ([[User talk:Svennik|talk]]) 23:44, 22 October 2019 (UTC)
:This issue stems from [[Hypercomplex number#Two-dimensional real algebras]]. The discussion continued at [[Template talk:Number systems]].— [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 00:32, 19 November 2019 (UTC)

==Disambiguation link notification for January 18==

An automated process has detected that when you recently edited [[Allegory (mathematics)]], you added a link pointing to the disambiguation page [[Group]] ([//dispenser.info.tm/~dispenser/cgi-bin/dablinks.py/Allegory_%28mathematics%29 check to confirm]&nbsp;|&nbsp;[//dispenser.info.tm/~dispenser/cgi-bin/dab_solver.py/Allegory_%28mathematics%29?client=notify fix with Dab solver]). 

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== November 2020 ==
[[File:Information.svg|25px|alt=Information icon]] Hi Rgdboer! I noticed that you recently marked an edit as minor&#32;at [[:Music and mathematics]] that may not have been. "Minor edit" has a very specific definition on Wikipedia{{Snd}} it refers only to superficial edits that could never be the subject of a dispute, such as [[typographical error|typo corrections]] or reverting obvious [[Wikipedia:Vandalism|vandalism]]. Any edit that changes the ''meaning'' of an article is not a minor edit, even if it only concerns a single word. Please see [[Help:Minor edit]] for more information. Thank you. <!-- Template:uw-minor --> [[User:Kj cheetham|Kj cheetham]] ([[User talk:Kj cheetham|talk]]) 18:48, 20 November 2020 (UTC)
: The change was a disambiguation of [[musical performance]] to [[musical phrasing]]. My impression was that [[WP:Dab]] is a minor edit, but that may be wrong. The article WP:Dab does not indicate either way. Thank you for the notification and caution in marking an edit as minor is in order. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 04:46, 21 November 2020 (UTC)
:: It was the edit before that about 53 equal temperament I was thinking of. Happy editing in any case though! -[[User:Kj cheetham|Kj cheetham]] ([[User talk:Kj cheetham|talk]]) 09:44, 21 November 2020 (UTC)

== bounded, negative, finite ordinals  ==

A simpler version of the Russell idea you mentioned at [[Ordinals]] and its talk page, that does work adequately with the usual idea of ordinals, is to pre-pend a specified finite number of negative steps before the start point.  E.g., begin counting at -17 rather than 0 or 1.   This doesn't change the order type of any infinite ordinal, or finite ordinals if the definition of (the notation for) those is modified to mean the interval between the number and 0.  The union of all such negative prefixes to the usual ordinals is not allowed, in that it violates well ordering, but particular cases are compatible with the standard language. [[Special:Contributions/73.89.25.252|73.89.25.252]] ([[User talk:73.89.25.252|talk]]) 20:19, 3 December 2020 (UTC)
:Hello Somerville, Massachusetts, USA, yes, we clicked at [[Talk:Scientific notation#Order as a scale, not a number]]. The consequent [[doubly infinite]] sequence came up on another article. The issue has existed since Russell mentioned in [[The Principles of Mathematics]] the counting backward from any  position in a progression. Perhaps he forsaw the study of luminosity of Campanus, planets, moon, and sun on  the  scale of Hipparchus. Your suggestion appeals as an accomodation of that situation  in an order of magnitudes. But negative twenty-seventh magnitude for the Sun is at one astronomic unit, so a scale going closer to the sun, would call for another position for the zero. Admitting the doubly infinite is part of scientific notation, regardless of Georg Cantor. Indeed, the doubly infinite [[geometric progression]] 10<sup>n</sup>, n in Z, sections the positive reals for access. You are invited to become a [[WP:User]].— [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 02:19, 7 December 2020 (UTC)
:: The accomodationist strategy is often used where allowing some kind of extension, but only a finite amount of it, does not qualitatively change things (e.g. field or ring extensions, coverings) but throwing in all the finite adjustments at once gives a different sort of creature that does not belong to the [[category]] of interest.  Typical use case is where a finiteness condition appears, such as finite dimension, finite ascending or descending chains, well ordering. Or using "almost" to denote a finite number of  exceptions.

:: The problem with allowing the infinite modifications is not that it's wrong or can't exist but that the category of allowed objects would lose nice properties in the name of inclusiveness.  Literal "can't have nice things" so that the extension is allowed for its own sake. [[Special:Contributions/73.89.25.252|73.89.25.252]] ([[User talk:73.89.25.252|talk]]) 18:01, 7 December 2020 (UTC)
: {{tq|Indeed, the doubly infinite geometric progression 10^n sections the positive reals for access.}}  The distinction between "ordinal number" (having levels or layers or a hierarchy), and "integer" as in the stuff of arithmetic, seems to be a matter of linguistic custom or historical tradition that is orthogonal to the scientific notation discussion.   The problems with OOM as an integer approximation function to the logarithm are practical mathematical concerns.  1) that anything physically meaningful (invariant) for dimensionful quantities has to be a binary relation, i.e., based on a ratio; 2) that the specific binary relation "same OOM" does not reduce to a unary function; 3) that if you do take it to be a function of one variable, it becomes dependent on a choice of rounding scheme, so again non-invariant; 4) if you do fix a rounding scheme anyway, it has to be discontinuous, so that almost identical quantities "have different order of magnitude" if OOM is defined in such a way; 5) that log-scale is unnatural for OOM approximations, we want them to be on the same scale as the input.  All this is why (6) cognoscenti use the binary relation and the unary convention hasn't caught on, except maybe for people who only teach (or are forced to learn-and-forget) the stuff rather than use it for real.  I tried drafting a re-write of the [[order of magnitude]] article and it's quite a pain to start over.  Probably easier to do a minor fix on [[scientific notation]] first.  [[Special:Contributions/73.89.25.252|73.89.25.252]] ([[User talk:73.89.25.252|talk]]) 06:42, 8 December 2020 (UTC)
:: This is being discussed at the Decade talk page in case you are interested. [[Special:Contributions/73.89.25.252|73.89.25.252]] ([[User talk:73.89.25.252|talk]]) 01:27, 18 December 2020 (UTC)
==  [[Wikipedia:Proposed deletion|Proposed deletion]] of [[:2 × 2 real matrices]] ==
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The article [[:2 × 2 real matrices]] has been [[Wikipedia:Proposed deletion|proposed for deletion]]&#32;because of the following concern:
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== Nomination of [[:2 × 2 real matrices]] for deletion ==
<div class="afd-notice">
<div class="floatleft" style="margin-bottom:0">[[File:Ambox warning orange.svg|48px|alt=|link=]]</div>A discussion is taking place as to whether the article '''[[:2 × 2 real matrices]]''' is suitable for inclusion in Wikipedia according to [[Wikipedia:List of policies and guidelines|Wikipedia's policies and guidelines]] or whether it should be [[Wikipedia:Deletion policy|deleted]].

The article will be discussed at [[Wikipedia:Articles for deletion/2 × 2 real matrices]] until a consensus is reached, and anyone, including you, is welcome to contribute to the discussion. The nomination will explain the policies and guidelines which are of concern. The discussion focuses on high-quality evidence and our policies and guidelines.

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<!-- Template:Afd notice --></div> [[User:D.Lazard|D.Lazard]] ([[User talk:D.Lazard|talk]]) 10:20, 9 February 2021 (UTC)

:The article, slightly edited, is available through [[Wikibooks]]:
* [[b:Abstract Algebra/2x2 real matrices]]
Readers may comment on linear algebra here. [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 04:16, 10 October 2021 (UTC) [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 04:26, 10 October 2021 (UTC)

== Your edit of "transformation semigroup" 03:13, 3 October 2019‎ ==

Hi: I somehow feel that your changes at  03:13, 3 October 2019‎ were adding confusion, if not wrong. You changed the explanation of "transformation" from "function" to "partial function", which seems to be in contradiction to the definition of "transformation semigroup" in the first sentence, which reads:

"a transformation semigroup (or composition semigroup) is a collection of functions from a set to itself that is closed under function composition."

It seems also in contradiction to a paragraph below:

"The set of all transformations of X is a transformation monoid called the full transformation monoid (or semigroup) of X. "

where the "full transformation monoid/semigroup" usually means the monoid/semigroup of all functions (e.g., in Howie's book), not partial functions.

Or did I misunderstand your edits?  [[User:ALife|ALife]] ([[User talk:ALife|talk]]) 07:19, 22 February 2021 (UTC)
:See [[Transformation semigroup]]. The reader was right, thank you. Link to [[Partial function]] now placed in next sentence. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 03:43, 22 February 2021 (UTC)

::Looks good. Thanks. [[User:ALife|ALife]] ([[User talk:ALife|talk]]) 07:19, 22 February 2021 (UTC)

==  [[Wikipedia:Proposed deletion|Proposed deletion]] of [[:Abraham Cornelius Benjamin]] ==
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The article [[:Abraham Cornelius Benjamin]] has been [[Wikipedia:Proposed deletion|proposed for deletion]]&#32;because of the following concern:
<blockquote>'''Not notable by [[WP:GNG]] or [[WP:PROF]]'''</blockquote>

While all constructive contributions to Wikipedia are appreciated, pages may be [[WP:DEL#REASON|deleted for any of several reasons]].

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Please consider improving the page to address the issues raised. Removing {{Tlc|proposed deletion/dated}} will stop the [[Wikipedia:Proposed deletion|proposed deletion process]], but other [[Wikipedia:deletion process|deletion process]]es exist. In particular, the [[Wikipedia:Criteria for speedy deletion|speedy deletion]] process can result in deletion without discussion, and [[Wikipedia:Articles for deletion|articles for deletion]] allows discussion to reach [[Wikipedia:Consensus|consensus]] for deletion.<!-- Template:Proposed deletion notify --> – [[User:Fayenatic london|Fayenatic]] [[User talk:Fayenatic london|'''<span style="color:#FF0000;">L</span>'''ondon]] 10:25, 14 April 2022 (UTC)
:References to many reviews of his books were added; notability per Author. [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 04:37, 18 May 2022 (UTC)

== The utility for mechanics was noted by Aleksandr Kotelnikov. ==

Do you have a source for ''"The utility for mechanics was noted by Aleksandr Kotelnikov."''? I consolidating this history page: https://en.wikipedia.org/wiki/Cross_product#History  <!-- Template:Unsigned --><span class="autosigned" style="font-size:85%;">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:'wɪnd|'wɪnd]] ([[User talk:'wɪnd#top|talk]] • [[Special:Contributions/'wɪnd|contribs]]) 13:36, 17 May 2022 (UTC)</span> <!--Autosigned by SineBot-->
:The thesis he wrote at Kazan University refers to cross product in its title. Reference entered in History today. [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 04:33, 18 May 2022 (UTC)
Great. :) Do you know if the paper is accessible somewhere in the Russian original, in a collection, translation, quoted, or otherwise a way to verify its content? I find nothing here https://zbmath.org/?q=ia%3Akotelnikov.a-p and a mention without source here: https://mathshistory.st-andrews.ac.uk/Biographies/Kotelnikov/ [[User:&#39;wɪnd|&#39;wɪnd]] ([[User talk:&#39;wɪnd|talk]]) 16:06, 18 May 2022 (UTC)
:Going to [[All-Russian Mathematical Portal]] and entering 1895 and Kotelnikov generates an article in the University journal where [[screw theory]] replaces cross product in the title. Perhaps the thesis ''is'' the article, with some translator substituting cross product. The [[screw displacement]] at the heart of the theory is a sufficient generator of the [[Euclidean group]] E(3). Like the vector representation of the cross product, the screw displacement has a [[screw axis]]. It involves  both a rotation about the axis and a displacement along it. I have not read Kotelnikov’s work, but this Euclidean kinematic motion (somewhat related to cross product) is another subject, so the sentence you note may be a misdirection, so it can be deleted.[[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 17:10, 20 May 2022 (UTC)
:Mention of Kotelnikov at [[Cross product#History]] has been removed as unverified.[[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 03:38, 23 May 2022 (UTC)

[[Screw theory]] look fascinating! :) Thank you also for the pointer to [[All-Russian Mathematical Portal]]. That will help me research another article I'm working on: https://en.wikipedia.org/wiki/Moment_(physics)#History

I've heard that Chebychev and others might have played a role in the origins of moments in probability theory and statistics, but I haven't found any direct attestations. This might help. [[User:&#39;wɪnd|&#39;wɪnd]] ([[User talk:&#39;wɪnd|talk]]) 20:48, 23 May 2022 (UTC)

== Questions regarding your use of "beam space" ==

Hi Robert,

In [[Rapidity]], you introduced the notion of "beam-space" which is novel to me. For some time now, I have tried to find other references on this particular parametrization of the Lorentz transform and have not been successful. The nearest I have come is in some work by Garret Sobczyk where he makes use of a similar technique that he identifies as a novel type of spectral decomposition. In particular, I am interested in whether there is a "beam-space" version of (2+1) and (3+1) Minkowski spacetime. I have tried using a simple 3x3 matrix transformation, but I seem to be missing some crucial conceptual ingredients.


I have intended to contact you for some time on this topic, so I hope that I am not overly forward in writing directly to your wikipedia talk page. Please let me know if there is a better way to contact you (for instance, over email would be very convenient for me as well).

Sincerely yours,

John Fries [[User:Jqgatsby|Jqgatsby]] ([[User talk:Jqgatsby|talk]]) 22:41, 15 November 2022 (UTC)
:Thank you for your interest in this topic. The answer in mathematics lies with the equivalence of [[binary quadratic form]]s xy and xx &minus; yy . The points (x,y) satisfying the quadratic forms when set to 1 lie on hyperbolic curves. The latter is called the [[unit hyperbola]] as it has minimal radius 1 while the other, a standard hyperbola, passes closest to the origin at (1,1), a distance of square root of two. The [[natural logarithm]] was born from this standard, but the unit hyperbola is used with rapidity in spacetime. The equivalence of the two quadratic forms uses a linear transformation that moves the clock and meter-stick coordinates to the beam space. Perhaps the article on [[split-complex number]]s, where the unit hyperbola replaces the unit circle, with its references 3 to 8 on spacetime interpretation, will be helpful. The stories of young Einstein imagining chasing light, and the two alternate directions, form a popular background to this topic. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 01:17, 16 November 2022 (UTC) Revised [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 04:02, 16 November 2022 (UTC)
:Let’s stick to two dimensions here, relating temporal to spatial metrics. The linear transformation
:<math>(x,\ t) \begin{pmatrix}1 & 1 \\ -1 & 1 \end{pmatrix} = (x-t,\  x+t)</math> has determinant 2 so the equivalence at [[binary quadratic form]] does not apply.

:Nevertheless, the connection of the two [[quadratic form]]s is made linearly, and the form xy occurs when the asymptotes of the hyperbola are the coordinate axes. In the temporal interpretation, they are the beams to the left and right from a given (here, now). — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 01:10, 17 November 2022 (UTC)

:See [[Squeeze mapping#Relativistic spacetime]] and [[Light-cone coordinates]] for this concept. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 02:24, 7 February 2023 (UTC)

== Reference desk answer 23/09/23 ==

[[Gregoire de Saint-Vincent]] noted in 1647 that rectangular hyperbolas are [[Invariant_(mathematics)#Invariant_set|stable]] under [[squeeze mapping]], so planar areas are preserved not only in the whole plane, but also under the hyperbola. Thus the [[hyperbolic logarithm]] developed a century before Euler’s exponential functions a<sup>x</sup>.

:The correct statement is <math>\log x = \int_1^x \frac{dt}{t}</math> where ''t'' is a [[bound variable]].

Here the case a>1 and b>1 is considered first so the areas extend to the right of ''x''=1 and the integral is seen as the area over [1,''x''] and under the hyperbola ''xy''=1. Using ''b'' as squeeze parameter, 
:<math>\log a = \int_1^a \frac{dt}{t} = \int_b^{ab} \frac{dt}{t} .</math> Then
:<math>\log b + \log a = \int_1^b \frac{dt}{t} + \int_b^{ab} \frac{dt}{t} = \int_1^{ab} \frac{dt}{t} = \log ab .</math>
The cases where one or both of ''a, b'' are in the [[unit interval]] are similar when [[signed area]]s are noted.

Copied here for ease of reference. [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 22:34, 26 September 2023 (UTC)

== Your edit in [[Binary relation]] ==

In your recent edit in [[Binary relation]], you changed "functional relation" to "univalent relation" in the definition of this type of relation. This change leaves many occurences of "functional" (in this article) without any definition. Also, there are many articles that contain "functional relation" and certinly some of them redirect to [[Binary relation]]. Please, fix these issues. 

By the way, per [[WP:LEAST]], it is not a good idea to redirect [[Univalent relation]] to [[Partial function]], and I have reverted this. [[User:D.Lazard|D.Lazard]] ([[User talk:D.Lazard|talk]]) 12:55, 28 January 2024 (UTC)

:IMO, "functional relation" must be restored in the article. However, this requires some care, as it appears that, depending on the author it may refer either to a function or to a partial function. [[User:D.Lazard|D.Lazard]] ([[User talk:D.Lazard|talk]]) 14:20, 28 January 2024 (UTC)
::The term ''functional relation'' is fraudulent. The redirect has been proposed for deletion. Inclusion of the term at Binary relation is expected to be removed. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 22:28, 31 January 2024 (UTC)

== Edit warring ==

[[File:Ambox warning pn.svg|30px|link=]] You currently appear to be engaged in an [[WP:Edit warring|edit war]]&#32; according to the reverts you have made on [[:Relativity of simultaneity]]. This means that you are repeatedly changing content back to how you think it should be although other editors disagree. Users are expected to [[Wikipedia:Consensus#In talk pages|collaborate]] with others, to avoid editing [[WP:Disruptive editing|disruptively]], and to [[WP:Consensus|try to reach a consensus]], rather than repeatedly undoing other users' edits once it is known that there is a disagreement.

Points to note:
# '''Edit warring is disruptive regardless of how many reverts you have made;'''
# '''Do not edit war even if you believe you are right.'''
If you find yourself in an editing dispute, use the article's [[Help:Talk pages|talk page]] to discuss controversial changes and work towards a version that represents consensus among editors. You can post a request for help at an [[WP:Noticeboards|appropriate noticeboard]] or seek [[Wikipedia:Dispute resolution|dispute resolution]]. In some cases, it may be appropriate to [[WP:Requests for page protection|request temporary page protection]]. If you engage in an edit war, you '''may be [[WP:Blocking policy|blocked]] from editing.''' <!-- Template:uw-ew --> - [[User:DVdm|DVdm]] ([[User talk:DVdm|talk]]) 06:12, 13 March 2024 (UTC)
:See discussion at [[Talk:Relativity of simultaneity#Conjugate hyperbola & diameter]] — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 02:22, 15 March 2024 (UTC)
::Yes, ''do'' see discussion at [[Talk:Relativity of simultaneity#Conjugate hyperbola & diameter]] indeed. - [[User:DVdm|DVdm]] ([[User talk:DVdm|talk]]) 08:03, 15 March 2024 (UTC)

== Administrator research ==

* [[Research:Wikipedia_Administrator_Recruitment,_Retention,_and_Attrition]] contains a link to a project surveying Administration. — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 00:53, 25 October 2024 (UTC)
* updated: [https://meta.wikimedia.org/wiki/Research:Wikipedia_Administrator_Recruitment,_Retention,_and_Attrition Wikimedia research page] — [[User:Rgdboer|Rgdboer]] ([[User talk:Rgdboer#top|talk]]) 00:57, 13 November 2024 (UTC)