Wikipedia:Reference desk/Archives/Mathematics/2019 October 19

= October 19 =

Linear algebra
Is hybrid number a notable concept? — Rgdboer (talk) 23:43, 19 October 2019 (UTC)


 * The fact that we have a full article (not just a stub) with 18 refs certainly implies that it is, although the first ref is the only one which mentions them in the title . Since that article apparently introduced the name in 2018, I'm not sure if the term has a wider acceptance or not. I suggest checking the other 17 refs to see if they actually use the term. SinisterLefty (talk) 23:47, 19 October 2019 (UTC)
 * Almost all of them predate the 2018 paper. So they're not expected to include the term. -- Meni Rosenfeld (talk) 05:03, 20 October 2019 (UTC)


 * it would seem not to be, although this sort of question is probably better raised at WT:WPM. The main reference for the topic is a paper from 2018 which states in its abstract, "In this study, we define a new non-commutative number system called hybrid numbers."  This is a pretty good indication that WP:GNG is  met.  –Deacon Vorbis (carbon &bull; videos) 00:01, 20 October 2019 (UTC)


 * I believe that no, it is not.
 * This system is completely equivalent to the ring of 2x2 real matrices. If it was like, say, the quaternions, which can be represented as a subset of the ring of 4x4 matrices, it could be interesting. But as it is, it is just the well-known matrices, just dressed in a different way. While this might not be the case here - taking a well-known, extensively studied concept and calling it with a different name as if it's new, is often a symptom of a mathematical crank.
 * It first appears with this name in an article from 2018. And it's not clear that it appeared by any other author.
 * Finally, the Wikipedia page was created - and most of the content added - by the author of that single paper.
 * So this looks like self-promotion of an article of questionable novelty, rather than a genuine effort to document something objectively notable. -- Meni Rosenfeld (talk) 05:03, 20 October 2019 (UTC)


 * The article was proposed for deletion by, which proposal was reverted by an IP user (presumably the article creator not logged in). Agree with others that this doesn't seem Wiki-notable, and probably taking to AfD would be reasonable. --JBL (talk) 16:57, 20 October 2019 (UTC)
 * I'm a bit concerned that the article went through the AfC process and is now being considered for AfD. Apparently the person who reviewed and accepted the proposed article did not apply the GNG very thoroughly, which defeats the whole point of having an AfC process to start with. Perhaps this isn't the right forum for this discussion but, seeing as there are no actual math questions at the moment, I don't see the need to be a stickler about it. --RDBury (talk) 17:31, 20 October 2019 (UTC)
 * WP:AFC reviews are done by 1 user, and they're not expected to get the result right 100% of the time. The rule of thumb I've seen used at WT:AFC is that a good reviewer should avoid their acceptances being deleted by WP:CSD, and should have a ~50% chance of surviving an WP:AFD discussion. I don't see this acceptance as being unreasonable. Iffy★Chat -- 17:58, 20 October 2019 (UTC)
 * Thanks for the clarification. Given that the consensus here seems to be that the article pretty clearly does not meet the GNG and the fact that the GNG for math articles are relatively straightforward to apply, it's still a bit surprising to me that it would would have passed the reviewer. But in my experience with AfD discussions the 50% survival criterion is a pretty low bar since lack of consensus or just lack of interest is enough for an article to survive. --RDBury (talk) 22:20, 20 October 2019 (UTC)


 * Well, the article isn't vandalism or utter nonsense. It seems to have some meat to it, and there are 18 sources, and the title of the first source does match the article title. So, unless you dig deeper and look at each of the sources, at first glance it does look like a proper article. So, I wouldn't give the person who approved it a hard time. They can continue to sift out the utter chaff, and make it easier on the rest of us in that way. SinisterLefty (talk) 01:48, 21 October 2019 (UTC)

There should be a clear reference to the three planar number systems somewhere, possibly in Template:number systems. Such a reference should also make it clear that they can be represented as 2x2 real matrices. There used to be such a reference in Template:number systems before it was refactored, see here: https://en.wikipedia.org/w/index.php?title=Template:Number_systems&oldid=716069457. In the refactored form, the dual numbers are moved away from the split-complex numbers, which makes it less likely that a user would look at them one after the other. As John Baez said, the planar number systems are a great introduction to the freedom of mathematics. [edit] Added a section to the Template:number systems for planar hypercomplex numbers. Unfortunately, it repeats the reference to the Complex numbers and Split-complex numbers. --Svennik (talk) 07:42, 22 October 2019 (UTC)


 * One of the diagrams in the article is misspelled "eliptic" rotation. ←2A00:23C6:AA05:6500:70CE:68A1:CC10:5EBB (talk) 18:11, 22 October 2019 (UTC)


 * Yes, this one: . I replaced that 13.4 MB Tiff file with a 0.1 MB PNG file with the spelling corrected. As it's only used in this article, the misspelled version should be a moot point once the article is deleted. SinisterLefty (talk) 19:21, 22 October 2019 (UTC)


 * I just sent the article to AfD and have referenced the discussion here, so I'm keeping it pinned (assuming the archive bot respects pinning). I'll remove the pin when the AfD finishes.  –Deacon Vorbis (carbon &bull; videos) 14:38, 25 October 2019 (UTC)