# Tag management 2023

New year, new tag management thread.

Rules of the game are basically the same:

• A particularly bad tag (a rule of thumb: “if I can't imagine a person classifying a tag as either interesting or ignored, I'm getting rid of it”),
• A tag that should be a synonym of an existing one,
• A tag that used for two or more completely unrelated things,
• A need to create a new tag.
• Wait a couple of days before implementing a suggestion.
• After the problem described in an answer is resolved, please edit it to say so.

Also, note that one may use [tag:calculus] for , i.e. tags on the main site, and [meta-tag:discussion] for , i.e. for tags on the meta site.

Note that, in some cases, it might be better to have a separate question. Typically this happens when a longer discussion is needed and several possible answers are expected, since answers to a question provide more space for a more detailed discussion than comments under an answer in this thread.

• I will just mention that the list in the question will show a pending synonym only to users with sufficient score to vote for (or against) the synonym. Still, one can get list of all pending synonyms from SEDE: main, meta. (Keeping in mind that the database is only updated once a week.) Jan 20 at 16:20

Proposal: Delete tag .

This is a useless tag. It is only on two questions and is reminiscent of the old 'homework' tag.

• Actually, the tags called (math-school) and (school-math) have been created and removed a few times already. Jan 31 at 15:16
• I edited it off those questions. It should be gone soon. Feb 1 at 2:09

Proposal: Delete . I just created this tag but Elliot Yu pointed out rightly in a comment here that it is ambiguous. To solve this, I just created the better tag , which is unambiguous. Because of the existence of the latter, the former doesn't serve any purpose anymore.

I propose the tag Fractional-differential-equations (FDE). They are increasingly becoming important. To give a flavor of its importance I'm including an article in which the Covid pandemic was studied with FDE: Application of piecewise fractional differential equation to COVID-19 infection dynamics - 2022 - Xiao-Ping Li et.al.

The tags ordinary-differential equation, and partial-differential-equation already exist. Some fractional calculus questions do not deal with fractional differential equations, while other questions do, therefore showing the difference is important. Second, I had to tag my question Fractional Bernoulli equation and logistic function with the incorrect tag ordinary-differential-equation, to explain that the question dealt with differential equations; but the tag I added is misleading if one is searching for the subject of fractional differential equations and excludes questions dealing with ordinary differential equations.

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Proposal: Add tag witt-vectors.

There are quite a few existing questions about Witt vectors, and most of them are tagged with some combination of , , , , , and so on. Witt vectors are a rather specific construction, so I don't feel that any of these generic tags really does these questions justice.

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• I created a tag synonym proposal for this. Feb 1 at 6:11
• Why did people downvote the tag-synonym? Feb 1 at 16:01
• If a question about dice is about probability, it should tagged probability. Dice is just a funny unnecessary additional tag, like Cards or Coins. I think there is nothing wrong in it given it is not used instead of probability. Feb 6 at 10:12

• Some older posts related to the tag (birthday): The birthday tag and Tag merging and synonyms. Feb 1 at 5:58
• @MartinSleziak I created a tag synonym proposal for this. Feb 1 at 6:11
• I see, maybe you should include a link to the list of proposed synonyms for problability. In the list of all tag synonyms on can see that it was proposed in December 2022. The same information can be obtained from SEDE. Feb 1 at 6:58
• @mathlander, did you see the "Wait a couple of days before implementing a suggestion" in the rules? Feb 1 at 9:00
• @PeterPhipps As far as I can tell, the OP suggested the synonym already on December 2 - about two months before this post. It seems that in the meantime, the suggestion was downvoted to $-2$ and removed. (But it was there today - and it is still shown in SEDE.) Feb 1 at 11:15

Proposal: Add tag dual-numbers.

Although the dual numbers are a well-known hypercomplex number system, there is no tag for the dual numbers in SE (e.g. for this Question). As far as I've seen so far, there are no synonyms for dual numbers too.

• Probably it is worth pointing out that the tag (dual-numbers) was created and removed a few times in the past. I was able to find four questions, they are listed in the tagging chatroom. (I think that the most recent one was precisely the question you linked.) Feb 1 at 17:02

I think that at least 1 new tag for questions based on Bourbaki's math' treatises is needed, especially for their measure theory which is practically another subject than what is found under that title elsewhere. This is not always a problem, but it can be, due to different definitions - one can often "identify" corresponding concepts, but this may be invalid in some cases.

Too bad that there are still so many anti-bourbaki-ists among mathematicians. I myself am not a Bourbaki fanatic but appreciate much of their publications (Bourbaki is not an individual but a name for a group of mathematicians with variable membership, they publish in French) - not being a fanatic I sometimes want to study math' literature based on foundations possibly conflicting with Bourbaki's, and then I may have problems to "integrate" such literature with what I learned from Bourbaki. This is especially the case with measure theory which is never a simple thing. That's why it happens that if one of my questions gets attention, I can receive answers / comments not fitting my needs and when I indicate that I am using other definitions, the potential answerers lack the needing bases, so I get no usable answer. While on the other hand people with a Bourbaki background - if there are at all some using this site ... despite the language barrier which might also play a role - will not look into my questions if they have no reason to think I might have a compatible background.

Without a corresponding tag I have to mention this background in the title of such questions. I have already edited the title of one of them (call it X) - for which I eventually found and published myself an answer. In my opinion this justifies the creation of Bourbaki-related tags, especially one like [Bourbaki-measure-theory] ... I cannot do this myself, not having yet the priviledge needed. The already mentioned Q&A item X could be used to create the new tag. If my idea gets a priori approval I'll produce content for the description of the tag.

• My proposal has been immediately been down-voted. Is this a rational reaction or one based on hate of Bourbaki? Feb 8 at 0:21
• Can you expand on why mentioning this in the title is insufficient? Titles are generally more widely read than the tags, and being clear about the setup for problems here at MSE is something that we already encourage quite a lot. Feb 8 at 2:15
• The tag (bourbaki) was created and removed in the past, I have posted some statistics in the Tagging chatroom. There is a related post in an older tag management thread. (And there was a separate question today - now deleted: I want at least one new tag for questions specific to Bourbaki's math' treatises, especially measure theory.) Feb 8 at 5:04
• @MartinSleziak the target of the last links (a now deleted question) was mine. After receiving a duplicate mention and realizing that I was supposed to enter my proposal here (and doing this) I deleted that myself. From another of your links, I found written: "The tag [bourbaki] is entirely useless. It gives nothing that searching "Bourbaki" doesn't already do". How is such a search done? Is it only finding Bourbaki when mentioned in a title? And who might do that? IMHO the same argument might apply to all tags ... so why tags at all? (continued) Feb 8 at 14:52
• I take the opportunity to mention that I did not find how to search for 2+ tags at the same time (combined with AND) Is this possible, if yes, how is it done? Same question for a tag and a non-tag word Feb 8 at 14:56
• @KReiser I will not answer your question for the moment, because I logically wait for answers to the two comments I just made Feb 8 at 14:59
• @UlysseKeller The basics of searching are unrelated to the discussion here - in order to avoid a long discussion unrelated to this topic, I posted some examples of possible searches in chat. Feb 8 at 15:00
• "My proposal has been immediately been down-voted. Is this a rational reaction or one based on hate of Bourbaki?" Votes on meta work differently. An upvote means "I agree with this suggestion," while a downvote means "I disagree with this suggestion". Downvotes on meta have no effect on reputation. There is no reason to read "hate" into these votes.
– Xander Henderson Mod
Feb 9 at 17:42
• @KReiser My little question to Martin a few comments above got no answer yet. I mean this: IMHO the same argument might apply to all tags ... so why tags at all? Once this is answered, I will be able to form a new opinion on your Q. Can you expand on why mentioning this in the title is insufficient? (or not - depending on that answer) Feb 9 at 17:57
• @XanderHenderson I clearly said "hate of Bourbaki" not of my person. Don't identify me with B. Feb 9 at 18:03
• There are issues of scale here. It's good to separate analysis and algebra by tag: they are large, distinct areas of math where many people will want to look at one instead of the other. Sometimes, as the resolution increases, this can be a more interesting ask - do we need to separate questions on Dummit and Foote's algebra text versus Fraleigh's algebra text? Probably not. Where does your request fall on this continuum and why? Feb 9 at 19:18
• @KReiser May-be a Bourbaki tag is really useless for nearly every situation where Bourbaki plays a role. BUT the case of measure theory is special: Bourbaki's and the classical MTs are like two different theories because at the start they differ wildly and much has to be done until what comes later is more or less the same. At the base the terminologies are not compatible; this problem ends only once the theories allow identifications (an abuse of language normally accepted because it simplifies things). But here things are not even 1 to 1 (continued) Feb 9 at 21:23
• (my last comment cont.) Bourbaki-style measures on a given l. c. space build a vector space. The difference of two positive measures in (say) Halmos may not exist. You can't even say that for $\mu$ = the Lebesgue measure on the real line, then $\mu - \mu = 0$ ... because this difference is undefined due to the essentially undefined charachter of oo - oo. And some Bourbaki-style non >=0 or complex measures have no counterpart in Halmos-style. This could be solved by some changes on the Halmos side, but this might be even more complicated than I first thought due to a detail I found @ Halmos Feb 9 at 21:46
• @UlysseKeller I do not think that you should read any hate into the downvotes, either for yourself, or for Bourbaki. That simply isn't what votes here mean.
– Xander Henderson Mod
Feb 16 at 17:29
• The problem ImhO are other people knowing Bourbaki - espec. their measure theory (MT) - who'd look here for answers & give answers ONLY IF they know that Bourbaki MT is ALSO a theme here (I think esp. about French lang. people with sufficient English-knowledge) ... the any way little chances would be better if they see a tag like say [Bourbaki-measure] ... after what has already been discussed here I don't imagine getting a general Bourbaki tag but only 1 for MT, for which it is like ANOTHER SUBJECT altogether (not the name B. is what matters but the special subject best described by using it) Feb 21 at 9:50