# Tag management 2015 [duplicate]

Tags need a regular cleanup. This is a customary thread for tag synonyms etc.

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;
• let's wait a couple of days before implementing a suggestion;
• after the problem described in an answer is resolved, please edit it to say so.

(Of course if a proposal requires an extended discussion you can post it as a separate question.)

• A possible tool for finding not-so-great tags: Tags by percentage closed. I hypothesize that some tags, by their mere existence, encourage poor and/or offtopic questions; this query attempts to sort tags by badness of questions. – apnorton Aug 4 '15 at 16:51
• @apnorton I guess great minds think alike! Though mine is a horrible SQL mess (I think because I also wanted to have the overall % of closed questions, I don't remember). – Najib Idrissi Aug 4 '15 at 16:52
• @NajibIdrissi I swear I searched before writing mine! :P – apnorton Aug 4 '15 at 16:53

Can we also have a look at the tags on this site? (the meta site)

the so tag sorry don't know how to link (yet?)

and also

PS these are tags on the meta-mathematics site , not of the mathematics site

• You can link to meta tags using syntax similar to the one for main tags, namely [meta-tag:name] like etiquette – quid Jan 8 '15 at 23:00
• I assume you mean to delete those two? I hope my edits were correct. – 6005 Jan 8 '15 at 23:00
• I don't see any meta.so tag. – 6005 Jan 8 '15 at 23:00
• tags like (seeded-questions) looks both rather useless and harmless — they can be removed but frankly I don't see the point – Grigory M Jan 8 '15 at 23:12
• @Goos i ment the so tag , thanks for the correction – Willemien Jan 8 '15 at 23:13
• ok, making (behaviour) synonym might improve discoverability (both of the tag and the tagged questions); but for other suggestions?.. – Grigory M Jan 8 '15 at 23:14
• I would prefer keeping (seeded-questions) for historical reasons. The tag comes from the early days of this site. – Martin Sleziak Jan 11 '15 at 9:26
• I'm definately for deleting or synonymizing so into stackexchange. I've also retagged the two behaviour questions to etiquette, but still suggest making the former a synonym. – AlexR Mar 10 '15 at 18:59

As suggested before in What's the [problem-solving] tag for?, I propose to delete blacklist .
Consider its tag wiki:

Use this tag when you want to determine the thinking that is needed to solve a certain type of problem, as opposed to looking for a specific answer to a question.

while we also have , which says

For questions about approaches and techniques for discovering a proof, as opposed to writing it down clearly (which involves ). Should not be used unless the focus is on the technique of the proof instead of the solution.

I agree that is different from , but:

• the difference between them is very small
• the name 'problem solving' is misleading and leads to incorrect tagging
• as a meta-math tag seems to localised to encompass a significant amount of questions
• – Bart Michels Feb 20 '15 at 19:40
• Another related thread Which questions falls under the tag 'problem-solving'?. I will also add links to the revision history for tag-wiki and tag-excerpt. (So that it is easier to find them even in the case the tag is removed.) – Martin Sleziak Feb 21 '15 at 7:05
• I might be wrong, but IIRC every discussion about (tag-blacklist) so far has a separate thread. (Or at least most of them.) Maybe it's worth considering whether blacklisting something is a change important enough to deserve its own thread (and, consequently, a bit more attention from the community). – Martin Sleziak Feb 21 '15 at 7:08

Resolved

Rename to .
Rename to .
This is just for the sake of consistency, since the other tags containing the word 'polynomial' are in plural too.

Burninate and blacklist

The tag has been questioned long ago but is still in use, while I think it is not useful. Moreover the tag is being used for (at least) three different things:

• even and odd numbers;
• even and odd functions;
• even and odd permutations.
• I think (parity) should just be burninated. It's not very descriptive and doesn't really mean much. – Cameron Williams Mar 28 '15 at 4:04

Is the tag strictly about matrices, like the tag excerpt would suggest? If the answer is yes some questions need a change of tag, if the answer is no the tag excerpt should be updated.

• Vote this comment up if you think the tag should strictly be about nilpotence of matrices. – Najib Idrissi Apr 8 '15 at 18:34
• Vote this comment up if you don't think the tag should strictly be about nilpotence of matrices. (I know it's crude -- low visibility and no ability to withdraw the vote, but it's better than two answers IMO). – Najib Idrissi Apr 8 '15 at 18:34
• While I think it should not be only for matrices, I find it not optimal it is even used for nilpotent groups. – quid Apr 8 '15 at 18:44
• @quid The tag nilpotent-groups was removed last year. – Najib Idrissi Apr 16 '15 at 7:05
• Thanks for the info. Perhaps then the current tag could be renamed to nilpotent-elements or something like this, possibly with nilpotent-matrices as a synonym. And the questions on groups are retagged to something. – quid Apr 16 '15 at 10:59

Resolved: is now a synonym of . (see here.)

This is suggested here. The tag description for in fact describes math education instead of describing teaching in particular, so it looks like the two tags are being used interchangeably. I suggest be the parent tag since it is used more frequently.

In the future, can be for questions about math education, and for questions that are specifically about the process of learning.

(In some broad sense is a special case of but I think the distinction between these two is useful.)

Resolved: The tag was renamed.

I propose to make a synonym $\to$ .

The (double-factorial) tag was previously discussed here: http://meta.math.stackexchange.com/questions/17011/should-double-factorials-be-under-the-factorial-tag The voting on that post seems to indicate that the questions about double factorial should fall under (factorial) tag.

The (double-factorial) was removed at the time of the previous discussion, but it was recreated again. (Probably here, as that is the only question currently having this tag at the moment.) Even the tag-excerpt and tag-wiki were created.

To avoid repeated creating and removing of the same tag, I proposed the synonym mentioned above. If you have sufficient score in the (factorial) tag, you can vote for (or against) this synonym here.

Resolved The tag was removed. See also the separate post for this tag: Can we delete the [basis] tag?

Do we really need ?

More specifically, there are different notions of basis in mathematics, and the tag is practically useless without adding a distinction between them.

• It might be a useful tag. In any case: a) If we decide we do not want the tag, it should probably be made synonym of (linear-algebra). (As to prevent repeated creation of the same tag.) b) If we decide that we want this tag, then the tag-wiki should definitely be clarified. (For example, there are some questions about basis for a topology in this tag at the moment.) Link to a related conversation in chat: chat.stackexchange.com/rooms/3740/conversation/basis-tag – Martin Sleziak Jun 30 '15 at 17:31
• Martin, at 30 questions and gaining, this tag becomes a big mess. Any advice? – Asaf Karagila Jul 25 '15 at 23:02
• I created tag-info which says that this is for questions for basis of a vector space. I will try to retag the questions which do not belong here and add (linear-algebra) to questions which do not have this tag. (This activity might help some other users to notice the issue.) If you prefer to get rid of this tag, you can either suggest a synonym (basis) -> (linear-algebra) and wait for enough users to vote. Or you can open a separate thread on meta, if you prefer. – Martin Sleziak Jul 26 '15 at 7:12
• Thanks, Martin. I've suggested a synonym. It really seems like a bad tag. – Asaf Karagila Jul 26 '15 at 7:18
• There is now a separate thread discussing this tag. (Just adding the link - so that if somebody comes across this post, they see the other discussion too.) – Martin Sleziak Jul 29 '15 at 6:33

Resolved: The tag was removed.

I can't see the utility of a tag like created here: Krull's height theorem in the non-Noetherian case. I can't also see why M.SE gives permission to low rated users to create new tags. (In my opinion this could be given to users rated >20k as one of the last privileges.)

There exist tag, which was created for the question about divisors in algebraic geometry. At least this seems to be the case based on the tag-wiki and tag-excerpt. Current revision looks like this:

For questions involving divisors, invertible sheaves and/or line bundles on varieties and schemes.

However, it is very likely that a tag with such an ambiguous name will be used by people who do not read the tag-excerpt for questions from elementary number theory (and perhaps ring theory). (Probably most of such question could be tagged by appropriately by already existing tags, such as , , , etc.)

To avoid these problems, I suggest to change the name of the tag to or some other suitable name. Since at the moment there are only 4 questions in this tag (three of them about algebraic geometry), this can be done manually without bumping too many questions.

(The name would be probably better, but it does not fit 25 character limit for names of tags.)

• If we must shorten it, wouldn't "alg-geo" be better, or at least "algebraic-geo"? – Asaf Karagila Sep 30 '15 at 15:40
• There are now 23 questions in the tag :( – Najib Idrissi Jan 5 '16 at 14:07

Resolved ( made synonym of and merged with )

We have tags and . Now I'm not an expert so I could have gotten it wrong, but it seems to me that these two things are actually the same. Could the tags be made synonyms? Preferably with as the main tag?

Resolved

After posting a question in , I realized that the tag got kind of mixed up. Any ideas how to solve this...?

Do we need 2 tags? For currently 10 questions...

EDIT: By mixed up it's meant that it contains question both about graphs of functions (and their symmetries) and questions from graph theory.

• I'd propose to drop the tag. – quid Jan 18 '15 at 23:31
• By mixed up you mean that it contains question both about graphs of functions (and their symmetries) and questions from graph theory? (Basically a little brother of problematic situation with (graph) tag before that tag was blacklisted.) – Martin Sleziak Jan 27 '15 at 7:59
• @MartinSleziak exactly... – draks ... Jan 27 '15 at 8:10
• Perhaps it would be useful to add the clarification to the post. (Not everybody immediately realizes what is meant by midex-up. It might save time of other users, so they do not have to go to check the questions to see what exactly the problem with this tag is.) – Martin Sleziak Jan 27 '15 at 8:12
• BTW there also is (symmetry) which could be used in combination with either (graphing-functions) or (graph-theory). – Martin Sleziak Jan 27 '15 at 8:17
• @Martin right, sorry to everyone who wasted time, figuring out what I meant. If combining tags to classify a question is a good way, I would go with quid's comment and also vote to retag the questions and delete the tag. Or better: what if we put a remark in the tag wiki saying: "If your question addresses symmetry of graph use the combination of blablabla..." ? – draks ... Jan 27 '15 at 11:34
• What would graph symmetry refer to within graph theory? Isomorphisms or planar symmetries? – user142198 Jan 28 '15 at 12:51
• @Committingtoachallenge I would say both. – draks ... Jan 29 '15 at 6:20
• Problem with this tag is that upper level math people are going to think algebraic-graph-theory, and calc 101 people are going to think even/odd/origin symmetry. If we map to algebraic-graph-theory we're gonna get confused wanderers in that tag, if we map to some lower level tag we're going to get belligerent graph theorists. It's only on 10 questions, so I'm propose we sweep it under the rug and pretend it never existed. – Alexander Gruber Mar 26 '15 at 0:19

Update: The synonym is no more.

(While questions that were tagged before the synonym was introduced have regained their tag, this is not the case for questions that "should" have been tagged while the synonym was up. These are still tagged .)

has been made a synonym of . We decided not to do so, see Should the tag (fractions) be a synonym of (rational-numbers)? and The [fractions] tag. The synonym suggestion was pending for a long time already but for some reason has been approved just now.

Important note: Martin Sleziak posted two answers in one of the linked discussions to count votes for and against the synonym. Consider voting up (not down) your preferred choice.

• Here is link to tag-wiki and tag-excerpt for fractions. (It seems that the tag-info can survive synonymization.) – Martin Sleziak Jun 16 '15 at 15:06
• I don't understand why this happened, since I think the consensus was against it both times it was proposed. – MJD Jun 25 '15 at 11:08
• @Martin The tag wiki and excerpt does not accurately reflect the general usage of these terms (which span from elementary to advanced level). What is the process for revising these entries? – Bill Dubuque Jun 25 '15 at 13:32
• @BillDubuque I think you can simply change the wiki if you want; though perhaps you might want to mention the suggested edit in the tagging room first to see if anyone disagrees. – Bart Michels Jun 25 '15 at 13:40
• @BillDubuque At the moment, the two tags are synonymized, so if we want to edit tag-info, the synonym must first be cancelled. But in general: Every user with sufficient rep can edit them. If a user below 20k edits tag-info, the edit must be review by at least two users. However, I think it is better to discuss changes on meta - at least in cases where there is a probability that there might be some disagreement about the usage of tags. – Martin Sleziak Jun 25 '15 at 13:55
• I will add that it is not important whether the the tag-info reflects the usage of terms. It is more important that it correctly describes how the tags should be used on this site. For example, if the discussion on meta and tag-info clarified that the tag (filters) is for filters in set-theoretic and order-theoretic sense, then this tag should not be used for Kalman filters and other filters used in digital signal processing and various related areas. – Martin Sleziak Jun 25 '15 at 13:58
• In any case, if further discussion about editing tag-info (=tag-wiki or tag-excerpt) is needed, we can continue in chat. (If needed, it can be discussed even in a separate post on meta. But it would be good to search first whether there already have been some discussions related to this.) – Martin Sleziak Jun 25 '15 at 14:09

Currently the tag is used for both primitive roots in modular arithmetic and questions involving primitive roots of unity. Since these two things aren't immediately related this is undesirable. I once edited the tag wiki, adding

For questions about primitive roots of unity, use the (roots-of-unity) tag instead.

hoping that this would help users to use the tag appropriately, but I think it will be more effective to introduce a tag.
I suggest either clarifying the tag (renaming it if necessary) in order to make it exclusively for primitive roots in modular arithmetic, or creating a new tag for primitive roots of unity instead, though such tag would not be of much value.

Note: previously I asked this as a question, receiving the following comments:

There's a thread dedicated to tag management issues. Anyway I disagree with the creation of a tag: there is no way that someone would want to search of that tag or ignore it and not do the same with . Clarifying is the way to go (either include both topics or rename it/edit the tag wiki to something clearer). – Najib Idrissi

and

I agree with the preceding comment. If at all the tag you propose should be a synonym of the existing one. – quid

• There were only twelve cases, I re-tagged them manually using roots-of-unity. – Bart Michels Jan 24 '15 at 20:26

The tag has inconsistent plurality. I suggest renaming to .

Resolved

I think that (covering-maps) is a good synonym for .

Do we really need both and ?

I'm honestly asking, since both these tags seem to be way out of my league. Perhaps someone better versed can make some comments. Are they even both needed at all?

• Background: Do we need more stability?. In the comments, I was in favor of [stability-theory] but David Speyer pointed out different intepretations of it. Of course, most of tagging is done by users less knowledgeable than David Speyer...Maybe your answer could be posted there, for better proximity to the roots of the tag... – user147263 Jul 28 '15 at 23:37
• Tags are a Folksonomy anyway; if most users think that stability-theory is the way to tag ODE questions, then so be it... – user147263 Jul 28 '15 at 23:40
• I really don't know. This is way out of my water, and I'm honestly asking if we need two stability tags. If someone from the field of ODE wants to say "yes", then I'm willing to take their word for it. – Asaf Karagila Jul 28 '15 at 23:41
• I understand; My main suggestion is to move the discussion to the already-existing dedicated thread. Since it already exists.... – user147263 Jul 28 '15 at 23:42

Update: The tag was created by Martin. So it seems that the best course of action is now to merge these two tags, or add them as synonyms.

Do we need the and ?

I have no opinion on the matter, but maybe those should be merged into a single tag somehow?

And if we keep the tags as they are, someone should probably write at least a tag wiki excerpt.

• @Martin: Thanks. I haven't even noticed that. – Asaf Karagila Jul 19 '15 at 11:02
• I don't think we need these tags, just like we don't need tags like "coproduct", "equalizer" and every possible (co)limit shape one can think of -- that's way too many tags for a very limited payoff (if there's a payoff at all, I can't think of any). – Najib Idrissi Jul 24 '15 at 9:13
• @Najib: What about the recently created limits-colimits? – Asaf Karagila Jul 29 '15 at 17:00
• I think making both direct-limits and inverse-limits a synonym of limits-colimits would make sense. – Najib Idrissi Jul 29 '15 at 18:12
• @Najib: That's a good idea. I don't have the needed reputation, though. – Asaf Karagila Jul 29 '15 at 18:14
• Neither do I... – Najib Idrissi Jul 29 '15 at 19:56
• @Najib: Well. I raised a flag asking the moderators to take care of that. So now we play the waiting game. – Asaf Karagila Jul 29 '15 at 19:57
• I've just retagged the four inverse-limits questions, there are still 8 direct-limits questions left (I'll probably wait a bit so as not to flood the front page). – Najib Idrissi Sep 7 '15 at 12:00
• Both tags have been removed. Perhaps this can be marked as resolved? Or do you still wish make the synonym? – Martin Sleziak Sep 11 '15 at 15:27
• @Martin: I guess we can mark that as solved for now, and if they return we can sue for synonyms further. – Asaf Karagila Sep 11 '15 at 16:37

I propose creating the tag and also adding the tags and as synonyms.

This seems to be relatively important topic and we have enough questions about definiteness of matrices. You can also notice that some users use the tag for this purpose. (A few examples are listed here.) Creating the new tag would prevent such mistaggings.

Suggested tag-excerpt:

For questions asking whether some matrix is positive definite (negative definite, positive/negative semidefinite, ...) and for questions asking about properties of positive definite (negative definite, positive/negative semidefinite, ...) matrices.

• What sorts of questions would be included under this tag? Would questions about a specific matrix which happens to be positive-definite fit? What about semi-definiteness? For an answer here proposing a new tag, I would much prefer to see information about how you think the proposed tag should be used. Tag-excerpt and -wiki proposals might also be valuable additions. – user642796 Aug 12 '15 at 10:10
• I'd say it is more or less self-evident that not every question containing positive definite matrix would fall under the tag. If the fact that it is positive definite is relevant, then it is a good fit. – Martin Sleziak Aug 12 '15 at 10:15
• I don't support (definiteness) but (positive-definite) seems pretty acceptable to me. – Cameron Williams Aug 15 '15 at 0:51
• @CameronWilliams The reason for suggesting (definiteness) was that it seems reasonable to have under same tag questions about positive (semi)definite matrices and negative (semi)definite matrices. So I looked for a word encompassing both of these notions: en.wikipedia.org/wiki/Definiteness_%28disambiguation%29 – Martin Sleziak Aug 15 '15 at 8:42
• Yeah I actually retract my comment. I think it's a better tag for sure. – Cameron Williams Aug 15 '15 at 13:55
• It seems that (positive-definite) was created here. Maybe it will survive. (In that case we can consider this resolved.) – Martin Sleziak Oct 13 '15 at 10:01
• There is now a positive-semidefinite tag. I think it should be made a synonym of positive-definite. – user856 Jun 22 '16 at 0:13

I don't have sufficient privileges on this site to create a tag, but I think that it would be useful to have a new tag imprecise-probability, which I would have applied, instead of four other somewhat misleading tags, to this question that I recently asked. [EDIT: There is at least one other question for which imprecise probability would be appropriate.]

Imprecise probability is a broad term for a class of concepts and methods that generalize ideas probability theory beyond real-valued probability measures. It's most readily viewed as a way of extending Bayesian probability to reflect uncertainty in degrees of confidence, but there are uses of the idea that don't necessarily reflect these Bayesian roots. The term covers, among other things, upper and lower previsions, upper and lower probability, interval-valued probability, credal sets, lower envelopes, and Choquet capacities (see e.g. Fabio Cozman's introductory page). There are at least three book-length mathematical treatments: Walley's classic Statistical Reasoning with Imprecise Probability, Augustin et al.'s Introduction to Imprecise Probability, and Troffaes and de Cooman's Lower Previsions (along with earlier works of mathematical philosophy such as Levi's The Enterprise of Knowledge). There is an academic society with regular conferences on the topic, the The Society for Imprecise Probability: Theories and Applications.

Imprecise probability is related to ideas for which we already have tags: probability-theory (obviously), fuzzy-logic and fuzzy-sets (the focus is usually on different axioms), and robust-statistics (since these make use of sets of probability measures). The expectation tag is also related, since upper and lower previsions generalize expectation. However, none of these tags seems correct for the topics mentioned at the beginning of the second paragraph above. I do think that "imprecise probability" is sometimes used in sense that allows it to overlap with the domains of the tags I just mentioned, but those tags nevertheless misleading for a question such as the one I asked.

Here's a possible tag description, copied from the SIPTA website:

Imprecise probability is understood in a very wide sense. It is used as a generic term to cover all mathematical models which measure chance or uncertainty without sharp numerical probabilities. It includes both qualitative (comparative probability, partial preference orderings, …) and quantitative modes (interval probabilities, belief functions, upper and lower previsions, …). Imprecise probability models are needed in inference problems where the relevant information is scarce, vague or conflicting, and in decision problems where preferences may also be incomplete.

(Ellipses in the original.)

Resolved: The tag is gone

What is for?

It is often misused, and when it is used correctly it seems to be synonymous with , though I don't have the expertise to say so for sure.

• Yes, it would be a synonym of distribution-theory. There is a (poorly written) tag wiki. I don't think we need this tag. – user147263 Nov 28 '15 at 20:38
• I retagged and edited those questions. The tag should go away soon. – user147263 Nov 28 '15 at 20:54

the different tags for like

and maybe more

combine them all to one tag (and make the rest synonyms)

ps how do you link to a tag?

• To note puzzle and riddle are already synonyms. – quid Jan 6 '15 at 15:50
• I'm not sure to what extent (recreational-mathematics) ends up being useful, as there are a lot of things which could qualify. But I do like (puzzle)/(riddle), which seems much more concrete. I am not sure I would like them all to be combined. – 6005 Jan 8 '15 at 22:29

Resolved: the tags have been deleted

These 2 tags: and seem to be created for just one question. Even the tag names are not math-related. Why do they still exist?

• They still exist because nobody removed them. Anybody with edit privileges can edit the question to remove these tags, and they will be deleted in 24h. It doesn't look like the question is primarily mathematical in nature anyway... – Najib Idrissi Mar 4 '15 at 12:50

The -issue should not be forgotten. It has been mentioned more than a year ago in http://meta.math.stackexchange.com/questions/11232 but has not been solved since.

Rename to and make it a synonym of

It should be noted that congruences are in fact more generally used in algebra, whereas modular arithmetic technically only covers the integers.

Make a synonym of . Perhaps pluralize .

has about 15 questions at this time of posting.

I don't think we need this tag at all. Does anyone have any arguments in favor of keeping it?

• This falls into same category as Klein bottle or Sorgenfrey line. We probably have a few tags about particular topological space. I think such tags might be useful. In particular, Cantor set is frequently used in real analysis. (Maybe posts about Cantor function could go into the same tag - they are closely related.) – Martin Sleziak Apr 29 '15 at 5:49
• Maybe. I'm not sure that those tags are useful either. They don't give you anything that the half-working search system couldn't give you easily. – Asaf Karagila Apr 29 '15 at 6:11
• I've made this argument already (@Martin linked to it), but it seems that the community's opinion (or at least, the people who browse meta) is that such tags are useful. – Najib Idrissi Apr 29 '15 at 7:59
• @Najib: Some people make mistakes. :-P – Asaf Karagila Apr 29 '15 at 16:49

We have a tag, apparently. I think it could be either removed or merged/synonymized into .

• I was thinking the same thing myself. There is a very slight difference in meaning (or at least a difference in connotation), but it is so extremely slight that most askers will simply use the word their textbook uses. – Carl Mummert May 29 '15 at 13:32

There are tags and . While there is a slight difference, I do not think we need these as separate tags. (Especially not as there is also which could be use for questions on more "formal" aspects.)

I propose to make these two and synonyms. Actually, I think they could even be merged into .

I noticed that we have available. And I think it should be merged/made a synonym for .

While the distinction has merits, much like the distinction between first-order logic and predicate calculus into two tags has merits, these tags are barely used, and it makes sense to bunch them together. Not to mention that only 4 of the current 16 questions are not tagged with the modal logic tag.

• What if someone asks about Kripke models in the context of intuitionistic logic? – user642796 Aug 6 '15 at 4:12
• There seems to be a question about intuitionisitic propositional calculus under this tag. But it also has the modal logic tag... – Asaf Karagila Aug 6 '15 at 7:21