There is a tag called . (It seems that it was created by this user.) Both tag-wiki and tag-excerpt are currently empty, so the usage is unclear.1 If we consider just the name of the tag, there are plenty of situations where it can be used: vector spaces, topological spaces, metric spaces, normed spaces, ... At the moment there are 53 questions having this tag. Majority seems to be about subspaces of vector spaces.

It seems that we have basically two options:

  • Use this tag as a kind of "meta tag" - the meaning will be clear from other tags added.
  • Specify for which of the possible meanings it should be used. (Although in that case it would probably be good to rename tag to something more descriptive.)

I will mention that some similar tags have been discussed -- I mean various tags related to creating new structures from old ones, where the particular construction is applicable to various types of structures.

1In the meantime, the tag-info has been added. The current wording seems to suggest that the tag is for vector subspaces. (I will also add link to the revision history of the tag-excerpt and the same for the tag-wiki.)


1 Answer 1


Update. The tag has been removed thanks to a friendly neighbourhood Community Manager.

There's another possibility that hasn't been mentioned in the OP, and the one I would prefer: kill it!

I don't see as a tag that will ever be consistently used, and not something that has a concrete enough meaning to allow for an easy delineation of when it should be used. Should you apply the tag if you are asking about a specific subspace of some specific ambient space (e.g., "Does this subspace $Y$ of $X$ have property $\mathfrak{P}$?")? Should you apply the tag if you are asking about types of subspaces of some specific ambient space (e.g., "Does $X$ have a subspace having property $\mathfrak{P}$?")? Should it be used when you are talking about the general notion (e.g., "How do you test that something is a subspace?")? I feel that these sorts of questions have about an equal likelihood of ever being given the tag, but have vastly different connections to the concept itself. (I feel that these types are listed in more-or-less increasing connection to the concept.)

Even if it were or , I wouldn't be much in favour of the tag.

(And I'd say we should kill a number of the tags mentioned in the OP.)

  • $\begingroup$ By "kill it" you mean removing the tag from all questions or do you want even to blacklist it. $\endgroup$ Sep 10, 2015 at 16:26
  • $\begingroup$ I agree that I would definitely prefer two separate tags (or more if needed) to having only one tag. Let's wait to see how other users vote on your post and what they say in the comments - based on this we can take some action. $\endgroup$ Sep 10, 2015 at 16:28
  • $\begingroup$ @MartinSleziak Simple removal would be fine for now. If it becomes a recurring problem, then a blacklist might be appropriate. But there's no need to involve CMs at this moment. $\endgroup$
    – user642796
    Sep 10, 2015 at 16:37
  • $\begingroup$ About last sentence: I'd say we should kill a number of the tags mentioned in the OP. Would it perhaps be better to make a new question to discuss this type of tags in general? (I suppose it is more-or-less clear what is mean by "this type of tags". Having one post about the general issue would probably be better than the current situation - we have several post about various tags which are, to some extent, of the same nature.) This is a digression from the original topic, so perhaps we may continue this discussion in chat (if needed). $\endgroup$ Sep 10, 2015 at 16:42
  • $\begingroup$ Where are we on the burnination of this tag? $\endgroup$
    – Asaf Karagila Mod
    May 6, 2016 at 18:59

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