Reappearance of (topology) tag

Question

I have noticed that topology tag was created again. According to list of new tags it was created Jun 9 at 7:55. There are currently 3 questions having this tag.

I was not able to find a discussion on meta where this was decided, but I know that this tag was not used. Since 2013 it had tag-excerpt saying: "Deprecated; please use a more specific tag." (Another example of deprecated tag is geometry - at least according to the tag-excerpt.) The tag (topology) has been completely removed in 2014.

What should be done about the topology tag if it reappears again, like it did now? Should we try to do something to prevent it from being created again?

• Should we simply rely on the fact that many users of this site know that this tag is deprecated and if it is created again, some users will remove the tag from the questions (and in the next 24 hours it will be removed from the site)?
• Should some reasonable tag-synonym be created, for example, topology $\to$ gn.general-topology? (This would prevent users from creating this tag as a new tag; if somebody will use it, the tag will automatically be changed to the master tag. The disadvantage is that some users might not notice that the tag they typed in was changed to the synonym.)
• Should the moderators request the SE team to blacklist this tag? (The obvious disadvantage is that users trying to use this tag might wonder why the tag called topology is not allowed. However, it is possible to customize the messages shown when a user tries to make a post containing some blacklisted input, see here and here.)

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EDIT: Now the topology tag has been already removed from all questions. So in 24 hours the tag should disappear completely, unless it is used in another question.

But the question whether something should be done to prevent this tag from being creating again remains.

Answer 1

The SE team has the ability to blacklist tags. The most efficient way to request this is probably to list all tags that should be blacklisted into a single (new) meta post "Blacklist [topology], ..." and where possible link to the meta posts that support this blacklisting. (As far as I can tell none of the links in your post why the topology tag should be disallowed.)

Tag synonyms are an efficient way of making sure that variant spellings are the same tag, e.g. four-manifolds → 4-manifolds. I think that topology → gn.general-topology is a reasonable synonym.

It might not be so straight-forward for geometry (which still has 533 questions, though).

Users are able to create suggestions for synonyms, but it's probably easier to have a moderator create the synonym.

Answer 2

One of the possible suggestions (both in the question and in this comment) is to create a synonym topology $\to$ gn.general-topology.

It is worth mentioning that many people use the term topology in wider sense, including general topology, algebraic topology, differential topology, etc. (The fact that the tag was used in this way is probably the reason why the tags had previously to be removed manually and not simply by synonymizing the two tags.)

So making a synonym could lead to a danger that some users will use this tag incorrectly. (I.e., not as a synonym of gn.general-topology, but using the word topology in the wider, more inclusive, sense.)

Considering this, it might be better not to create the synonym and try to think of other possible solutions instead.

You can use upvotes/downvotes on this post to show whether you agree with this assessment.

EDIT:

It might be worth mentioning that on math.SE there is was a synonym topology $\to$ general-topology for a long time, it was later removed. However, it might be rather difficult to find out whether the synonym has caused some questions to be incorrectly tagged.

But the situation on these two sites is somewhat different. On math.SE, (general-topology) is by far the largest from the topology-related tags. (Which is not surprising, considering that elementary questions are more often asked on MSE than on MO.) On Mathoverflow, the biggest topology-related tag is at.algebraic-topology with above 4k questions at the moment. Both gt.geometric-topology and gn.general-topology are somewhere around 2k.