The word covering has various meanings in mathematics. Quite often choosing a tag-name which has several unrelated meanings can lead to problems - typically bunch of rather unrelated questions end up under the same tag.
Probably the most common meanings are covering spaces and covering maps in algebraic topology, covering and packing in discrete geometry, various types of covers in graph theory (vertex cover, edge cover) and covers in the meaning which is used in definition of compact topological space.
Not too long ago there was a discussion about these tags in chat. I will quote from this discussion:
François G. Dorais said:
Todd Trimble mentioned:
People seem to be using the tag however they like, which makes it virtually impossible to provide tag info as things stand. But the main division seems to be between covering maps/spaces in algebraic topology and uses in discrete math, so the solution may involve first re-tagging some of those as covering-spaces.
Not too long after this conversation the tag packing-and-covering was created. (Probably near the beginning of September). I will also add that there are separate tags for sphere-packing and circle-packing.
Still, some points remain unclear even after the discussion in chat. And bringing this up on meta might help to clear up things and also bring the issue to the attention of the community. (There were only three users involved in the discussion in chat.)
- The tags packing-and-covering and covering-spaces currently have empty tag-info. Would somebody knowledgeable be willing to add at least a tag-excerpt?
- If the questions from covering which actually are from discrete geometry/algebraic topology are retagged with the above two tags, what will happen to the rest? Are there some other "covering-related" tags which should be created?
- What are plans with the current covering tag? Is it supposed to be deprecated and eventually removed?
- Or should the tag covering be kept, but with tag-info stating explicitly for which meaning of the word covering is the tag intended?
- Maybe it would be good to state in the tag-excerpt (currently empty) at least the fact that there are tags (packing-and-covering) and (covering-spaces) and questions from these areas should use these tags rather than (covering).
Should this be a factor when discussing what to do with this tag, I will add that even if the tag is removed, the taxonomist badge awarded for creation of this tag will not be taken away.