Question: New year, new tag management thread.

Rules of the game are basically [the same](https://math.meta.stackexchange.com/q/27653/43351):

* Post your suggestion as an answer here if you see
	+ 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;
* Upvote/downvote/comment as your agree/disagree with suggestions, so please post different suggestions in separate answers;
* Wait a couple of days before implementing a suggestion.
* After the problem described in an answer is resolved, please edit it to say so.
* If your tag suggestion exists in a separate question, please provide a link to the question in your suggestion.

See also:

* The [list with pending and approved synonyms](https://math.stackexchange.com/tags/synonyms).
* The [tagging chatroom](http://chat.stackexchange.com/rooms/3740/tagging) for extended discussion on tagging.
* [Last year's thread](https://math.meta.stackexchange.com/q/27653/43351) to look for suggestions that need to be implemented.

Also, note that one may use `[tag:calculus]` for [calculus](https://math.stackexchange.com/questions/tagged/calculus "show questions tagged 'calculus'"), i.e. tags on the main site, and `[meta-tag:discussion]` for [discussion](/questions/tagged/discussion "show questions tagged 'discussion'"), i.e. for tags on the meta site.

Answer: 
> 
> **Resolved:** The [tag synonym](https://math.stackexchange.com/tags/differential-graded-algebras/synonyms) was created.
> 
> 
> 

I suggest a synonym [dg-algebras](https://math.stackexchange.com/questions/tagged/dg-algebras "show questions tagged 'dg-algebras'") $\to$ [differential-graded-algebras](https://math.stackexchange.com/questions/tagged/differential-graded-algebras "show questions tagged 'differential-graded-algebras'"). 

The tag (dg-algebras) was created in [July 2017](https://chat.stackexchange.com/transcript/3740/2017/7/9) (shortly before allowed length of tag names was increased). A short tag-excerpt was also [created at the time](https://math.stackexchange.com/posts/2351655/revisions). The tag (differential-graded-algebras) was created recently ([July 2019](https://chat.stackexchange.com/transcript/3740/2019/7/6)).

It seems clear that both tags are intended for the same meaning. Hence they should be synonymized. (Probably the tag with full name might be more suitable for the master tag - although I'd guess that either way would be acceptable.)

I'll add that synonym between the tags with these names [exists on MathOverflow](https://mathoverflow.net/tags/differential-graded-algebras/synonyms).

Since the two tag names are probably due to change in the character limit for tag names, I'll add also a link to the thread about [Expanding abbreviated tag names](https://math.meta.stackexchange.com/q/26776).
**Proposal: rename [eulerian-path](https://math.stackexchange.com/questions/tagged/eulerian-path "show questions tagged 'eulerian-path'") to [euler-trail](https://math.stackexchange.com/questions/tagged/euler-trail "show questions tagged 'euler-trail'")**

First off, a walk that traverses every edge of a graph is generally not a path but a trail. Second, when this situation occurs, it is the graph that is described as Eulerian and not the walk (at least IME). 

While I'm here, I may as well add that the tag is used to discuss Euler circuits (not to be confused with the again incorrect Euler cycles). If we were decide to go with [euler-circuit](https://math.stackexchange.com/questions/tagged/euler-circuit "show questions tagged 'euler-circuit'") then we may as well also change [hamiltonian-path](https://math.stackexchange.com/questions/tagged/hamiltonian-path "show questions tagged 'hamiltonian-path'") to [hamilton-cycle](https://math.stackexchange.com/questions/tagged/hamilton-cycle "show questions tagged 'hamilton-cycle'") for two of the three above reasons. 

I just read a wearying [debate](https://en.wikipedia.org/wiki/Talk:Eulerian_path#'path') on Wikipedia about whether they should rename their page from "Eulerian path". The opponents claimed that computer scientists misuse mathematical language all the time and "path" beats "trail" in Google Fight. The proponents' claim that it's wrong did not carry the day. As a community of mathematicians, I wonder if we might weight the debate differently.