At the moment there is the oddly named synthetic-differential tag, which is being used for questions about synthetic differential geometry. I propose that this tag be renamed to synthetic-differential-geometry.
@MartinSleziak Regarding the TRE on chemistry, it is already a huge job for 10k questions. Now imagine doing it for 500k questions. Right, there will probably be more participants, but I think that it is undoable.
More to the point I wanted to get to, should fft (1 question) be a synonym of fourier-analysis or shoud it just be removed?
@wythagoras Personally I would consider keeping the tag and leaving them separate as a valid option. (At least, I think this possibility is worth considering.) I do not know much about it, but I think that the fast Fourier transform is a relatively important topic.