8:25 AM
I'd guess - which was chosen by the OP - is not a good tag for H-infinity methods in control theory and Hardy space.. I have added . But since the question is quite far from the stuff I know at least something about, I am not really confident in how to choose the tags there. (Although the title suggests might be a fitting tag...?)
2

Sorry this is very simple but I do not know. Why the H-infinity methods that are used in control theory are said to work on Hardy space? If the question is not appropriate then how H-infinity methods are related to Hardy space? May I request few comments? Sorry if the question is not clear:It ref...

5 hours later…
1:32 PM
@MartinSleziak: A lot of adding/removing tags at
75

$x,y,z >0$, prove $$\frac{x^4}{8x^3+5y^3}+\frac{y^4}{8y^3+5z^3}+\frac{z^4}{8z^3+5x^3} \geqslant \frac{x+y+z}{13}$$ Note: Often Stack Exchange asked to show some work before answering the question. This inequality was used as a proposal problem for National TST of an Asian country a few yea...

Now the contest-math (and other) tags have been removed again (which makes no sense, as you already commented). I wonder why this is done.
Perhaps only to bump it to the home page? – Most of the recent edits are a “tagging war” between OP and Michael R. I do not always agree with Michael's tag edits, but this is definitely a contest question.

@quid Should situation as above (see Martin R's message) be flagged for moderators' attention? Or do mods get automatically notified if there are many edits on some post?
Although in this specific case the two recent edits (adding and removing the tags) is the first activity on that post since August.

2:41 PM
0

According to the tag info of divergence, it is used when questions are about vector calculus. However, it is often tagged with convergence, at questions about convergence/divergence of sequences, series, or improper integrals. Here are such examples: Determine if \$\sum_{n=0}^{\infty}(-1)^n\frac...

8 hours later…
11:01 PM
@MartinSleziak there are autoflag for many edits and also for rollback wars but there is no harm in raising a custom flag too, especially as the former might not be triggered for some reason.
I am not sure what to do there.
Alright I rolled back to some version of OP, that includes contest math, but not other possibly more controverial tags.
I hope it'll stay that way.
Any further ideas for changes of the tags here must be first proposed to me. — quid ♦ 1 min ago
Please do not hesitate to signal deviations from this.