unify set notations to [q]

The first usage is in abstract, so I added a footnote to clarify it.
I'm not it's good to have footnotes in abstract.

Also, from typographical perspective, it's really ugly
that our abstract doesn't fit on one page.
rework the table with asymptotic bounds

I see no point in having the same formula twice on every line.
unify style of logarithms

This is disputable a bit, but easy to revert/change as you like.
I denote:
- simple arguments always without parentheses, like $\log n$ or $\log \log n$;
- power of logarithms by compromise notation $n (\log n)^2$.
replace all \choose by \binom

AMS was warning before \choose.