Now I use "mid" for all vertical bars, but I wonder what's the proper ways.
The first scenario is vertical bar for absolute value. Now I just right
$x\leq \mid x \mid$. but is this correct?
The second scenario is in conditional expectation. Now I write
E[x \mid y], but sometimes if the "x" part is complex, it might be quite "tall", I wonder if there's a way to have a "automatically adjusted" vertical bar. Is there?