Problem I would like to type some extensible right double arrows with texts above it. But I don't know how to do it in MathStack Exchange.I have attached an example in the picture below. I used extarrows.sty package to produce these arrows in Latex.
Btw, I don't know how to tag this question or if I am putting it in the right place...So I just tagged it randomly.
$\stackrel{U\text{ is open}}\implies$
gives $\stackrel{U\text{ is open}}\implies$. $\endgroup$\xrightarrow{\because U\text{ is open}}
gives $\xrightarrow{\because U\text{ is open}}$ but you might do better to ask this at tex.stackexchange and mention MathJax $\endgroup$