Write text upon equivalent

Question

I want to get below the image. But when I write this $F \equiv^{SAT} G$, not getting the intended result.

Answer 1

As José Carlos Santos has already pointed out in the comments, \stackrel will do the trick. Here is the MWE.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
[
    F\stackrel{\text{\scriptsize SAT}}{\equiv}G
]
\end{document}

Note \mathclap is not used here because SAT is too wide to discard its width (inevitably ugly otherwise).