# Put some text under a relation symbol

How to put some text under a binary operation symbol?

For example like this - the text "m" under the symbol "=".

About using \scriptscriptstyle. This command don't give the disired result. Because, space between "m" and "=" is too big. For example

    \documentclass{article}
\usepackage{amsmath}
\begin{document}
$A \underset{m}{=} B$ $A \underset{\scriptscriptstyle{m}}{=} B$
\end{document}


There is the same vertical size of formula in both cases.

You can do it with \underset. Of course if the text is wider than the = sign, you should use \clap, or \mathclap if it's a formula in order to ensure proper spacing of the = sign:

\documentclass{article}
\usepackage{mathtools}

\begin{document}

$A \underset{m}{=} B$%
$A \underset{\mathclap{m + n}}{=} B$%

\end{document}


• I often combine this with \scriptscriptstyle to get these as amsll as possible so the down disturb too much – daleif Jul 5 '18 at 9:20
• @daleif: Very useful observation. That's indeed another possibility I also sometimes use. It's all a matter of context. – Bernard Jul 5 '18 at 9:40
• About using \scriptscriptstyle. This command don't give the disired result. Because, space between "m" and "=" is too big. For example $A \underset{m}{=} B$ $A \underset{\scriptscriptstyle{m}}{=} B$ There is the same vertical size of formula in both cases. – Alex E. Jul 5 '18 at 16:21
• @Alex E.: You can cheat with this code A \underset{\mathclap{{}^{m + n}}}{=} B. – Bernard Jul 5 '18 at 16:44