# Why is the \underbrace off the line?

I have the following problem with \underbrace:

As you can see, the third underbrace and its comment are not in the line with the first two. Here is my code:

\documentclass[a4paper,12pt]{article}
\usepackage{amsmath}
\begin{document}

$\underbrace{\text{A long word}}_{=a}$,
$\underbrace{\text{Another long word}}_{=b}$,
$\underbrace{\text{Word}}_{=c}$

\end{document}


Update: It looks like it's because of the g's and not the length. But still: is there a way to make them in the line?

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That's because you have no letter with positive depth (e.g., g, y, p, q,… have depth). You can just add in the last Word\vphantom{g}. – Manuel Jul 25 '14 at 21:17

This is because Word has no descenders, while A long word and Another long word both have a descender (g). Here are some options:

\documentclass{article}
\usepackage{amsmath}
\begin{document}

$\underbrace{\text{A long word}}_{=a}$,
$\underbrace{\text{Another long word}}_{=b}$,
$\underbrace{\text{Word}}_{=c}$

$\underbrace{\text{A long word}}_{=a}$,
$\underbrace{\text{Another long word}}_{=b}$,
$\underbrace{\text{\vphantom{g}Word}}_{=c}$

$\underbrace{\text{\strut A long word}}_{=a}$,
$\underbrace{\text{\strut Another long word}}_{=b}$,
$\underbrace{\text{\strut Word}}_{=c}$

\end{document}


I've overlaid the bounding boxes associated with each \text string to highlight its vertical/horizontal scope.

The first option is to provide a vertical strut equivalent to the other descenders (using \vphantom{<chars>}), while the second uses a uniform \strut across the entire usage.

The same holds for an \overbrace:

\documentclass{article}
\usepackage{amsmath}
\begin{document}

$\overbrace{\text{A long word}}^{=a}$,
$\overbrace{\text{Another long word}}^{=b}$,
$\overbrace{\text{pop rows}}^{=c}$

$\overbrace{\text{A long word}}^{=a}$,
$\overbrace{\text{Another long word}}^{=b}$,
$\overbrace{\text{\vphantom{A}pop rows}}^{=c}$

$\overbrace{\text{\strut A long word}}^{=a}$,
$\overbrace{\text{\strut Another long word}}^{=b}$,
$\overbrace{\text{\strut pop rows}}^{=c}$

\end{document}


This time pop rows have no ascenders in them, while the letters A, t, h, l and d all have ascenders. Choose a representative ascender in \vphantom, or use a \strut.

In both all instances above it should be clear how the bounding box is adjusted with the struts to properly align the \underbrace/overbrace.

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\strut is indeed the solution! – Juan A. Navarro Jul 30 '14 at 9:19