\underline
command will place an unbroken line
under its argument, and the \overline
command will place
an unbroken line over its argument. These two commands can also
be used in normal paragraphing mode (but be careful: LATEX will
not break the line within an under- or overlined phrase, so don't
go operating on large phrases).
You can place horizontal braces above or below an expression
by making that expression the argument of \overbrace
or \underbrace
. You can place a label on an overbrace
(resp. underbrace) by superscripting (resp. subscripting the
group defined by the bracing command.
And some examples of horizontal bracing:
0.1
$A^n=\overbrace{A \times A \times \ldots \times A}^{\mbox{$n$ terms}}$ $\forall x \underbrace{\exists y (y \succ x)}_{\mbox{scope of $\forall$}}$will produce