I guess this is off-topic, but I’m always forgetting how to do stuff in . Here are two useful things:

### Braces with labels

Do this:

$\ell_p^d=\overbrace{\ell_p^k\oplus\dots\oplus\ell_p^k}^{m \text{ times}}\oplus\ell_p^r$

to get this:

With the obvious variation

$\ell_p^d=\underbrace{\ell_p^k\oplus\dots\oplus\ell_p^k}_{m \text{ times}}\oplus\ell_p^r$

to get this:

### Breaking “n-dimensional”

In order to convince to break -dimensional correctly, use

$n$\nobreakdash-\hspace{0pt}dimensional

(Otherwise will not do anything).

### Latex blogs

For more serious stuff, see the Blog on Latex Matters or the Blog on Latex Matters (yes, you’re seeing double). The WordPress FAQ is also useful for latexblogging.