# Geometry and Combinatorics

## Tverberg’s theorem

At Combinatorics and More, Gil Kalai has a nice explanation of the beautiful theorems of Helly, Radon, Carathéodory, and Tverberg (here and here). I’m looking forward to the next installment.

26th November 2008 at 10.53 am

Posted in Discrete Geometry

## LaTeX hints

I guess this is off-topic, but I’m always forgetting how to do stuff in $\LaTeX$. 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:

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

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:

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

### Breaking “n-dimensional”

In order to convince $\LaTeX$ to break $n$-dimensional correctly, use

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

(Otherwise $\LaTeX$ 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.