I'm running ubuntu 11.04, and trying tableau to draw logic diagrams for the first time.

```
\documentclass[english]{article}
\usepackage[T1]{fontenc}
\usepackage[latin9]{inputenc}
\usepackage{ifsym}
\usepackage{amstext}
\usepackage{amssymb}
\usepackage{tableau}
\usepackage{babel}
\begin{document}

\
Here I use $\Box$ to represent necessity and $\Diamond$ to represent
possibility.

a) Whether $\Diamond(P\parallel Q) \vdash\Diamond P\parallel\Dimaond Q$

\end{document}

```

I'm getting this error:

```
...
(/usr/share/texmf-texlive/tex/latex/amsfonts/amssymb.sty
(/usr/share/texmf-texlive/tex/latex/amsfonts/amsfonts.sty))
(/usr/share/texmf-texlive/tex/latex/tableaux/tableau.sty
! Undefined control sequence.
l.151 \newpsstyle
                 {TabDblBarre}{linewidth=.4pt,doubleline=true,doublesep=.6pt}
? 

```