Problem with beamer and tikz

Question

For some reason this code doesn't work and I don't know why:

\documentclass[pdf]{beamer}
\usepackage{amsmath}
\usepackage{enumerate}
\usepackage{graphicx}
\usepackage{tikz}
\usetikzlibrary{arrows}
\usepackage{upgreek}
\usepackage{textcomp}
\usepackage{extarrow}
\usepackage{fontenc,mathtext}
\usepackage{todonotes}
\usepackage{mathrsfs}
\usetikzlibrary{matrix,arrows}
\usetikzlibrary{chains}
\tikzset{join/.code=\tikzset{after node path={%
\ifx\tikzchainprevious\pgfutil@empty\else(\tikzchainprevious)%
edge[every join]#1(\tikzchaincurrent)\fi}}}
\tikzset{>=stealth',every on chain/.append style={join},every join/.style={->}}

[...]

\hypersetup{pdfpagemode=FullScreen}
\usecolortheme{progressbar}
\usefonttheme{progressbar}
\useinnertheme{progressbar}
\useoutertheme{progressbar}
\usepackage{pgf}
\usepackage{fancybox}
\usetikzlibrary{mindmap,trees,arrows}

[...]

\begin{document}
\frame{
\[
\begin{tikzpicture}[>=angle 90]
\matrix(a)[matrix of math nodes,
row sep=2.5em, column sep=2.5em,
text height=1.5ex, text depth=0.20ex]
{\bigwedge^2 S^m&S^m&S&0\\
F_2&F_1&S&0\\};
\path[->](a-1-1) edge (a-1-2);
\path[->](a-1-2) edge (a-1-3);
\path[->](a-1-3) edge (a-1-4);
\path[->](a-2-1) edge (a-2-2);
\path[->](a-2-2) edge (a-2-3);
\path[->](a-2-3) edge (a-2-4);
\path[->](a-1-1) edge node[auto] {$\gamma$}(a-2-1);
\path[->](a-1-2) edge node[auto] {$\cong$}(a-2-2);
\path[->](a-1-3) edge node[auto] {$id$}(a-2-3);
\path[->](a-2-3) edge (a-1-3);
\end{tikzpicture}
\]
}

Any idea of why doesn't it work?

Answer 1

I have not tried specifically on your example, so I cannot be sure if it works or not. However I remember having a similar problem when using tikz and matrix. What I did was adding an option to the matrix :

ampersand replacement=\&

and then replace every piece of my code as such:

  \matrix[row sep=0.01cm,column sep=0.5cm,ampersand replacement=\&] {
    \&
    \node (A) [tree] {$\mathbf{A}$}; \&
    \&
    \\
    \node (v0) [state] {$v_{src};v'_{src})$}; \&
    \&
    \node (vn)   [state] {$(v_{snk};v'_{snk})$};     \&
    \\
    \&
    \node (B)   [tree] {$\mathbf{B}$};       \&
    \&
    \\
  }

I hope this helped. Sorry I did not have much time to really check your issue specifically.

Answer 2

The \matrix command of TikZ changes the catcode of & and is therefore not allowed in an argument of another macro like \frame or an pseudo-environment like {frame}. This can be fixed by using \begin{frame}[fragile] .. \end{frame} instead. It makes sure that all catcode changes (for verbatim mode etc.) work correctly.

Works:

\begin{frame}[fragile]
\[
\begin{tikzpicture}[>=angle 90]
\matrix(a)[matrix of math nodes,
row sep=2.5em, column sep=2.5em,
text height=1.5ex, text depth=0.20ex]
{\bigwedge^2 S^m&S^m&S&0\\
F_2&F_1&S&0\\};
\path[->](a-1-1) edge (a-1-2);
\path[->](a-1-2) edge (a-1-3);
\path[->](a-1-3) edge (a-1-4);
\path[->](a-2-1) edge (a-2-2);
\path[->](a-2-2) edge (a-2-3);
\path[->](a-2-3) edge (a-2-4);
\path[->](a-1-1) edge node[auto] {$\gamma$}(a-2-1);
\path[->](a-1-2) edge node[auto] {$\cong$}(a-2-2);
\path[->](a-1-3) edge node[auto] {$id$}(a-2-3);
\path[->](a-2-3) edge (a-1-3);
\end{tikzpicture}
\]
\end{frame}