--- a/document/root.tex	Wed Jan 09 13:35:09 2013 +0000
+++ b/document/root.tex	Thu Jan 10 01:46:51 2013 +0000
@@ -5,6 +5,8 @@
 \usepackage{amssymb}
 \usepackage{mathpartir}
 \usepackage{pdfsetup}
+\usepackage{tikz}
+\usepackage{pgf}
 
 % urls in roman style, theory text in math-similar italics
 \urlstyle{rm}
@@ -13,6 +15,10 @@
 % for uniform font size
 %\renewcommand{\isastyle}{\isastyleminor}
 
+\def\dn{\,\stackrel{\mbox{\scriptsize def}}{=}\,}
+\renewcommand{\isasymequiv}{$\dn$}
+\renewcommand{\isasymemptyset}{$\varnothing$}
+\renewcommand{\isacharunderscore}{\mbox{$\_$}}
 
 \begin{document}