--- a/style.sty	Mon Feb 22 22:09:31 2016 +0000
+++ b/style.sty	Tue Mar 22 17:09:24 2016 +0000
@@ -9,6 +9,11 @@
 \definecolor{darkblue}{rgb}{0,0,0.6}
 \usepackage[colorlinks=true,urlcolor=darkblue,linkcolor=darkblue]{hyperref}
 
+%%% fo regular expressions
+\newcommand{\ZERO}{\mbox{\bf 0}}
+\newcommand{\ONE}{\mbox{\bf 1}}
+
+
 %%% for trees
 %% http://anorien.csc.warwick.ac.uk/mirrors/CTAN/graphics/pgf/contrib/forest/forest.pdf