diff -r 26c4d576e155 -r 20de3d710f77 pnas/preamble.tex
--- a/pnas/preamble.tex	Tue Nov 09 17:48:16 2010 -0800
+++ b/pnas/preamble.tex	Thu Nov 11 15:48:47 2010 -0800
@@ -12,6 +12,8 @@
 \newcommand{\CH}[1]{CH_*(#1)}
 
 \newcommand{\cl}[1]{\underrightarrow{#1}}
+\newcommand{\clh}[1]{\underrightarrow{#1}_{{}_{{}_{{}_h}}}}
+
 
 \newcommand{\Set}{\text{\textbf{Set}}}
 \newcommand{\Vect}{\text{\textbf{Vect}}}