--- a/preamble.tex	Mon Oct 26 17:14:35 2009 +0000
+++ b/preamble.tex	Tue Oct 27 02:11:36 2009 +0000
@@ -119,6 +119,11 @@
 
 \newcommand{\lmod}[1]{\leftidx{_{#1}}{\operatorname{mod}}{}}
 
+\newcommand{\HC}{\operatorname{Hoch}}
+\newcommand{\HH}{\operatorname{HH}}
+
+\newcommand{\selfarrow}{\ensuremath{\!\!\!\!\!\!\xymatrix{ \ar@(ru,rd)@<-1ex>[]}\phantom{++.}}}
+
 \def\bc{{\mathcal B}}
 
 \newcommand{\into}{\hookrightarrow}