--- a/pnas/pnas.tex	Thu Jan 13 14:48:47 2011 -0800
+++ b/pnas/pnas.tex	Sat Jan 15 15:32:37 2011 -0800
@@ -446,7 +446,7 @@
 \subsection{$n$-categories} \mbox{}
 
 In this section we give a definition of $n$-categories designed to work well with TQFTs.
-The main idea is to base the definition on actual balls, rather combinatorial models of them.
+The main idea is to base the definition on actual balls, rather than combinatorial models of them.
 This has the advantages of avoiding a proliferation of coherency axioms and building in a strong
 version of duality from the start.