--- a/cws/main_cw03.tex	Thu Nov 10 20:10:20 2022 +0000
+++ b/cws/main_cw03.tex	Mon Nov 14 12:04:21 2022 +0000
@@ -237,7 +237,7 @@
 \end{center}  
 
 \noindent
-The alternative regular expressions comes in two versions: one is
+The alternative regular expression comes in two versions: one is
 binary (+ / \texttt{ALT}) and the other is n-ary ($\sum$ /
 \texttt{ALTs}). The latter takes a list of regular expressions as
 argument.  In what follows we shall use $rs$ to stand for lists of