diff -r 2f33c51cac48 -r fd7f8aff848c cws/main_cw03.tex
--- a/cws/main_cw03.tex	Thu Nov 13 21:53:20 2025 +0000
+++ b/cws/main_cw03.tex	Fri Nov 14 10:57:21 2025 +0000
@@ -508,7 +508,7 @@
 
 \subsection*{Background}
 
-Although easily implementable in Scala (ok maybe the \texttt{simp} functions and
+Although easily implementable in Scala (ok maybe the \texttt{simp} function and
 the constructors \texttt{ALT}/\texttt{SEQ}/\texttt{AND} needs a bit more thinking), the idea behind the
 derivative function might not so easy to be seen. To understand its
 purpose better, assume a regular expression $r$ can match strings of