
diff -r f6c2e8c48a1c -r a526f7f20cad handouts/ho05.tex
--- a/handouts/ho05.tex	Mon Jun 29 21:13:49 2020 +0100
+++ b/handouts/ho05.tex	Mon Jun 29 21:14:50 2020 +0100
@@ -24,16 +24,17 @@
 
 \section*{Handout 5 (Grammars \& Parser)}
 
-While regular expressions are very useful for lexing and for recognising
-many patterns in strings (like email addresses), they have their
-limitations. For example there is no regular expression that can
-recognise the language $a^nb^n$ (where you have strings starting with $n$ $a$'s
-followed by the same amount of $b$'s). Another example for which there
-exists no regular expression is the language of well-parenthesised
-expressions. In languages like Lisp, which use parentheses rather
-extensively, it might be of interest to know whether the following two
-expressions are well-parenthesised or not (the left one is, the right
-one is not):
+So far we have focused on regular expressions as well as matching and
+lexing algorithms. While regular expressions are very useful for lexing
+and for recognising many patterns in strings (like email addresses),
+they have their limitations. For example there is no regular expression
+that can recognise the language $a^nb^n$ (where you have strings
+starting with $n$ $a$'s followed by the same amount of $b$'s). Another
+example for which there exists no regular expression is the language of
+well-parenthesised expressions. In languages like Lisp, which use
+parentheses rather extensively, it might be of interest to know whether
+the following two expressions are well-parenthesised or not (the left
+one is, the right one is not):
 
 \begin{center}
 $(((()()))())$  \hspace{10mm} $(((()()))()))$




