--- a/hws/hw01.tex	Wed Apr 06 12:18:54 2016 +0100
+++ b/hws/hw01.tex	Wed Apr 06 15:55:01 2016 +0100
@@ -9,27 +9,28 @@
 
 \begin{enumerate}
 
-\item {\bf (Optional)} If you want to run the code presented in the
-  lectures, install the Scala programming language available (for
-  free) from
+\item {\bf (Optional)} If you want to run the code presented
+      in the lectures, install the Scala programming language
+      available (for free) from
 
 \begin{center}
 \url{http://www.scala-lang.org}
 \end{center}
 
-      If you want to follow the code I present during the lectures,
-      read the handout about Scala.
+      If you want to follow the code I present during the
+      lectures, read the handout about Scala.
 
-\item {\bf (Optional)} Have a look at the crawler programs.  Can you
-  find a usage for them in your daily programming life? Can you
-  improve them? (For example in cases there are links that appear on
-  different recursion levels, the crawlers visit such web-pages
-  several times. Can this be avoided?)
+\item {\bf (Optional)} Have a look at the crawler programs.
+      Can you find a usage for them in your daily programming
+      life? Can you improve them? (For example in cases there
+      are links that appear on different recursion levels, the
+      crawlers visit such web-pages several times. Can this be
+      avoided?)
 
-\item Read the handout of the first lecture and the handout about
-  notation. Make sure you understand the concepts of strings and
-  languages.  In the context of the AFL-course, what is meant by the
-  term \emph{language}?
+\item Read the handout of the first lecture and the handout
+      about notation. Make sure you understand the concepts of
+      strings and languages. In the context of the AFL-course,
+      what is meant by the term \emph{language}?
 
 \item Give the definition for regular expressions. What is the
       meaning of a regular expression? (Hint: The meaning is
@@ -55,9 +56,9 @@
 
 \item How many basic regular expressions are there to match
       the string $abcd$? (ii) How many if they cannot include
-      $\epsilon$ and $\varnothing$? (iii) How many if they are
-      also not allowed to contain stars? (iv) How many if they
-      are also not allowed to contain $\_ + \_$?
+      $\ONE$ and $\ZERO$? (iii) How many if they are also not
+      allowed to contain stars? (iv) How many if they are also
+      not allowed to contain $\_ + \_$?
 
 \item When are two regular expressions equivalent? Can you
       think of instances where two regular expressions match