
diff -r 86b2aeae3e98 -r a259eec25156 hws/hw01.tex
--- a/hws/hw01.tex	Fri Oct 16 14:27:20 2015 +0100
+++ b/hws/hw01.tex	Sat Oct 17 11:24:41 2015 +0100
@@ -31,33 +31,40 @@
   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 defined recursively.)
+\item Give the definition for regular expressions. What is the
+      meaning of a regular expression? (Hint: The meaning is
+      defined recursively.)
 
-\item Assume the concatenation operation of two strings is written as
-  $s_1 @ s_2$. Define the operation of \emph{concatenating}, written
-  $\_ \,@\, \_$, two sets of strings.
+\item Assume the concatenation operation of two strings is
+      written as $s_1 @ s_2$. Define the operation of
+      \emph{concatenating} two sets of strings. This operation
+      is also written as $\_ \,@\, \_$.
 
-\item Assume a set $A$ contains 4 strings and a set $B$ 7 strings. None
-  of the strings is the empty string. How many strings are in $A \,@\, B$?
+\item Assume a set $A$ contains 4 strings and a set $B$
+      contains 7 strings. None of the strings is the empty
+      string. How many strings are in $A \,@\, B$?
 
 \item How is the power of a language defined? (Hint: There are two
   rules, one for $\_^0$ and one for $\_^{n+1}$.)
 
-\item Let $A = \{[a], [b], [c], [d]\}$. How many strings are in $A^4$?
-  Consider the case of $A^4$ where one of the strings in $A$ is the 
-  empty string, for example $A = \{[a], [b], [c], []\}$.
+\item Let $A = \{[a], [b], [c], [d]\}$. (1) How many strings
+      are in $A^4$? (2) Consider the case of $A^4$ where one of
+      the strings in $A$ is the empty string, for example $A =
+      \{[a], [b], [c], []\}$.
 
-\item How many regular expressions are there to match the string
-  $abc$? How many if they cannot include $\epsilon$ and $\varnothing$?
-  How many if they are also not allowed to contain stars? How many if
-  they are also not allowed to contain $\_ + \_$?
+\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 $\_ + \_$?
 
-\item When are two regular expressions equivalent? Can you think of
-  instances where two regular expressions match the same strings, but
-  it is not so obvious that they do? For example $a + b$ and $b + a$
-  do not count\ldots they obviously match the same strings, namely
-  $[a]$ and $[b]$.
+\item When are two regular expressions equivalent? Can you
+      think of instances where two regular expressions match
+      the same strings, but it is not so obvious that they do?
+      For example $a + b$ and $b + a$ do not count\ldots they
+      obviously match the same strings, namely $[a]$ and
+      $[b]$.
+  
 \end{enumerate}
 
 \end{document}




