--- a/hws/hw02.tex Mon Oct 07 09:34:12 2013 +0100
+++ b/hws/hw02.tex Mon Oct 07 09:45:11 2013 +0100
@@ -14,7 +14,9 @@
in general for arbitrary languages $A$, $B$ and $C$:
\begin{eqnarray}
(A \cup B) @ C & = & A @ C \cup B @ C\nonumber\\
-A^* \cup B^* & = & (A \cup B)^*\nonumber\\
A^* @ A^* & = & A^*\nonumber\\
(A \cap B)@ C & = & (A@C) \cap (B@C)\nonumber
+A^* \cup B^* & = & (A \cup B)^*\nonumber\\
+A^* @ A^* & = & A^*\nonumber\\
+(A \cap B)@ C & = & (A@C) \cap (B@C)\nonumber
\end{eqnarray}
\noindent
@@ -36,8 +38,6 @@
\item Given the regular expression $r = (a \cdot b + b)^*$. Compute what the derivative of $r$ is with respect to
$a$ and $b$. Is $r$ nullable?
-\item What is a regular language?
-
\item Prove that for all regular expressions $r$ we have
\begin{center}
$\text{nullable}(r)$ \quad if and only if \quad $\texttt{""} \in L(r)$