diff -r a6093b0ad246 -r 2a62f0845f98 hws/hw05.tex
--- a/hws/hw05.tex	Fri Oct 20 00:01:39 2017 +0100
+++ b/hws/hw05.tex	Fri Oct 20 11:29:48 2017 +0100
@@ -1,7 +1,7 @@
 \documentclass{article}
 \usepackage{../style}
 \usepackage{../graphics}
-
+\usepackage{../grammar}
 
 \begin{document}
 
@@ -88,6 +88,27 @@
 Observe the maximal munch rule and the priorities of your regular
 expressions that make the process of lexing unambiguous.)
 
+\item Given the following context-free grammar $G$
+  
+\begin{plstx}[margin=1cm]
+  : \meta{S\/} ::= \meta{A\/}\cdot\meta{S\/}\cdot\meta{B\/} \;\mid\;
+                   \meta{B\/}\cdot\meta{S\/}\cdot\meta{A\/} \;\mid\; \epsilon\\
+  : \meta{A\/} ::= a \mid \epsilon\\
+  : \meta{B\/} ::= b\\
+\end{plstx}
+
+which of the following strings are in the language of $G$?
+
+\begin{itemize}
+\item[$\bullet$] $a$
+\item[$\bullet$] $b$
+\item[$\bullet$] $ab$
+\item[$\bullet$] $ba$
+\item[$\bullet$] $bb$
+\item[$\bullet$] $baa$
+\end{itemize}  
+
+
 \item {\bf(Optional)} Recall the definitions for $Der$ and $der$
       from the lectures. Prove by induction on $r$ the
       property that