
diff -r f345e89895f5 -r fba480bbc9f7 hws/hw06.tex
--- a/hws/hw06.tex	Mon Jun 29 21:05:34 2020 +0100
+++ b/hws/hw06.tex	Mon Jun 29 21:13:49 2020 +0100
@@ -57,34 +57,19 @@
 and (ii) give a sample string involving all rules given in 1.-4.~that 
 can be parsed by this grammar.
 
-\item Given the regular expressions
 
-\begin{center}
-\begin{tabular}{ll}    
-  1) & $(ab + a)\cdot (\ONE + b)$\\
-  2) & $(aa + a)^*$\\
-\end{tabular}
-\end{center}
-
-there are several values for how these regular expressions can
-recognise the strings (for 1) $ab$ and (for 2) $aaa$. Give in each case
-\emph{all} the values and indicate which one is the POSIX value.
-
-\item Given the regular expression $(a + b)^* \cdot b \cdot (a + b)^*$,
-  which of the following regular expressions are equyivalent
-
-\begin{center}
-\begin{tabular}{ll}    
-  1) & $(ab + bb)^* \cdot (a + b)^*$\\                     % no
-  2) & $(a + b)^* \cdot (ba + bb + b) \cdot (a + b)^*$\\   % yes
-  3) & $(a + b)^* \cdot (a + b) \cdot (a + b)^*$           % no
-\end{tabular}
-\end{center}
 
 \item Parsing combinators consist of atomic parsers, alternative
   parsers, sequence parsers and semantic actions.  What is the purpose
   of (1) atomic parsers and of (2) semantic actions?
 
+\item Parser combinators can directly be given a string as
+      input, without the need of a lexer. What are the
+      advantages to first lex a string and then feed a
+      sequence of tokens as input to the parser?
+
+
+  
 \item \POSTSCRIPT        
 \end{enumerate}
 




