hws/hw02.tex
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    12 \item What is the difference between \emph{basic} regular expressions  
    12 \item What is the difference between \emph{basic} regular expressions  
    13   and \emph{extended} regular expressions?
    13   and \emph{extended} regular expressions?
    14 
    14 
    15   \solution{Basic regular expressions are $\ZERO$, $\ONE$, $c$, $r_1 + r_2$,
    15   \solution{Basic regular expressions are $\ZERO$, $\ONE$, $c$, $r_1 + r_2$,
    16     $r_1 \cdot r_2$, $r^*$. The extended ones are the bounded
    16     $r_1 \cdot r_2$, $r^*$. The extended ones are the bounded
    17     repetitions, not, etc.}
    17     repetitions, not, etc.
       
    18 
       
    19 
       
    20     Maybe explain here how the extended regular expressions
       
    21     are defined in terms of the basic ones.
       
    22   }
    18   
    23   
    19 \item What is the language recognised by the regular
    24 \item What is the language recognised by the regular
    20   expressions $(\ZERO^*)^*$.
    25   expressions $(\ZERO^*)^*$.
    21 
    26 
    22   \solution{$L(\ZERO^*{}^*) = \{[]\}$,
    27   \solution{$L(\ZERO^*{}^*) = \{[]\}$,