hws/hw04.tex
changeset 768 34f77b976b88
parent 726 fba480bbc9f7
child 843 97b622202547
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767:bdd12391d345 768:34f77b976b88
    39   \end{itemize}
    39   \end{itemize}
    40 
    40 
    41   In case they can, can you give the corresponding token
    41   In case they can, can you give the corresponding token
    42   sequences.
    42   sequences.
    43 
    43 
    44 \item Assume that $s^{-1}$ stands for the operation of reversing a
    44 \item Assume $r$ is nullable. Show that
       
    45   \[ 1 + r + r\cdot r \;\equiv\; r\cdot r
       
    46   \]
       
    47 
       
    48   holds.
       
    49 
       
    50 \item \textbf{(Deleted)} Assume that $s^{-1}$ stands for the operation of reversing a
    45   string $s$. Given the following \emph{reversing} function on regular
    51   string $s$. Given the following \emph{reversing} function on regular
    46   expressions
    52   expressions
    47 
    53 
    48   \begin{center}
    54   \begin{center}
    49     \begin{tabular}{r@{\hspace{1mm}}c@{\hspace{1mm}}l}
    55     \begin{tabular}{r@{\hspace{1mm}}c@{\hspace{1mm}}l}