\begin{frame}{Deterministic Pushdown Automata}
  \begin{block}{}
    A \emph{deterministic pushdown automaton} (\emph{DPDA})
    is an NPDA such that
    \begin{itemize}
      \item 
        $\delta(q,\alert{\alpha},b)$ contains at most one element
      \item 
        If $\delta(q,\alert{\lambda},b) \neq \emptyset$, 
        then $\delta(q,\alert{a},b) = \emptyset$ for every $a \in \Sigma$.
    \end{itemize}
  \end{block}
  \pause\medskip

  \begin{block}{}
    A language $L$ is \emph{deterministic context-free} 
    if there exists a DPDA $M$ with $L(M) = L$.
  \end{block}
  \medskip

  A deterministic context-free $L$ allows for \alert{efficient parsing}.
\end{frame}