\begin{frame}{LL Parsing}
  \begin{goal}{LL parsing}
    Parsing \emph{top-down} with a \emph{leftmost} strategy.
    Backtracking is \alert{not} allowed.
  LL parsing does not work for every context-free grammar.

    Starting point is a context-free grammar $G = (V,T,S,P)$:
      \item \alert{without useless variables}
      \item $\lambda$-productions and unit productions are allowed\\
        (elimination often increases the size of the grammar)
  Steps of LL parsing:
    \item Construct sets $\first{A}$ and $\follow{A}$ for every variable $A$.
    \item Construct a parsing table.
    \item Parse the input word using the parsing table.