\begin{frame}{Ambiguous Grammars} \begin{exampleblock}{} Is the following grammar ambiguous? \begin{talign} S \to S+0 \mid 0 \end{talign} \pause No, every word has precisely one derivation tree. \end{exampleblock} \pause\bigskip \begin{exampleblock}{} Note that both grammars \begin{talign} S \to S+S \mid 0 && S \to S+0 \mid 0 \end{talign} generate the same language: \begin{talign} \{\, 0(+0)^n \mid n \geq 0 \,\} \end{talign} \end{exampleblock} \end{frame}