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\begin{frame}{Operations on Languages (2)}
\begin{block}{Power}
The $n$-th power of a language $L$ is defined by induction on $n$:
\begin{talign}
\alert{L^0} &= \{\, \lambda \,\} \\
\end{talign}
\end{block}
\pause

Attention: $L^2 = \{uv \mid u,v \in L \} \neq \{ uu \mid u \in L \}$
Thus $L^*=L^+\cup\{\lambda\}$.