\begin{frame}{Operations on Words}
  \begin{block}{Concatenation}
    If $v = a_1 \cdots a_n$ and $w = b_1 \cdots b_m$,
    then
    \begin{talign}
    \alert{vw} = a_1 \cdots a_n b_1 \cdots b_m
    \end{talign}
  \end{block}
  
  \begin{exampleblock}{}
    The concatenation of $abb$ and $ba$ is $abbba$.
  \end{exampleblock}
  \pause\bigskip
    
  \begin{block}{Length}
    If $v = a_1 \cdots a_n$, then $\alert{|v|} = n$.
    \medskip
    
    The length can be defined inductively:
    \begin{talign}
      |\lambda| &= 0 &
      |va| &= |v|+1
    \end{talign}
  \end{block}
  
  \begin{exampleblock}{}
    The length of $abbba$ is $|abbba| = 5$.
  \end{exampleblock}
\end{frame}