\begin{frame}
\small

\begin{definitions}[Operations on Terms]
\smallskip
\begin{itemize}
\item
$\alert<-2>{|\cdot|}$, the \alert<-2>{size of a term} \hfill \onslide<2->{%
$|\GREEN{(\alert<2>{2:x})\alert<2>{+}((\alert<2>{1:x})\alert<2>{:y})}| =
\alert<2>{9}$ ~} \\[1ex]
\(
| t | =
\begin{cases}
1 & \text{if $t \in \VV$} \\
\displaystyle 1 + \sum_{i=1}^n |t_i| & \text{if $t = f(\seq{t})$}
\end{cases}
\)
\bigskip
\item<3->
$\alert<-4>{\|\cdot\|}$, the \alert<-4>{number of function symbols} \hfill \onslide<4->{%
$\|\GREEN{(\alert<4>{2:}x)\alert<4>{+}((\alert<4>{1:}x)\alert<4>{:}y)}\| =
\alert<4>{6}$ ~} \\[1ex]
\(
\| t \| =
\begin{cases}
0 & \text{if $t \in \VV$} \\
\displaystyle 1 + \sum_{i=1}^n \| t_i \| & \text{if $t = f(\seq{t})$}
\end{cases}
\)
\end{itemize}
\end{definitions}

\end{frame}