\begin{frame}
\small

\begin{definitions}[Operations on Terms]
\smallskip
\begin{itemize}
\item
$\alert<-3>{\Var(\:\cdot\:)}$, the \alert<-3>{variables of a term}  \hfill \onslide<2->{\GREEN{%
$\Var((2:\alert<2>{x})+((1:\alert<2>{x}):\alert<2>{y})) = \onslide<3->{\{x,y\}}$} ~}
\\[1ex]
\(
\Var(t) =
\begin{cases}
\{ t \} & \text{if $t \in \VV$} \\[.5ex]
\displaystyle \bigcup_{i=1}^n \Var(t_i) & \text{if $t = f(\seq{t})$}
\end{cases}
\)
\bigskip
\item<4->
$\alert<-6>{\Fun(\:\cdot\:)}$, the \alert<-6>{function symbols} \hfill \onslide<5->{%
\GREEN{$\Fun((\alert<5>{2:}x)\alert<5>{+}((\alert<5>{1:}x)\alert<5>{:}y)) = \onslide<6->{\{1,2,:,+\}}$} ~}
\\[1ex]
\(
\Fun(t) =
\begin{cases}
\varnothing & \text{if $t \in \VV$} \\[.5ex]
\displaystyle \{ f \} \cup \bigcup_{i=1}^n \Fun(t_i) &
\text{if $t = f(\seq{t})$}
\end{cases}
\)
\smallskip
\end{itemize}
\end{definitions}

\end{frame}