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\begin{frame}[t,fragile]
  \small
  
  \vspace{-1ex}
  
  \mode{
  \newcommand{\OfG}[2]{\alert<#1>{\fbox{\GREEN{$#2$}}}}%
  }
  \mode{
  \newcommand{\OfG}[2]{\fbox{\GREEN{$#2$}}}%
  }
  \begin{example}[cont'd]
  \smallskip
  term \qquad\qquad\qquad\qquad
  \setlength{\fboxrule}{.5pt}%
  \setlength{\fboxsep}{2.5pt}%
  \(
  \GREEN{\OfG{2,4,6}{\OfG{0}{0 : \OfG{3,5,7}{1 + 2}} + \OfG{3,7}{3 + 4}} +
  \OfG{2,3,6,7}{5 + 6}}
  \)
  \setlength{\fboxrule}{4pt}%
  \setlength{\fboxsep}{10pt}%
  
  \bigskip
  
  tree representation
  \vspace{-2ex}
  \begin{center}
  \GREEN{\begin{tikzpicture}[scale=.5]
  \node (1) at (5.5,8) {$+$};
  \node (2) at (3,6)   {$+$} edge (1);
  \node (3) at (1,4)   {$:$} edge (2);
  \node (4) at (0,2)   {$0$} edge (3);
  \node (5) at (2,2)   {$+$} edge (3);
  \node (6) at (1,0)   {$1$} edge (5);
  \node (7) at (3,0)   {$2$} edge (5);
  \node (8) at (5,4)   {$+$} edge (2);
  \node (9) at (4,2)   {$3$} edge (8);
  \node (10) at (6,2)  {$4$} edge (8);
  \node (11) at (8,6)  {$+$} edge (1);
  \node (12) at (7,4)  {$5$} edge (11);
  \node (13) at (9,4)  {$6$} edge (11);
  \draw<1,3,5,7>[rounded corners,draw=black]
   (5.north west) -- (6.north west) -- (6.south west) --
   (7.south east) -- (7.north east) -- (5.north east) -- cycle;
  \only{
  \fill<3,5,7>[rounded corners,nearly transparent,fill=orange]
   (5.north west) -- (6.north west) -- (6.south west) --
   (7.south east) -- (7.north east) -- (5.north east) -- cycle;
  }
  \draw<1>[rounded corners,draw=black]
   (.4,4.5) -- (-.6,2.6) -- (-.6,-.65) -- (3.6,-.65) -- (3.6,.6) --
   (1.7,4.5) -- cycle;
  \only{
  \draw<3,7>[rounded corners,draw=white]
   (.4,4.5) -- (-.6,2.6) -- (-.6,-.65) -- (3.6,-.65) -- (3.6,.6) --
   (1.7,4.5) -- cycle;
  }
  \draw<1,2,4,6>[rounded corners,draw=black]
   (2.2,6.4) -- (.3,4.8) -- (-.8,2.8) -- (-.8,-.8) -- (6.6,-.8) --
   (6.6,2.6) -- (5.6,4.7) -- (3.6,6.4) -- cycle;
  \only{
  \draw<3,5,7>[rounded corners,draw=white]
   (2.2,6.4) -- (.3,4.8) -- (-.8,2.8) -- (-.8,-.8) -- (6.6,-.8) --
   (6.6,2.6) -- (5.6,4.7) -- (3.6,6.4) -- cycle;
  \fill<2,4,6>[rounded corners,nearly transparent,fill=orange]
   (2.2,6.4) -- (.3,4.8) -- (-.8,2.8) -- (-.8,-.8) -- (6.6,-.8) --
   (6.6,2.6) -- (5.6,4.7) -- (3.6,6.4) -- cycle;
  \draw<5>[rounded corners,draw=white]
   (8.north west) -- (9.north west) -- (9.south west) --
   (10.south east) -- (10.north east) -- (8.north east) -- cycle;
  }
  \draw<1,3,7>[rounded corners,draw=black]
   (8.north west) -- (9.north west) -- (9.south west) --
   (10.south east) -- (10.north east) -- (8.north east) -- cycle;
  \only{
  \fill<3,7>[rounded corners,nearly transparent,fill=orange]
   (8.north west) -- (9.north west) -- (9.south west) --
   (10.south east) -- (10.north east) -- (8.north east) -- cycle;
  \draw<4,5>[rounded corners,draw=white]
   (11.north west) -- (12.north west) -- (12.south west) --
   (13.south east) -- (13.north east) -- (11.north east) -- cycle;
  }
  \draw<1,2,3,6,7>[rounded corners,draw=black]
   (11.north west) -- (12.north west) -- (12.south west) --
   (13.south east) -- (13.north east) -- (11.north east) -- cycle;
  \only{
  \fill<2,3,6,7>[rounded corners,nearly transparent,fill=orange]
   (11.north west) -- (12.north west) -- (12.south west) --
   (13.south east) -- (13.north east) -- (11.north east) -- cycle;
  }
  \end{tikzpicture}}
  \end{center}
  \begin{center}
  \only{
  \alt<2,3>{\makebox[4cm][r]{\alert{\alt<2>{outermost}{innermost}}}
  \makebox[2cm][l]{redexes}}{\onslide<4-7>{\makebox[4cm][r]{\alert{
  \alt<4>{leftmost outermost}{
  \alt<5>{leftmost innermost}{
  \alt<6>{parallel outermost}{
  \alt<7>{parallel innermost}{
  }}}}}} \makebox[2cm][l]{strategy}}}\strut
  }
  \only{
  \structure{parallel}/\structure{leftmost}
  \structure{outermost}/\structure{innermost} strategies\strut
  }
  \smallskip
  \end{center}
  \end{example}
\end{frame}