  \begin{exercice}
    Compléter l'arbre 2 en utilisant l'arbre 1 :
    \setlength{\columnseprule}{0pt}
    \vspace{-\baselineskip}\begin{multicols}{2}

    \begin{center}
  \textbf{Arbre 1}\vspace{0.5\baselineskip}

      \pstree[treemode=R,labelsep=0mm,levelsep=8ex,treesep=3mm]{\TR{}}
            {
              \pstree[labelsep=0mm,levelsep=8ex]{\TR{$A$}\taput{$1/5$}}
              {
                \TR{$B$}\taput{$1/8$}
                \TR{$\overline{B}$}\tbput{$7/8$}
              }
              \pstree[labelsep=0mm,levelsep=8ex]{\TR{$\overline{A}$}\tbput{$4/5$}}
              {
                \TR{$B$}\taput{$4/9$}
                \TR{$\overline{B}$}\tbput{$5/9$}
              }

            }	
      \end{center}


       \begin{center}
      \textbf{Arbre 2}\vspace{0.5\baselineskip}


      \pstree[treemode=R,labelsep=1mm,levelsep=8ex,treesep=3mm]{\TR{}}
            {
              \pstree[labelsep=1mm,levelsep=8ex]{\TR{$B$}\taput{\ldots}}
              {
                \TR{$A$}\taput{\ldots}
                \TR{$\overline{A}$}\tbput{\ldots}
              }
              \pstree[labelsep=1mm,levelsep=8ex]{\TR{$\overline{B}$}\tbput{\ldots}}
              {
                \TR{$A$}\taput{\ldots}
                \TR{$\overline{A}$}\tbput{\ldots}
              }

            }	
      \end{center}
    \end{multicols}
  \end{exercice}

