^^Albero; rappresentazione tramite parentesi; esempio.

    *                 (g(ef)(c(ab)d))
   /|\                (()(()())(()(()())()))
  / | \
 /  |  \
g   |   \
    *    \            (ef)         (()())
   / \    \
  /   \    \
 e     f    \
             \
              *       (c(ab)d)     (()(()())())    
             /|\
            / | \
           c  |  d
              |
              *       (ab)         (()())
             / \
            /   \
           a     b

                      (g (e f )(c (a b )d ))
                      (()(()())(()(()())()))

                      (                    )
                       ()(    )(          )
                          ()()  ()(    )()
                                   ()()

                      (g (e f )(c (a b )d ))
                      (()(()())(()(()())()))
                          ()()     ()()
                       ()(    ) ()(    )()
                       ()(    )(          )
                      (                    )