Figure 4

Derivation of tree T using the grammar, with the set of production rules shown in Figure 3. The trees surrounded by the dotted curves are derived from nonterminal symbols U 1 and U 2, respectively.
Derivation of tree T using the grammar, with the set of production rules shown in Figure 3. The trees surrounded by the dotted curves are derived from nonterminal symbols U 1 and U 2, respectively.