Figure shows an alternate representation of the tree defined in Equation . In this case, the tree is represented as a set of nested regions in the plane. In fact, what we have is a Venn diagram which corresponds to the view that a tree is a set of sets.
Figure: An Alternate Graphical Representation for Trees
This hierarchical, set-within-a-set view of trees is also evoked by considering the nested structure of computer programs. E.g., consider the following fragment of C++ code:
D: { E: { F: statement(); } G: { H: { I: statement(); } J: { K: statement(); L: statement(); } M: statement(); } }The nesting structure of this program and the tree given in Equation are isomorphic . Therefore, it is not surprising that trees have an important rôle in the analysis and translation of computer programs.