Data Structures, Algorithms, & Applications in Java
Chapter 12, Exercise 1
The class hierarchy of Figure 1.1 satisfies the definition of a tree.
The element set is {Object, Number, String, Throwable, ... }.
This is a finite nonempty set.
The root node is the node for Object (the remaining
classes derive from Object).
The remaining elements are partitioned into subtrees (the fact that these are
subtrees may be verified recursively).
The hierarchy (or tree) with root and level numbers labeled is given below.
The depth or height of the tree is 4.