Generalization Relationships
A generalization specifies "is a kind of" (or simply is-a) relationship. It is most commonly used to depict any inheritance hierarchy.
The above example shows that the classes UndergradStudent and GradStudent are each derived from the class Student.
Generalization is represented by an arrow with a hollow head points to the superclass. If a class implements an interface, you draw an arrow having a dotted shaft and hollow head from the class to the interface.
Abstract classes and interfaces may be shown using the textual annotation
<<abstract>>and<<interface>>above or below their name.