Class-Based Generalization and Specialization

This paper proposes class-based generalization and specialization. The attributes common to subclasses (superclasses, respectively) are inherited upward (downward) to the superclass (subclass) in the ordinary generalization (specialization). The attribute name of the superclass is the same as that of the subclass. In the class-based generalization (specialization, respectively), the names of the attributes of the superclass (subclass) are changed according to the name of the superclass (subclass). These enable database designers and class designers to put appropriate names to the attributes generalized or specialized. These could improve understandability and maintainability of databases and classes. This paper tries to represent the class-based generalization (specialization, respectively) by using the semantic generalization (specialization). As it is cumbersome to prepare viewpoints, which are needed in the semantic generalization and specialization, for the class-based ones, the functions making viewpoints based on a class lattice are introduced.