Object class definition by generalization using upward inheritance

The authors show how the process of object class definition by generalization can be incorporated into object-oriented systems. Traditional message handling, which is mainly based on downward property inheritance, is revised and extended to upward property inheritance, so that a maximum of reusability of code and data can be achieved. Different types of semantic relationships that may hold between a generalization class´s subclasses and their attributes are identified. The different semantic relationships can then be utilized to produce different default treatments of messages and upward property propagation.