Compaction of Large Class Hierarchies in Engineering Databases

Engineering knowledge is characterized by variant and alternative designs for each problem. To alleviate reuse these variants should be captured as classes in the schema. This results in a class hierarchy bloated by many intersection classes, if 'standard' object models are used. This paper proposes a mechanism, called 'aspects', which uses a restricted form of multiple instantiation to avoid intersection classes. Unlike similar approaches, such as 'roles', our work allows various interdependencies between the diierent aspects of a class to be modeled. We demonstrate these abilities on an example taken from chemical process engineering.