Active Knowledge Modeling

Properties define the data values that are important in a domain. In product design, properties and parameters are used for quantifying requirements, for setting agreed upon targets, and for assessing the qualities of different solutions. Product data management (PDM) therefore places properties at the centre of attention, and properties are perhaps the most important kind of elements in PDM standards, cf. independent property definition in STEP, and e.g. the DIN product property dictionary. Design methodology processes are defined according to what kind of properties are defined, related, mapped, balanced, estimated, calculated etc. in each step. Generally, required and target properties are defined long before the objects that will eventually possess them are properly identified or classified.

Yet in IT, properties and attributes are normally treated as second class citizens compared to objects. In database schema, they define the columns of entities, while in object oriented design, they are just subordinate features of object classes. OWL (Web Ontology Language) is a notable exception. It supports property modeling independent of object classes. In the reflective variant OWL Full users may remove the differences between objects and properties, to model features of and relationships between properties. This variant is however seldom applied, because it cannot guarantee sound formal reasoning for automatic execution. In information systems research, Jeffrey Parsons has shown how properties determine classification structures, rather than vice versa. These examples, however, are exceptions to the common practice. This is why our modeling principles include the representation of properties as first class citizens. Read the rest of this entry »