Chapter 14 - Good and bad modeling practices

Abstract

The basic assumptions behind the Semantic Web—the AAA, Open World, and Nonunique Naming assumptions—place very specific restrictions on the modeling language. The structure of RDF is in the form of statements with familiar grammatical constructs like subject, predicate, and object. The structure of Web Ontology Language (OWL) includes familiar concepts like class, subClassOf, and property. But the meaning of a model is given by the inference rules of OWL, which incorporate the assumptions of the Semantic Web. One can tell if one has built a useful model, one that conforms to these assumptions, by making sure that the inferences it supports are useful and meaningful. According to the AAA slogan, one cannot say that any of the practices in the chapter are “errors” because Anyone can say Anything about Any topic. All of these models are valid expressions in RDF/OWL. However, they are erroneous in the sense that they do not accomplish what the modeler intended by creating them. In each case, the mismatch can be revealed through careful examination of the inferences that the model entails. There are occasions where these modeling constructs are insufficient, and more advanced capabilities are required. Many of these have been included in version 2 of the OWL standard. This chapter outlines some fundamental new capabilities. It provides some of the background one will need to search through the OWL standard documents to explore its rich landscape.