The Role of Roles: Some Aspects of Real World Knowledge Representation

Abstract

Our aim is to build a knowledge base for a Natural Language Understanding System. Having chosen the Si-Net formalism as our tool for knowledge representation, we try to develop some progmatics for its use. Since a prominent feature of Si-Nets is the distinction between concepts and roles this article concentrates on the question which part of the knowledge should be represented as concepts and which part as roles. We distinguish between descriptional (intrinsic) properties, represented as attributes of a concept, and functional properties described through relationships between concepts. Evaluated attributes of concepts can be regarded as states. In the last section of the paper there is a short discussion of the change of these states over a period of time.