KADS : A Modelling Approach to Knowledge Engineering

This paper discusses the KADS approach to knowledge engineering. In KADS, the development of a knowledge-based system (KBS) is viewed as a modelling activity. A KBS is not a container filled with knowledge extracted from an expert, but an operational model that exhibits some desired behaviour that can be observed in terms of real-world phenomena. Five basic principles underlying the KADS approach are discussed, namely (i) the introduction of partial models as a means to cope with the complexity of the knowledge engineering process, (ii) the KADS four-layer framework for modelling the required expertise, (iii) the reusability of generic model components as templates supporting top-down knowledge acquisition, (iv) the process of differentiating simple models into more complex ones, and (v) the importance of structure preserving transformation of models of expertise into design and implementation. The actual activities that a knowledge engineer has to undertake are briefly discussed. We compare the KADS approach to related approaches and discuss experiences and future developments. The approach is illustrated throughout the paper with examples in the domain of troubleshooting audio equipment.

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