1 Modeling Expertise Using KADS and MODEL-ECS Roberto Flores-Méndez Knowledge Science Institute, University of Calgary, Canada. robertof@cpsc.ucalgary.ca Pim van Leeuwen Faculty of Mathematics and Computer Science, Vrije Universiteit, Amsterdam, The Netherlands. pvleeuw@cs.vu.nl Dickson Lukose Department of Mathematics and Computer Science, University of New England, Australia. lukose@peirce.une.edu.au Abstract In this paper, the authors will outline the knowledge level modeling of a simple diagnosis task in the Audio System Diagnosis domain. The Knowledge Analysis and Design Support (KADS) (Schreiber, Wielinga, and Breuker, 1993) methodology is adopted in carrying out the knowledge modeling activity, and MODEL-ECS is used as the implementation of the model. This paper attempts to demonstrate that by using a sophisticated graph-based executable modeling language (i.e., MODEL-ECS), we are able to construct an executable conceptual model of the problem solving behaviour of a domain expert. This is, indeed, a major advantage in comparison to the conventional approach that involves transforming the conceptual model into a design model, and then implementing this design model as a knowledge-based system. The approach outlined in this paper enables rapid prototyping of problem-solving behaviour (i.e., problem-solving methods (PSM)) of domain experts. Introduction In the mid-1980s, the idea of transferring knowledge from domain experts into computers to develop knowledge-based systems was replaced by the notion of modeling the behaviour of the domain expert. This fundamental shift in knowledge engineering motivated the development of a large number of knowledge modeling languages, ranging from “specification” to “programming” languages. Figure 1.1 depicts some of the methodologies and the modeling languages that have been developed in the last five years. Knowledge Modeling Methodology Knowledge Modeling Language Algorithmic KADS (Wielinga, Schreiber and Breuker, 1992) MODEL-K (Karbach and Vo, 1993) Component of Expertise (Steels, 1990) TroTelC (Vanwelkenhuysen et al., 1990) Generic Tasks (Chandrasekaran and Johnson,1993) TIPS (Punch and Chandrasekaran, 1993) Graphical Modeling DESIRE (Brazier et al., 1996) CG-DESIRE (Moller and Willems, 1995) KADS (Wielinga, Schreiber and Breuker, 1992) [CG]->(ON)->[KADS] (Moller, 1995) KADS (Wielinga, Schreiber and Breuker, 1992) MODEL-ECS (Lukose,1995) Figure. 1.1. Knowledge Modeling Methodologies and Languages.