Use of KADS to create a conceptual model of the ONCOCIN task

Abstract

In recent years, builders of expert systems have become increasingly interested in the Knowledge Acquisition and Design Structuring (KADS) method of knowledge acquisition. Despite the apparent face validity of the KADS approach, reports of the use of KADS to develop large application systems are virtually non-existent. We used KADS to model the task of cancer-chemotherapy administration performed by ONCOCIN, a large medical expert system developed at Stanford University in the 1980s. Based on a knowledge-level description of ONCOCIN and on a review of the features of KADS, we developed K-ONCOCIN, a model of the ONCOCIN cancer-chemotherapy task that can be understood in terms of the four layers required by the KADS approach. In this paper, we offer a detailed description of the elements and layers of the K-ONCOCIN conceptual model. We also describe briefly a design model that implements K-ONCOCIN as a functional expert system. The K-ONCOCIN model provides a data point for understanding the strengths and limitations of the KADS method when applied to a complex domain task.