STRUCTURE OF MEDICAL KNOWLEDGE AND DEEP REASONING(Research 5upp by National Library of Medicine Career Development Award

Extended Abstract In this talk we will provide a historical/conceptual account of the evolution of expert systems in general, and medical diagnostic expert systems in particular, from the viewpoint of the degree to which such systems embody capabilities for functional or "causal" reasoning . We distinguish between deep models in the sense of scientific first principles and deep cognitive models where the problem solver has a qualitative symbolic representation of the system or device . that accounts qualtitatively for how the system works .". We analyze diagnostic reasoning as an information processing task ., and identify the generic types of knowledge (and reasoning) that are needed for the task to be performed adequately . If these types of knowledge are available, then we show how an integrated collection of generic problem solvers can produce a diagnostic conclusion . The need for deep or causal models arises when some or all of the knowledge of the types identified above are missing in the problem solver . We provide a typology of different knowledge structures and reasoning processes that play a role in qualitative or functional reasoning . We indicate where the work of Kuipers, de Kleer and Brown, Davis, Forbus, Bylander,