FUNCTIONAL AND TELEOLOGICAL KNOWLEDGE IN THE MULTIMODELING APPROACH FOR REASONING ABOUT PHYSICAL SYSTEMS - A CASE-STUDY IN DIAGNOSIS

This paper first presents the basic concepts of the multimodeling approach to the representation of physical systems. The key point of this approach is the exploitation of many, diverse models of a system for the execution of complex problem solving tasks, such as interpretation, diagnosis, design, simulation, etc. The considered models are based on different ontologies, representational assumptions, epistemological types, and aggregation levels. After a brief survey of the techniques adopted for representing structural and behavioral knowledge, attention is focused on function and teleology. A novel approach is proposed for defining, representing, and using these two types of knowledge which play a fundamental role both from the representation and reasoning perspectives. The fundamental claim here is that while teleological knowledge concerns the specific purposes for which the system has been designed, functional knowledge is devoted to bridge the gap between such abstract purposes and the actual structure and behavior of the system, through the concepts of phenomena, processes, and functional roles. Moreover, the paper provides a clear definition of all the various epistemological and ontological links existing between the different models, which allow the execution of complex reasoning activities by cooperation among all the models. Finally, the proposed approach is applied to the specific task of diagnosis. An experimental system called DYNAMIS is described, which has been used as a testbed for original diagnostic strategies exploiting the problem solving power offered by the multimodeling approach and, in particular, by functional and teleological knowledge. Three sample diagnostic sessions with DYNAMIS are illustrated, which focus on the issues of operator diagnosis, diagnosis focusing, and functional conflict recognition.