Model-based diagnosis and conditional logic

The model-based diagnostic approach was first introduced to overcome the li mitations of heuristic systems. However, research on model-based systems sh owed that the model-based diagnosis approaches resort to assumptions that c an be viewed as the return, though controlled, of heuristics into diagnosti c reasoning. In this paper we focus on diagnosis with component-oriented de vice models. We argue for the need to represent and reason with these assum ptions. We present a conditional logic, DL, That is suitable for diagnostic reasoning and allows us to represent and reason with assumptions.