Modelling when connections are the problem
Most of the AI diagnostic reasoning approaches for digital systems presume that digital components are pure functions of their inputs, all signals can be represented by ``1''s and ``0''s, wires between components cannot fail, and do not model replacement of components or wires. None of these assumptions are valid for the challenges diagnosticians encounter in real systems. Although digital systems can be modeled at the analog level with programs such as SPICE or at the digital/analog level with VHDL-based simulators, they are not designed for diagnostic use, require accurate hard-to-obtain component models and do not present results in a way a human diagnostician can understand. This paper presents a digital expert (DEX) which can reason over digital systems much like an electrical engineer would: at a qualitative, causal level but more accurate than the simple ``0''/''1'' level without incurring the costs of full-scale numerical algorithms.
de Kleer, J. Modelling when connections are the problem. Twentieth International Conference on Qualitative Reasoning; 2006 July 10; Hanover; NH; USA.