Multifault diagnosis of digital systems using nonmonotoning reasoning [for nonmonotoning read nonmonotonic]

The authors present the design principles and the development of an expert system (called FAULT.ENT) for diagnosing multiple simultaneous faults in digital circuits (from first principles) using nonmonotonic reasoning and especially the default theory developed by R. Reiter. They give a detailed presentation of the algorithm, which has been implemented on a PC-AT 286 compatible machine, giving emphasis to the scheme developed for updating the conclusions that the system draws under uncertainty. They point out the similarities and differences between FAULT.ENT and other `intelligent systems´, particularly the GDE system of J. De Kleer, which incorporates an ATMS. A method is presented for increasing considerably the system efficiency in terms of complexity