It is often possible to describe the correct functioning of a system bya mathematical model. As long as observations or measurements correspondto the predictions made by the model, the system may be assumedto be functioning correctly. When, however, a discrepancy arises betweenthe observations and the model-based predictions, then an explanationfor this fact has to be found. The foundation of this approach to diagnosticshas been laid by Reiter (1987). The explanations generated by...