A diagnostic reasoner correlates the results of one or more tests and produces a diagnosis based on the results of those tests. In the simplest case, this amounts to little more than a process of elimination. For example, if a failed test indicates that there is a fault within a set of three components and a passed test proves that two of those components are functioning properly, then the diagnostic reasoner can easily determine that the third component is faulty. More complex forms of inference allow the diagnostic reasoner to determine the status of a component based on tests at various levels of hierarchical indenture, mixed functional and failure-based testing, and different assumptions about the number of components that are simultaneously malfunctioning during diagnosis.
The eXpress diagnostic engine supports following types of diagnostic inferences:
