Abstract
Every complex system is liable to faults and failures. In the most general terms, a fault is any change in a system that prevents it from operating in the proper manner. Here, the diagnosis of catastrophic defects in complex digital circuits. In fact, today the technical diagnosis is great challenge for design engineers because diagnostic problems are generally under determinate. It is also a deductive process with one set of data creating, in general, unlimited number of hypotheses among which one should try to get the solution. So the diagnosis methods are based on proprietary knowledge and personal experience, although they were built into integrated diagnostic equipment. The approach proposed here is an alternative to existing solutions, and it is expected to encompass all phases of the diagnostic process: symptom detection, hypotheses generation, and hypotheses discrimination.