The detection and diagnosis of malfunctions in technical systems. Such systems include production equipment (chemical plants, steel mills, paper mills, and power stations), transportation vehicles (ships, airplanes, automobiles), and household appliances (washing machines, air conditioners). In any of these systems, malfunctions of components may lead to damage of the equipment itself, degradation of its function or product, jeopardy of its mission, and hazard to human life. While the need to detect and diagnose malfunctions is not new, advanced fault detection has been made possible only by the proliferation of the computer. Fault detection and diagnosis actually means a scheme in which a computer monitors the technical equipment to signal any malfunction and determines the components responsible. The detection and diagnosis of the fault may be followed by automatic actions, enabling the fault to be corrected such that the system may operate successfully even under the particular faulty condition.