  Second, as the limits of expert systems and production rule programming in the area of artificial intelligence became increasingly clear to computer scientists, they began to search for methods beyond those that depended merely on imitating experts. One promising line of research has been to automate phases of (Peirce’s concept of) the scientific method, complete with techniques for hypothesis generation and making assessments of the costs and benefits of exploring hypotheses. In some areas of research added impetus has been provided by the similarity of Peircean techniques to techniques that have already proven useful. For example, in the field of automated multi-track radar, the similarity of Peircean scientific method to the so-called “Kalman filter” has been noted by many systems analysts. Again, those interested in military command-and-control often note the similarity of Peircean scientific method to the classic OODA loop (“observe, orient, decide, act”) of command-and-control-theory. The aerospace industry, especially in France and the United States, is currently investigating Peircean ideas in connection with avionics systems that monitor aircraft “health.”