Expert System Consultation Control Strategy

User interfaces to expert systems represent a bottleneck since consultation time is proportional to the amount of information the system asks the user to supply. An efficient, rather than exhaustive, strategy to direct user questioning will reduce consultation time and effort. An intelligent strategy to minimize questioning, the merit system, has been successfully implemented in Battle, an expert consultant system developed for the Marine Corps. The merit strategy enables Battle to focus the consultation process on the most meritorious questions allowing the military commander to respond quickly awith the most pertinent information The merit system, originally defined for logical functions in the iVultiple program, has been extended to the Mycin style of propagation and to the method of subjective Bayesian assignments used by Prospector. A procedure for merit calculations with any differentiable, real-valued ass;gnment function is presented. Our experience has shown that merit values provide an efficient flow of control for expert consultation,