The project is large and has a number of components that have been documented at length. These components have never been drawn together in one document; thus, this article describes the project and gives a taste of the individual subprojects that have kept the project members so busy for so long. A large number of publications have emerged from the project, so a full bibliography of the work appears for the reader who wants to follow up on any intriguing topics. AAP straddles a number of research areas and, thus, does not fall easily into any one sphere of interest. A certain amount of work has been done on the parallelizing of expert systems, most notably by Gupta (1986).

The Stanford Heuristic Programming Project: Goals and Activities

Some of the more popular alternativo used to build knowledge systems are production systems, backward-chained reasoning, logic programming, heuristic search, and the Blackboard framework. Many of the applications implemented in production systems have been written in the OPS language [8]. In this framework, knowledge is represented as a set of homogeneous rules that are scanned for applicability in a data base that contains the current state of solution. Backward chaining also has a homogeneous set of rules, but the search for applicable rules is driven by a hierarchy of goals and sub-goals. The best known system for implementing this type of program is EMYCIN [4].

Current subprojects include applications of the program Gerring.

Table 1: Measured comparison of three control strategies.

During the quarter century since the birth of "artificial intelligence" (Al), attempts to develop symbolic models of human reasoning processes have been a major focus of the ongoing research. It is only in the last half-dozen years or so, however, that several related Al research themes have come together in the formation of what is now known as "expert systems researoh" CI], In this brief paper I would 1.ke to review the key aspects of A: and expert syste-.s

JANICE S. AIKINS Dr. Aikins received her Ph.D. in computer science from Stanford University in 1980. She is currently a research computer scientist at IBM's Palo Alto Scientific Center. She specializes in designing systems with an emphasis on the explicit representation of control knowledge in expert systems. ROBERT L. BLUM Dr. Blum received his M.D. from the University of California Medical School at San Francisco in 1973. From 1973 to 1976 he did an internship and residency in the Department of Internal Medicine at the Kaiser Foundation Hospital in Oakland, California, where he was chief resident in 1976.

The Advanced Architectures Project at Stanford University's Knowledge Systems Laboratory seeks to gain higher performance for expert system applications through the design of new, innovative software and hardware architectures. This research concentrates particularly on the use of parallel machines to gain speedup and the design of the software to exploit emergent paral-lel hardware architectures. This article describes the project and details its goals and the work performed in the pursuance of these goals. A brief description is given of each of the project components, and a complete bibliography appears of the publications produced for the project.

The Heuristic Programming Project of the Stanford University Computer Science Department is a laboratory of about fifty people whose main goals are to model the nature of scientific reasoning processes in various types of scientific problems and various areas of science and medicine; and to construct expert systems — programs that achieve high levels of performance on tasks that normally require significant human expertise for their solution.