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Expert system validation in prologAn overview of the Expert System Validation Assistant (EVA) is being implemented in Prolog at the Lockheed AI Center. Prolog was chosen to facilitate rapid prototyping of the structure and logic checkers and since February 1987, we have implemented code to check for irrelevance, subsumption, duplication, deadends, unreachability, and cycles. The architecture chosen is extremely flexible and expansible, yet concise and complementary with the normal interactive style of Prolog. The foundation of the system is in the connection graph representation. Rules and facts are modeled as nodes in the graph and arcs indicate common patterns between rules. The basic activity of the validation system is then a traversal of the connection graph, searching for various patterns the system recognizes as erroneous. To aid in specifying these patterns, a metalanguage is developed, providing the user with the basic facilities required to reason about the expert system. Using the metalanguage, the user can, for example, give the Prolog inference engine the goal of finding inconsistent conclusions among the rules, and Prolog will search the graph intantiations which can match the definition of inconsistency. Examples of code for some of the checkers are provided and the algorithms explained. Technical highlights include automatic construction of a connection graph, demonstration of the use of metalanguage, the A* algorithm modified to detect all unique cycles, general-purpose stacks in Prolog, and a general-purpose database browser with pattern completion.
Document ID
19890006204
Document Type
Conference Paper
Authors
Stock, Todd (Lockheed Missiles and Space Co. Austin, TX, United States)
Stachowitz, Rolf (Lockheed Missiles and Space Co. Austin, TX, United States)
Chang, Chin-Liang (Lockheed Missiles and Space Co. Austin, TX, United States)
Combs, Jacqueline (Lockheed Missiles and Space Co. Austin, TX, United States)
Date Acquired
September 5, 2013
Publication Date
October 1, 1988
Publication Information
Publication: NASA, Marshall Space Flight Center, Fourth Conference on Artificial Intelligence for Space Applications
Subject Category
COMPUTER PROGRAMMING AND SOFTWARE
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.