Accession Number : ADP003919

Title :   Diagnosis Based on Description of Structure and Function,


Personal Author(s) : Davis,R. ; Shrobe,H. ; Hamscher,W. ; Wieckert,K. ; Shirley,M.

Report Date : JUN 1984

Pagination or Media Count : 12

Abstract : While expert systems have traditionally been built using large collections of rules based on empirical associations, interest has grown recently in the use of systems that reason from representations of structure and function. Our work explores the use of such models in troubleshooting digital electronics. We describe our work to date on (i) a language for describing structure, (ii) a language for describing function, and (iii) a set of principles for troubleshooting that uses the two descriptions to guide its investigation. In discussing troubleshooting we show why the traditional approach -- test generation -- solves a different problem and we discuss number of its practical shortcomings. We consider next the style of debugging known as discrepancy. Further exploration, however, demonstrates that in this standard from this approach is incapable of dealing with commonly known classes of faults. We explain the shortcoming as arising from a number of interesting assumptions made implicity when using the technique. In discussing how to repair the problems uncovered, we argue for the primacy of models of causal interaction, rather than the traditional fault models. We point out the importance of making these models explicit, separated from the troubleshooting mechanism, and retractable in much the same sense that inferences are retracted in current systems. We report on progress to date in implementing this approach. (Author)

Descriptors :   *Systems approach, *Computer applications, *Maintenance management, Electronics, Modules(Electronics), Models

Distribution Statement : APPROVED FOR PUBLIC RELEASE