HPRL: A Language for Building Expert Systems

Aside from this dif ference in emphasis, KL-ONE and HPRL contain a similar set of representat ion tools. The init ial representation components were both developed at approximately the same time 1977. Cur ren t l y KL-ONE is being extended to allow for the expression of logical relations among elements in a separate syntax (Brachman and Levesque, 1982). HPRL has gone the route described in this paper of in tegrat ing reasoning and representat ion wi th in a declarative semantics. This paper describes an extension of FRL (Frame Representation Language) which supports the encoding of reasoning knowledge wi th in a frame-based formalism. The extension is called HPRL (Heur ist ic Programming and Representation Language). The declarat ive representation of reasoning knowledge in the same formalism that is used to represent domain knowledge results in a powerful tool for the construct ion of expert systems. Reasoning knowledge is easy to descr ibe, examine and modify. Rules can be ref lex ive, allowing the construct ion of powerful meta-rules. HPRL runs on a Vax 11/780, and on the HP-9836. It has been used for various exploratory projects at Hewlet t -Packard, inc luding a program to diagnose faul ts du r ing IC manufactur ing, a program for analyzing dual-channel ECG information to diagnose ar rhy thmias, and a program for analyzing spectra from in f rared and mass spectrometers.