A KNOWLEDGE REPRESENTATION LANGUAGE bY

. This paper describes KRL, a Knowledge Representation Language designed for use in’ understander systems. It outlines both the general.concepts which underlie our research and the details of K RL-0, an experimental implementation of some of these concepts. KRL is an attempt to integrate procedural knowledge with a broad base of declarative forms. These forms provide a variety of ways to express the logical structure of the knowledge, in order to give flexibility in associating procedures (for memory and reasoning) with specific pieces of knowledge, and to control the relative accessibility of different facts and descriptions. The formalism for declarative knowledge is based or1 structured conceptual objects with associated descriptions. These objects form a network of memory units with several different sorts of linkages, each having wellspecified implications for the retrieval process. Procedures can be associated directly with the internal structure of a conceptual object. This procedurul attachment allows the steps for a particular operation to be determined by characteristics of the specific entities involved. The control structure of KRL is based on the belief that the next generation of intelligent programs will integrate data-directed and goal-directed processing by using multi-processing. It provides for a priority-ordered multi-process agenda with explicit (user-provided) strategies for scheduling and resource allocation. It provides pvacedure directories which operate along with process frnmerclods to allow procedural parameteritation of the fundamental system processes for building, comparing, and retrieving memory structures. Future development of KRL will include integra’ting procedure definition with the descriptive formalism. Daniel Bobrow is afiliatcd with Xerox Palo Alto Research Center, Palo Alto, CaliJornia. This document is also being issued as Xerox PARC report CSL-76-4, and will appear in the journal Cognitive Science, V. 1, No. I, 1377.