PalymSys - An Extended Version of CLIPS for Construction and Reasoning Using Blackboards

This paper describes PalymSys -an extended version of the CLIPS language that is designed to facilitate the implementation of blackboard systems. The paper first describes the general characteristics of blackboards and shows how a control blackboard architecture can be used by AI systems to examine their own behavior and adapt to real-time problem-solving situations by striking a balance between domain and control reasoning. The paper then describes the use of PalymSys in the development of a situation assessment subsystem for use aboard Army helicopters. This system performs real-time inferencing about the current battlefield situation using multiple domain blackboards as well as a control blackboard. A description of the control and domain blackboards and their implementation is presented. The paper also describes modifications made to the standard CLIPS 6.02 language in PalymSys 2.0. These include: 1. A dynamic Dempster-Shafer belief network whose structure is completely specifiable at run-time in the consequent of a PalymSys rule, 2. Extension of the run command including a continuous run feature that enables the system to run even when the agenda is empty, and 3. A built-in communications link that uses shared memory to communicate with other independent processes.