TASK MODELING WITH REUSABLE PROBLEM-SOLVING METHODS

Problem-solving methods for knowledge-based systems establish the beha vior of such systems by defining the roles in which domain knowledge i s used and the ordering of inferences. Developers can compose problem- solving methods that accomplish complex application tasks from primiti ve, reusable methods. The key steps in this development approach are t ask analysis, method selection (from a library), and method configurat ion. PROTBGB-II is a knowledge-engineering environment that allows dev elopers to select and configure problem-solving methods. In addition, PROTBGB-II generates domain-specific knowledge-acquisition tools that domain specialists can use to create knowledge bases on which the meth ods may operate. The board-game method is a problem-solving method tha t defines control knowledge for a class of tasks that developers can m odel in a highly specific way. The method adopts a conceptual model of problem solving in which the solution space is construed as a ''game board'' on which the problem solver moves ''playing pieces'' according to prespecified rules. This familiar conceptual model simplifies the developer's cognitive demands when configuring the board-game method t o support new application tasks. We compare configuration of the board -game method to that of a chronological-backtracking problem-solving m ethod for the same application tasks (for example, towers of Hanoi and the Sisyphus room-assignment problem), We also examine how method des igners can specialize problem-solving methods by making ontological co mmitments to certain classes of tasks. We exemplify this technique by specializing the chronological-backtracking method to the board-game m ethod.