A task structure for case-based design

The methodology of task analysis is used in case-based design to address the questions of what tasks the system needs to perform, what methods are applicable to these tasks, what knowledge the methods use, and what control they exercise over the processing. An abstract task is analyzed in terms of the methods applicable to it. A method is characterized by the types of knowledge it uses, the subtasks it sets up, and the control it exercises over the processing of the subtasks. Each subtask is similarly analyzed in terms of the methods applicable to it, and so on, up to some elementary level of decomposition. This analysis yields an integrative functional task structure for solving behavior-to-structure design tasks by the method of case-based reasoning in the domain of simple physical devices. The task structure is functional in that each method in it is directed towards some specific task. It is integrative in that it combines the methods of case-based reasoning, causal analysis, plan instantiation, heuristic association, heuristic search, and generate and test for solving the design task