Component-Based Approach in the Development of a Knowledge-Based Planning Support System. Part 2: The Model and Knowledge Management Systems of KBPSS

In part 1 of our paper on the architecture of a component-based knowledge-based planning support system (KBPSS), we briefly introduced the ModelObjects model-management component and the KBSAgents knowledge-management component of the system. In this part we further examine the issues of model management and knowledge development in the ModelObjects and KBSAgents components. Model generalization and representation of ModelObjects are defined according to object-oriented methods and techniques. These procedures allow users to understand how planning models are processed in the system environment; and how the models in the system libraries can be reused to build more flexible domain models based on the users' problem definition and the interaction with the system interface. The model-retrieval and model-execution functions in ModelObjects can be further enhanced by KBSAgents from which model knowledge is constructed and managed; and models can be easily retrieved and selected on the basis of the user's request and the input to the system. To support model and model-knowledge development in KBSAgents, a frame-type object-oriented model-knowledge representation scheme is defined and constructed in the system. We discuss knowledge-based model selection by developing an Intelligent Model Selection System, an application subsystem in KBPSS which combines the functions of ModelObjects and KBSAgents and can be applied to assist users to select appropriate models from the model library for their problems. Throughout the paper, spatial interaction models are used as an example to illustrate the procedures and processes proposed in the system.