TASK STRUCTURES AS A BASIS FOR MODELING KNOWLEDGE-BASED SYSTEMS

Recently, there has been an increasing interest in improving the relia bility and quality of Al systems. As a result, a number of approaches to knowledge-based systems modeling have been proposed. However, these approaches are limited in formally verifying the intended functionali ty and behavior of a knowledge-based system. In this article, we propo sed a formal treatment to task structures to formally specify and veri fy knowledge-based systems modeled using these structures. The specifi cation of a knowledge-based system modeled using task structures has t wo components: a model specification that describes static properties of the system, and a process specification that characterizes dynamic properties of the system. The static properties of a system are descri bed by two models: a model about domain objects (domain model), and a model about the problem-solving states (state model). The dynamic prop erties of the system are characterized by (1) using the notion of stat e transition to explicitly describe what the functionality of a task i s, and (2) specifying the sequence of tasks and interactions between t asks (i.e., behavior of a system) using task state expressions (TSE). The task structure extended with the proposed formalism not only provi des a basis for detailed functional decomposition with procedure abstr action embedded in, but also facilitates the verification of the inten ded functionality and behavior of a knowledge-based system. (C) 1997 J ohn Wiley gr Sons, Inc.