Validation of rule-based reactive systems by sound scenario generalization

Validation of reactive systems, such as telephone switching systems and traffic controllers, is made unusually difficult by the fact that such systems must perform heterogeneous behaviors robustly in complex, dynamic environments. This renders them unusually difficult to specify and even to state requirements for. In the ISAT project (Hall, 1992) end-user requirements are stated as concrete behavior scenarios, and a multi-functional apprentice system aids the human developer in acquiring and maintaining a knowledge-based specification consistent with the scenarios. This paper describes ISAT´s novel approach to validating the acquired specification by using sound scenario generalization to construct descriptions of scenario classes with guaranteed behavior. It also describes the key technical problems that must be solved in order to implement sound scenarios generalization using explanation-based techniques, as well as ISAT´s solution to the problems. The approach is implemented and has been tested on two reactive systems; an email system and a telephone switching system