System Specification and Refinement in Temporal Logic

We consider two types of speciications of reactive systems: requirement speciication which lists properties the system should satisfy, and System speciica-tion which describes the response of the system to each incoming input. Some of the diierences between these two styles of speciication are analyzed with the conclusion that both types are needed in an orderly system development. Traditionally, temporal logic was used for requirement speciication while process algebras, such as csp and ccs, were used for system speciication. Recent developments , mainly represented in Lamport's temporal logic of actions (tla), demonstrated that temporal logic can be used eeectively also for system speciication. This paper explores the use of temporal logic for systems speciication, evaluates some of the advantages and disadvantages of such a use, and demonstrates the use of temporal logic for reenement and systematic development of systems. To allow simulation of a single high level step by several lower level steps, we go back to the temporal logic tlr which is based on a dense time domain, such as the reals.