A Framework for Time in FDTs

Abstract. ASM is recognized as a useful formalism for defining the semantics of programming languages and modeling formalisms, but it has not initially been intended for expressing non functional properties. Also, during the work with the SDL formal semantics, problems of expression of time progress occurred at several places. Several proposals for timed ASM based on quite different approaches have been made. On the other hand, there exist a number of frameworks for modeling timed computations outside the world of ASM. It seems useful to try to elaborate a common understanding of time in ASM. We propose a general time model based on timed events, where time passes only in states, to which the existing frameworks can be reduced. Furthermore, we provide a number of options for defining useful time frameworks and discuss some of their consequences. We use this framework to give an overview on a number of approaches on modeling time in and outside the context of ASM. As ASM are a very general framework for specifying state-transition systems, our approach is valid for state-transition systems in general.