An abstract state machine semantics for discrete event simulation

Abstract

We define an operational (transition system) semantics for the two most basic forms of Discrete Event Simulation (DES): event-based simulation (without objects) and object-event simulation. We show that under our operational semantics, DES models correspond to a certain form of abstract state machines (ASMs) such that the Future Event List (FEL) is part of the transition system state and the transition function is based on event routines. Unlike other formalisms proposed for DES (such as Petri Nets or DEVS), our ASM semantics takes all basic DES concepts (like event types and the FEL) into consideration and allows for expressive transition system states representing the objects, properties, relations and functions of the evolving possible worlds of a simulation run. As a direct formal semantics of DES, it provides a basis for comparing, and explaining design choices in, different DES approaches.