RPDEVS: Revising the Parallel Discrete Event System Specification

Abstract

In this work, we present a Revised Parallel DEVS (RPDEVS) formalism. The Classic Discrete Event System Specification (DEVS) and Parallel DEVS (PDEVS) formalisms do not support modelling of ‘true’ mealy behaviour, i.e. reacting to an input message immediately with an output message. Instead, such behaviour has to be modelled via transitory states and multiple state updates. This not only increases model complexity, it also impedes reusability of model components in different contexts.RPDEVS enhances PDEVS with the capability to model mealy behaviour directly. Hence, the output function λ can access the input bag. This introduces some challenges regarding the simulation algorithm which we will take a look at.Further, the terms algebraic loop and illegitimate model will be discussed in the context of RPDEVS. It is shown that RPDEVS models which are free of algebraic loops are also legitimate. Finally, it will be demonstrated that like Classic DEVS and PDEVS, also RPDEVS provides closure under coupling.