Symbolic discrete event system specification

An extension of the discrete event system specification modeling formalism (DEVS) that facilitates symbolic expression of event times by extending the time base from the real numbers to the field of linear polynomials over the reals is presented. A simulation algorithm is developed to generate the branching trajectories resulting from the underlying nondeterminism. To efficiently manage symbolic constraints, a consistency checking algorithm for linear polynomial constraints based on a feasibility checking algorithm borrowed from linear programming is developed. The extended formalism offers a convenient means to conduct multiple, simultaneous explorations of model behaviors. Examples of application are given with concentration on fault model analysis.>