Descripción:
This paper consists of two parts, appearing in consecutive issues of this Journal. It deals with some of the many aspects of modelling physical systems in terms of differential equations (DE>, ordinary and partial. Among the issues touched upon figure a) the important role played by the assumptions underlying a DE based ma.themati cal model <Part I>, and b > the- interplay between modelling and .simulation when using differential equation models <Part I I). . In a more phi 1 osophi cal vein, there is a section on determinism as well as one on model validation; while fairly general in scope, the concepts examined therein are introduced in direct relation to DE models.