Closure under coupling: concept, proofs, DEVS recent examples (wip)

With the growth in new variants of DEVS, the concept of closure under coupling has reached a level of importance where it stands discussion in its own right. As emphasized in (Zeigler et al 2000), closure under coupling justifies hierarchical construction. Here we show that it also provides assurance that the class under consideration is well-defined and enables checking for the correct functioning of feedback coupled models. Absence of closure is also informative as it begs for characterizing the smallest closed class that includes the given class. This illustrated here as we discuss closure under coupling for several recently introduced subclasses of the DEVS formalism.