Extending the Hierarchy of System Specifications and Morphisms with SES Abstraction

This article works toward a unification of two related concepts that underpin system-theory-based modeling and simulation–the hierarchy of system specifications and morphisms and the System Entity Structure (SES). The hierarchy organizes system specification along levels ranging from behavior to structure capturing increasing knowledge of the system input/output processing and state dynamics. The SES is a constructive ontology describing compositions of modular components via coupling of input/output ports. Toward unification of these concepts, we propose an abstraction of the SES called the MetaSES that supports the construction of complex systems of systems with multiple components belonging to specified classes. Moreover, we place the MetaSES within a computational framework with the goal of making it easier to design and build complex hierarchical DEVS models and to communicate their structures and intended behaviors to foster continued reuse and development. We discuss several examples of applications to illustrate how the MetaSES-based enhancement of the hierarchy of system specifications and morphisms helps to push the boundaries of complexity management in the theory and practice of modeling and simulation. Research directions stemming from the proposed concepts are suggested.