Towards a theory for cyber-physical systems modeling.

Modeling the heterogeneous composition of physical, computational and communication systems is an important challenge in engineering Cyber-Physical Systems (CPS), where the major sources of heterogeneity are causality, time semantics, and different physical domains. Classical physical laws capture acausal continuous-time dynamics, thus the behavior of physical systems are inherently characterized by acausal continuous-time equations. On the other hand, computational and communication systems are based on the notion of causality and discrete-time semantics. Connecting the two worlds is challenging, and calls for proper formalization of the composition. In this paper, we discuss a formalism that captures both acausal physical laws, unidirectional analog signals, and is capable of describing causal computational systems, as well as the composition of CPS models.