Approximate simulation relations for hybrid systems

Approximate simulation relations have recently been introduced as a powerful tool for the approximation of discrete and continuous systems. In this paper, we extend this abstraction framework to hybrid systems. Using the notion of simulation functions, we develop a characterization of approximate simulation relations which can be used for hybrid systems approximation. For several classes of hybrid systems, this characterization leads to effective algorithms for the computation of approximate simulation relations. An application in the context of reachability analysis is shown.