Hybrid systems show both discrete and continuous behaviour. Several process algebras for modelling these systems have appeared in the literature in recent years. These all assume that continuous variables in the system are modelled monolithically, often with the differential equations embedded explicitly in the syntax of the process algebra expression. In HYPE an alternative approach offers finer-grained modelling with each flow or influence affecting a variable modelled separately. The overall behaviour then emerges as the composition of these flows. This approach is supported by an operational semantics which distinguishes states as collections of flows and a semantic equivalence which satisfies the property that bisimilar HYPE models give rise to the same sets of continuous behaviours. The theory of HYPE will be presented, examples of how to use HYPE to model hybrid systems will be shown and some ideas for extending HYPE with stochastic features will be discussed.
This seminar is based on work presented at CONCUR 2009 and is joint work with Jane Hillston (University of Edinburgh) and Luca Bortolussi (University of Trieste).