Communicating B Machines

This paper describes a way of using the process algebra CSP to enable controlled interaction between concurrent B machines This approach supports compositional veri cation each of the controlled ma chines and the combination of controller processes can be analysed and veri ed separately in such a way as to guarantee correctness of the com bined communicating system Reasoning about controlled machines sep arately is possible due to the introduction of guards and assertions into description of the controller processes in order to capture assumptions about other controlled machines and provide guarantees to the rest of the system The veri cation process can be completely supported by di erent tools The use of separate controller processes facilitates the iterative development and analysis of complex control ows within the system The approach is motivated and illustrated with a non trivial running example