Towards the Composition of Specifications in Event-B

The development of a system can start with the creation of a specification. Following this viewpoint, we claim that often a specification can be constructed from the combination of specifications which can be seen as composition. Event-B is a formal method that allows modelling and refinement of systems. The combination, reuse and validation of component specifications are not currently supported in Event-B. We extend the Event-B formalism using shared event composition as an option for developing (distributed) systems. Refinement is used in the development of specifications using composed machines and we prove that properties and proof obligations of specifications can be reused to ensure valid composed specifications. The main contributions of this work are the Event-B extension to support shared event composition and refinement including the proof obligations for a composed machine.