A correct-by-construction approach for proving distributed algorithms in spanning trees

Dynamic networks are characterized by frequent topology changes due to the unpredictable appearance and disappearance of mobile devices and/or communication links. In this paper, we propose a correct-by-construction approach for proving distributed algorithms in a forest of spanning trees. Our approach consists in two phases. The first one aims to control the dynamic structure of the network by triggering a maintenance operation when the forest is altered. To do so, we develop a formal pattern using the Event-B method which is based on an existing model for building and maintaining a spanning forest in dynamic networks. The second phase of our approach deals with distributed algorithms which can be applied to spanning trees. We illustrate our pattern through an example of a leader election algorithm. The proof statistics show that our solution can save efforts on specifying as well as proving the correctness of distributed algorithms in a forest of spanning trees.