Model Composition in Rosetta

We describe the various composition operations available in the Rosetta specification language, provide examples, and discuss reasoning compositionally about specified systems. Composing specifications allows for more than the usual benefits of modularity and re-use: reasoning about specifications also may rely explicitly on the nature of composition. Rosetta facilitates composition of differing views, called 'facets', of a system. This heterogeneous specification approach allows for separation of concerns and also admits any applicable multi-domain reasoning.