Hierarchical System Design with Vertical Contracts

Abstract

We propose the notions of heterogeneous refinement and vertical contracts as additions for any contract framework to provide full methodological support for multi-view and multi-layer system design with heterogeneous models. We rethink the relation of contract refinement in the context of layered design and discuss how it can be extended, via heterogeneous refinement and vertical contracts, to deal with hierarchies of models that present heterogeneous architectures as well as behaviors expressed by heterogeneous formalisms. We then show via design examples that such an extension can, indeed, encompass a richer set of design refinement relations, including support for synthesis methods and optimized mappings of specifications into implementations.