Approximating behaviors in embedded system design

Embedded systems are electronic devices that function in the contextof a physical environment, by sensing and reacting to a set of stimuli. To sim-plify the design of embedded systems, different parts are best described usingdifferent notations and analyze with different techniques, i.e., the system is saidto beheterogeneous. We informally refer to the notation and the rules that areused to specify and verify the elements of heterogeneous systems and their col-lective behavior as amodel of computation. In this paper, the use ofconservativeapproximations(recently introduced by the authors) is reviewed to establish rela-tionships between different models of computation in a design. After presentingthe basic definitions, we propose three different models at different levels of ab-straction for describing a system and the progression towards its implementation.Then, we derive associated conservative approximations starting from simple ho-momorphisms between sets of behaviors of the different models.