Darren Cofer

During the development and verification of complex airborne systems, a variety of languages and development environments are used for different levels of the system hierarchy. As a result, there may be manual steps to translate requirements between these different environments. This paper presents a tool-supported export technique that translates high-level requirements from the software architecture modeling environment into observers of requirements that can be used for verification in the software component environment. This allows efficient verification that the component designs comply with their high-level requirements. It also provides an automated tool chain supporting formal verification from system requirements down to low-level software requirements that is consistent with certification guidance for avionics systems. The effectiveness of the technique has been evaluated and demonstrated on a medical infusion pump and an aircraft wheel braking system.

Virtual integration techniques focus on building architectural models of systems that can be analyzed early in the design cycle to try to lower cost, reduce risk, and improve quality of complex embedded systems. Given appropriate architectural descriptions and compositional reasoning rules, these techniques can be used to prove important safety properties about the architecture prior to system construction. Such proofs build from "leaf-level" assume/guarantee component contracts through architectural layers towards top-level safety properties. The proofs are built upon the premise that each leaf-level component contract is realizable; i.e., it is possible to construct a component such that for any input allowed by the contract assumptions, there is some output value that the component can produce that satisfies the contract guarantees. Without engineering support it is all too easy to write leaf-level components that can't be realized. Realizability checking for propositional contracts has been well-studied for many years, both for component synthesis and checking correctness of temporal logic requirements. However, checking realizability for contracts involving infinite theories is still an open problem. In this paper, we describe a new approach for checking realizability of contracts involving theories and demonstrate its usefulness on several examples.