University of Minnesota
Software Engineering Center
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Darren Cofer

Recent Publications

Towards Realizability Checking of Contracts using Theories

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.

Requirements Analysis of a Quad-Redundant Flight Control System

In this paper we detail our effort to formalize and prove requirements for the Quad-redundant Flight Control System (QFCS) within NASA’s Transport Class Model (TCM). We use a compositional approach with assume-guarantee contracts that correspond to the requirements for software components embedded in an AADL system architecture model. This approach is designed to exploit the verification effort and artifacts that are already part of typical software verification processes in the avionics domain.

Hierarchical Circular Compositional Reasoning

We describe a composition rule for hierarchically composed components that may involve circular reasoning between the components. It is similar to previous work by McMillan, specialized to component level reasoning. In contrast to McMillan's work, our composition rule can be used in provers that only support safety properties (e.g. k-induction model checkers) as long as the system and component contracts consist of state invariants. The composition rule still holds for richer contracts, but the resulting verification conditions then require a general purpose model checker.

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