University of Minnesota
Software Engineering Center

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Insup Lee

Recent Publications

Representation of Confidence in Assurance Cases using the Beta Distribution

Assurance cases are used to document an argument that a system---such as a critical software system---satisfies some desirable property (e.g., safety, security, or reliability). Demonstrating high confidence that the claims made based on an assurance case can be trusted is crucial to the success of the case. Researchers have proposed quantification of confidence as a Baconian probability ratio of eliminated concerns about the assurance case to the total number of identified concerns.

Representation of Confidence in Assurance Case Evidence

When evaluating assurance cases, being able to capture the confidence one has in the individual evidence nodes is crucial, as these values form the foundation for determining the confidence one has in the assurance case as a whole. Human opinions are subjective, oftentimes with uncertainty---it is difficult to capture an opinion with a single probability value. Thus, we believe that a distribution best captures a human opinion such as confidence.

Hierarchical Multi-Formalism Proofs of Cyber-Physical Systems

To manage design complexity and provide verification tractability, models of complex cyber-physical systems are typically hierarchically organized into multiple abstraction layers. High-level analysis explores interactions of the system with its physical environment, while embedded software is developed separately based on derived requirements. This separation of lowlevel and high-level analysis also gives hope to scalability, because we are able to use tools that are appropriate for each level. When attempting to perform compositional reasoning in such an