Cofer, DarrenGacek, AndrewWhalen, Michael2020-12-102020-12-102011Department of Computer Science and Engineering University of Minnesota 200 Union St. Minneapolis, MN 55455https://hdl.handle.net/11299/217402Associated research group: Critical Systems Research GroupWe 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.Report