This paper presents a Hoare-style calculus for formal reasoning about reconfiguration programs of distributed systems. Such programs delete or create interactions or components while the system components change state according to their local behaviour. Our proof calculus uses a configuration logic that supports local reasoning and that relies on inductive predicates to describe distributed systems with an unbounded number of components. The validity of reconfiguration programs relies on havoc invariants, assertions about the ongoing interactions in the system. We present a proof system for such invariants in an assume/rely-guarantee style. We illustrate the feasibility of our approach by proving the correctness of self-adjustable tree architectures and provide tight complexity bounds for entailment checking in the configuration logic.
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