Why3-do: The way of harmonious distributed system proofs

We study principles and models for reasoning inductively about properties of distributed systems, based on programmed atomic handlers equipped with contracts. We present the Why3-do library, leveraging a state of the art software verifier for reasoning about distributed systems based on our models. A number of examples involving invariants containing existential and nested quantifiers (including Dijsktra’s self-stabilizing systems) illustrate how the library promotes contract-based modular development, abstraction barriers, and automated proofs.The development of Why3-do was initiated during a visit of the second author to the Toccata team at Inria Saclay-ˆIle-de-France/LRI Univ Paris-Saclay/CNRS and greatly benefited from the team’s hospitality and Why3 expertise. This work is financed by the ERDF – European Regional Development Fund through the North Portugal Regional Operational Programme - NORTE 2020 Programme and by National Funds through the Portuguese funding agency, FCT - Fundação para a Ciência e a Tecnologia within project NORTE-01-0145-FEDER-028550 - PTDC/EEI-COM/28550/2017