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VERIDIS Research team

Activity reports

Overall Objectives

The VeriDis project team includes members of the MOSEL group at LORIA, the computer science laboratory in Nancy, and members of the research group Automation of Logic at Max-Planck-Institut für Informatik in Saarbrücken. It is headed by Stephan Merz and Christoph Weidenbach. VeriDis was created in 2010 as a local research group of Inria Nancy – Grand Est and has been an Inria project team since July 2012.

The objectives of VeriDis are to contribute to advances in verification techniques, including automated and interactive theorem proving, and to make them available for the formal development and analysis of concurrent and distributed algorithms and systems, within the framework of mathematically precise and practically applicable development methods. We intend to assist designers of algorithms and systems in carrying out formally proved developments, where proofs of relevant properties, as well as bugs, can be found with a high degree of automation.

Verification techniques based on theorem proving are already having substantial impact. In particular, they have been successfully applied to the verification and analysis of sequential programs, often in combination with static analysis and software model checking. Ideally, systems and their properties would be specified in high-level, expressive languages, errors in specifications would be discovered automatically, and finally, full verification could also be performed completely automatically. Due to the inherent complexity of the problem, this cannot be achieved in general. We have, however, observed significant advances in theorem proving in recent years. We are particularly interested in the integration of different deduction techniques and tools, such as automated theorem proving for relevant theories, such as different fragments of arithmetic. These advances suggest that a substantially higher degree of automation can be achieved in system verification than what is available in today's verification tools.

VeriDis aims at exploiting and further developing automation in system verification, and at applying its techniques within the context of concurrent and distributed algorithms, which are by now ubiquitous and whose verification is a big challenge. Concurrency problems are central for the development and verification of programs for multi- and many-core architectures, and distributed computation underlies the paradigms of grid and cloud computing. The potential of distributed systems for increased resilience to component failures makes them attractive in many contexts, but also makes formal verification important and challenging. We aim at moving current research in this area to a new level of productivity and quality. To give a concrete example: today the designer of a new distributed protocol may validate it using testing or model checking. Model checking will help finding bugs, but can only guarantee properties of a high-level model of the protocol, usually restricted to finite instances. Testing distributed systems and protocols is notoriously difficult because corner cases are hard to establish and reproduce. Also, many testing techniques require an executable, whose production is expensive and time-consuming, and since an implementation is needed, errors are found only when they are expensive to fix. The techniques that we develop aim at automatically proving significant properties of the protocol as early as during the design phase. Our methods mainly target designs and algorithms at high levels of abstraction; we aim at components of operating systems, distributed services, and down to the (mobile) network systems industry.