Systems of Systems (SoS) are composed with interconnected dynamical subsystems with communication facilities, the natures of which lead to different mathematical models: ordinary differential equations, differential inclusions, time delay systems, partial differential equations .... Information technology revolution has become a reality together with its new challenges. One of them being the need to manage such SoS with communication facilities, while requiring the best achievable performances: in particular robustness as well as severe time response constraints (for safety reasons, or simply to improve productivity). These technologies will deeply impact society and economy, in particular concerning the following areas: Service robotics, Embedded systems, multi-modal transportation, ... Finite4SoS aims at developing a new promising framework to address control and estimation issues of SoS subject to this model diversity, while achieving robustness as well as severe time response constraints. The key ingredients are: finite-time concepts, which will help in managing severe time constraints; homogeneity and time-varying feedback, which are the main tools for achieving the finite-time property for both convergence and input-to-state stability for each class of system. These concepts will help for both cascade and feedback connections (for example, feedback homogeneization will preserve the finite-time property). Finite4SoS will develop: firstly finite-time concepts and their characterization (Objective 1.), then finite-time control and estimation algorithms for each class of systems: Oridnary differential equations ODE and Differential Inclusion DI (Objective 2.), Time Delay Systems TDS (Objective 3.), Partial Differential Equations PDE (Objectives 4.) and lastly, tools to connect and analyse these subsystems together (Objective 6.). This will provide a framework to address control and estimation issues of SoS whose subsystems are described by ODE, DI, TDS and PDE while achieving the desired time performances. Three research groups with the right level of complementary expertise in control, estimation and finite time concepts will collaborate on this project: the NON-A team from Inria Lille (Inria-CNRS-Ecole Centrale de Lille), LJLL from UPMC (in partnership with CNRS) and CAOR from ARMINES (Mines ParisTech).

The ANR MEDSALT project aims to consolidate and expand a scientific network recently formed with the purpose to use scientific drilling to address the causes, timing, emplacement mechanisms and consequences of the largest and most recent 'salt giant' on Earth: the late Miocene (Messinian) salt deposit in the Mediterranean basin. After obtaining the endorsement of the International Ocean Discovery Program (IODP) on a Multiplatform Drilling Proposal (umbrella proposal) in early 2015, the network is planning to submit a site-specific drilling proposal to drill a transect of holes with the R/V Joides Resolution in the evaporite-bearing southern margin of the Balearic promontory in the Western Mediterranean - the aim is to submit the full proposal before the IODP dealine of April 1st 2017, following the submission of a pre-proposal on October 1st 2015. Four key issues will be addressed: 1) What are the causes, timing and emplacement mechanisms of the Mediterranean salt giant ? 2) What are the factors responsible for early salt deformation and fluid flow across and out of the halite layer ? 3) Do salt giants promote the development of a phylogenetically diverse and exceptionally active deep biosphere ? 4) What are the mechanisms underlying the spectacular vertical motions inside basins and their margins ? Our nascent scientific network will consit of a core group of 22 scientists from 10 countries (7 European + USA + Japan + Israel) of which three french scientists (G. Aloisi, J. Lofi and M. Rabineau) play a leading role as PIs of Mediterranean drilling proposals developed within our initiative. Support to this core group will be provided by a supplementary group of 21 scientists that will provide critical knowledge in key areas of our project. The ANR MEDSALT network will finance key actions that include: organising a 43 participants workshops to strengthen and consolidate the Mediterranean drilling community, supporting the participation of network scientists to seismic well site-survey cruises, organising meetings in smaller groups to work on site survey data and finance trips to the US to defend our drilling proposal in front of the IODP Environmental Protection and Safety Panel (EPSP). The MEDSALT drilling initiative will impact the understanding of issues as diverse as submarine geohazards, sub-salt hydrocarbon reservoirs and life in the deep subsurface. This is a unique opportunity for the French scientific community to play a leading role, next to our international partners, in tackling one of the most intellectually challenging open problems in the history of our planet.

Verifying correctness and robustness of programs and systems is a major challenge in a society which relies more and more on safety-critical systems controlled by embedded software. This issue is even more critical when the computations involve floating-point number arithmetic, an arithmetic known for its quite unusual behaviors, and which is increasingly used in embedded software. Note for example the "catastrophic cancellation" phenomenon where most of the significant digits of a result are cancelled or, numerical sequences whose limit is very different over the real numbers and over the floating-point numbers. A more important problem arises when we want to analyse the relationship between floating-point computations and an "idealized" computation that would be carried out with real numbers, the reference in the design of the program. The point is that for some input values, the control flow over the real numbers can go through one conditional branch while it goes through another one over the floating-point numbers. Certifying that a program, despite some control flow divergences, computes what it is actually expected to compute with a minimum error is the subject of the robustness or continuity analysis. Providing a set of techniques and tools for verifying the accuracy, correctness and robustness for critical embedded software is a major challenge. The aim of this project is to address this challenge by exploring new methods based on a tight collaboration between abstract interpretation (IA) and constraint programming (CP). In other words, the goal is to push the limits of these two techniques for improving accuracy analysis, to enable a more complete verification of programs using floating point computations, and thus, to make critical decisions more robust. The cornerstone of this project is the combination of the two approaches to increase the accuracy of the proof of robustness by using PPC techniques, and, where appropriate, to generate non-robust test cases. The goal is to benefit from the strengths of both techniques: PPC provides powerful but computationally expensive algorithms to reduce domains with an arbitrary given precision whereas AI does not provide fine control over domain precision, but has developed many abstract domains that quickly capture program invariants of various forms. Incorporating some PPC mechanisms (search tree, heuristics) in abstract domains would enable, in the presence of false alarms, to refine the abstract domain by using a better accuracy. The first problem to solve is to set the theoretical foundations of an analyser based on two substantially different paradigms. Once the interactions between PPC and IA are well formalized, the next issue is to handle constraints of general forms and potentially non-linear abstract domains. Last but not least, an important issue concerns the robustness analysis of more general systems than programs, like hybrid systems which are modeling control command programs. Research results will be evaluated on realistic benchmarks coming from industrial companies, in order to determine their benefits and relevance. For the explored approaches, using realistic examples is a key point since the proposed techniques often only behave in an acceptable manner on a given sub classes of problems (if we consider the worst-case computational complexity all these problems are intractable). That's why many solutions are closely connected to the target problems.

RainbowFS proposes a “just-right” approach to storage and consistency, for developing distributed, cloud-scale applications. Existing approaches shoehorn the application design to some predefined consistency model, but no single model is appropriate for all uses. Instead, we propose tools to co-design the application and its consistency protocol. Our approach reconciles the conflicting requirements of availability and performance vs. safety: common-case operations are designed to be asynchronous; synchronisation is used only when strictly necessary to satisfy the application's integrity invariants. Furthermore, we deconstruct classical consistency models into orthogonal primitives that the developer can compose efficiently, and provide a number of tools for quick, efficient and correct cloud-scale deployment and execution. Using this methodology, we will develop an entreprise-grade, highly-scalable file system, exploring the rainbow of possible semantics, and we demonstrate it in a massive experiment.

The overall objective of PARDI is the formal, machine-supported verification of parameterized distributed systems. A parameterized system specification is a specification for a whole class of systems, parameterized by the number of entities and the properties of the interaction, such as the communication model (synchronous/asynchronous, order of delivery of message, application ordering) or the fault model (crash failure, message loss). To be able to verify such systems without explicitly instantiating all the parameters, new theoretical results and dedicated tools are required. Due to the fundamental undecidability of the problem, automatic tools are not powerful enough to verify rich parameterized systems: they are limited in their expressiveness and do not handle the variety of the interaction models. To assist and automate verification without parameter instantiation, PARDI uses two complementary approaches. First, a fully automatic model checker modulo theories is considered. Then, to go beyond the intrinsic limits of parameterized model checking, the project advocates a collaborative approach between proof assistant and model checker. This collaboration is two-ways: in one direction, the model checker is used as an explorer to generate elementary invariants that can be used and combined in interactive verification; in the other direction, a property which is needed by the proof assistant is discharged to the parameterized model checker. Cubicle, a model checker for array-based systems, and TLAPS, a proof assistant well-adapted to study distributed algorithms, are the basis of this project. Using case studies, both in parameterized distributed systems and in parameterized workflow-based systems, a theoretical analysis is required to exhibit the relevant parameters and to prove generic results (e.g. substitutability). This analysis is needed to define the richer data structures that will extend the model checker's expressiveness, and to inject these generic results into checkers and provers. A first contribution of the project will be the verification of parameterized distributed systems, for an arbitrary number of sites. A library of results for the many communication models and fault models which exist and their integration in the verification tools will be a second contribution. A third contribution will be the design and implementation of a verification toolchain based on a close interaction between a proof assistant and a model checker. A fourth contribution will be a new DSL for parameterized workflow-based systems with rich explicit parameterization features, and its translation into the checker and prover input language.