A Mechanically Checked Generation of Correlating Programs Directed by Structured Syntactic Differences

International audienceWe present a new algorithm for the construction of a correlating program from the syntactic difference between the original and modified versions of a program. This correlating program exhibits the semantics of the two input programs and can then be used to compute their semantic differences, following an approach of Partush and Yahav [12]. We show that Partush and Yahav's correlating program is unsound on loops that include an early exit. Our algorithm is defined on an imperative language with while-loops, break, and continue. To guarantee its correctness, it is formalized and mechanically checked within the Coq proof assistant. On a series of examples, we experimentally find that the static analyzer dizy is at least as precise on our correlating program as on Partush and Yahav's

Le projet BWare : une plate-forme pour la vérification automatique d'obligations de preuve B

National audienceLe projet de recherche industrielle BWare (ANR-12-INSE-0010) est financé pour 4 ans par le programme " Ingénierie Numérique & Sécurité " (INS) de l'Agence Nationale de la Recherche (ANR) et a débuté en septembre 2012 (voir le site web du projet : http://bware.lri.fr). Le consortium du projet BWare associe les partenaires académiques Cedric, LRI, et Inria, ainsi que les partenaires industriels Mitsubishi Electric R&D Centre Europe (MERCE), ClearSy, et OCamlPro

ADHOCFS: A Serverless File System for Mobile Users

Among other features, pervasive computing aims at offering access to users' data, anytime, anywhere, in a transparent manner. However, realizing such a vision necessitates several improvements in the way servers and users terminals interact. In particular, users terminals should not tightly rely on an information server, which can be temporarily unavailable in a mobile situation. They should rather exploit all the information servers available in a given context through loose coupling with both fixed servers and groups of mobile terminals, in a serverless manner. This paper presents the AdHocFS serverless file system that realizes transparent adaptive file access according to the users' specific situations (e.g. device in use, network connectivity, etc)

Oracle-based Differential Operational Semantics (long version)

Program dierences are pervasive in software development and understanding them is crucial. However, such changes are usually represented as textual dierences with no regard to the syntactic nature of programs or their semantics. Such a representation may be hard to read or reason about and often fails to convey insight on the semantic implications of a change. In this paper, we propose a formal framework to characterize the dierence of behavior between two close programs equivalent or notin terms of their small-step semantics. To this end, we introduce small-step-prediction oracles that consume one reduction step of one program and produce a sequence of reduction steps of the other. Such oracles are operational, handle diverging or stuck computations, and are well-suited for describing local changes, while expressive enough to describe arbitrary ones. They can also be composed, to characterize a dierence as a sequence of simpler dierences. Last but not least, small-prediction-step oracles can be explained to programmers in terms of evaluation of the compared programs. We illustrate this framework by instantiating it on the Imp imperative language, with oracles ranging from trivial equivalence-preserving syntactic transformations to characterized semantic dierences. Through these examples, we show how our framework can be used to relate syntactic changes with their eect on the semantics, or to describe higher-level changes by abstracting away from the small-step semantics presentation. We have dened and proved the framework and the presented examples in the Coq proof assistant, and implemented a proof-of-concept inference tool for the Imp language

Formalization and Verification of Coherence Protocols with the Gamma Framework

This paper presents an approach to formalize coherence protocols for shared virtual memories as multiset rewriting systems. The global state of the protocol is represented as a multiset and rewriting rules are used to describe state changes. Invariants are expressed as properties on the cardinality of subsets which characterize specific relations. We present an automatic algorithm to check that a property is an invariant of a protocol. Both the formalization and the verification steps are illustrated on the Li and Hudak single-writer/multiple-readers coherence protocol

Automated Formal Analysis of Temporal Properties of Ladder Programs

International audienceProgrammable Logic Controllers are industrial digital computers used as automation controllers in manufacturing processes. The Ladder language is a programming language used to develop software for such controllers. In this work, we consider the description of the expected behaviour of a Ladder program under the form of a timing chart, describing a scenario of execution. Our aim is to prove that the given Ladder program conforms to the expected temporal behaviour given by such a timing chart. Our approach amounts to translating the Ladder code, together with the timing chart, into a program for the Why3 environment for deductive program verification. The verification proceeds with the generation of verification conditions: mathematical formulas to be checked valid using automated theorem provers. The ultimate goal is twofold. On the one hand, by obtaining a complete proof, one verifies the conformity of the Ladder code with respect to the timing chart with a high degree of confidence. On the other hand, in the case the proof is not fully completed, one obtains a counterexample, illustrating a possible execution scenario of the Ladder code which does not conform to the timing chart

Autoantibodies neutralizing type I IFNs are present in ~4% of uninfected individuals over 70 years old and account for ~20% of COVID-19 deaths

Publisher Copyright: © 2021 The Authors, some rights reserved.Circulating autoantibodies (auto-Abs) neutralizing high concentrations (10 ng/ml; in plasma diluted 1:10) of IFN-alpha and/or IFN-omega are found in about 10% of patients with critical COVID-19 (coronavirus disease 2019) pneumonia but not in individuals with asymptomatic infections. We detect auto-Abs neutralizing 100-fold lower, more physiological, concentrations of IFN-alpha and/or IFN-omega (100 pg/ml; in 1:10 dilutions of plasma) in 13.6% of 3595 patients with critical COVID-19, including 21% of 374 patients >80 years, and 6.5% of 522 patients with severe COVID-19. These antibodies are also detected in 18% of the 1124 deceased patients (aged 20 days to 99 years; mean: 70 years). Moreover, another 1.3% of patients with critical COVID-19 and 0.9% of the deceased patients have auto-Abs neutralizing high concentrations of IFN-beta. We also show, in a sample of 34,159 uninfected individuals from the general population, that auto-Abs neutralizing high concentrations of IFN-alpha and/or IFN-omega are present in 0.18% of individuals between 18 and 69 years, 1.1% between 70 and 79 years, and 3.4% >80 years. Moreover, the proportion of individuals carrying auto-Abs neutralizing lower concentrations is greater in a subsample of 10,778 uninfected individuals: 1% of individuals 80 years. By contrast, auto-Abs neutralizing IFN-beta do not become more frequent with age. Auto-Abs neutralizing type I IFNs predate SARS-CoV-2 infection and sharply increase in prevalence after the age of 70 years. They account for about 20% of both critical COVID-19 cases in the over 80s and total fatal COVID-19 cases.Peer reviewe

Vaccine breakthrough hypoxemic COVID-19 pneumonia in patients with auto-Abs neutralizing type I IFNs

Life-threatening `breakthrough' cases of critical COVID-19 are attributed to poor or waning antibody response to the SARS- CoV-2 vaccine in individuals already at risk. Pre-existing autoantibodies (auto-Abs) neutralizing type I IFNs underlie at least 15% of critical COVID-19 pneumonia cases in unvaccinated individuals; however, their contribution to hypoxemic breakthrough cases in vaccinated people remains unknown. Here, we studied a cohort of 48 individuals ( age 20-86 years) who received 2 doses of an mRNA vaccine and developed a breakthrough infection with hypoxemic COVID-19 pneumonia 2 weeks to 4 months later. Antibody levels to the vaccine, neutralization of the virus, and auto- Abs to type I IFNs were measured in the plasma. Forty-two individuals had no known deficiency of B cell immunity and a normal antibody response to the vaccine. Among them, ten (24%) had auto-Abs neutralizing type I IFNs (aged 43-86 years). Eight of these ten patients had auto-Abs neutralizing both IFN-a2 and IFN-., while two neutralized IFN-omega only. No patient neutralized IFN-ss. Seven neutralized 10 ng/mL of type I IFNs, and three 100 pg/mL only. Seven patients neutralized SARS-CoV-2 D614G and the Delta variant (B.1.617.2) efficiently, while one patient neutralized Delta slightly less efficiently. Two of the three patients neutralizing only 100 pg/mL of type I IFNs neutralized both D61G and Delta less efficiently. Despite two mRNA vaccine inoculations and the presence of circulating antibodies capable of neutralizing SARS-CoV-2, auto-Abs neutralizing type I IFNs may underlie a significant proportion of hypoxemic COVID-19 pneumonia cases, highlighting the importance of this particularly vulnerable population

Higher COVID-19 pneumonia risk associated with anti-IFN-α than with anti-IFN-ω auto-Abs in children

We found that 19 (10.4%) of 183 unvaccinated children hospitalized for COVID-19 pneumonia had autoantibodies (auto-Abs) neutralizing type I IFNs (IFN-alpha 2 in 10 patients: IFN-alpha 2 only in three, IFN-alpha 2 plus IFN-omega in five, and IFN-alpha 2, IFN-omega plus IFN-beta in two; IFN-omega only in nine patients). Seven children (3.8%) had Abs neutralizing at least 10 ng/ml of one IFN, whereas the other 12 (6.6%) had Abs neutralizing only 100 pg/ml. The auto-Abs neutralized both unglycosylated and glycosylated IFNs. We also detected auto-Abs neutralizing 100 pg/ml IFN-alpha 2 in 4 of 2,267 uninfected children (0.2%) and auto-Abs neutralizing IFN-omega in 45 children (2%). The odds ratios (ORs) for life-threatening COVID-19 pneumonia were, therefore, higher for auto-Abs neutralizing IFN-alpha 2 only (OR [95% CI] = 67.6 [5.7-9,196.6]) than for auto-Abs neutralizing IFN-. only (OR [95% CI] = 2.6 [1.2-5.3]). ORs were also higher for auto-Abs neutralizing high concentrations (OR [95% CI] = 12.9 [4.6-35.9]) than for those neutralizing low concentrations (OR [95% CI] = 5.5 [3.1-9.6]) of IFN-omega and/or IFN-alpha 2