Building certified static analysers by modular construction of well-founded lattices

International audienceThis paper presents fixpoint calculations on lattice structures as example of highly modular programming in a dependently typed functional language. We propose a library of Coq module functors for constructing complex lattices using efficient data structures. The lattice signature contains a well-foundedness proof obligation which ensures termination of generic fixpoint iteration algorithms. With this library, complex well-foundedness proofs can hence be constructed in a functorial fashion. This paper contains two distinct contributions. We first demonstrate the ability of the recent Coq module system in manipulating alge- braic structures and extracting efficient Ocaml implementations from them. The second contribution is a generic result, based on the constructive notion of accessibility predicate, about preservation of accessibility properties when combining relations

A Certified Denotational Abstract Interpreter

International audienceAbstract Interpretation proposes advanced techniques for static analysis of programs that raise specific challenges for machine-checked soundness proofs. Most classical dataflow analysis techniques iterate operators on lattices without infinite ascending chains. In contrast, abstract interpreters are looking for fixpoints in infinite lattices where widening and narrowing are used for accelerating the convergence. Smart iteration strategies are crucial when using such accelerating operators because they directly impact the precision of the analysis diagnostic. In this paper, we show how we manage to program and prove correct in Coq an abstract interpreter that uses iteration strategies based on program syntax. A key component of the formalization is the introduction of an intermediate semantics based on a generic least-fixpoint operator on complete lattices and allows us to decompose the soundness proof in an elegant manner

Spy Game: Verifying a Local Generic Solver in Iris

International audienceWe verify the partial correctness of a "local generic solver", that is, an on-demand, incremental, memoizing least fixed point computation algorithm. The verification is carried out in Iris, a modern breed of concurrent separation logic. The specification is simple: the solver computes the optimal least fixed point of a system of monotone equations. Although the solver relies on mutable internal state for memoization and for "spying", a form of dynamic dependency discovery, it is apparently pure: no side effects are mentioned in its specification. As auxiliary contributions, we provide several illustrations of the use of prophecy variables, a novel feature of Iris; we establish a restricted form of the infinitary conjunction rule; and we provide a specification and proof of Longley's modulus function, an archetypical example of spying

Verasco: un analyseur statique pour C formellement vérifié

In order to develop safer software for critical applications, some static analyzers aim at establishing, with mathematical certitude, the absence of some classes of bug in the input program. A possible limit to this approach is the possibility of a soundness bug in the static analyzer itself, which would nullify the guarantees it is supposed to deliver.In this thesis, we propose to establish formal guarantees on the static analyzer itself: we present the design, implementation and proof of soundness using Coq of Verasco, a formally verified static analyzer based on abstract interpretation handling most of the ISO C99 language, including IEEE754 floating-point arithmetic (except recursion and dynamic memory allocation). Verasco aims at establishing the absence of erroneous behavior of the given programs. It enjoys a modular extendable architecture with several abstract domains and well-specified interfaces. We present the abstract iterator of Verasco, its handling of bounded machine arithmetic, its interval abstract domain, its symbolic abstract domain and its abstract domain of octagons. Verasco led to the development of new techniques for implementing data structure with sharing in Coq.Afin de développer des logiciels plus sûrs pour des applications critiques, certains analyseurs statiques tentent d'établir, avec une certitude mathématique, l'absence de certains types de bugs dans un programme donné. Une limite possible à cette approche est l'éventualité d'un bug affectant la correction de l'analyseur lui-même, éliminant ainsi les garanties qu'il est censé apporter.Dans cette thèse, nous proposons d'établir des garanties formelles sur l'analyseur lui-même : nous présentons la conception, l'implantation et la preuve de sûreté en Coq de Verasco, un analyseur statique formellement vérifié utilisant l'interprétation abstraite pour le langage ISO C99 avec l'arithmétique flottante IEEE754 (à l'exception de la récursion et de l'allocation dynamique de mémoire). Verasco a pour but d'établir l'absence d'erreur à l'exécution des programmes donnés. Il est conçu selon une architecture modulaire et extensible contenant plusieurs domaines abstraits et des interfaces bien spécifiées. Nous détaillons le fonctionnement de l'itérateur abstrait de Verasco, son traitement des entiers bornés de la machine, son domaine abstrait d'intervalles, son domaine abstrait symbolique et son domaine abstrait d'octogones. Verasco a donné lieu au développement de nouvelles techniques pour implémenter des structures de données avec partage dans Coq

Proceedings of the First NASA Formal Methods Symposium

Topics covered include: Model Checking - My 27-Year Quest to Overcome the State Explosion Problem; Applying Formal Methods to NASA Projects: Transition from Research to Practice; TLA+: Whence, Wherefore, and Whither; Formal Methods Applications in Air Transportation; Theorem Proving in Intel Hardware Design; Building a Formal Model of a Human-Interactive System: Insights into the Integration of Formal Methods and Human Factors Engineering; Model Checking for Autonomic Systems Specified with ASSL; A Game-Theoretic Approach to Branching Time Abstract-Check-Refine Process; Software Model Checking Without Source Code; Generalized Abstract Symbolic Summaries; A Comparative Study of Randomized Constraint Solvers for Random-Symbolic Testing; Component-Oriented Behavior Extraction for Autonomic System Design; Automated Verification of Design Patterns with LePUS3; A Module Language for Typing by Contracts; From Goal-Oriented Requirements to Event-B Specifications; Introduction of Virtualization Technology to Multi-Process Model Checking; Comparing Techniques for Certified Static Analysis; Towards a Framework for Generating Tests to Satisfy Complex Code Coverage in Java Pathfinder; jFuzz: A Concolic Whitebox Fuzzer for Java; Machine-Checkable Timed CSP; Stochastic Formal Correctness of Numerical Algorithms; Deductive Verification of Cryptographic Software; Coloured Petri Net Refinement Specification and Correctness Proof with Coq; Modeling Guidelines for Code Generation in the Railway Signaling Context; Tactical Synthesis Of Efficient Global Search Algorithms; Towards Co-Engineering Communicating Autonomous Cyber-Physical Systems; and Formal Methods for Automated Diagnosis of Autosub 6000

Tools and Algorithms for the Construction and Analysis of Systems

This open access book constitutes the proceedings of the 28th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2022, which was held during April 2-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 46 full papers and 4 short papers presented in this volume were carefully reviewed and selected from 159 submissions. The proceedings also contain 16 tool papers of the affiliated competition SV-Comp and 1 paper consisting of the competition report. TACAS is a forum for researchers, developers, and users interested in rigorously based tools and algorithms for the construction and analysis of systems. The conference aims to bridge the gaps between different communities with this common interest and to support them in their quest to improve the utility, reliability, exibility, and efficiency of tools and algorithms for building computer-controlled systems

Tools and Algorithms for the Construction and Analysis of Systems

This open access book constitutes the proceedings of the 28th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2022, which was held during April 2-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 46 full papers and 4 short papers presented in this volume were carefully reviewed and selected from 159 submissions. The proceedings also contain 16 tool papers of the affiliated competition SV-Comp and 1 paper consisting of the competition report. TACAS is a forum for researchers, developers, and users interested in rigorously based tools and algorithms for the construction and analysis of systems. The conference aims to bridge the gaps between different communities with this common interest and to support them in their quest to improve the utility, reliability, exibility, and efficiency of tools and algorithms for building computer-controlled systems

CLARIN

The book provides a comprehensive overview of the Common Language Resources and Technology Infrastructure – CLARIN – for the humanities. It covers a broad range of CLARIN language resources and services, its underlying technological infrastructure, the achievements of national consortia, and challenges that CLARIN will tackle in the future. The book is published 10 years after establishing CLARIN as an Europ. Research Infrastructure Consortium

CLARIN. The infrastructure for language resources

CLARIN, the "Common Language Resources and Technology Infrastructure", has established itself as a major player in the field of research infrastructures for the humanities. This volume provides a comprehensive overview of the organization, its members, its goals and its functioning, as well as of the tools and resources hosted by the infrastructure. The many contributors representing various fields, from computer science to law to psychology, analyse a wide range of topics, such as the technology behind the CLARIN infrastructure, the use of CLARIN resources in diverse research projects, the achievements of selected national CLARIN consortia, and the challenges that CLARIN has faced and will face in the future. The book will be published in 2022, 10 years after the establishment of CLARIN as a European Research Infrastructure Consortium by the European Commission (Decision 2012/136/EU)