Section: New Results

Certification of Languages, Tools and Systems

• M. Clochard, C. Marché, and A. Paskevich developed a general setting for developing programs involving binders, using Why3. This approach was successfully validated on two case studies: a verified implementation of untyped lambda-calculus and a verified tableaux-based theorem prover. This work was presented at the PLPV conference in January 2014 [32] .

• M. Clochard, J.-C. Filliâtre, C. Marché, and A. Paskevich developed a case study on the formalization of semantics of programming languages using Why3. This case study aimed at illustrating recent improvements of Why3 regarding the support for higher-order logic features in the input logic of Why3, and how these are encoded into first-order logic, so that goals can be discharged by automated provers. This case study also illustrates how reasoning by induction can be done without need for interactive proofs, via the use of lemma functions. This works was presented at the VSTTE conference [31] .

• M. Clochard and L. Gondelman developed a formalization of a simple compiler in Why3. It compiles a simple imperative language into assembler instructions for a stack machine. This case study was inspired by a similar example developed using Coq and interactive theorem proving. The aim is to improve significantly the degree of automation in the proofs. This is achieved by the formalization of a Hoare logic and a Weakest Precondition Calculus on assembly programs, so that the correctness of compilation is seen as a formal specification of the assembly instructions generated. This work conducted in 2014 will be presented at the JFLA conference in January 2015 [75] .

• S. Dumbrava and É. Contejean, with V. Benzaken (VALS team, at LRI) proposed a Coq formalization of the relational data model which underlies relational database systems. More precisely, they have presented and formalized the data definition part of the model including integrity constraints. They have modelled two different query language formalisms: relational algebra and conjunctive queries. They also present logical query optimization and prove the main “database theorems”: algebraic equivalences, the homomorphism theorem and conjunctive query minimization. This work has been published at ESOP 2014 [27] .

• A. Charguéraud, together with the other members of the JsCert team have developed this year the first complete formalization of the semantics of the JavaScript programming language. This project is joint work with Philippa Gardner, Sergio Maffeis, Gareth Smith, Daniele Filaretti and Daiva Naudziuniene from Imperial College, and Alan Schmitt and Martin Bodin from Inria Rennes (see http://jscert.org ). The formalization consists of a set of inductive rules translating the prose from the ECMAScript Language Specification, version 5, using the pretty-big-step semantics [74] . These rules can be used to formally reason about program behaviors or to establish the correctness of program transformations. In addition to the inductive rules, a reference interpreter has been proved correct. This interpreter may be used to run actual JavaScript program following the rules of the formal semantics. It has been used in particular to validate the formal semantics against official JavaScript test suites. The formalization of JavaScript has been published at POPL [28] .