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6-month Master Internship on Formal Semantics of the Specification Language ACSL H/F

Vacancy details

General information


The French Alternative Energies and Atomic Energy Commission (CEA) is a key player in research, development and innovation in four main areas :
• defence and security,
• nuclear energy (fission and fusion),
• technological research for industry,
• fundamental research in the physical sciences and life sciences.

Drawing on its widely acknowledged expertise, and thanks to its 16000 technicians, engineers, researchers and staff, the CEA actively participates in collaborative projects with a large number of academic and industrial partners.

The CEA is established in ten centers spread throughout France



Description de l'unité

The Software Safety and Security Laboratory (LSL) at CEA List Institute has an ambitious goal : help designers, developers and validation experts ship high-confidence systems and software. Objects in our surroundings are getting more and more complex, and we have built a reputation for efficiently using formal reasoning to demonstrate their trustworthiness. In collaboration with the most creative people in academia and the industry, we design methods and tools that leverage innovative approaches to ensure that real-world systems can comply with the highest safety and security standards. Our organizational structure is simple : those who pioneer new concepts are the ones who get to
implement them. We are a forty-person team, and your work will have a direct and visible impact on the state of formal verification. CEA LIST's offices are located at the heart of Campus Paris Saclay, in the largest European cluster of public and private research.

Position description


Mathematics, information, scientific, software



Job title

6-month Master Internship on Formal Semantics of the Specification Language ACSL H/F


The internship will be dedicated to provide a formal semantics to ACSL, the ANSI/ISO C Specification language ( that is at the heart of the Frama-C code analysis platform (, in order to ensure that all Frama-C plug-ins share a common understanding of each ACSL annotation. This internship can easily morph into a PhD thesis topic for interested candidate.

Contract duration (months)


Job description

Our team develops Frama-C, an Open-Source code analysis platform for C programs which provides several collaborative analyzers as plug-ins. Frama-C allows the user to annotate C programs with formal specifications written in the ACSL specification language. Frama-C can then ensure that a C program satisfies its formal specification by relying on several techniques, notably abstract inter-
pretation (plug-in Eva), weakest preconditions calculus (plug-in Wp), and runtime verification (plug-in E-ACSL). Therefore, ACSL is the lingua franca shared by the Frama-C plug-ins. It is one of the key for plug-in collaborations. For instance, some ACSL properties may be proved by a plug-in A under a few hypotheses that are expressed as another set of ACSL properties that may in turn be proved by
another plug-in B. Yet, the soundness of the whole verification process assumes that every plug-in shares the same semantics of ACSL. Currently, this semantics is only described by the reference manual written in natural language (American English). It leads to several issues that already occurred these last years. For instance, the ACSL manual may contain partial definitions and/or insufficient explanations that open the door to inconsistent interpretations (by plug-in developers, or end-users). This internship, possibly followed by a PhD thesis on the same topic, aims at fixing these issues by defining a formal semantics for (a subset of) ACSL with respect to an existing formal semantics of the C programming language (e.g. CompCert memory model, the executable semantics formalized in the K framework, or Robbert Krebber's PhD thesis), expanding upon the work done by Paolo Herms in his PhD thesis on the implementation of a certified verification condition generator. Ideas could also come from similar works for other specification languages such as JML. The internship will focus on key constructs of ACSL, such as assertions and function contracts containing integer and pointer arithmetics, as well as memory-related predicates in order to define their formal semantics in one proof environment such as Coq. The intern will also propose and implement a methodology for validating existing verification tools based on ACSL (such as the Frama-C plug-ins Wp, Eva, and E-ACSL) with respect to the defined formal semantics.

Methods / Means

the intern will be provided with a workstation under Linux (preferred) or Windows

Applicant Profile

Knowledge in formal semantics of programming languages is required.
Knowledge in the following fields would be welcome:
- The C programming language
- proof environment (e.g. the Coq proof assistant)
- formal specification languages
- program verification

Position localisation



Job location

France, Ile-de-France, Essonne (91)



Candidate criteria


  • French (Intermediate)
  • English (Intermediate)

Prepared diploma

Bac+5 - Master 2

Recommended training

Master in Computer Science or Engineering School

PhD opportunity



Position start date