Overall Objectives
Research Program
Application Domains
Software and Platforms
New Results
Bilateral Contracts and Grants with Industry
Partnerships and Cooperations
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Section: New Results

New Formal Languages and their Implementations

LNT is a next generation formal description language for asynchronous concurrent systems, which attempts to combine the best features of imperative programming languages and value-passing process algebras. LNT is increasingly used by CONVECS for industrial case studies and applications (see §  6.5 ) and serves also in university courses on concurrency, in particular at ENSIMAG (Grenoble) and at Saarland University.

Translation from LNT to LOTOS

Participants : Hubert Garavel, Frédéric Lang, Wendelin Serwe.

The LNT2LOTOS, LNT.OPEN, and LPP tools convert LNT code to LOTOS, thus allowing the use of CADP to verify LNT descriptions. These tools have been used successfully for many different systems (see §  6.5 and §  9.1 ).

In 2013, in addition to 15 bug fixes, the following enhancements have been brought to these tools:

Translation from LOTOS to Petri nets and C

Participants : Hubert Garavel, Wendelin Serwe.

The LOTOS compilers CAESAR and CAESAR.ADT, which were once the flagship of CADP, now play a more discrete role since LNT (rather than LOTOS) has become the recommended specification language of CADP. Thus, CAESAR and CAESAR.ADT are mostly used as back-end translators for LOTOS programs automatically generated from LNT or other formalisms such as Fiacre, and are only modified when this appears to be strictly necessary.

In 2013, in addition to fixing four bugs, the type checking algorithm of CAESAR and CAESAR.ADT was entirely revised to display less and better messages in case of typing errors, avoiding cascading error messages, e.g., when an undefined variable or constant is used, or when an overloaded function is improperly used in a context where a unique type is expected.

Also, the CAESAR compiler found a new usefulness as a means to easily produce large-size, realistic Petri nets that can be used as benchmarks by the Petri net community. To make this possible, a new option was added to CAESAR to export the BPN (Basic Petri Net) file generated from a LOTOS specification. The definition of the BPN format was made more precise by adding semantic constraints. The CAESAR.BDD tool of CADP was enhanced with two new options, one that checks whether a BPN file satisfies all semantic constraints, and another one that converts a BPN file into PNML (Petri Net Markup Language) format.

This work has been done in coordination with Fabrice Kordon and Lom-Messan Hillah (UPMC/LIP6, Paris, France) for the MCC (Model Checking Contest) workshop ( ). H. Garavel was in charge of redesigning the model forms used for this contest. One Petri net generated using CAESAR was selected as a benchmark for MCC'2013 and five Petri nets generated using CAESAR have been submitted to MCC'2014.

Translation from an Applied Pi-Calculus to LNT

Participants : Radu Mateescu, Gwen Salaün.

The π-calculus is a process algebra defined by Milner, Parrow, and Walker two decades ago for describing concurrent mobile processes. Despite a substantial body of theoretical work in this area, only a few verification tools have been designed for analysing π-calculus specifications automatically. Our objective is to provide analysis features for the π-calculus by reusing the verification technology available for process algebras without mobility. For this purpose, we extended the original polyadic π-calculus with the data types and functions of LNT. This yields a general-purpose applied π-calculus, which is suitable for specifying mobile value-passing concurrent systems belonging to various application domains. Our approach is based on a novel translation from the finite control fragment of π-calculus to LNT, making possible the analysis of applied π-calculus specifications using all verification tools of CADP. This translation is fully automated by the PIC2LNT translator (see §  5.3 ).

In 2013, we continued our work on the applied π-calculus and its translation to LNT. This resulted in a new version PIC2LNT 3.0 of the tool, which fixes several bugs and brings the following improvements:

A paper describing this work has been published in an international conference [16] .

Translation from EB3 to LNT

Participants : Frédéric Lang, Radu Mateescu.

In collaboration with Dimitris Vekris (University Paris-Est Créteil), we considered a translation from the EB3 language  [39] for information systems to LNT. EB3 has a process algebraic flavor, but has the particularity to contain so-called attribute functions, whose semantics depend on the history of events. We have proposed a formal translation scheme, which ensures the strong equivalence between the LTSs corresponding to an EB3 specification and to the LNT code generated. A prototype translator has been developed at University Paris-Est Créteil, which enables EB3 specifications to be formally verified using CADP.

In 2013, a paper has been published in an international conference [19] .

Coverage Analysis for LNT

Participants : Gwen Salaün, Lina Ye.

In the classic verification setting, the designer has a specification of a system in a value-passing process algebra, a set of temporal properties to be verified on the corresponding LTS model, and a data set of examples (test cases) for validation purposes. At this stage, building the set of validation examples and debugging the specification is a complicated task, in particular for non-experts.

In 2013, we proposed a new framework for debugging value-passing process algebraic specifications by means of coverage analysis and we illustrated our approach with LNT. We define several coverage notions before showing how to instrument the specification without affecting its original behavior. Our approach helps the specifier to find dead code, ill-formed conditional structures, and other errors in the specification, but also to improve the quality of a data set of examples used for validation purposes. We have implemented a prototype tool, named CAL, for automating the verification of coverage analysis, and we applied it to several real-world case studies in different application areas. A paper has been submitted to an international conference.

Other Compiler Developments

Participants : Soraya Arias, Hubert Garavel, Frédéric Lang, Wendelin Serwe.