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Section: Software and Platforms
Software and Platform
Software
libalf : the Automata Learning Framework
Participant : Benedikt Bollig [correspondant] .
libalf is a comprehensive, open-source library for learning finite-state automata covering various well-known learning techniques (such as, Angluin s L, Biermann, and RPNI, as well as a novel learning algorithm for NFA. libalf is highly flexible and allows for facilely interchanging learning algorithms and combining domain-specific features in a plug-and-play fashion. Its modular design and its implementation in C++ make it a flexible platform for adding and engineering further, efficient learning algorithms for new target models (e.g., Büchi automata).
Details on libalf can be found at http://libalf.informatik.rwth-aachen.de/
Mole/Cunf: unfolders for Petri Nets
Participants : Stefan Schwoon [correspondant] , César Rodríguez.
Mole computes, given a safe Petri net, a finite prefix of its unfolding. It is designed to be compatible with other tools, such as PEP and the Model-Checking Kit, which are using the resulting unfolding for reachability checking and other analyses. The tool Mole arose out of earlier work on Petri nets. Details on Mole can be found at http://www.lsv.ens-cachan.fr/~schwoon/tools/mole/ . Mole served as an experimentation platform for several of our papers this year, notably [38] and [46] .
In the context of MExICo, we have created a new tool called Cunf [47] , which is able to handle contextual nets, i.e. Petri nets with read arcs [12] .While in principle every contextual net can be transformed into an equivalent Petri net and then unfolded using Mole, Cunf can take advantage of their special features to do the job faster and produce a smaller unfolding. Cunf has recently been extended with a verification component that takes advantage of these features; More details can be found at http://www.lsv.ens-cachan.fr/~rodrigue/tools/cunf/ . Moreover, Cunf has been integrated into the CosyVerif environment (see section 5.1.2.1 ). Cunf has also participated in the Model Checking Contest held at the Petri Nets conference in 2013.
COSMOS : a Statistical Model Checker for the Hybrid Automata Stochastic Logic
Participant : Benoît Barbot [correspondant] .
COSMOS is a statistical model checker for the Hybrid Automata Stochastic Logic (HASL). HASL employs Linear Hybrid Automata (LHA), a generalization of Deterministic Timed Automata (DTA), to describe accepting execution paths of a Discrete Event Stochastic Process (DESP), a class of stochastic models which includes, but is not limited to, Markov chains. As a result HASL verification turns out to be a unifying framework where sophisticated temporal reasoning is naturally blended with elaborate reward-based analysis. COSMOS takes as input a DESP (described in terms of a Generalized Stochastic Petri Net), an LHA and an expression Z representing the quantity to be estimated. It returns a confidence interval estimation of Z; recently, it has been equipped with functionalities for rare event analysis. COSMOS is written in C++ and is freely available to the research community.
Details on COSMOS can be found at http://www.lsv.ens-cachan.fr/~barbot/cosmos/
Platforms
CosyVerif
Participants : Serge Haddad, Alban Linard [correspondant] , Benoît Barbot.
CosyVerif (http://www.cosyverif.org/ ) is a platform dedicated to the formal specification and verification of dynamic systems. It allows to specify systems in a graphical editor, using several formalisms (such as automata and Petri nets) and to run verification tools on these models in a dedicated execution server. These tools are mainly developed by researchers of the MeFoSyLoMa group (a Parisian verification group, http://www.mefosyloma.fr/ ).
The platform is available as installable bundles, that contain both the client, the server, and the tools. It is also usable through two public servers: one with the latest release, one with the development version.
CosyVerif does not only handle several formalisms, but also allows to easily define new ones and integrate them within the platform. To the best of our knowledge, no other verification framework presents such a feature.
It has different kinds of users:
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Tool developers, that are usually researchers, can use the platform to distribute their tools, and have a demonstration version easily available.
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Students can use this platform in modeling and verification courses.
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Industrial case studies are also a target of the CosyVerif platform, in order to promote the practice of formal verification in industry.
The platform is managed by a steering committee consisting of researchers and engineers. This committee decides strategic orientations as well as technical choices.
This year, we have improved the platform in several ways.
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Tools: the platform handles two families of formalisms: automata and Petri nets, both with extensions. It currently integrates 10 tools with 4 new ones this year. Some of them perform structural analyses like invariant computations, while other tools perform behavioural analyses: symbolic reachability graph building, unfolding, stochastic simulations, etc.
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Server: the execution server has been enhanced with asynchronous executions, that allow to disconnect and reconnect the client in long executions. It has also been improved by the ability to communicate between servers to share their available tools.
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Client: a new command line client has been developed for scripting the executions.
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Usability: the client and server are new distributed as one bundle that can be installed easily on all platforms. The server and its tools are embedded within a virtual machine to achieve this portability.
All the developed software are open source and free software tools.
Two engineers have worked this year on CosyVerif:
CosyVerif has been the subject of two international communications [28] , [29] . It has been presented at the french-speaking PhD school ETR'2013 in Toulouse. and used for teaching in the master SAR of University Pierre et Marie Curie.