Section: Software and Platforms

The veriT solver

Participants : David Déharbe, Pablo Dobal, Haniel Barbosa, Pascal Fontaine [correspondent] .

The veriT solver is an SMT (Satisfiability Modulo Theories) solver developed in cooperation with David Déharbe from the Federal University of Rio Grande do Norte in Natal, Brazil. The solver can handle large quantifier-free formulas containing uninterpreted predicates and functions, and arithmetic over integers and reals. It features a very efficient decision procedure for difference logic, as well as a simplex-based reasoner for full linear arithmetic. It also has some support for user-defined theories, quantifiers, and lambda-expressions. This allows users to easily express properties about concepts involving sets, relations, etc. The prover can produce an explicit proof trace when it is used as a decision procedure for quantifier-free formulas with uninterpreted symbols and arithmetic. To support the development of the tool, a regression platform using Inria's grid infrastructure is used; it allows us to extensively test the solver on thousands of benchmarks in a few minutes. The veriT solver is available as open source under the BSD license at the veriT Web site .

Efforts in 2013 have been focused on efficiency, and more specifically on arithmetic. A preliminary prototype integrating the solver Redlog for non-linear arithmetic has been stabilized. First results are encouraging; this prepares the ground for the starting ANR project SMArT (Satisfiability Modulo Arithmetic Theories), involving both sites of the VeriDis team (veriT being developed in Nancy and Redlog being designed in Saarbrücken), as well as Systerel as an industrial partner.

In late 2013, Haniel Barbosa joined the team as a PhD student. He will work on theoretical and practical aspects of handling quantifiers in SMT frameworks, which is currently an important challenge for SMT, and he will implement his techniques in veriT.

We target applications where validation of formulas is crucial, such as the validation of TLA⁺ and B specifications, and work together with the developers of the respective verification platforms to make veriT even more useful in practice. The solver is available as a plugin for the Rodin platform for discharging proof obligations generated in Event-B [39] ; on a large repository of industrial and academic cases, this SMT-based plugin decreased by 75% the number of proof obligations requiring human interactions, compared to the original B prover.