Section: Bilateral Contracts and Grants with Industry

Proving formulas over streams

Participants : Pascal Fontaine, Stephan Merz.

In an exploratory project with Atelier de Qualification Logicielle of RATP, we studied the use of SAT solving techniques for proving certain formulas expressed over infinite Boolean streams. Such formulas arise as proof obligations generated from SCADE models used by RATP, and they are currently proved using proprietary tools. We showed that in the absence of recursive definitions, checking a small number of instances of a proof obligation ensures its validity for all instances. For models that contain recursive definitions, the bound on the number of instances that must be checked becomes much bigger, making it unwieldy to apply the same technique, and inductive reasoning should be used. We implemented our proposal in a prototype checker and validated it using several benchmarks provided by RATP.