Syntax-Driven Reachable State Space Construction of Synchronous Reactive Programs

We consider in the current paper the issue of exploiting the structural form of Esterel programs [BG92] to partition the algorithmic RSS (reachable state space) fix-point construction used in modelchecking techniques [CGP99]. The basic idea sounds utterly simple, as seen on the case of sequential composition: in P ;Q, first compute entirely the states reached in P , and then only carry on to Q, each time using only the relevant local transition relation part. Here a brute-force symbolic breadth-first search would have mixed the exploration of P and Q instead. The introduction of parallel (state product) operators, as well as loop iterators and local synchronizing signals make the problem more difficult (and more interesting). We propose techniques to partition statically (“at compile time”) the program body, so as to obtain a good trade-off between locality and multiplicity of steps.