Extensible Symbolic System Analysis∗

Unification and narrowing are a key ingredient not only to solve equations modulo an equational theory, but also to perform symbolic system analysis. The key idea is that a concurrent system can be naturally specified as a rewrite theory R = (Σ, E, R), where (Σ, E) is an equational theory specifying the system’s states as an algebraic data type, and R specifies the system’s concurrent, and often non-deterministic, transitions. One can perform such symbolic analysis by describing sets of states as (the instances of) terms with logical variables, and using narrowing modulo E to symbolically perform transitions. Under reasonable conditions on R, this idea can be applied not only for complete reachability analysis, but also for temporal logic model checking. This approach is quite flexible but has some limitations. Could it be possible to make symbolic system analysis techniques more extensible and more widely applicable by simultaneously combining the powers of rewriting, narrowing, SMT solving and model checking? We give a progress report on current work aiming at such a unified symbolic approach.