Approximate symbolic model checking for incomplete designs

We consider the problem of checking whether an incomplete design can still be extended to a complete design satisfying a given CTL formula and whether the property is satisfied for all possible extensions. Motivated by the fact that well-known model checkers like SMV or VIS produce incorrect results when handling unknowns by using the programs' non-deterministic signals, we present a series of approximate, yet sound algorithms to process incomplete designs with increasing quality and computational resources. Finally we give a series of experimental results demonstrating the effectiveness and feasibility of the presented methods.