  Recently there has been a great attention from the scientific community
towards the use of the model-checking technique as a tool for test generation
in the simulation field. This paper aims to provide a useful mean to get more
insights along these lines. By applying recent results in the field of graded
temporal logics, we present a new efficient model-checking algorithm for
Hierarchical Finite State Machines (HSM), a well established symbolism long and
widely used for representing hierarchical models of discrete systems.
Performing model-checking against specifications expressed using graded
temporal logics has the peculiarity of returning more counterexamples within a
unique run. We think that this can greatly improve the efficacy of
automatically getting test cases. In particular we verify two different models
of HSM against branching time temporal properties.
