Equivalence checking of NuSMV specifications

We present a technique for checking the equivalence of NuSMV specifications. The approach is founded on the notion of equivalence between Kripke structures. The necessity to tackle this problem arisen working on using mutation to asses the static analysis fault detection capability. Indeed, mutation, consisting into introducing simple syntactic changes -- representing typical mistakes designers often make -- into specifications, may produce equivalent mutants, namely models behaving as the original one. Equivalent mutants should be detected since they do not represent actual faults. In program mutation, detecting equivalent mutants is an undecidable problem and, when possible, is a time-consuming activity, difficult to automatize. In this work we focus on how detecting equivalence of NuSMV specifications. The novel technique we propose, consists in building a merging unique specification and proving by model checking a series of CTL properties.