1. A method for classifying a fault, comprising: receiving a circuit representation describing a circuit; receiving a fault set comprising one or more faults; establishing a circuit model corresponding to the circuit representation, the circuit model associated with a number of time frames; and repeating the following for each fault of the fault set: selecting a fault from the fault set; generating a satisfiability problem corresponding to the selected fault as associated with the circuit model; determining whether the satisfiability problem is unsatisfiable; and classifying the selected fault as untestable if the satisfiability problem is unsatisfiable.