Fault masking by multiple timing faults in timed EFSM models

Detection of multiple timing faults is a challenging task because these faults, although may be detectable individually, can mask each other’s faulty behavior, making a faulty implementation under test (IUT) indistinguishable from a non-faulty one during testing. This phenomenon, called fault masking, is formally defined in this paper. It is proven that graph augmentation algorithms proposed for timed Extended Finite State Machines (EFSMs) with multiple timers can detect pairwise occurrences of classes of timing faults in an IUT and, hence, detects fault masking.