On System Diagnosability in the Presence of Hybrid Faults

This correspondence deals with the problem of testing the diagnosmbllity of a system in presence of hybrid faults (that is, when some of the units of the system have failed intermittently and some have failed permanently). Presence of intermittent faults can lead to incomplete diagnosis and usually complicates the diagnosis problem in comparison to permanent fault situation. Alternative characterizations for hybrid fault diagnosability of a system to those originally presented in [3] are derived in this paper. It is shown that these conditions lead to the testing of the hybrid diagnosability of a system with fewer computations than that in [3].