On the Behaviour of Failure Frequency Bounds

The behaviour of failure frequency bounds has been studied in this paper. The alternate bounds are indeed upper and lower bounds to the failure frequency. These bounds can diverge at intermediate steps though they finally converge to the exact value. The divergent behaviour is likely to occur when ¿/¿ is relatively large. It is preferrable to use the margin between fUimin and fLimax, rather than between fUi and fLi as the criterion for truncating the computations.