Abstract
A maintenance monitoring system with multiple dependent monitors was investigated, and a necessary and sufficient condition was derived for the optimal maintenance policy to be given by a "monotone procedure." This condition is that the conditional probability mass function of the output of any monitor, given the system's true state and the outputs of the other monitors being fixed, has a property of monotone likelihood ratio. This condition is the same as that of the conditional probabilities of monitor observations having a property of a weak-multivariate monotone likelihood ratio (weak-MLR). Limiting the optimal policy to a monotone procedure greatly reduces the amount of calculation time needed to identify an optimal decision. This enables an optimal decision to be found quickly.
