Optimum group maintenance policies for a set of N machines subjected to stochastic failures under continuous and periodic inspections are considered. Under very general conditions it is shown that a control limit policy minimizes the expected cost per unit time over an infinite horizon, when...

Consider a production process where the categories of successive units form a Markov chain with known transition matrix. Whenever a unit is produced, we may, at a fixed cost, inspect it. If its value is less than maximal, we may replace it with a perfect (maximal value) unit. We obtain optimal...