Diagnosing double regular systems

We consider the problem of testing sequentially the components of a multi-component system, when the testing of each component is costly. We propose a new testing policy, that can be executed in polynomial time in the input size, and show that it is cost-minimal in the average case sense, for certain double regular systems that include regular (in particular, threshold) systems with identical components. This result generalizes known results for series, parallel, and, more generally, for k-out-of-n systems.