A POMDP Formulation of Multistep Failure Model with Software Rejuvenation

This paper derives a POMDP (partially observable Markov decision process) formulation for a software rejuvenation model. The POMDP is a generalized framework of MDP that handles the unobserved information. The POMDP gives qualitative insights for the effects of unobserved information based on their modeling. The main objective of this paper is to reveal the effect of system degradation information on rejuvenation strategies in a multistep failure model with rejuvenation. More specifically, we present a POMDP formulation and the optimality equations for the maximization of system availability in the multistep failure model. In a numerical example, we compare the maximum system availabilities when the system degradation is observable and unobservable and reveal the value of information on system degradation.