  Recently we developed supervisor localization, a top-down approach to
distributed control of discrete-event systems. Its essence is the allocation of
monolithic (global) control action among the local control strategies of
individual agents. In this paper, we extend supervisor localization by
considering partial observation; namely not all events are observable.
Specifically, we employ the recently proposed concept of relative observability
to compute a partial-observation monolithic supervisor, and then design a
suitable localization procedure to decompose the supervisor into a set of local
controllers. In the resulting local controllers, only observable events can
cause state change. Further, to deal with large-scale systems, we combine the
partial-observation supervisor localization with an efficient architectural
synthesis approach: first compute a heterarchical array of partial-observation
decentralized supervisors and coordinators, and then localize each of these
supervisors/coordinators into local controllers.
