“…In the present study, we aim to extend the chain-scattering matrix description approach (see e.g., [1], [6], [9], [16], [17], [24]) to the H ∞ state-delayed control problem, because this kind of approach can be described by block diagrams, which always make the solving process brief. It is shown that, while the discrete-time state-delayed systems are stabilizable and detectable, there always exist right-and left-coprime factorization with each coprime factor possessing the same delayed states as that of the original system.…”