This paper considers the minimization of the em-induced norm of the closed
loop in linear multirate systems when full state information is available f
or feedback. A state-space approach is taken and concepts of viability theo
ry and controlled invariance are utilized. The essential idea is to constru
ct a set such that the state may be confined to that set and that such a co
nfinement guarantees that the output satisfies the desired output norm cond
itions. Once such a set is computed, it is shown that a memoryless nonlinea
r controller results, which achieves near-optimal performance. The construc
tion involves the solution of several finite linear programs and generalize
s to the multirate case earlier work on linear time-invariant (LTI) systems
.