When is a controllerH∞-optimal?

@article{Lenz1988WhenIA,
  title={When is a controllerH∞-optimal?},
  author={Kathryn E. Lenz and Pramod P. Khargonekar and John Doyle},
  journal={MCSS},
  year={1988},
  volume={1},
  pages={107-122}
}
This paper examines conditions under which a given single input, single output, linear time invariant control system is H| with respect to weighted combinations of its sensitivity function and its complementary sensitivity function. The specific weighting functions considered are defined in terms of the given plant and nominal controller. This paper shows that a large class of practical controllers are H| including typical stable controllers.