Comments on "Output feedback stabilization for uncertain systems: constrained Riccati approach"

For original paper, by Cheng, see ibid., vol.43, p.81-4 (1998). In that paper, a sufficient condition for the static output feedback stabilization of uncertain systems with mismatched uncertainties has been derived under the assumption that rank(B)/spl les/rank(C) where B and C are the input matrix and the output matrix respectively. In this note, we show that the sufficient condition of the original paper is not solvable if rank(B)