Abstract :
Xie and Giua (see ibid. p.1217-20, 2004) pointed out, in terms of counterexamples, that our main theorems in the above paper (K. He and M. Lemmon, IEEE Trans. Automat. Contr., vol. 47, pp. 1042-1055, July 2002) are flawed. This note attempts to explain the intuitions behind our theorems, discuss the impact of these counterexamples upon our original analysis, and outline some possible solutions that could correct the flaws.