“…Suppose that the domain D is symmetric with respect to the real axis of the complex plane C, and that its boundary above the real axis, denoted by dD + , possesses the parametric representation: (8) where (j)(qo) is a complex-valued function, e.g., 0(//o) =jqo, j=\J-1 for the Hurwitz stability domain, and 0(q o )=e i ' l o for the Schur stability domain. Then, according to the zero-exclusion principle, we know that all the members of the polynomial family p(s; E r (q°, w)) are D-stable if and only if there is a parameter vector q such that p(s;q) is D-stable and the value set p(dD + ; E r (q°, w)) does not contain the origin 0+/0.…”