Eigenvalue assignment and stabilization of interconnected systems using local feedbacks

We consider the eigenvalue assignment and the stabilization of a standard state space system description of an arbitrary interconnection of subsystems, using two structural levels of local feedbacks. We show that for both constant state feedback and dynamic output feedback 1) the higher structural level feedbacks are sufficient for arbitrary eigenvalue assignment, and 2) the lower structural level feedbacks are sufficient for stabilization, but not sufficient for arbitrary eigenvalue assignment.