A Problem on Riesz Basis Formed by a Closed-Loop System
闭环系统的Riesz基生成问题

In this paper, we deal with the spectrum and Riesz basis of infinite dimensional linear systems with infinite dimensional input output state spaces and unbounded input output operators. Using perturbation theory for basis, we give a sufficient condition which ensures all the generalized eigenvectors of the system to form a Riesz basis. A typical example is presented to illustrate the application of our result.