Feedback invariants of restrictions - a polynomial approach

The possible feedback invariants of a linear time-invariant dynamical syste m, represented by a pair of matrices (A, B): are studied when the only info rmation about the system is that it has an (A, B)-invariant subspace, Y, wh ose restriction is an autonomous system and the quotient is controllable. T his problem is shown to be related to the problem of designing a control ma trix B-1 for a series connected system to have prescribed feedback invarian ts. (C) 2000 Elsevier Science Ltd. All rights reserved.