In this paper, we consider a general discrete-time spectral factorization
problem for rational matrix-valued functions. We build on a recent result
establishing existence of a spectral factor whose zeroes and poles lie in any
pair of prescribed regions of the complex plane featuring a geometry compatible
with symplectic symmetry. In this general setting, uniqueness of the spectral
factor is not guaranteed. It was, however, conjectured that if we further
impose stochastic minimality, uniqueness can be recovered. The main result of
his paper is a proof of this conjecture.Comment: 14 pages, no figures. Revised version with minor modifications. To
appear in IEEE Transactions of Automatic Contro
