DARLINGTON REALIZATION OF MATRIX-VALUED FUNCTIONS

For matrix-valued functions of Schur class (holomorphic and contractive in the circle ) the author considers the Darlington realization and isolates the set of those for which this realization is possible. For the case in which satisfies the condition 0$ SRC=http://ej.iop.org/images/0025-5726/7/6/A06/tex_im_2088_img5.gif/>, a description is obtained of all Darlington realizations of and the minimum realizations are isolated.