An expansive multiplier property for operator-valued Bergman inner functions
We show that operator-valued Bergman inner functions have the so-called expansive multiplier property generalizing a well-known result of Hedenmalm in the scalar case. This analysis leads to norm bounds for input output maps for a related class of discrete time linear systems. The proof uses properties of the biharmonic Green function. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim