A commutant lifting theorem on analytic polyhedra
Volume 67 / 2005
Abstract
In this note a commutant lifting theorem for vector-valued functional Hilbert spaces over generalized analytic polyhedra in is proved. Let T be the compression of the multiplication tuple M_z to a *-invariant closed subspace of the underlying functional Hilbert space. Our main result characterizes those operators in the commutant of T which possess a lifting to a multiplier with Schur class symbol. As an application we obtain interpolation results of Nevanlinna-Pick and Carathéodory-Fejér type for Schur class functions. Our methods apply in particular to the unit ball, the unit polydisc and the classical symmetric domains of types I, II and III.