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Joseph A. Ball and Vladimir Bolotnikov
Nevanlinna-Pick interpolation for Schur-Agler class functions on domains with matrix polynomial defining function in Cn
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Published: |
June 22, 2005 |
Keywords: |
Operator valued functions, Schur-Agler class, Nevanlinna-Pick interpolation |
Subject: |
47A57 |
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Abstract
We consider a bitangential interpolation problem for operator-valued
functions defined on a general class of domains in Cn (including
as particular cases, Cartan domains of types I, II and
III) which satisfy a type of von Neumann inequality
associated with the domain.
The compact formulation of the
interpolation conditions via a functional calculus with
operator argument includes prescription of various combinations of
functional values and of higher-order partial derivatives along
left or right directions at a prescribed subset of the domain as
particular examples.
Using realization results for such functions
in terms of unitary colligation and the defining polynomial for the
domain, necessary and sufficient conditions for the problem to have a
solution were established recently in Ambrozie and Eschmeier (preprint, 2002),
and Ball and Bolotnikov, 2004.
In this paper we present a parametrization of the set of all solutions in
terms of a Redheffer linear fractional transformation acting on a
free-parameter function from the class subject to no interpolation
conditions. In the finite-dimensional case
when functions are matrix-valued, the matrix of the linear fractional
transformation is given explicitly in terms of the interpolation data.
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Author information
Joseph A. Ball:
Department of Mathematics, Virginia Polytechnic Institute, Blacksburg, VA 24061-0123, USA
ball@calvin.math.vt.edu
Vladimir Bolotnikov:
Department of Mathematics, The College of William and Mary, Williamsburg VA 23187-8795, USA
vladi@math.wm.edu
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