These lecture notes present an extensive review of the factorization theory of matrix
functions relative to a curve with emphasis on the developments of the last 20–25 years. The …

Concise treatment focuses on theory of shift operators, Toeplitz operators and Hardy classes
of vector-and operator-valued functions. Topics include general theory of shift operators on a …

This book is an introduction to convolution operators with matrix-valued almost periodic or
semi-almost periodic symbols. The basic tools for the treatment of the operators are Wiener …

Page 1 COnferenCB board Of the mathematical SCiênces regional COnferenCE SETBS in
mathematics number 6 8 J. William Helton With the assistance of Joseph A. Ball, Charles R …

The finite-size effects in the spectrum of the integrable XXZ Heisenberg chain with arbitrary
spin-S are studied analytically on the basis of the string hypothesis for bound states and …

This paper concerns a Lie group of 2n X In matrices over the field 8 functions on the unit
circle with rational continuations to the complex p group we will study consists of all such …

The celebrated theorem of Beurling [Brl] and Lax's vectorial generalization ([L, HL]), as in the
form given in Helson's book [Hls], characterize the form of the simply invariant subspaces for …

>- E JR. fl(f) = {AE JR : 1(>-) cF O}, L l(>-)eA AP± = {f E AP : 1(>-) = 0 for ± >- < O}, Page 1
Operator Theory: Advances and Applications, Vol. 103 © 1998 Birkhauser Verlag Basel/Switzerland …

Using results of the companion paper, the authors obtain effective criteria for the existence of
canonical factorization for new classes of triangular almost periodic matrix functions of the …

The notion of a transfer function from systems theory serves as an important tool in dealing
with certain problems in operator and matrix theory. This is illustrated with a variety of …