Integral Equations and Operator Theory vol. 27, no. 3, pp. 324 - 333
Indexed
SCI; SCIE; SCOPUS
Document Type
Article
Abstract
In [Ko 2] we extend Putinar's theorem to every operator on a finite dimensional space by generalizing Putinar's techniques. Using these techniques, we construct a functional model for the unilateral backward shift. We show, in particular, that the unilateral backward shift is w-quasisubscalar. As a corollary we prove that every strict contraction is w-subscalar, i.e., is similar to the restriction to an invariant subspace of a w-scalar operator.