A Subnormal Completion Problem for Weighted Shifts on Directed Trees
Publication Date
11-18-2018
Description
Given a directed tree and a collection of weights on a subtree, the subnormal completion problem is to determine whether the weights may be completed to the weights of an injective, bounded, subnormal weighted shift on the Hilbert space arising from the full tree. We study this problem (which generalizes significantly the classical subnormal completion problem for weighted shifts) both from a measure-theoretic point of view and in terms of initial data, for various classes of trees with a single branching point. We give several characterizations of when such a completion is possible. Considered also are connections with Stieltjes moment sequences, flatness of a completion, completions in which the resulting measures may be taken to be finitely atomic, and we provide a result showing that in certain circumstances the present completion problem is equivalent to a related classical completion problem.
Journal
Integral Equations and Operator Theory
Volume
90
Department
Mathematics
Link to Published Version
https://link.springer.com/article/10.1007/s00020-018-2496-9
DOI
https://doi.org/10.1007/s00020-018-2496-9
Recommended Citation
Exner, George R.; Jung, Il Bong; Stochel, Jan; and Yun, Hye Yeong. "A Subnormal Completion Problem for Weighted Shifts on Directed Trees." (2018) .