28 citations · 50 across the 16 of their papers we have counts for
16 papers
Notes on (the Birmak-Krein-Vishik theory on) selfadjoint extensions of semibounded symmetric operators
Tiberiu Constantinescu, Aurelian Gheondea
We give an explicit and versatile parametrization of all positive selfadjoint extensions of a densely defined, closed, positive operator. In addition, we identify the Friedrichs ex…
Orthogonal polynomials in several non-commuting variables. II
T. Banks, T. Constantinescu
In this paper we continue to investigate a certain class of Hankel-like positive definite kernels using their associated orthogonal polynomials. The main result of this paper is ab…
Tensor algebras and displacement structure. IV. Invariant kernels
T. Banks, T. Constantinescu, Nermine El-Sissi
In this paper we investigate the class of invariant positive definite kernels on the free semigroup on N generators. We provide a combinatorial description of the positivity of the…
Relations on noncommutative variables and associated orthogonal polynomials
T. Banks, T. Constantinescu, J. L. Johnson
This semi-expository paper surveys results concerning three classes of orthogonal polynomials: in one non-hermitian variable, in several isometric non-commuting variables, and in s…
Parametrization of Quantum States and Channels
T. Constantinescu, V. Ramakrishna
In this manuscript, a parametrization of positive matrices together with some of its many applications in quantum information theory is given.
Tensor Algebras and Displacement Structure. III. Asymptotic properties
M. Barakat, T. Constantinescu
We continue to investigate some classes of Szegö type polynomials in several variables. We focus on asymptotic properties of these polynomials and we extend several classical resul…