24 citations · 80 across the 39 of their papers we have counts for
44 papers
Solutions to the 'moment property implies subnormality' and injectivity problems for composition operators on one-circuit graphs
Piotr Budzyński, Zenon Jan Jabłoński, Il Bong Jung +1
We consider composition operators in , where is a discrete measure. Our main result shows that, for every integer , there exists a non-hyponormal composition ope…
CPD th roots of subnormal operators are subnormal
Zenon Jan Jabłoński, Il Bong Jung, Paweł Pietrzycki +1
We investigate the th root problem for bounded operators on a Hilbert space within the class of conditionally positive definite (CPD) operators determined by the Lévy--Khintchin…
Hyperrigidity III
Paweł Pietrzycki, Marcel Scherer, Jan Stochel
In this paper, we study hyperrigidity for -algebras. We will show that hyperrigidity can be expressed solely in terms of representations, without the need to involve general u…
When is a CPD weighted shift similar to a subnormal operator?
Zenon Jan Jabłoński, Il Bong Jung, Jan Stochel
We prove that a CPD unilateral weighted shift of type III is a quasi-affine transform of the operator of multiplication by the independent variable on the -clos…
Hyperrigidity II: -dilations, ideals and decompositions
Paweł Pietrzycki, Jan Stochel
We investigate the hyperrigidity of subsets of unital -algebras annihilated by states (or, more generally, by completely positive maps). This is closely related to the concept…
Bishop-like theorems for non-subnormal operators
Zenon Jan Jabłoński, Il Bong Jung, Jan Stochel
The celebrated Bishop theorem states that an operator is subnormal if and only if it is the strong limit of a net (or a sequence) of normal operators. By the Agler-Stankus theorem,…