24 citations · 51 across the 17 of their papers we have counts for
5 papers · 1 filter
A multiplicative property characterizes quasinormal composition operators in -spaces
Piotr Budzynski, Zenon Jan Jablonski, Il Bong Jung +1
A densely defined composition operator in an -space induced by a measurable transformation is shown to be quasinormal if and only if the Radon-Nikodym derivatives $h_{ϕ^n}…
Operators with absolute continuity properties: an application to quasinormality
Zenon Jan Jablonski, Il Bong Jung, Jan Stochel
An absolute continuity approach to quasinormality which relates the operator in question to the spectral measure of its modulus is developed. Algebraic characterizations of some cl…
Unbounded subnormal weighted shifts on directed trees I
Piotr Budzyński, Zenon Jan Jabłoński, Il Bong Jung
A new method of verifying the subnormality of unbounded Hilbert space operators based on an approximation technique is proposed. Diverse sufficient conditions for subnormality of u…
Unbounded subnormal weighted shifts on directed trees. II
Piotr Budzyński, Zenon Jan Jabłoński, Il Bong Jung +1
Criteria for subnormality of unbounded injective weighted shifts on leafless directed trees with one branching vertex are proposed. The case of classical weighted shifts is discuss…
On Unbounded Composition Operators in -Spaces
Piotr Budzyński, Zenon Jan Jabłoński, Il Bong Jung +1
Fundamental properties of unbounded composition operators in -spaces are studied. Characterizations of normal and quasinormal composition operators are provided. Formally norm…