Displaying similar documents to “Quasinormal operators are hyperreflexive”

Projections onto the spaces of Toeplitz operators

Marek Ptak (2005)

Annales Polonici Mathematici

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Projections onto the spaces of all Toeplitz operators on the N-torus and the unit sphere are constructed. The constructions are also extended to generalized Toeplitz operators and applied to show hyperreflexivity results.

An introduction to Rota’s universal operators: properties, old and new examples and future issues

Carl C. Cowen, Eva A. Gallardo-Gutiérrez (2016)

Concrete Operators

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The Invariant Subspace Problem for Hilbert spaces is a long-standing question and the use of universal operators in the sense of Rota has been an important tool for studying such important problem. In this survey, we focus on Rota’s universal operators, pointing out their main properties and exhibiting some old and recent examples.

On the reflexivity and hyperreflexivity of algebras and subspaces

Marek Ptak (2007)

Banach Center Publications

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A review of recent reflexivity and hyperreflexivity results is presented. We concentrate particularly on a finite-dimensional situation, Toeplitz operators and partial isometries. Open problems in this area are given.

Asymmetric truncated Toeplitz operators equal to the zero operator

Joanna Jurasik, Bartosz Łanucha (2016)

Annales Universitatis Mariae Curie-Sklodowska, sectio A – Mathematica

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Asymmetric truncated Toeplitz operators are compressions of multiplication operators acting between two model spaces. These operators are natural generalizations of truncated Toeplitz operators. In this paper we describe symbols of asymmetric truncated Toeplitz operators equal to the zero operator.

Properties of two variables Toeplitz type operators

Elżbieta Król-Klimkowska, Marek Ptak (2016)

Annales Universitatis Paedagogicae Cracoviensis. Studia Mathematica

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The investigation of properties of generalized Toeplitz operators with respect to the pairs of doubly commuting contractions (the abstract analogue of classical two variable Toeplitz operators) is proceeded. We especially concentrate on the condition of existence such a non-zero operator. There are also presented conditions of analyticity of such an operator.

On the reflexivity of subspaces of Toeplitz operators on the Hardy space on the upper half-plane

Wojciech Młocek, Marek Ptak (2013)

Czechoslovak Mathematical Journal

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The reflexivity and transitivity of subspaces of Toeplitz operators on the Hardy space on the upper half-plane are investigated. The dichotomic behavior (transitive or reflexive) of these subspaces is shown. It refers to the similar dichotomic behavior for subspaces of Toeplitz operators on the Hardy space on the unit disc. The isomorphism between the Hardy spaces on the unit disc and the upper half-plane is used. To keep weak* homeomorphism between L ∞ spaces on the unit circle and the...