Essential norms of weighted composition operators from the -Bloch space to a weighted-type space on the unit ball.
Stević, Stevo (2008)
Abstract and Applied Analysis
Pascal Lefèvre (2009)
Studia Mathematica
We estimate the essential norm of a weighted composition operator relative to the class of Dunford-Pettis operators or the class of weakly compact operators, on the space of Dirichlet series. As particular cases, we obtain the precise value of the generalized essential norm of a composition operator and of a multiplication operator.
Olli Hyvärinen, Ilmari Nieminen (2015)
Concrete Operators
In this paperwe study both the spectra and the essential spectra ofweighted composition operators on Hardy spaces Hp(ⅅ), standard weighted Bergman spaces Apα(ⅅ) and weighted H∞1-type spaces when the symbols are of hyperbolic type
Oubbi, L. (2000)
Portugaliae Mathematica
Tadesse, Abebaw (2004)
International Journal of Mathematics and Mathematical Sciences
Harish Chandra, Bina Singh (2010)
Matematički Vesnik
Manuel D. Contreras, Santiago Díaz-Madrigal (2005)
Revista Matemática Iberoamericana
In this paper we characterize the semigroups of analytic functions in the unit disk which lead to semigroups of operators in the disk algebra. These characterizations involve analytic as well as geometric aspects of the iterates and they are strongly related to the classical theorem of Carathéodory about local connection and boundary behaviour of univalent functions.
Zhu, Yongsheng (2001)
International Journal of Mathematics and Mathematical Sciences
Gajath Gunatillake (2017)
Concrete Operators
Let Ω be an open simply connected proper subset of the complex plane and φ an analytic self map of Ω. If f is in the Hardy-Smirnov space defined on Ω, then the operator that takes f to f ⃘ φ is a composition operator. We show that for any Ω, analytic self maps that induce bounded Hermitian composition operators are of the form Φ(w) = aw + b where a is a real number. For ceratin Ω, we completely describe values of a and b that induce bounded Hermitian composition operators.
Luciano O. Condori, M. Lilian Lourenço (2007)
Mathematica Bohemica
It is shown that a homomorphism between certain topological algebras of holomorphic functions is continuous if and only if it is a composition operator.
Bahmann Yousefi, S. Haghkhah (2007)
Czechoslovak Mathematical Journal
In this paper we give some sufficient conditions for the adjoint of a weighted composition operator on a Hilbert space of analytic functions to be hypercyclic.
Bahman Yousefi, Leila Bagheri (2006)
Bulletin of the Polish Academy of Sciences. Mathematics
Suppose that X is a Banach space of analytic functions on a plane domain Ω. We characterize the operators T that intertwine with the multiplication operators acting on X.
Valentin Matache (2016)
Concrete Operators
Operators on function spaces of form Cɸf = f ∘ ɸ, where ɸ is a fixed map are called composition operators with symbol ɸ. We study such operators acting on the Hilbert Hardy space over the right half-plane and characterize the situations when they are invertible, Fredholm, unitary, and Hermitian. We determine the normal composition operators with inner, respectively with Möbius symbol. In select cases, we calculate their spectra, essential spectra, and numerical ranges.
Rajeev Kumar (2007)
Matematički Vesnik
Shi-An Han, Ze-Hua Zhou (2016)
Czechoslovak Mathematical Journal
We investigate isometric composition operators on the weighted Dirichlet space with standard weights , . The main technique used comes from Martín and Vukotić who completely characterized the isometric composition operators on the classical Dirichlet space . We solve some of these but not in general. We also investigate the situation when is equipped with another equivalent norm.
Li, Geng-Lei, Zhou, Ze-Hua (2010)
Journal of Inequalities and Applications [electronic only]
Piotr Budzyński, Jan Stochel (2007)
Studia Mathematica
Joint subnormality of a family of composition operators on L²-space is characterized by means of positive definiteness of appropriate Radon-Nikodym derivatives. Next, simplified positive definiteness conditions guaranteeing joint subnormality of a C₀-semigroup of composition operators are supplied. Finally, the Radon-Nikodym derivatives associated to a jointly subnormal C₀-semigroup of composition operators are shown to be the Laplace transforms of probability measures (modulo a C₀-group of scalars)...
Piotr Budzyński, Jan Stochel (2009)
Studia Mathematica
In the previous paper, we have characterized (joint) subnormality of a C₀-semigroup of composition operators on L²-space by positive definiteness of the Radon-Nikodym derivatives attached to it at each rational point. In the present paper, we show that in the case of C₀-groups of composition operators on L²-space the positive definiteness requirement can be replaced by a kind of consistency condition which seems to be simpler to work with. It turns out that the consistency condition also characterizes...
M. R. Jabbarzadeh, S. Khalil Sarbaz (2011)
Matematički Vesnik
De Pascale, Luigi (1999)
Zeitschrift für Analysis und ihre Anwendungen