Results 21 to 30 of about 389,674 (277)
On Unbounded Composition Operators in $L^2$-Spaces
, 2012 Fundamental properties of unbounded composition operators in $L^2$-spaces are studied. Characterizations of normal and quasinormal composition operators are provided. Formally normal composition operators are shown to be normal.
A Brown +52 more
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Hardy spaces of generalized analytic functions and composition operators
Concrete Operators, 2018 We present some recent results on Hardy spaces of generalized analytic functions on D specifying their link with the analytic Hardy spaces. Their definition can be extended to more general domains Ω . We discuss the way to extend such definitions to more
Pozzi Elodie
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Composite operators in QCD [PDF]
Nuclear Physics B, 1992 We give a formula for the derivatives of a correlation function of composite operators with respect to the parameters (i.e., the strong fine structure constant and the quark mass) of QCD in four-dimensional euclidean space. The formula is given as spatial integration of the operator conjugate to a parameter. The operator product of a composite operator
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Compact composition operators [PDF]
Journal of the Australian Mathematical Society, 1979 AbstractLet (Хζ,λ) be a σ-finite measure space, and let ϕ be a non-singular measurable transformation from X into itself. Then a composition transformation Cϕ on L2(λ) is defined by Cϕf = f ∘ ϕ. If Cϕ is a bounded operator, then it is called a composition operator.
Singh, R. K., Kumar, Ashok
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Universal composition operators
Journal of Operator Theory, 2021 A Hilbert space operator U is called \textit{universal} (in the sense of Rota) if every Hilbert space operator is similar to a multiple of U restricted to one of its invariant subspaces. It follows that the \textit{invariant subspace problem} for Hilbert spaces is equivalent to the statement that all minimal invariant subspaces for U are one ...
Carmo, João R., Noor, S. Waleed
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MathematicsWe introduce the space of holomorphic growth spaces with values in a Banach lattice. We provide norm and essential norm estimates of the embedding operator, and we completely characterize the bounded and compact embeddings of the growth spaces using ...
Nihat Gökhan Göğüş
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Weighted composition operators between different Fock spaces
, 2017 We study weighted composition operators acting between Fock spaces. The following results are obtained: (1) Criteria for the boundedness and compactness; (2) Characterizations of compact differences and essential norm; (3) Complete descriptions of path ...
Khoi, Le Hai, Tien, Pham Trong
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Essential Spectra of Quasi-parabolic Composition Operators on Hardy Spaces of the Poly-disc
, 2012 This work is a generalization of the results in [Gul] to bi-disc case. As in [Gul], quasi-parabolic composition operators on the Hilbert-Hardy space of the bi-disc are written as a linear combination of Toeplitz operators and Fourier multipliers.
Gül, Uğur
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Centered weighted composition operators via measure theory [PDF]
Mathematica Bohemica, 2018 We describe the centered weighted composition operators on $L^2(\Sigma)$ in terms of their defining symbols. Our characterizations extend Embry-Wardrop-Lambert's theorem on centered composition operators.
Mohammad Reza Jabbarzadeh +1 more
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The weighted composition operators on the large weighted Bergman spaces
, 2018 In this paper, we characterize bounded, compact or Schatten class weighted composition operators acting on Bergman spaces with the exponential type weights. Moreover, we give the proof of the necessary part for the boundedness of composition operators on
Park, Inyoung
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