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Composition Operators and Endomorphisms [PDF]
Complex Analysis and Operator Theory, 2010 If $b$ is an inner function, then composition with $b$ induces an endomorphism, $\beta$, of $L^\infty(\mathbb{T})$ that leaves $H^\infty(\mathbb{T})$ invariant.
Dennis Courtney +15 more
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On approximation numbers of composition operators [PDF]
Journal of Approximation Theory, 2011 We show that the approximation numbers of a compact composition operator on the weighted Bergman spaces $\mathfrak{B}_\alpha$ of the unit disk can tend to 0 arbitrarily slowly, but that they never tend quickly to 0: they grow at least exponentially, and ...
Li, Daniel +2 more
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Composition operators on the Schwartz space [PDF]
Revista Matemática Iberoamericana, 2015 We study composition operators on the Schwartz space of rapidly decreasing functions. We prove that such a composition operator is never a compact operator and we obtain necessary or sufficient conditions for the range of the composition operator to be ...
A. Galbis, E. Jord'a
semanticscholar +6 more sources
Antinormal Weighted Composition Operators [PDF]
Abstract and Applied Analysis, 2016 Let l2=L2N,μ, where N is set of all positive integers and μ is the counting measure whose σ-algebra is the power set of N. In this paper, we obtain necessary and sufficient conditions for a weighted composition operator to be antinormal on the Hilbert ...
Dilip Kumar, Harish Chandra
doaj +3 more sources
Spectrum of a Composition Operator [PDF]
Proceedings of the American Mathematical Society, 1973 A composition operator is a linear operator induced on a subspace of K X {K^X} by a point transformation ϕ \phi on a set X (where K denotes the scalar field) by the formula T f ( x ) = f ∘ ϕ ( x )
William C. Ridge
openalex +2 more sources
Subnormal composition operators [PDF]
Proceedings of the American Mathematical Society, 1988 Let C C be the composition operator on L 2 ( X , Σ , m ) {L^2}(X,\Sigma ,m) given by C f = f ∘ T Cf = f \circ T , where T T is a Σ
Alan Lambert
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Composition of maximal operators [PDF]
Publicacions Matemàtiques, 1996 Consider the Hardy-Littlewood maximal operator $$ Mf(x)=\sup_{Q\owns x}\frac{1}{|Q|}\int_Q |f(y)|\,dy. $$ It is known that $M$ applied to $f$ twice is pointwise comparable to the maximal operator $M_{L\log L}f$, defined by replacing the mean value of $|f|$ over the cube $Q$ by the $L\log L$-mean, namely $$ M_{L\log L}f(x)=\sup_{x\in Q} \frac{1}{|Q ...
M. Carozza +1 more
openaire +7 more sources
Composite operators near the boundary [PDF]
Journal of High Energy Physics, 2020 Abstract We use renormalization group methods to study composite operators existing at a boundary of an interacting conformal field theory. In particular we relate the data on boundary operators to short-distance (near-boundary) divergences of bulk two-point functions.
Vladimír Procházka +1 more
openaire +4 more sources
Renormalization of composite operators [PDF]
Physical Review D, 2001 The blocked composite operators are defined in the one-component Euclidean scalar field theory, and shown to generate a linear transformation of the operators, the operator mixing. This transformation allows us to introduce the parallel transport of the operators along the RG trajectory. The connection on this one-dimensional manifold governs the scale
Janos Polonyi +2 more
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Extended eigenvalues of composition operators
Journal of Mathematical Analysis and Applications, 2021 A complex scalar λ is said to be an extended eigenvalue of a bounded linear operator A on a complex Hilbert space if there is a nonzero operator X such that . The results in this paper provide a full solution to the problem of computing the extended eigenvalues for those composition operators induced on the Hardy space by linear fractional ...
Miguel Lacruz +3 more
openaire +5 more sources