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Hankel forms

Henry Helson (2010)

Studia Mathematica

It is an open question whether Nehari's theorem on the circle group has an analogue on the infinite-dimensional torus. In this note it is shown that if the analogue holds, then some interesting inequalities follow for certain trigonometric polynomials on the torus. We think these inequalities are false but are not able to prove that.

Hankel multipliers and transplantation operators

Krzysztof Stempak, Walter Trebels (1997)

Studia Mathematica

Connections between Hankel transforms of different order for L p -functions are examined. Well known are the results of Guy [Guy] and Schindler [Sch]. Further relations result from projection formulae for Bessel functions of different order. Consequences for Hankel multipliers are exhibited and implications for radial Fourier multipliers on Euclidean spaces of different dimensions indicated.

Hankel operators and weak factorization for Hardy-Orlicz spaces

Aline Bonami, Sandrine Grellier (2010)

Colloquium Mathematicae

We study the holomorphic Hardy-Orlicz spaces Φ ( Ω ) , where Ω is the unit ball or, more generally, a convex domain of finite type or a strictly pseudoconvex domain in ℂⁿ. The function Φ is in particular such that ¹ ( Ω ) Φ ( Ω ) p ( Ω ) for some p > 0. We develop maximal characterizations, atomic and molecular decompositions. We then prove weak factorization theorems involving the space BMOA(Ω). As a consequence, we characterize those Hankel operators which are bounded from Φ ( Ω ) into ¹(Ω).

Hankel type operators on the unit disk

Jie Miao (2001)

Studia Mathematica

We study Hankel operators and commutators that are associated with a symbol and a kernel function. If the kernel function satisfies an upper bound condition, we obtain a sufficient condition for commutators to be bounded or compact. If the kernel function satisfies a local bound condition, the sufficient condition turns out to be necessary. The analytic and harmonic Bergman kernels satisfy both conditions, therefore a recent result by Wu on Hankel operators on harmonic Bergman spaces is extended....

Hardy Inequality in Variable Exponent Lebesgue Spaces

Diening, Lars, Samko, Stefan (2007)

Fractional Calculus and Applied Analysis

Mathematics Subject Classification: 26D10, 46E30, 47B38We prove the Hardy inequality and a similar inequality for the dual Hardy operator for variable exponent Lebesgue spaces.

Hardy space estimates for multilinear operators (I).

Ronald R. Coifman, Loukas Grafakos (1992)

Revista Matemática Iberoamericana

In this article we study bilinear operators given by inner products of finite vectors of Calderón-Zygmund operators. We find that necessary and sufficient condition for these operators to map products of Hardy spaces into Hardy spaces is to have a certain number of moments vanishing and under this assumption we prove a Hölder-type inequality in the Hp space context.

Hardy space estimates for multilinear operators (II).

Loukas Grafakos (1992)

Revista Matemática Iberoamericana

We continue the study of multilinear operators given by products of finite vectors of Calderón-Zygmund operators. We determine the set of all r ≤ 1 for which these operators map products of Lebesgue spaces Lp(Rn) into the Hardy spaces Hr(Rn). At the endpoint case r = n/(n + m + 1), where m is the highest vanishing moment of the multilinear operator, we prove a weak type result.

Hereditarily finitely decomposable Banach spaces

V. Perenczi (1997)

Studia Mathematica

A Banach space is said to be H D n if the maximal number of subspaces of X forming a direct sum is finite and equal to n. We study some properties of H D n spaces, and their links with hereditarily indecomposable spaces; in particular, we show that if X is complex H D n , then dim ( ( X ) / S ( X ) ) n 2 , where S(X) denotes the space of strictly singular operators on X. It follows that if X is a real hereditarily indecomposable space, then ℒ(X)/S(X) is a division ring isomorphic either to ℝ, ℂ, or ℍ, the quaternionic division ring....

Hermitian composition operators on Hardy-Smirnov spaces

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.

Hilbert inequality for vector valued functions

Namita Das, Srinibas Sahoo (2011)

Archivum Mathematicum

In this paper we consider a class of Hankel operators with operator valued symbols on the Hardy space Ξ 2 ( 𝕋 ) where Ξ is a separable infinite dimensional Hilbert space and showed that these operators are unitarily equivalent to a class of integral operators in L 2 ( 0 , ) Ξ . We then obtained a generalization of Hilbert inequality for vector valued functions. In the continuous case the corresponding integral operator has matrix valued kernels and in the discrete case the sum involves inner product of vectors in the...

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