Displaying similar documents to “A Marcinkiewicz type multiplier theorem for H¹ spaces on product domains”

The Marcinkiewicz multiplier condition for bilinear operators

Loukas Grafakos, Nigel J. Kalton (2001)

Studia Mathematica

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This article is concerned with the question of whether Marcinkiewicz multipliers on 2 n give rise to bilinear multipliers on ℝⁿ × ℝⁿ. We show that this is not always the case. Moreover, we find necessary and sufficient conditions for such bilinear multipliers to be bounded. These conditions in particular imply that a slight logarithmic modification of the Marcinkiewicz condition gives multipliers for which the corresponding bilinear operators are bounded on products of Lebesgue and Hardy...

Fourier coefficients of continuous functions and a class of multipliers

Serguei V. Kislyakov (1988)

Annales de l'institut Fourier

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If x is a bounded function on Z , the multiplier with symbol x (denoted by M x ) is defined by ( M x f ) ^ = x f ^ , f L 2 ( T ) . We give some conditions on x ensuring the “interpolation inequality” M x f L p C f L 1 α M x f L q 1 - α (here 1 < p < q and α = α ( p , q , x ) is between 0 and 1). In most cases considered M x fails to have stronger L 1 -regularity properties (e.g. fails to be of weak type (1,1)). The results are applied to prove that for many sets E Z every positive sequence in 2 ( E ) can be majorized by the sequence { | f ^ ( n ) | } n E for some continuous funtion f with spectrum...

Multipliers of the Hardy space H¹ and power bounded operators

Gilles Pisier (2001)

Colloquium Mathematicae

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We study the space of functions φ: ℕ → ℂ such that there is a Hilbert space H, a power bounded operator T in B(H) and vectors ξ, η in H such that φ(n) = ⟨Tⁿξ,η⟩. This implies that the matrix ( φ ( i + j ) ) i , j 0 is a Schur multiplier of B(ℓ₂) or equivalently is in the space (ℓ₁ ⊗̌ ℓ₁)*. We show that the converse does not hold, which answers a question raised by Peller [Pe]. Our approach makes use of a new class of Fourier multipliers of H¹ which we call “shift-bounded”. We show that there is a φ which...

Multiplier transformations on H p spaces

Daning Chen, Dashan Fan (1998)

Studia Mathematica

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The authors obtain some multiplier theorems on H p spaces analogous to the classical L p multiplier theorems of de Leeuw. The main result is that a multiplier operator ( T f ) ( x ) = λ ( x ) f ̂ ( x ) ( λ C ( n ) ) is bounded on H p ( n ) if and only if the restriction λ ( ε m ) m Λ is an H p ( T n ) bounded multiplier uniformly for ε>0, where Λ is the integer lattice in n .

Multipliers of Hardy spaces, quadratic integrals and Foiaş-Williams-Peller operators

G. Blower (1998)

Studia Mathematica

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We obtain a sufficient condition on a B(H)-valued function φ for the operator Γ φ ' ( S ) to be completely bounded on H B ( H ) ; the Foiaş-Williams-Peller operator | St Γφ | Rφ = | | | 0 S | is then similar to a contraction. We show that if ⨍ : D → B(H) is a bounded analytic function for which ( 1 - r ) | | ' ( r e i θ ) | | B ( H ) 2 r d r d θ and ( 1 - r ) | | " ( r e i θ ) | | B ( H ) r d r d θ are Carleson measures, then ⨍ multiplies ( H 1 c 1 ) ' to itself. Such ⨍ form an algebra A, and when φ’∈ BMO(B(H)), the map Γ φ ' ( S ) is bounded A B ( H 2 ( H ) , L 2 ( H ) H 2 ( H ) ) . Thus we construct a functional calculus for operators of Foiaş-Williams-Peller...

Unconditionality, Fourier multipliers and Schur multipliers

Cédric Arhancet (2012)

Colloquium Mathematicae

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Let G be an infinite locally compact abelian group and X be a Banach space. We show that if every bounded Fourier multiplier T on L²(G) has the property that T I d X is bounded on L²(G,X) then X is isomorphic to a Hilbert space. Moreover, we prove that if 1 < p < ∞, p ≠ 2, then there exists a bounded Fourier multiplier on L p ( G ) which is not completely bounded. Finally, we examine unconditionality from the point of view of Schur multipliers. More precisely, we give several necessary and sufficient...

Multilinear Fourier multipliers with minimal Sobolev regularity, I

Loukas Grafakos, Hanh Van Nguyen (2016)

Colloquium Mathematicae

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We find optimal conditions on m-linear Fourier multipliers that give rise to bounded operators from products of Hardy spaces H p k , 0 < p k 1 , to Lebesgue spaces L p . These conditions are expressed in terms of L²-based Sobolev spaces with sharp indices within the classes of multipliers we consider. Our results extend those obtained in the linear case (m = 1) by Calderón and Torchinsky (1977) and in the bilinear case (m = 2) by Miyachi and Tomita (2013). We also prove a coordinate-type Hörmander integral...

Spherical summation : a problem of E.M. Stein

Antonio Cordoba, B. Lopez-Melero (1981)

Annales de l'institut Fourier

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Writing ( T R λ f ) ^ ( ξ ) = ( 1 - | ξ | 2 / R 2 ) + λ f ^ ( ξ ) . E. Stein conjectured j | T R j λ f i | 2 1 / 2 p C j | f j | 2 1 / 2 p for λ &gt; 0 , 4 3 p 4 and C = C λ , p . We prove this conjecture. We prove also f ( x ) = lim j T 2 j λ f ( x ) a.e. We only assume 4 3 + 2 λ &lt; p &lt; 4 1 - 2 λ .

Multipliers for the twisted Laplacian

E. K. Narayanan (2003)

Colloquium Mathematicae

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We study ¹ - L p boundedness of certain multiplier transforms associated to the special Hermite operator.

Variants of the Calderón-Zygmund theory for L-spaces.

Anthony Carbery (1986)

Revista Matemática Iberoamericana

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The purposes of this paper may be described as follows: (i) to provide a useful substitute for the Cotlar-Stein lemma for Lp-spaces (the orthogonality conditions are replaced by certain fairly weak smoothness asumptions); (ii) to investigate the gap between the Hörmander multiplier theorem and the Littman-McCarthy-Rivière example - just how little regularity is really needed? (iii) to simplify and extend the work of Duoandikoetxea...

Endpoint bounds of square functions associated with Hankel multipliers

Jongchon Kim (2015)

Studia Mathematica

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We prove endpoint bounds for the square function associated with radial Fourier multipliers acting on L p radial functions. This is a consequence of endpoint bounds for a corresponding square function for Hankel multipliers. We obtain a sharp Marcinkiewicz-type multiplier theorem for multivariate Hankel multipliers and L p bounds of maximal operators generated by Hankel multipliers as corollaries. The proof is built on techniques developed by Garrigós and Seeger for characterizations of...