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On some extremal problems in Bergman spaces in weakly pseudoconvex domains

Romi F. Shamoyan, Olivera R. Mihić (2018)

Communications in Mathematics

We consider and solve extremal problems in various bounded weakly pseudoconvex domains in n based on recent results on boundedness of Bergman projection with positive Bergman kernel in Bergman spaces A α p in such type domains. We provide some new sharp theorems for distance function in Bergman spaces in bounded weakly pseudoconvex domains with natural additional condition on Bergman representation formula.

On some new sharp embedding theorems in minimal and pseudoconvex domains

Romi F. Shamoyan, Olivera R. Mihić (2016)

Czechoslovak Mathematical Journal

We present new sharp embedding theorems for mixed-norm analytic spaces in pseudoconvex domains with smooth boundary. New related sharp results in minimal bounded homogeneous domains in higher dimension are also provided. Last domains we consider are domains which are direct generalizations of the well-studied so-called bounded symmetric domains in n . Our results were known before only in the very particular case of domains of such type in the unit ball. As in the unit ball case, all our proofs are...

On the maximal operator associated with the free Schrödinger equation

Sichun Wang (1997)

Studia Mathematica

For d > 1, let ( S d f ) ( x , t ) = ʃ n e i x · ξ e i t | ξ | d f ̂ ( ξ ) d ξ , x n , where f̂ is the Fourier transform of f S ( n ) , and ( S d * f ) ( x ) = s u p 0 < t < 1 | ( S d f ) ( x , t ) | its maximal operator. P. Sjölin ([11]) has shown that for radial f, the estimate (*) ( ʃ | x | < R | ( S d * f ) ( x ) | p d x ) 1 / p C R f H 1 / 4 holds for p = 4n/(2n-1) and fails for p > 4n/(2n-1). In this paper we show that for non-radial f, (*) fails for p > 2. A similar result is proved for a more general maximal operator.

On the singular numbers for some integral operators.

Alexander Meskhi (2001)

Revista Matemática Complutense

Two-sided estimates of Schatten-von Neumann norms for weighted Volterra integral operators are established. Analogous problems for some potential-type operators defined on Rn are solved.

Parabolic Marcinkiewicz integrals on product spaces and extrapolation

Mohammed Ali, Mohammed Al-Dolat (2016)

Open Mathematics

In this paper, we study the the parabolic Marcinkiewicz integral [...] MΩ,hρ1,ρ2 Ω , h ρ 1 , ρ 2 on product domains Rn × Rm (n, m ≥ 2). Lp estimates of such operators are obtained under weak conditions on the kernels. These estimates allow us to use an extrapolation argument to obtain some new and improved results on parabolic Marcinkiewicz integral operators.

Periodic solutions for second order integro-differential equations with infinite delay in Banach spaces

Shangquan Bu, Yi Fang (2008)

Studia Mathematica

We study the maximal regularity on different function spaces of the second order integro-differential equations with infinite delay ( P ) u ' ' ( t ) + α u ' ( t ) + d / d t ( - t b ( t - s ) u ( s ) d s ) = A u ( t ) - - t a ( t - s ) A u ( s ) d s + f ( t ) (0 ≤ t ≤ 2π) with periodic boundary conditions u(0) = u(2π), u’(0) = u’(2π), where A is a closed operator in a Banach space X, α ∈ ℂ, and a,b ∈ L¹(ℝ₊). We use Fourier multipliers to characterize maximal regularity for (P). Using known results on Fourier multipliers, we find suitable conditions on the kernels a and b under which necessary and sufficient conditions...

Pointwise multipliers for reverse Holder spaces

Stephen Buckley (1994)

Studia Mathematica

We classify weights which map reverse Hölder weight spaces to other reverse Hölder weight spaces under pointwise multiplication. We also give some fairly general examples of weights satisfying weak reverse Hölder conditions.

Pointwise multipliers on weighted BMO spaces

Eiichi Nakai (1997)

Studia Mathematica

Let E and F be spaces of real- or complex-valued functions defined on a set X. A real- or complex-valued function g defined on X is called a pointwise multiplier from E to F if the pointwise product fg belongs to F for each f ∈ E. We denote by PWM(E,F) the set of all pointwise multipliers from E to F. Let X be a space of homogeneous type in the sense of Coifman-Weiss. For 1 ≤ p < ∞ and for ϕ : X × + + , we denote by b m o ϕ , p ( X ) the set of all functions f L l o c p ( X ) such that s u p a X , r > 0 1 / ϕ ( a , r ) ( 1 / μ ( B ( a , r ) ) ʃ B ( a , r ) | f ( x ) - f B ( a , r ) | p d μ ) 1 / p < , where B(a,r) is the ball centered at a and of...

Problems on averages and lacunary maximal functions

Andreas Seeger, James Wright (2011)

Banach Center Publications

We prove three results concerning convolution operators and lacunary maximal functions associated to dilates of measures. First we obtain an H¹ to L 1 , bound for lacunary maximal operators under a dimensional assumption on the underlying measure and an assumption on an L p regularity bound for some p > 1. Secondly, we obtain a necessary and sufficient condition for L² boundedness of lacunary maximal operator associated to averages over convex curves in the plane. Finally we prove an L p regularity result...

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