Operador de Hardy-Littlewood reiterado y clases de Orlicz de funciones maximales.
Opérateurs de Calderón-Zygmund, fonctions para-accrétives et interpolation.
Opérateurs de Fourier
Opérateurs différentiels d'ordre infini dans des espaces de fonctions entières
Opérateurs d'intégrale singulière sur les surfaces régulières
Opérateurs intégraux de Fourier sans phases
Opérateurs intégraux singuliers sur certaines courbes du plan complexe
Operator valued BMO and commutators .
Operators Associated with Hermite Semigroup - A Survey.
Operators associated with representations of amenable groups singular integrals induced by ergodic flows, the rotation method and multipliers
Operators of Bochner-Riesz type for the helix
Operators on some function spaces
Operators preserving orthogonality of polynomials
Let S be a degree preserving linear operator of ℝ[X] into itself. The question is if, preserving orthogonality of some orthogonal polynomial sequences, S must necessarily be an operator of composition with some affine function of ℝ. In [2] this problem was considered for S mapping sequences of Laguerre polynomials onto sequences of orthogonal polynomials. Here we improve substantially the theorems of [2] as well as disprove the conjecture proposed there. We also consider the same questions for polynomials...
Optimal boundedness of central oscillating multipliers on compact Lie groups
Fefferman-Stein, Wainger and Sjölin proved optimal boundedness for certain oscillating multipliers on . In this article, we prove an analogue of their result on a compact Lie group.
Optimal control systems by time-dependent coefficients using CAS wavelets.
Optimal discrete signal representation by the system of discrete orthonormal exponentials in conjugate pairs of exponents
Optimal estimates for the fractional Hardy operator
Let be the n-dimensional fractional Hardy operator, where 0 < α ≤ n. It is well-known that is bounded from to with when n(1-1/p) < α ≤ n. We improve this result within the framework of Banach function spaces, for instance, weighted Lebesgue spaces and Lorentz spaces. We in fact find a ’source’ space , which is strictly larger than X, and a ’target’ space , which is strictly smaller than Y, under the assumption that is bounded from X into Y and the Hardy-Littlewood maximal operator...
Optimal universal approximations of Fourier coefficients in spaces of continuous periodic functions
Optimality of the range for which equivalence between certain measures of smoothness holds
Recently it was proved for 1 < p < ∞ that , a modulus of smoothness on the unit sphere, and , a K-functional involving the Laplace-Beltrami operator, are equivalent. It will be shown that the range 1 < p < ∞ is optimal; that is, the equivalence does not hold either for p = ∞ or for p = 1.
O-Regularly Varying Convergence Moduli of Fourier and Fourier-Stieltjes Series.