Información del autor
Autor Cobos, Fernando |
Documentos disponibles escritos por este autor (121)
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We work with logarithmic interpolation methods (A0,A1)?,q,A where ?=0 or 1. On the contrary to the case 0![]()
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Let S,q be the collection of all compact operators T on a (complex) Hilbert space H such that (INVALID INPUT),q(T) = (P1 n=1((n)sn(T))qn?1)1/q![]()
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Cobos, Fernando ; Fernández-Cabrera, Luz M. | 2020We review several results on duality of logarithmic interpolation spaces and applications to Besov spaces. We also establish some new results on Besov spaces with smoothness close to zero defined by differences.![]()
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We work with spaces (A0;A1)?;q;A which are logarithmic perturbations of the real interpolation spaces. We determine the dual of (A0;A1)?;q;A when0![]()
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We investigate dual spaces of interpolation spaces defined by means of polygons. We first show that dual spaces may fail to be intermediate spaces with respect to the dual N-tuple, and then we prove that dual spaces of J-spaces can be identified[...]![]()
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For a compact metric space X let ? be a finite Borel measure on X. The authors investigate the asymptotic behavior of eigenvalues of integral operators on L2(X, ?). These integral operators are assumed to have a positive definite kernel which sa[...]![]()
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We determine the asymptotic order of decay of eigenvalues of weakly singular integral operators. The singularities are of quite general form, containing power and logarithmic terms. We give a unified elementary proof of all known results in this[...]![]()
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This paper deals with Besov spaces of logarithmic smoothness B-p,T(0,b) formed by periodic functions. We study embeddings of B-p,T(0,b) into Lorentz-Zygmund spaces L-p,L-q(log L)(beta). Our techniques rely on the approximation structure of B-p,T[...]![]()
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The paper deals with ideals of operators for which the sequence of their entropy numbers(en(T)) belongs to a Lorentz-Marcinkiewicz space `,q, where is a so-called function parameter. In the case (t) = tp the classical Lorentz space `p,q results[...]![]()
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We establish two-sided estimates for entropy numbers of embeddings between certain weighted Banach sequence spaces with mixed norms. These estimates are‘‘almost’’ sharp, in the sense that upper and lower bounds differ only by logarithmic terms a[...]![]()
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We consider limiting real interpolation spaces defined by using powers of iterated logarithms and show their description by means of the J -functional. Our results allow to complement some estimates on approximation of stochastic integrals.![]()
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We study spectral properties of operators on logarithmic perturbations of the real interpolation spaces with ? = 0 or 1. We also establish estimates for the measure of non-compactness of operators interpolated by those methods.![]()
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We provide a simple algorithm that constructs an exact minimizer for the E-functional E(t, f ; L?, BV) = inf ?g?L??t ? f ? g?BV . Here L?, BV stand for the space of bounded functions and the space of functions with bounded variation on the inter[...]![]()
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We establish abstract extrapolation results for entropy numbers of operators in Banach spaces. The results apply to extrapolation in the source spaces and also in the target spaces. As an illustration of the abstract results, applications to lim[...]