Información del autor
Autor Cobos, Fernando |
Documentos disponibles escritos por este autor (121)
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We prove that the classical Lions-Peetre compactness theorems for linear operators still hold for Lipschitz operators. As a consequence, we deduce that certain Uryson integral operators are compact. We also show that Lipschitz operators can be i[...]texto impreso
The authors extend a result of K. Hayakawa [J. Math. Soc. Jap. 21, 189-199 (1969; Zbl 0181.137)], and prove: If T is a linear operator such that T: A0 ! B0, is bounded,and T: A1 ! B1 is compact, and moreover, A1 A0, then T: ¯ A,q ! ¯B,q is comp[...]texto impreso
We describe the spaces obtained by applying the interpolation methods associated to polygons to N-tuples of weighted Lp-spaces, N-tuples of classical Lorentz spaces and some other N-tuples of function spaces.texto impreso
We improve the known results on interpolation of strictly singular operators and strictly co-singular operators in several directions. Applications are given to embeddings between symmetric spaces.texto impreso
We revised the known results on interpolation of the measure of noncompactness and we announce a new approach to establishing the interpolation formula for the real method.texto impreso
We describe the behaviour under interpolation of a limit class of approximation spaces. We characterize them as extrapolation spaces. Moreover, we study the boundedness of certain operators on these spaces. As an application, we derive several r[...]texto impreso
Cobos, Fernando ; Domínguez, Oscar ; Kühn, Thomas | 2018Let Bp,qs,?(?) be the Besov space with classical smoothness s and additional logarithmic smoothness of order ? on a bounded Lipschitz domain ? in Rd. For s1, s2 ? R, 1 ? p1, p2, q1, q2 ? ? and s1 ? s2 = d ? d(1/p2 ? 1/p1)+, we show a su?cient co[...]texto impreso
We work with spaces of periodic functions on the d-dimensional torus. We show that estimates for L?-approximation of Sobolev functions remain valid when we replace L1 by the isotropic periodic Besov space B01;1 or the periodic Besovspace with do[...]texto impreso
We show abstract versions for Banach couples of several limiting compact interpolation theorems established by Edmunds and Opic for couples of Lp spaces.texto impreso
We show abstract versions for Banach couples of several limiting compact interpolation theorems established by Edmunds and Opic for couples of Lp spaces.texto impreso
This article deals with K- and J-spaces defined by means of polygons. First we establish some reiteration formulae involving the real method, and then we study the behaviour of weakly compact operators. We also show optimality of the weak compac[...]texto impreso
We establish interpolation formulae for operator spaces that are components of a given quasi-normed operator ideal.texto impreso
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The authors prove a representation theorem in terms of finite rank operators for operators´T on Banach spaces which satisfy sup n2N (log n) an(T)texto impreso
Let E be a Banach function lattice such that L1[0; 1] ,! E ,! L1[0; 1]. We characterize the strict singularity of the embedding L1[0; 1] ,! E and the strict cosingularity of E ,! L1[0; 1] in terms of functionals de_ned by using characteristic fu[...]