Una nota sobre los espacios de Sobolev.
Una nota sobre los espacios de Sobolev anisótropos vectoriales LΓp (E)*.
Una representación del espacio Cok (Ω,E).
Unbounded Hermitian operators and relative reproducing kernel Hilbert space
We study unbounded Hermitian operators with dense domain in Hilbert space. As is known, the obstruction for a Hermitian operator to be selfadjoint or to have selfadjoint extensions is measured by a pair of deficiency indices, and associated deficiency spaces; but in practical problems, the direct computation of these indices can be difficult. Instead, in this paper we identify additional structures that throw light on the problem. We will attack the problem of computing deficiency spaces for a single...
Unbounded symmetric homogeneous domains in spaces of operators
Uncomplementability of the spaces of norm continuous functions in some spaces of "weakly" continuous functions
Unconditional biorthogonal wavelet bases in
We prove that a biorthogonal wavelet basis yields an unconditional basis in all spaces with 1 < p < ∞, provided the biorthogonal wavelet set functions satisfy weak decay conditions. The biorthogonal wavelet set is associated with an arbitrary dilation matrix in any dimension.
Unconditional decompositions and local unconditional structures in some subspaces of , 1≤p<2
Unconditionality of general Franklin systems in , 1 < p < ∞
By a general Franklin system corresponding to a dense sequence = (tₙ, n ≥ 0) of points in [0,1] we mean a sequence of orthonormal piecewise linear functions with knots , that is, the nth function of the system has knots t₀, ..., tₙ. The main result of this paper is that each general Franklin system is an unconditional basis in , 1 < p < ∞.
Unconditionality of orthogonal spline systems in H¹
We give a simple geometric characterization of knot sequences for which the corresponding orthonormal spline system of arbitrary order k is an unconditional basis in the atomic Hardy space H¹[0,1].
Unconditionality of orthogonal spline systems in
We prove that given any natural number k and any dense point sequence (tₙ), the corresponding orthonormal spline system is an unconditional basis in reflexive .
Unconditionally converging holomorphic mappings between Banach spaces
Unconditionally covering and Dunford-Pettis operators on
Uncountable sets of unit vectors that are separated by more than 1
Let X be a Banach space. We study the circumstances under which there exists an uncountable set 𝓐 ⊂ X of unit vectors such that ||x-y|| > 1 for any distinct x,y ∈ 𝓐. We prove that such a set exists if X is quasi-reflexive and non-separable; if X is additionally super-reflexive then one can have ||x-y|| ≥ slant 1 + ε for some ε > 0 that depends only on X. If K is a non-metrisable compact, Hausdorff space, then the unit sphere of X = C(K) also contains such a subset; if moreover K is perfectly...
Une caractérisation des sous espaces de et ses applications
Une classe d'espaces de Banach réticulés.
Une condition asymptotique pour le calcul de constantes de Sobolev logarithmiques sur la droite
On présente une formule explicite pour la constante de Sobolev logarithmique correspondant à des diffusions réelles ou à des processus entiers de vie et de mort, sous l’hypothèse que certaines quantités, naturellement associées à des inégalités de Hardy dans ce contexte, approchent leur supremum au bord de leur domaine de définition. La preuve se ramène au cas de la constante de Poincaré, à l’aide de comparaisons exactes entre entropie et variances appropriées.
Une nouvelle classe d'espaces de Banach vérifiant le théorème de Grothendieck
Soit un espace et soit un sous-espace réflexif de dimension infinie de . Nous montrons que le quotient vérifie le théorème de Grothendieck, c’est-à-dire que tout opérateur de dans un espace de Hilbert est 1-sommant; par ailleurs, n’est pas un espace . Cela permet de répondre négativement à une question de Lindenstrauss-Pełczyński ainsi qu’à une question similaire de Grothendieck.
Une nouvelle démonstration d'un théorème de Grothendieck
Une propriété du type -stable