R-base dans les espaces séparables (2≤p<∞)
Real Banach Algebras. II.
Real interpolation and compactness.
The behavior of compactness under real interpolation real is discussed. Classical results due to Krasnoselskii, Lions-Peetre, Persson, and Hayakawa are described, as well as others obtained very recently by Edmunds, Potter, Fernández, and the author.
Real Interpolation between Row and Column Spaces
We give an equivalent expression for the K-functional associated to the pair of operator spaces (R,C) formed by the rows and columns respectively. This yields a description of the real interpolation spaces for the pair (Mₙ(R),Mₙ(C)) (uniformly over n). More generally, the same result is valid when Mₙ (or B(ℓ₂)) is replaced by any semi-finite von Neumann algebra. We prove a version of the non-commutative Khintchine inequalities (originally due to Lust-Piquard) that is valid for the Lorentz spaces...
Real interpolation for families of Banach spaces
We develop a new method of real interpolation for infinite families of Banach spaces that covers the methods of Lions-Peetre, Sparr for N spaces, Fernández for spaces and the recent method of Cobos-Peetre.
Real interpolation for families of Banach spaces (II).
Real interpolation for non-distant Marcinkiewicz spaces.
We describe the real interpolation spaces between given Marcinkiewicz spaces that have fundamental functions of the form t1/q (ln (e/t)a with the same exponent q. The spaces thus obtained are used for the proof of optimal interpolation theorem from [7], concerning spaces L∞,a,E.
Real linear isometries between function algebras. II
We describe the general form of isometries between uniformly closed function algebras on locally compact Hausdorff spaces in a continuation of the study by Miura. We can actually obtain the form on the Shilov boundary, rather than just on the Choquet boundary. We also give an example showing that the form cannot be extended to the whole maximal ideal space.
Real method of interpolation on subcouples of codimension one
We find necessary and sufficient conditions under which the norms of the interpolation spaces and are equivalent on N, where N is the kernel of a nonzero functional ψ ∈ (X₀ ∩ X₁)* and is the normed space N with the norm inherited from (i = 0,1). Our proof is based on reducing the problem to its partial case studied by Ivanov and Kalton, where ψ is bounded on one of the endpoint spaces. As an application we completely resolve the problem of when the range of the operator (S denotes the...
Real-linear isometries between certain subspaces of continuous functions
In this paper we first consider a real-linear isometry T from a certain subspace A of C(X) (endowed with supremum norm) into C(Y) where X and Y are compact Hausdorff spaces and give a result concerning the description of T whenever A is a uniform algebra on X. The result is improved for the case where T(A) is, in addition, a complex subspace of C(Y). We also give a similar description for the case where A is a function space on X and the range of T is a real subspace of C(Y) satisfying a ceratin...
Real-linear isometries between function algebras
Let A and B be uniformly closed function algebras on locally compact Hausdorff spaces with Choquet boundaries Ch A and ChB, respectively. We prove that if T: A → B is a surjective real-linear isometry, then there exist a continuous function κ: ChB → z ∈ ℂ: |z| = 1, a (possibly empty) closed and open subset K of ChB and a homeomorphism φ: ChB → ChA such that T(f) = κ(f ∘φ) on K and on ChB K for all f ∈ A. Such a representation holds for surjective real-linear isometries between (not necessarily...
Recent progress and open questions on the numerical index of Banach spaces.
The aim of this paper is to review the state-of-the-art of recent research concerning the numerical index of Banach spaces, by presenting some of the results found in the last years and proposing a number of related open problems.
Recognizing the topology of the space of closed convex subsets of a Banach space
Reconstruction of manifolds and subsets of normed spaces from subgroups of their homeomorphism groups [Book]
Rectangular modulus and geometric properties of normed spaces.
Rectangular modulus, Birkhoff orthogonality and characterizations of inner product spaces
Some characterizations of inner product spaces in terms of Birkhoff orthogonality are given. In this connection we define the rectangular modulus of the normed space . The values of the rectangular modulus at some noteworthy points are well-known constants of . Characterizations (involving of inner product spaces of dimension , respectively , are given and the behaviour of is studied.
Reflections on Dubinskiĭ's Nonlinear Compact Embedding Theorem
Reflexive Banach space and fixed point theorems.
Reflexive Banach spaces without equivalent norms which are uniformly convex or uniformly differentiable in every direction
Reflexive invariant subspaces of L... (G) are finite dimensional.