Interpolation spaces by complex methods

Interpolation Spaces by Complex Methods

where the infimum is taken over all pairs x^ÇzXj satisfying (2.1). One easily checks that (2.2) gives a norm on X 0 + X i when X0 and X% are compatible. Moreover, when X0+Xi is equipped with this norm, it becomes a Banach space (cf. [3]). Let Cfc denote the set of complex valued functions of the complex variable f = ̂ +irf which are continuous on bounded subsets of S, where fl is the strip 0 <£ ...

Complex Interpolation and Twisted Twisted Hilbert Spaces

Complex interpolation of weighted noncommutative Lp-spaces

Let M be a semifinite von Neumann algebra equipped with a semifinite normal faithful trace τ . Let d be an injective positive measurable operator with respect to (M, τ ) such that d is also measurable. Define Lp(d) = {x ∈ L0(M) : dx+ xd ∈ Lp(M)} and ‖x‖Lp(d) = ‖dx+ xd‖p . We show that for 1 6 p0 < p1 6 ∞, 0 < θ < 1 and α0 > 0, α1 > 0 the interpolation equality (Lp0(d 0), Lp1(d α))θ = Lp(d ) hol...

Interpolation by Weak Chebyshev Spaces

We present two characterizations of Lagrange interpolation sets for weak Chebyshev spaces. The rst of them is valid for an arbitrary weak Chebyshev space U and is based on an analysis of the structure of zero sets of functions in U extending Stockenberg's theorem. The second one holds for all weak Chebyshev spaces that possess a locally linearly independent basis. x1. Introduction Let U denote ...

Interpolation and Almost Interpolation by Weak Chebyshev Spaces

Some new results on univariate interpolation by weak Cheby-shev spaces, using conditions of Schoenberg-Whitney type and the concept of almost interpolation sets, are given. x1. Introduction Let U denote a nite-dimensional subspace of real-valued functions deened on some set K. We are interested in describing those conngurations T = dimU jT = s: T is called an interpolation set (I-set) w.r.t. U....