On bases and the shift operator
Define as the subspace of consisting of all harmonic functions in B, where B is the ball in the n-dimensional Euclidean space and E is any Banach space. Consider also the space consisting of all harmonic E*-valued functions g such that is bounded for some m>0. Then the dual is represented by through , . This extends the results of S. Bell in the scalar case.
We introduce a new “weak” BMO-regularity condition for couples (X,Y) of lattices of measurable functions on the circle (Definition 3, Section 9), describe it in terms of the lattice , and prove that this condition still ensures “good” interpolation for the couple of the Hardy-type spaces corresponding to X and Y (Theorem 1, Section 9). Also, we present a neat version of Pisier’s approach to interpolation of Hardy-type subspaces (Theorem 2, Section 13). These two main results of the paper are...
Given a compact Hausdorff space K we consider the Banach space of real continuous functions C(Kⁿ) or equivalently the n-fold injective tensor product or the Banach space of vector valued continuous functions C(K,C(K,C(K...,C(K)...). We address the question of the existence of complemented copies of c₀(ω₁) in under the hypothesis that C(K) contains such a copy. This is related to the results of E. Saab and P. Saab that contains a complemented copy of c₀ if one of the infinite-dimensional Banach...
We prove a conjecture of Wojtaszczyk that for 1 ≤ p < ∞, p ≠ 2, does not admit any norm one projections with dimension of the range finite and greater than 1. This implies in particular that for 1 ≤ p < ∞, p ≠ 2, does not admit a Schauder basis with constant one.
One proves the density of an ideal of analytic functions into the closure of analytic functions in a -space, under some geometric conditions on the support of the measure and the zero variety of the ideal.
Assume a finite set of functions in , the space of bounded analytic functions on the open unit disc. We give a sufficient condition on a function in to belong to the norm-closure of the ideal generated by , namely the propertyfor some function : satisfying The main feature in the proof is an improvement in the contour-construction appearing in L. Carleson’s solution of the corona-problem. It is also shown that the propertyfor some constant , does not necessary imply that is...
Let D be the open unit disc and μ a positive bounded measure on [0,1]. Extending results of Mateljević/Pavlović and Shields/Williams we give Banach-space descriptions of the classes of all harmonic (holomorphic) functions f: D → ℂ satisfying .
We provide a complete isomorphic classification of the Banach spaces of continuous functions on the compact spaces , the topological sums of Cantor cubes , with smaller than the first sequential cardinal, and intervals of ordinal numbers [0,α]. In particular, we prove that it is relatively consistent with ZFC that the only isomorphism classes of spaces with ≥ ℵ₀ and α ≥ ω₁ are the trivial ones. This result leads to some elementary questions on large cardinals.
We study the spaces where Ω is a disc with radius R and μ is a given probability measure on [0,R[. We show that, depending on μ, is either isomorphic to l₁ or to . Here Aₙ is the space of all polynomials of degree ≤ n endowed with the L₁-norm on the unit sphere.