Article contents
BMO Functions and Carleson Measures with Values in Uniformly Convex Spaces
Published online by Cambridge University Press: 20 November 2018
Abstract
This paper studies the relationship between vector-valued $\text{BMO}$ functions and the Carleson measures defined by their gradients. Let
$dA$ and
$dm$ denote Lebesgue measures on the unit disc
$D$ and the unit circle
$\mathbb{T}$, respectively. For
$1\,<\,q\,<\,\infty $ and a Banach space
$B$, we prove that there exists a positive constant
$c$ such that
$$\underset{{{z}_{0}}\in D}{\mathop{\sup }}\,{{\int }_{D}}{{\left( 1-\left| z \right| \right)}^{q-1}}{{\left\| \nabla f\left( z \right) \right\|}^{q}}{{P}_{{{Z}_{0}}}}\left( z \right)dA\left( z \right)\le {{c}^{q}}\underset{{{z}_{0}}\in D}{\mathop{\sup }}\,{{\int }_{\mathbb{T}}}{{\left\| f\left( z \right)-f\left( {{z}_{0}} \right) \right\|}^{q}}{{P}_{{{z}_{0}}}}\left( z \right)dm\left( z \right)$$
holds for all trigonometric polynomials $f$ with coefficients in
$B$ if and only if
$B$ admits an equivalent norm which is
$q$-uniformly convex, where
$${{P}_{{{z}_{0}}}}\left( z \right)=\frac{1-|{{z}_{0}}{{|}^{2}}}{|1-{{{\bar{z}}}_{0}}z{{|}^{2}}}.$$
The validity of the converse inequality is equivalent to the existence of an equivalent $q$-uniformly smooth norm.
Keywords
- Type
- Research Article
- Information
- Copyright
- Copyright © Canadian Mathematical Society 2010
References
- 5
- Cited by