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1. CMB 2000 (vol 43 pp. 355)
| A Dimension-Free Weak-Type Estimate for Operators on UMD-Valued Functions Let $\T$ denote the unit circle in the complex plane, and let $X$ be a
Banach space that satisfies\break Burkholder's UMD condition. Fix a natural
number, $N \in \N$. Let $\od$ denote the reverse lexicographical order
on $\Z^N$. For each $f \in L^1 (\T^N,X)$, there exists a strongly
measurable function $\wt{f}$ such that formally, for all $\bfn \in
\Z^N$, $\Dual{{\wt{f}}} (\bfn) = -i \sgn_\od (\bfn)
\Dual{f} (\bfn)$. In this paper, we present a summation method for
this conjugate function directly analogous to the martingale methods
developed by Asmar and Montgomery-Smith for scalar-valued functions.
Using a stochastic integral representation and an application of
Garling's characterization of UMD spaces, we prove that the associated
maximal operator satisfies a weak-type $(1,1)$ inequality with a
constant independent of the dimension~$N$.
Category:42A61 |

