Canadian Mathematical Society
Canadian Mathematical Society
  location:  PublicationsjournalsCMB
Abstract view

Boundedness of the $q$-Mean-Square Operator on Vector-Valued Analytic Martingales

 Printed: Jun 1999
  • Peide Liu
  • Eero Saksman
  • Hans-Olav Tylli
Format:   HTML   LaTeX   MathJax   PDF   PostScript  


We study boundedness properties of the $q$-mean-square operator $S^{(q)}$ on $E$-valued analytic martingales, where $E$ is a complex quasi-Banach space and $2 \leq q < \infty$. We establish that a.s. finiteness of $S^{(q)}$ for every bounded $E$-valued analytic martingale implies strong $(p,p)$-type estimates for $S^{(q)}$ and all $p\in (0,\infty)$. Our results yield new characterizations (in terms of analytic and stochastic properties of the function $S^{(q)}$) of the complex spaces $E$ that admit an equivalent $q$-uniformly PL-convex quasi-norm. We also obtain a vector-valued extension (and a characterization) of part of an observation due to Bourgain and Davis concerning the $L^p$-boundedness of the usual square-function on scalar-valued analytic martingales.
MSC Classifications: 46B20, 60G46 show english descriptions Geometry and structure of normed linear spaces
Martingales and classical analysis
46B20 - Geometry and structure of normed linear spaces
60G46 - Martingales and classical analysis

© Canadian Mathematical Society, 2015 :