English

Noncommutative weak $(1,1)$ type estimate for a square function from ergodic theory

Operator Algebras 2020-06-02 v2 Functional Analysis

Abstract

In this paper, we investigate the boundedness of a square function from ergodic theory on noncommutative LpL_{p}-spaces. The main result is a weak (1,1)(1,1) type estimate of this square function. We also show the (L,BMO)(L_{\infty},\mathrm{BMO}) estimate, and thus strong (Lp,Lp)(L_{p},L_{p}) estimate by interpolation. The main novel difficulty lies in the fact that the kernel of this square function does not enjoy any regularity, which is crucial in showing such endpoint estimates for standard noncommutative Calder\'on-Zygmund singular integral operators.

Keywords

Cite

@article{arxiv.1907.13499,
  title  = {Noncommutative weak $(1,1)$ type estimate for a square function from ergodic theory},
  author = {Guixiang Hong and Bang Xu},
  journal= {arXiv preprint arXiv:1907.13499},
  year   = {2020}
}

Comments

Based the feedbacks from colleagues, we improved substantially the presentation of the whole paper, especially the lengthy proof on weak type (1,1) estimate; among many others, in particular, we add Remark 3.8 on the geometric argument which help a lot in clarifying the rest of the proof

R2 v1 2026-06-23T10:36:04.524Z