English

A generalisation of Pisier homogeneous Banach algebra

Functional Analysis 2021-03-18 v1

Abstract

In 1979 Pisier proved remarkably that a sequence of independent and identically distributed standard Gaussian random variables determines, via random Fourier series, a homogeneous Banach algebra P\mathscr{P} strictly contained in C(T)C(\mathbb{T}), the class of continuous functions on the unit circle T\mathbb{T} and strictly containing the classical Wiener algebra A(T)\mathbb{A}(\mathbb{T}), that is, A(T)PC(T).\mathbb{A}(\mathbb{T}) \subsetneqq \mathscr{P} \subsetneqq C(\mathbb{T}). This improved some previous results obtained by Zafran in solving a long-standing problem raised by Katznelson. In this paper we extend Pisier's result by showing that any probability measure on the unit circle defines a homogeneous Banach algebra contained in C(T)C(\mathbb{T}). Thus Pisier algebra is not an isolated object but rather an element in a large class of Pisier-type algebras. We consider the case of spectral measures of stationary sequences of Gaussian random variables and obtain a sufficient condition for the boundedness of the random Fourier series nZf^(n)ξnexp(2πint)\sum_{n\in \mathbb{Z}}\hat f(n) \,\xi_n \exp(2\pi i n t) in the general setting of dependent random variables (ξn)(\xi_n).

Keywords

Cite

@article{arxiv.2103.09579,
  title  = {A generalisation of Pisier homogeneous Banach algebra},
  author = {Safari Mukeru},
  journal= {arXiv preprint arXiv:2103.09579},
  year   = {2021}
}