English

Pointwise Convergence for Random Ergodic Averages in Non-commutative $L^p$-spaces

Operator Algebras 2026-04-29 v1 Dynamical Systems Probability

Abstract

Let MM be a semifinite von Neumann algebra and TT a positive contraction on both L1(M)L^1(M) and L(M)L^\infty(M). We consider ergodic averages along a random sparse subsequence determined by independent Bernoulli variables (Xn)n1(X_n)_{n\geq 1} with P(Xn=1)=nα\mathbb{P}(X_n = 1) = n^{-\alpha}, and set WN=n=1NE[Xn]W_N = \sum_{n=1}^N \mathbb{E}[X_n]. We prove that, almost surely, the averages 1WNn=1NXnTn(x)\frac{1}{W_N} \sum_{n=1}^N X_n\, T^n(x) converge bilaterally almost uniformly to the ergodic projection for all 1<p<1 < p < \infty. This extends a theorem of Bourgain to the non-commutative setting.

Keywords

Cite

@article{arxiv.2604.25029,
  title  = {Pointwise Convergence for Random Ergodic Averages in Non-commutative $L^p$-spaces},
  author = {Christian Le Merdy and Safoura Zadeh},
  journal= {arXiv preprint arXiv:2604.25029},
  year   = {2026}
}
R2 v1 2026-07-01T12:38:11.659Z