English

Convergence of permuted products of exponentials

Functional Analysis 2025-04-04 v1 Probability

Abstract

Let {Ai,n}\{A_{i,n}\} be a triangular array of elements in a Banach algebra, whose norms do not grow too fast, and whose row averages converge to AA. Let σS(n)\sigma \in S(n) be a permutation drawn uniformly at random. If the array only contains o(n/logn)o(n / \log n) distinct elements, then almost surely, for all 0<s<t<10 < s < t < 1, the permuted product of their exponentials i=[sn][tn]eAσ(i),n/n\prod_{i = [s n]}^{[t n]} e^{A_{\sigma(i),n}/n} converges in norm to e(ts)Ae^{(t - s) A}. For an array of finite-dimensional matrices, convergence holds without this restriction. The proof of the latter result consists of an estimate valid in a general Banach algebra, and an application of a matrix concentration inequality.

Keywords

Cite

@article{arxiv.2504.02681,
  title  = {Convergence of permuted products of exponentials},
  author = {Michael Anshelevich and Anh Nguyen},
  journal= {arXiv preprint arXiv:2504.02681},
  year   = {2025}
}