English

A zero-one law for linear transformations of Levy noise

Probability 2009-08-25 v1 Group Theory

Abstract

A L\'evy noise on Rd\mathbb{R}^d assigns a random real "mass" Π(B)\Pi(B) to each Borel subset BB of Rd\mathbb{R}^d with finite Lebesgue measure. The distribution of Π(B)\Pi(B) only depends on the Lebesgue measure of BB, and if B1,...,BnB_1, ..., B_n is a finite collection of pairwise disjoint sets, then the random variables Π(B1),...,Π(Bn)\Pi(B_1), ..., \Pi(B_n) are independent with Π(B1>...Bn)=Π(B1)+...+Π(Bn)\Pi(B_1 \cup >... \cup B_n) = \Pi(B_1) + ... + \Pi(B_n) almost surely. In particular, the distribution of Πg\Pi \circ g is the same as that of Π\Pi when gg is a bijective transformation of Rd\mathbb{R}^d that preserves Lebesgue measure. It follows from the Hewitt--Savage zero--one law that any event which is almost surely invariant under the mappings ΠΠg\Pi \mapsto \Pi \circ g for every Lebesgue measure preserving bijection gg of Rd\mathbb{R}^d must have probability 0 or 1. We investigate whether certain smaller groups of Lebesgue measure preserving bijections also possess this property. We show that if d2d \ge 2, the L\'evy noise is not purely deterministic, and the group consists of linear transformations and is closed, then the invariant events all have probability 0 or 1 if and only if the group is not compact.

Keywords

Cite

@article{arxiv.0908.3339,
  title  = {A zero-one law for linear transformations of Levy noise},
  author = {Steven N. Evans},
  journal= {arXiv preprint arXiv:0908.3339},
  year   = {2009}
}

Comments

9 pages

R2 v1 2026-06-21T13:38:12.914Z