English

Independence relations induced by ideals

Logic 2026-07-09 v1

Abstract

Inspired by the non-meager independence nm\downarrow^{nm} introduced by Krupi\'{n}ski [3], we study further possible independence relations induced by ideals and provide a general framework for this topic. We show that the independence relation Haar\downarrow^\mathrm{Haar} induced by Haar null ideals is a good example for locally compact groups and provide an example showing Haarnm\downarrow^\mathrm{Haar}\neq \downarrow^{nm}. Moreover, we introduce an order on the collection of all well-behaved independence relations and conjecture that nm\downarrow^{nm} is the maximum one for Polish groups. We prove the conjecture under the extra hypothesis of σ\sigma-compactness. For Lie groups, we discuss SO(3)\mathrm{SO}(3) and SE(2)\mathrm{SE}(2) as examples, and prove that the independence relation is unique for nilpotent Lie groups.

Cite

@article{arxiv.2607.08126,
  title  = {Independence relations induced by ideals},
  author = {Zhentao Zhang},
  journal= {arXiv preprint arXiv:2607.08126},
  year   = {2026}
}