English

Haar-Type Measures on Topological Quasigroups and Kunen's Theorem

Group Theory 2026-03-12 v2 Functional Analysis

Abstract

Haar measure is a fundamental structure in harmonic analysis on locally compact groups. Its existence reflects the compatibility between topology and the associative algebraic structure of groups. In this paper we propose a framework for Haar-type measures on topological quasigroups. Since associativity is absent, strict translation invariance is generally too strong to expect. We therefore introduce quasi-invariant measures whose defect is measured by a modular cocycle attached to translations. We then explain, in a detailed and cautious form, how Moufang-type identities may impose strong constraints on this cocycle. In particular, under additional quasi-invariance assumptions for right translations, the Moufang-type identity (N1)(N1) leads naturally to a multiplicativity relation for the cocycle. This suggests a measure-theoretic interpretation of Kunen's theorem: the emergence of loop structure may be viewed as the collapse of a modular defect in the translation geometry of a quasigroup.

Keywords

Cite

@article{arxiv.2603.06174,
  title  = {Haar-Type Measures on Topological Quasigroups and Kunen's Theorem},
  author = {Takao Inoué},
  journal= {arXiv preprint arXiv:2603.06174},
  year   = {2026}
}

Comments

25 pages. Minor revisions. Added a conceptual conjecture (Modular Collapse Conjecture), improved appendix diagrams, and clarified the interpretation of Kunen's theorem