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

Fuente: arXiv
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Main Author: Inoué, Takao
Format: Preprint
Published: 2026
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author Inoué, Takao
author_facet Inoué, Takao
contents 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 $(N1)$ 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.
format Preprint
id arxiv_https___arxiv_org_abs_2603_06174
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Haar-Type Measures on Topological Quasigroups and Kunen's Theorem
Inoué, Takao
Group Theory
Functional Analysis
20N05, 22A05, 28C10, 43A05
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 $(N1)$ 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.
title Haar-Type Measures on Topological Quasigroups and Kunen's Theorem
topic Group Theory
Functional Analysis
20N05, 22A05, 28C10, 43A05
url https://arxiv.org/abs/2603.06174