On the cohomology of finite-dimensional nilpotent groups and Lie rings

Fuente: arXiv
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Main Author: Zamour, Samuel
Format: Preprint
Published: 2025
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author Zamour, Samuel
author_facet Zamour, Samuel
contents We establish vanishing results for the first cohomology group of nilpotent groups and Lie rings when the submodule of invariants is trivial. Our results are obtained within a model-theoretic setting, namely for structures that are definable in a finite-dimensional theory, which encompasses algebraic groups over algebraically closed fields, real semi-algebraic groups, and finite-dimensional Lie algebras over an algebraically or real closed field. Since classical tools - such as computations with spectral sequences and rigidity of the linear dimension - are not available in our setting, we develop an elementary algebraic approach. As applications, we derive a form of Frattini's argument for Cartan subrings and a definable version of Maschke's theorem for actions of definable connected p-divisible abelian groups, with a view toward the ongoing study of soluble finite-dimensional Lie rings.
format Preprint
id arxiv_https___arxiv_org_abs_2511_05249
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the cohomology of finite-dimensional nilpotent groups and Lie rings
Zamour, Samuel
Logic
Group Theory
03C60, 20J06
We establish vanishing results for the first cohomology group of nilpotent groups and Lie rings when the submodule of invariants is trivial. Our results are obtained within a model-theoretic setting, namely for structures that are definable in a finite-dimensional theory, which encompasses algebraic groups over algebraically closed fields, real semi-algebraic groups, and finite-dimensional Lie algebras over an algebraically or real closed field. Since classical tools - such as computations with spectral sequences and rigidity of the linear dimension - are not available in our setting, we develop an elementary algebraic approach. As applications, we derive a form of Frattini's argument for Cartan subrings and a definable version of Maschke's theorem for actions of definable connected p-divisible abelian groups, with a view toward the ongoing study of soluble finite-dimensional Lie rings.
title On the cohomology of finite-dimensional nilpotent groups and Lie rings
topic Logic
Group Theory
03C60, 20J06
url https://arxiv.org/abs/2511.05249