New evidence for Rémond's generalisation of Lehmer's conjecture

Fuente: arXiv
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Autores principales: Checcoli, Sara, Dill, Gabriel Andreas
Formato: Preprint
Publicado: 2025
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author Checcoli, Sara
Dill, Gabriel Andreas
author_facet Checcoli, Sara
Dill, Gabriel Andreas
contents In this article, we generalise a result of Pottmeyer from the multiplicative group of the algebraic numbers to almost split semiabelian varieties defined over number fields. This concerns a consequence of Rémond's generalisation of Lehmer's conjecture. Namely, for a finite rank subgroup $Γ$ of an almost split semiabelian variety $G$, we consider the group of rational points of $G$ over a finite extension of the field generated by the saturated closure of $Γ$, i.e. the division closure of the subgroup generated by $Γ$ and all its images under geometric endomorphisms of $G$. We show that this becomes a free group after one quotients out the saturated closure of $Γ$. The proof uses, amongst other ingredients, a criterion of Pottmeyer, which relies on a result of Pontryagin, together with a result from Kummer theory, of which we reproduce a proof by Rémond.
format Preprint
id arxiv_https___arxiv_org_abs_2506_18776
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle New evidence for Rémond's generalisation of Lehmer's conjecture
Checcoli, Sara
Dill, Gabriel Andreas
Number Theory
Algebraic Geometry
20K15, 11J95, 11R32, 11G50
In this article, we generalise a result of Pottmeyer from the multiplicative group of the algebraic numbers to almost split semiabelian varieties defined over number fields. This concerns a consequence of Rémond's generalisation of Lehmer's conjecture. Namely, for a finite rank subgroup $Γ$ of an almost split semiabelian variety $G$, we consider the group of rational points of $G$ over a finite extension of the field generated by the saturated closure of $Γ$, i.e. the division closure of the subgroup generated by $Γ$ and all its images under geometric endomorphisms of $G$. We show that this becomes a free group after one quotients out the saturated closure of $Γ$. The proof uses, amongst other ingredients, a criterion of Pottmeyer, which relies on a result of Pontryagin, together with a result from Kummer theory, of which we reproduce a proof by Rémond.
title New evidence for Rémond's generalisation of Lehmer's conjecture
topic Number Theory
Algebraic Geometry
20K15, 11J95, 11R32, 11G50
url https://arxiv.org/abs/2506.18776