Local-global divisibility on algebraic tori

Fuente: arXiv
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Autori principali: Alessandrì, Jessica, Chirivì, Rocco, Paladino, Laura
Natura: Preprint
Pubblicazione: 2023
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author Alessandrì, Jessica
Chirivì, Rocco
Paladino, Laura
author_facet Alessandrì, Jessica
Chirivì, Rocco
Paladino, Laura
contents We give a complete answer to the local-global divisibility problem for algebraic tori. In particular, we prove that given an odd prime $p$, if $T$ is an algebraic torus of dimension $r< p-1$ defined over a number field $k$, then the local-global divisibility by any power $p^n$ holds for $T(k)$. We also show that this bound on the dimension is best possible, by providing a counterexample of every dimension $r \geq p-1$. Finally, we prove that under certain hypotheses on the number field generated by the coordinates of the $p^n$-torsion point of $T$, the local-global divisibility still holds for tori of dimension less than $3(p-1)$.
format Preprint
id arxiv_https___arxiv_org_abs_2301_05922
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Local-global divisibility on algebraic tori
Alessandrì, Jessica
Chirivì, Rocco
Paladino, Laura
Number Theory
11E72, 14G05, 11G35
We give a complete answer to the local-global divisibility problem for algebraic tori. In particular, we prove that given an odd prime $p$, if $T$ is an algebraic torus of dimension $r< p-1$ defined over a number field $k$, then the local-global divisibility by any power $p^n$ holds for $T(k)$. We also show that this bound on the dimension is best possible, by providing a counterexample of every dimension $r \geq p-1$. Finally, we prove that under certain hypotheses on the number field generated by the coordinates of the $p^n$-torsion point of $T$, the local-global divisibility still holds for tori of dimension less than $3(p-1)$.
title Local-global divisibility on algebraic tori
topic Number Theory
11E72, 14G05, 11G35
url https://arxiv.org/abs/2301.05922