Linear relations of four conjugates of an algebraic number

Fuente: arXiv
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Auteurs principaux: Baronėnas, Ž., Drungilas, P., Jankauskas, J.
Format: Preprint
Publié: 2025
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author Baronėnas, Ž.
Drungilas, P.
Jankauskas, J.
author_facet Baronėnas, Ž.
Drungilas, P.
Jankauskas, J.
contents We characterize all algebraic numbers $α$ of degree $d\in\{4,5,6,7\}$ for which there exist four distinct algebraic conjugates $α_1$, $α_2$, $α_3$, $α_4$ of $α$ satisfying the relation $α_{1}+α_{2}=α_{3}+α_{4}$. In particular, we prove that an algebraic number $α$ of degree 6 satisfies this relation with $α_{1}+α_{2}\notin\mathbb{Q}$ if and only if $α$ is the sum of a quadratic and a cubic algebraic number. Moreover, we describe all possible Galois groups of the normal closure of $\mathbb{Q}(α)$ for such algebraic numbers $α$. We also consider similar relations $α_{1}+α_{2}+α_{3}+α_{4}=0$ and $α_{1}+α_{2}+α_{3}=α_{4}$ for algebraic numbers of degree up to 7.
format Preprint
id arxiv_https___arxiv_org_abs_2507_13831
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Linear relations of four conjugates of an algebraic number
Baronėnas, Ž.
Drungilas, P.
Jankauskas, J.
Number Theory
11R04, 11R32
We characterize all algebraic numbers $α$ of degree $d\in\{4,5,6,7\}$ for which there exist four distinct algebraic conjugates $α_1$, $α_2$, $α_3$, $α_4$ of $α$ satisfying the relation $α_{1}+α_{2}=α_{3}+α_{4}$. In particular, we prove that an algebraic number $α$ of degree 6 satisfies this relation with $α_{1}+α_{2}\notin\mathbb{Q}$ if and only if $α$ is the sum of a quadratic and a cubic algebraic number. Moreover, we describe all possible Galois groups of the normal closure of $\mathbb{Q}(α)$ for such algebraic numbers $α$. We also consider similar relations $α_{1}+α_{2}+α_{3}+α_{4}=0$ and $α_{1}+α_{2}+α_{3}=α_{4}$ for algebraic numbers of degree up to 7.
title Linear relations of four conjugates of an algebraic number
topic Number Theory
11R04, 11R32
url https://arxiv.org/abs/2507.13831