Existence of normal elements with prescribed norms

Fuente: arXiv
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Autores principales: Fernandes, Arthur, Panario, Daniel, Reis, Lucas
Formato: Preprint
Publicado: 2024
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author Fernandes, Arthur
Panario, Daniel
Reis, Lucas
author_facet Fernandes, Arthur
Panario, Daniel
Reis, Lucas
contents For each positive integer $n$, let $\mathbb F_{q^n}$ be the unique $n$-degree extension of the finite field $\mathbb F_q$ with $q$ elements, where $q$ is a prime power. It is known that for arbitrary $q$ and $n$, there exists an element $β\in \mathbb F_{q^n}$ such that its Galois conjugates $β, β^q, \ldots, β^{q^{n-1}}$ form a basis for $\mathbb F_{q^n}$ as an $\mathbb F_q$-vector space. These elements are called normal and they work as additive generators of finite fields. On the other hand, the multiplicative group $\mathbb F_{q^n}^*$ is cyclic and any generator of this group is a primitive element. Many past works have dealt with the existence of primitive and normal elements with specified properties, including the existence of primitive elements whose traces over intermediate extensions are prescribed. Inspired by the latter, in this paper we explore the existence of normal elements whose norms over intermediate extensions are prescribed. We combine combinatorial and number-theoretic ideas and obtain both asymptotic and concrete results. In particular, we completely solve the problem in the case where only one intermediate extension is considered.
format Preprint
id arxiv_https___arxiv_org_abs_2412_15384
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Existence of normal elements with prescribed norms
Fernandes, Arthur
Panario, Daniel
Reis, Lucas
Number Theory
11T30 and 11T24
For each positive integer $n$, let $\mathbb F_{q^n}$ be the unique $n$-degree extension of the finite field $\mathbb F_q$ with $q$ elements, where $q$ is a prime power. It is known that for arbitrary $q$ and $n$, there exists an element $β\in \mathbb F_{q^n}$ such that its Galois conjugates $β, β^q, \ldots, β^{q^{n-1}}$ form a basis for $\mathbb F_{q^n}$ as an $\mathbb F_q$-vector space. These elements are called normal and they work as additive generators of finite fields. On the other hand, the multiplicative group $\mathbb F_{q^n}^*$ is cyclic and any generator of this group is a primitive element. Many past works have dealt with the existence of primitive and normal elements with specified properties, including the existence of primitive elements whose traces over intermediate extensions are prescribed. Inspired by the latter, in this paper we explore the existence of normal elements whose norms over intermediate extensions are prescribed. We combine combinatorial and number-theoretic ideas and obtain both asymptotic and concrete results. In particular, we completely solve the problem in the case where only one intermediate extension is considered.
title Existence of normal elements with prescribed norms
topic Number Theory
11T30 and 11T24
url https://arxiv.org/abs/2412.15384