Monogenic Even Octic Polynomials and Their Galois Groups

Fuente: arXiv
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Main Author: Jones, Lenny
Format: Preprint
Published: 2024
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author Jones, Lenny
author_facet Jones, Lenny
contents A monic polynomial $f(x)\in {\mathbb Z}[x]$ of degree $N$ is called monogenic if $f(x)$ is irreducible over ${\mathbb Q}$ and $\{1,θ,θ^2,\ldots ,θ^{N-1}\}$ is a basis for the ring of integers of ${\mathbb Q}(θ)$, where $f(θ)=0$. In a series of recent articles, complete classifications of the Galois groups were given for irreducible polynomials \[{\mathcal F}(x):=x^8+ax^4+b\in {\mathbb Z}[x]\] and \[{\mathcal G}(x):=x^8+ax^6+bx^4+ax^2+1\in {\mathbb Z}[x], \quad a\ne 0.\] In this article, for each Galois group $G$ arising in these classifications, we either construct an infinite family of monogenic octic polynomials ${\mathcal F}(x)$ or ${\mathcal G}(x)$ having Galois group $G$, or we prove that at most a finite such family exists. In the finite family situations, we determine all such polynomials. Here, a ``family" means that no two polynomials in the family generate isomorphic octic fields.
format Preprint
id arxiv_https___arxiv_org_abs_2404_17921
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Monogenic Even Octic Polynomials and Their Galois Groups
Jones, Lenny
Number Theory
A monic polynomial $f(x)\in {\mathbb Z}[x]$ of degree $N$ is called monogenic if $f(x)$ is irreducible over ${\mathbb Q}$ and $\{1,θ,θ^2,\ldots ,θ^{N-1}\}$ is a basis for the ring of integers of ${\mathbb Q}(θ)$, where $f(θ)=0$. In a series of recent articles, complete classifications of the Galois groups were given for irreducible polynomials \[{\mathcal F}(x):=x^8+ax^4+b\in {\mathbb Z}[x]\] and \[{\mathcal G}(x):=x^8+ax^6+bx^4+ax^2+1\in {\mathbb Z}[x], \quad a\ne 0.\] In this article, for each Galois group $G$ arising in these classifications, we either construct an infinite family of monogenic octic polynomials ${\mathcal F}(x)$ or ${\mathcal G}(x)$ having Galois group $G$, or we prove that at most a finite such family exists. In the finite family situations, we determine all such polynomials. Here, a ``family" means that no two polynomials in the family generate isomorphic octic fields.
title Monogenic Even Octic Polynomials and Their Galois Groups
topic Number Theory
url https://arxiv.org/abs/2404.17921