English

The monogenicity and Galois groups of certain reciprocal quintinomials

Number Theory 2024-11-04 v1

Abstract

We say that a monic polynomial f(x)Z[x]f(x)\in {\mathbb Z}[x] of degree NN is monogenic if f(x)f(x) is irreducible over Q{\mathbb Q} and {1,θ,θ2,,θN1}\{1,\theta,\theta^2,\ldots ,\theta^{N-1}\} is a basis for ZK{\mathbb Z}_K, the ring of integers of K=Q(θ)K={\mathbb Q}(\theta), where f(θ)=0f(\theta)=0. For n2n\ge 2, we define the reciprocal quintinomial Fn,A,B(x):=x2n+Ax32n2+Bx2n1+Ax2n2+1Z[x].{\mathcal F}_{n,A,B}(x):=x^{2^n}+Ax^{3\cdot 2^{n-2}}+Bx^{2^{n-1}}+Ax^{2^{n-2}}+1\in {\mathbb Z}[x]. In this article, we extend our previous work on the monogenicity of Fn,A,B(x){\mathcal F}_{n,A,B}(x) to treat the specific previously-unaddressed situation of AB1(mod4)A\equiv B\equiv 1\pmod{4}. Moreover, we determine the Galois group over Q{\mathbb Q} of Fn,A,B(x){\mathcal F}_{n,A,B}(x) in special cases.

Keywords

Cite

@article{arxiv.2411.00523,
  title  = {The monogenicity and Galois groups of certain reciprocal quintinomials},
  author = {Lenny Jones},
  journal= {arXiv preprint arXiv:2411.00523},
  year   = {2024}
}

Comments

arXiv admin note: text overlap with arXiv:2404.17921