English

Factorization in almost Dedekind domain

Commutative Algebra 2026-05-19 v1

Abstract

Let FF be a field, pp a prime number, XX an indeterminate over FF, Dn=F[X1pn,X1pn]D_n =F[X^{\frac{1}{p^n}}, X^{-\frac{1}{p^n}}] for each integer n0n \geq 0 and D=nN0Dn.D = \bigcup\limits_{n\in\mathbb{N}_0}D_n. Then DD is a one-dimensional B{\'e}zout domain but not a Dedekind domain, and DD is an almost Dedekind domain if and only if char(F)p(F) \neq p. In this paper, we study the element-wise factorization properties of DD. For example, we determine when an irreducible element of DnD_n is an irreducible element of DD, in terms of nn and pp. In particular, we show that if FF is algebraically closed or a finite field of char(F)=p(F)=p, then DD has no irreducible element. We also show that if FF is a finite field of odd characteristic, then an irreducible element f(X)f(X) of D0D_0 is irreducible in DD if and only if it is a factor of a cyclotomic polynomial Φn(X)\Phi_n(X) for some integer n1n \geq 1 which satisfies a certain equation in terms of F|F| and deg(f(X))(f(X)). Finally, we introduce the notion of infinite product and we then show that if F=QF= \mathbb{Q} and p=2p=2, every nonzero nonunit of DD can be written as a product of countably many prime elements of DD and every proper nonzero principal ideal of DD can be uniquely written as a countable intersection of principal primary ideals.

Keywords

Cite

@article{arxiv.2605.17315,
  title  = {Factorization in almost Dedekind domain},
  author = {Gyu Whan Chang and Hyun Seung Choi},
  journal= {arXiv preprint arXiv:2605.17315},
  year   = {2026}
}