Groups of invertible ideals of one-dimensional Pr\"ufer domains as groups of integer-valued functions

TL;DR

This paper investigates the structure of groups of invertible ideals in one-dimensional Pr"ufer domains, showing they can be free under certain conditions and introducing dd-domains where these groups relate to integer-valued functions.

Contribution

It establishes conditions for the freeness of groups of invertible ideals in Pr"ufer domains and characterizes dd-domains as those with invertible ideal groups isomorphic to subgroups of integer-valued functions.

Findings

Groups of invertible ideals can be free under specific spectral conditions.

Introduces dd-domains as Pr"ufer domains with invertible ideal groups related to integer-valued functions.

Characterizes dd-domains via their spectrum and localizations as DVRs.

Abstract

Let $G$ be a one-dimensional $\ell$-subgroup of the group $\mathcal{F}(X,\mathbb{Z})$ of integer-valued functions on a set $X$. We show that $G$ is free under some hypothesis on the spectrum of $G$ and on its quotient groups at the prime ideals. We translate this result in the context of the study of freeness of the group $\mathrm{Inv}(D)$ of invertible ideals of a Pr\"ufer domain $D$: in particular, we introduce the class of \emph{dd-domains} as the class of Pr\"ufer domains having a set $X$ that is dense in $\mathrm{Spec}(D)$ (with respect to the inverse topology) and whose localizations are DVRs. This class is exactly the class of Pr\"ufer domains for which $\mathrm{Inv}(D)$ is isomorphic (as an $\ell$-group) to a subgroup of $\mathcal{F}(X,\mathbb{Z})$.