Smooth sequences and overring operators
Dario Spirito
TL;DR
The paper introduces smooth sequences of overrings and an overrings operator framework to study the structure of the group $Inv(D)$ of invertible ideals in integral domains, especially Prüfer domains. By linking algebraic structure to the inverse topology on $Spec(D)^{inv}$ and Cantor-Bendixson-type derivations, it develops criteria that reduce freeness of $Inv(D)$ to the freeness of overrings and their kernels. The framework unifies prior results on SP-scattered, InvXD, and pre-Jaffard settings and offers a constructive method to build smooth chains by iterating overrings operators. Applications to one-dimensional Prüfer domains yield decompositions of $Inv(D)$ via Theta-based constructions and enable reduction steps that streamline the freeness analysis.
Abstract
We introduce smooth sequences of integral domains as well-ordered ascending chains that behave well at limit ordinals. Subsequently, we use this notion to give some conditions on the freeness of kernels of extension maps between groups of invertible ideals of Prüfer domains. We also define overring operators to construct smooth sequences in a recursive way.
