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Main Authors: Bhardwaj, Neer, Moonen, Frodo
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2503.00440
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author Bhardwaj, Neer
Moonen, Frodo
author_facet Bhardwaj, Neer
Moonen, Frodo
contents Let $G$ be a proper subgroup of $\mathbb{Q}$ and $S_G$ be the set of primes $p$ for which $G$ is $p$-divisible. We show that the model-theoretic Grothendieck ring of the ordered abelian group $(G;+,<)$ is a quotient of $(\mathbb{Z}/q\mathbb{Z})[T]/(T+T^2)$, where $q$ is the largest odd integer that divides $p-1$ for all $p \notin S_G$. This implies that the Grothendieck ring of $(G;+,<)$ is trivial in various salient cases, for example when $S_G$ is finite, or when $S_G$ does not contain some prime of the form $2^n+1$, $n\in \mathbb{N}$.
format Preprint
id arxiv_https___arxiv_org_abs_2503_00440
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Grothendieck rings of ordered subgroups of $\mathbb{Q}$
Bhardwaj, Neer
Moonen, Frodo
Rings and Algebras
Logic
3C07, 03C64, 06F20
Let $G$ be a proper subgroup of $\mathbb{Q}$ and $S_G$ be the set of primes $p$ for which $G$ is $p$-divisible. We show that the model-theoretic Grothendieck ring of the ordered abelian group $(G;+,<)$ is a quotient of $(\mathbb{Z}/q\mathbb{Z})[T]/(T+T^2)$, where $q$ is the largest odd integer that divides $p-1$ for all $p \notin S_G$. This implies that the Grothendieck ring of $(G;+,<)$ is trivial in various salient cases, for example when $S_G$ is finite, or when $S_G$ does not contain some prime of the form $2^n+1$, $n\in \mathbb{N}$.
title Grothendieck rings of ordered subgroups of $\mathbb{Q}$
topic Rings and Algebras
Logic
3C07, 03C64, 06F20
url https://arxiv.org/abs/2503.00440