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Main Authors: Madarász, Judit, Stannett, Mike, Székely, Gergely
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2507.10279
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author Madarász, Judit
Stannett, Mike
Székely, Gergely
author_facet Madarász, Judit
Stannett, Mike
Székely, Gergely
contents We define general notions of coordinate geometries over fields and ordered fields, and consider coordinate geometries that are given by finitely many relations that are definable over those fields. We show that the automorphism group of such a geometry determines the geometry up to definitional equivalence; moreover, if we are given two such geometries $\mathcal{G}$ and $\mathcal{G}'$, then the concepts (explicitly definable relations) of $\mathcal{G}$ are concepts of $\mathcal{G}'$ exactly if the automorphisms of $\mathcal{G}'$ are automorphisms of $\mathcal{G}$. We show this by first proving that a relation is a concept of $\mathcal{G}$ exactly if it is closed under the automorphisms of $\mathcal{G}$ and is definable over the field; moreover, it is enough to consider automorphisms that are affine transformations.
format Preprint
id arxiv_https___arxiv_org_abs_2507_10279
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Definable coordinate geometries over fields, part 1: theory
Madarász, Judit
Stannett, Mike
Székely, Gergely
Logic
We define general notions of coordinate geometries over fields and ordered fields, and consider coordinate geometries that are given by finitely many relations that are definable over those fields. We show that the automorphism group of such a geometry determines the geometry up to definitional equivalence; moreover, if we are given two such geometries $\mathcal{G}$ and $\mathcal{G}'$, then the concepts (explicitly definable relations) of $\mathcal{G}$ are concepts of $\mathcal{G}'$ exactly if the automorphisms of $\mathcal{G}'$ are automorphisms of $\mathcal{G}$. We show this by first proving that a relation is a concept of $\mathcal{G}$ exactly if it is closed under the automorphisms of $\mathcal{G}$ and is definable over the field; moreover, it is enough to consider automorphisms that are affine transformations.
title Definable coordinate geometries over fields, part 1: theory
topic Logic
url https://arxiv.org/abs/2507.10279