Categoricity and non-arithmetic Fuchsian groups

John Baldwin; Joel Nagloo

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arXiv · 2602.11432

Categoricity and non-arithmetic Fuchsian groups

John Baldwin·Joel Nagloo

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Abstract

Let $Γ\subset PSL_2(\mathbb{R})$ be a non-arithmetic Fuchsian group of the first kind with finite covolume, and let $j_Γ$ be a corresponding uniformizer. In this paper we introduce a natural $L_{ω_1,ω}$-axiomatization $T^{\infty}_{SF}$ of the theory of $j_Γ$ viewed as a covering map. We show that $T^{\infty}_{SF}$ is categorical in all infinite cardinalities, extending to the non-arithmetic setting earlier results of Daw and Harris obtained in the arithmetic case. We also show that the associated first-order theory $T_{j_Γ}$ is complete, admits elimination of quantifiers, and is $ω$-stable.

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John Baldwin, Joel Nagloo. 2026-02-11. Categoricity and non-arithmetic Fuchsian groups. https://arxiv.org/abs/2602.11432

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