Categoricity and non-arithmetic Fuchsian groups

Abstract

Let $\Gamma \subset PSL_2(\mathbb{R})$ be a non-arithmetic Fuchsian group of the first kind with finite covolume, and let $j_{\Gamma}$ be a corresponding uniformizer. In this paper we introduce a natural $L_{\omega_1,\omega}$-axiomatization $T^{\infty}_{SF}$ of the theory of $j_{\Gamma}$ 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 $T_{j_{\Gamma}}$ is complete, admits elimination of quantifiers, and is $\omega$-stable.