The Unbounded Denominators Conjecture
Abstract
We prove the unbounded denominators conjecture in the theory of noncongruence modular forms for finite index subgroups of SL_2(Z). Our result includes also Mason's generalization of the original conjecture to the setting of vector-valued modular forms, thereby supplying a new path to the congruence property in rational conformal field theory. The proof involves a new arithmetic holonomicity bound of a potential-theoretic flavor, together with Nevanlinna's second main theorem, the congruence subgroup property of SL_2(Z[1/p]), and a close description of the Fuchsian uniformization D(0,1)/\Gamma_N of the Riemann surface C \setminus \mu_N.
Cite
@article{arxiv.2109.09040,
title = {The Unbounded Denominators Conjecture},
author = {Frank Calegari and Vesselin Dimitrov and Yunqing Tang},
journal= {arXiv preprint arXiv:2109.09040},
year = {2024}
}
Comments
Improved exposition and minor improvements taking into account the suggestions of the referees; results remain unchanged