A Modular Curve of Level 9 and the Class Number One Problem
arXiv:0801.4693 · doi:10.1016/j.jnt.2008.09.013
Abstract
In this note we give an explicit parametrization of the modular curve associated to the normalizer of a non-split Cartan subgroup of level 9. We determine all integral points of this modular curve. As an application, we give an alternative solution to the class number one problem.
18 pages