Categoricity of the two sorted j-function
arXiv:1304.4787
Abstract
We show that a natural, two sorted $\cL_{ω_1,ω}$ theory involving the modular -function is categorical in all uncountable cardinaities. It is also shown that a slight weakening of the adelic Mumford-Tate conjecture for products of elliptic curves is necessary and (along with a couple of other results from arithmetic geometry) sufficient for categoricity.