English

Andr\'e-Oort for a Nonholomorphic Modular Function

Number Theory 2019-04-04 v5 Logic

Abstract

The modular case of the Andr\'e-Oort Conjecture is a theorem of Andre and Pila, having at its heart the well-known modular function j. I give an overview of two other `nonclassical' classes of modular function, namely the quasimodular (QM) and almost holomorphic modular (AHM) functions. These are perhaps less well-known than j, but have been studied by various authors including for example Masser, Shimura and Zagier. It turns out to be sufficient to focus on a particular QM function χ\chi and its dual AHM function χ\chi^*, since these generate the relevant fields. After discussing some of the properties of these functions, I go on to prove some Ax-Lindemann results for χ\chi and χ\chi^*. I then combine these with a fairly standard method of o-minimality and point counting to prove the central result of the paper; a natural analogue of the modular Andr\'e-Oort conjecture for the function χ\chi^*.

Keywords

Cite

@article{arxiv.1607.03769,
  title  = {Andr\'e-Oort for a Nonholomorphic Modular Function},
  author = {Haden Spence},
  journal= {arXiv preprint arXiv:1607.03769},
  year   = {2019}
}
R2 v1 2026-06-22T14:53:36.991Z