06:48
@DavidZureick-Brown Hey. I have a dumb question to ask. In Katz-Mazur they say something like the disjoint of the legendre family and naive level three structure gives a cover of M_{1,1}. Why isn't the Legendre family alone a cover?
For example, every elliptic curve X \to S etale locally on S acquires a Legendre form (I think). Certainly Zariski locally we have a Weierstrass form, and then we pass to an etale cover (to extract roots and stuff) to get it into Legendre form.
Note I'm working over C so that I don't have issues like "what if 2 is not invertible bla bla"
