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3 votes
1 answer
441 views

Moduli space of genus 1 curves with a degree n divisors

I am sure this is well known, but I don't know what to search for: Consider $M_{1,n}$, the moduli space of genus 1 curves with $n$ marked points. The symmetric group on $n$ letters acts on this space ...
Asvin's user avatar
  • 7,746
2 votes
1 answer
258 views

picard group of moduli of elliptic r-prym curves

Let $\overline{\mathcal{M}}_{1,1}$ be the DM compactification of the moduli stack of elliptic curves. Its Picard group is $\mathbb{Z}$. Let us now consider stack of $r$-prym curves $\overline{\mathcal{...
IMeasy's user avatar
  • 3,779
4 votes
2 answers
661 views

What does this quotient of the upper half plane parametrize?

Let $G(N)$ be the congruence subgroup $\big\{ \begin{pmatrix} a&b \\ c&d \end{pmatrix} \in SL_2(\mathbb{Z}) \ \ | \ \ a \equiv d \mod N \textrm{ and } b \equiv c\equiv 0 \mod N \big\}$. $G(...
Adam Harris's user avatar
  • 1,905
5 votes
1 answer
412 views

Modular curve parametrizing two cyclic subgroups of an elliptic curve

The aim of this question is to better understand the following moduli space/modular curve, for which I propose (temporarily) the name $Y_0(M,N)$. We define $Y_0(M,N)$ as the moduli space parametrizing ...
OldMacdonaldHadaForm's user avatar
2 votes
0 answers
309 views

Moduli space of points of fixed order N on elliptic curves

Let us consider the moduli space $Y_1(N)$, parametrizing an elliptic curve, together with a choice of a point of N-torsion on it. Over the complex numbers, it is easy to see that this moduli space is ...
Math's user avatar
  • 63
2 votes
2 answers
334 views

For which composite $N$ does $X_0(N)$ possess a non-cuspidal rational point?

According the the introduction to Mazur's Rational Isogenies of Prime Degree the following question was open in 1978: Let $N$ be one of the integers 39, 65, 91, 125, or 169. Does the modular ...
James Weigandt's user avatar
25 votes
3 answers
5k views

Conceptual understanding of the Gross-Zagier theorem.

The Gross-Zagier paper "Heegner points and derivatives of $L$-series", is really computational and hard to plow through. It seems it is futile to read it as such and one must look for a more ...
Regenbogen's user avatar
  • 1,417