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8 votes
0 answers
333 views

Do automorphisms actually prevent the formation of fine moduli spaces?

I have found similar questions littered throughout this site and math.SE (for example [1], [2], [3],…), but I feel like like most of them usually just say that non-trivial automorphisms prevent the ...
Coherent Sheaf's user avatar
8 votes
0 answers
416 views

Stacky proof of no elliptic curves over Z

It is a well known result that there are no Elliptic curves over the integers with every where good reduction. In fact this is even true for abelian varieties (and hence higher genus curves) but let ...
Asvin's user avatar
  • 7,746
6 votes
0 answers
164 views

What are the genus 4 curves with Jacobians that are 4-th powers?

Consider the moduli space of all genus $4$ curves $\overline{\mathscr M_4}$ of dimension $3\times 4 - 3 = 9$. Under the Torelli map, there is a map to $\overline{\mathscr A_4}$ (which has dimension $...
Asvin's user avatar
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6 votes
0 answers
971 views

Curious propositon in "Les schemas de modules de courbes elliptiques"

Currently I am reading "Les schemas de modules de courbes elliptiques" by Deligne and Rapoport and I got myself seriously confused about the following proposition (in English translation): (II ...
Holger Partsch's user avatar
4 votes
0 answers
163 views

Regularity of the modular curves $Y(N)$, $Y_1(N)$

I'm reading the five chapter of the book of Katz-Mazur, Arithmetic moduli of elliptic curves, concerning regularity of the moduli problems of $\Gamma(N)$-structures, $\Gamma_1(N)$-structures and $\...
Jrodri26's user avatar
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4 votes
0 answers
412 views

A website which explains Mazur's torsion point theorem

I'm about to read Mazur's paper "Modular curves and the Eisenstein ideal". It's so long and difficult for me, but I found a website which shows the Mazur's theorem. This is very short and very very ...
k.j.'s user avatar
  • 1,364
3 votes
0 answers
159 views

The Weil pairing on a generalized elliptic curve

Now I'm trying the section 6 (and 3.20) of chapter IV of Deligne-Rapoport's "Les schemas de module de courbes elliptiques". I can't understand what $e_n$ (of 6.5.(d)) is. It seems to be the ...
k.j.'s user avatar
  • 1,364
3 votes
0 answers
278 views

Rationality of Eisenstein series g2 and g3 for elliptic curves defined over numberfields

Let $K$ be a number field and let $E/K$ be an elliptic curve. (Fix an embedding of $K$ into the complex numbers $\mathbb{C}$). Let $\eta$ be the invariant differential of $E/K$. Let $\omega_1$ and $\...
user51764's user avatar
  • 139
3 votes
0 answers
323 views

Lifting a real quadratic twist of an Elliptic Curve to the modular curve

Let $E$ be an elliptic curve of conductor $N\cdot p^2$ over $\mathbb{Q}$, defined by the equation $$y^2=x^3+p^2b\cdot x + p^3\cdot c$$ and parametrized by a map $$X_{0}(N\cdot {p}^{2})\rightarrow E$$ ...
The Thin Whistler's user avatar
2 votes
0 answers
94 views

Complex Structure Moduli of Elliptic Fibrations

Given an elliptically fibered Calabi-Yau threefold in Weierstrass form I want to compute the number of complex structure moduli of the fibration. I know how it is done for the generic Weierstrass ...
Stirling Suleiman'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
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1 vote
0 answers
115 views

Compactifications of product of universal elliptic curves

Let $\mathcal{E}$ be the universal elliptic curve over the moduli stack $\mathcal{M}$ of elliptic curves. As $\mathcal{E}$ is an abelian group scheme over $\mathcal{M}$, we obtain a product-preserving ...
Lennart Meier's user avatar
1 vote
0 answers
248 views

lifts of maps to $\mathcal{M}_{1,1}$

Hi, here's there's a construction about elliptic curves that I do not completely understand. Suppose I consider the two following families of elliptic curves over $\mathbb{C}^*$. The first, which I ...
IMeasy's user avatar
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0 votes
0 answers
130 views

Two elliptic curves with the same j-invariants

This is an interesting observation of mine when exploring moduli of elliptic curves. Let's fix a base field $k$ and assume that we have two elliptic curves $E$, $E'$ which are isomorphic over $\bar k$...
fe mu's user avatar
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