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An elliptic curve is an algebraic curve of genus one with some additional properties. Questions with this tag will often have the top-level tags nt.number-theory or ag.algebraic-geometry. Note also the tag arithmetic-geometry as well as some related tags such as rational-points, abelian-varieties, heights. Please do not use this tag for questions related to ellipses; instead use conic-sections.

4 votes

Structure of $E(Q_p)$ for elliptic curves with anomalous reduction modulo $p$

Hi, this is only a partial answer to (3), that was too long to be a comment. In a recent post of mine, Felipe Voloch pointed out a very useful tameness criterion proved by Gross ("A tameness criterio …
Álvaro Lozano-Robledo's user avatar
3 votes

Tate module of CM elliptic curves

You can find the answer to your question (and learn a whole lot more about complex multiplication) in another book by Joe Silverman, "Advanced Topics in the Arithmetic of Elliptic Curves". See Chapter …
Álvaro Lozano-Robledo's user avatar
12 votes

Why does the definition of modularity demand weight 2?

The reason why the weight needs to be $k=2$ becomes clear when you consider this (equivalent) version of modularity: $E/\mathbb{Q}$ is modular if there there exists a normalized newform $f$ for $\Gamm …
Álvaro Lozano-Robledo's user avatar
8 votes

understanding the main theorem of complex multiplication (of elliptic curves)

I would suggest the following reference: Karl Rubin's "Elliptic Curves with Complex Multiplication and the Conjecture of Birch and Swinnerton-Dyer". In particular, in Section 5 he states the main theo …
Álvaro Lozano-Robledo's user avatar
6 votes

Class Field Theory for Imaginary Quadratic Fields

Hello, In general $K(j,E[c])$ will not be abelian over $K$ (the reason being that $K(j,h(E[c]))$ is the ray class field of $K$ of conductor $c$, therefore maximal for abelian extensions of conductor …
Álvaro Lozano-Robledo's user avatar
5 votes
0 answers
697 views

Formal groups in the supersingular reduction case

Let $E/\mathbb{Q}$ be an elliptic curve with potential good supersingular reduction at $p$. Thus, there is a finite extension $K/\mathbb{Q}_p$ such that $E/K$ has good supersingular reduction. Let us …
Álvaro Lozano-Robledo's user avatar
5 votes
1 answer
371 views

Inertia subgroup in the ordinary reduction case when $p=2$

Dear MO, Let $K/\mathbb{Q}_2$ be a finite extension, and let $E/K$ be an elliptic curve with good ordinary reduction, and such that $\mathbb{Q}_2(j(E))=K$. Let $\rho:\operatorname{Gal}(\overline{K}/K …
Álvaro Lozano-Robledo's user avatar
8 votes

Modular curves of genus zero and normal forms for elliptic curves

Hello, I believe the following results that appear in papers of Rubin and Silverberg can be very useful here. Let $N=3,4,$ or $5$ and let $Y_N$ be the (non-compact) modular curve over $\mathbb{Q}$ wh …
Álvaro Lozano-Robledo's user avatar
12 votes
1 answer
1k views

Ramification in p-division fields associated to elliptic curves with good ordinary reduction

Dear MO, Let $p$ be a prime and let $E/\mathbb{Q}_p$ be an elliptic curve. Suppose that $E/\mathbb{Q}_p$ has good ordinary reduction at $p$. In his 1972 paper ``Propriétés galoisiennes des points d'o …
Álvaro Lozano-Robledo's user avatar
2 votes

Proofs of Mordell-Weil theorem

Already mentioned: Silverman and Tate's "Rational Points on Elliptic Curves" (undergraduate level) and Silverman's "The Arithmetic of Elliptic Curves" (graduate level). Another text at the undergradu …
Álvaro Lozano-Robledo's user avatar
4 votes

Points of elliptic curves over cyclotomic extensions

As for the torsion subgroup, Michael Chou has classified the possible subgroups that may occur as $E(\mathbb{Q}^{\text{ab}})_{\text{tors}}$ for an elliptic curve $E/\mathbb{Q}$. You can find a preprin …
Álvaro Lozano-Robledo's user avatar
9 votes
0 answers
586 views

Tameness criterion in the reducible case

Dear MO, This is a follow up to a previous question here in MO, but I will make this question self-contained for convenience. Those already familiar with the following paper [G] by Gross can safely s …
Álvaro Lozano-Robledo's user avatar