For questions regarding elliptic curves. Questions on ellipses should be tagged [conic-sections] instead.

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4
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2answers
375 views

On the relationship between Fermats Last Theorem and Elliptic Curves

I have to give a presentation on elliptic curves in general. It does not have to be very in depth. I have a very basic understanding of elliptic curves (The most I understand is the concept of ranks). ...
4
votes
2answers
148 views

Subvariety of Product of Elliptic Curves

This is almost certainly known (and maybe written down somewhere?). Is there an example of two elliptic curves $C, E/k$ that are not isomorphic, yet there is an embedding $C\hookrightarrow E\times E$ ...
3
votes
3answers
306 views

Show that the curve $y^2 = x^3 + 2x^2$ has a double point, and find all rational points

Show that the curve $y^2 = x^3 + 2x^2$ has a double point. Find all rational points on this curve. By implicit differentiation of $x$, $-3x^2 - 4x$ vanishes iff $x = -4/3$ and $0$. By implicit ...
3
votes
3answers
112 views

Show that if the curve $y^2 = p(x)$ has a double point, then it must be of the form $(r,0)$ where $r$ is a double root of $p(x)$.

Let $p(x) = ax^3 + bx^2 + cx + d$ where $a,b,c,d \in\mathbb{R}$. Show that if the curve $y^2 = p(x)$ has a double point, then it must be of the form $(r,0)$ where $r$ is a double root of $p(x)$. ...
8
votes
2answers
195 views

Clarifying a comment of Serre

Let $\rho_{\ell}$ be the "mod $\ell$" Galois representation associated to an elliptic curve $E/K$ (i.e., corresponding to the action of Galois on the $\ell$-torsion points). Serre proved that in the ...
3
votes
1answer
122 views

Reduction of endomorphism ring of elliptic curve

Let $E$ be an elliptic curve defined over a number field without complex multiplication and with ordinary reduction at a prime $p\in\mathbb{N}$. When is the reduction mod $p$ map a surjection on the ...
2
votes
2answers
132 views

Embedding elliptic curves into the general linear group

Is it possible to embedd an elliptic curve $E:\;\; y^2=x^3+ax+b$, defined over an algebraically closed field $k$, into some $GL_n(k)$ ?
2
votes
1answer
204 views

Congruence subgroups and modular curves of type (M,N)

I would like to study the "modular curve" $Y(M,N)$, parametrizing an elliptic curve $E$ together with $p \in E[M]$ and $q \in E[N]$ (here and in the following $M$ divides $N$). Let $\Gamma(M,N)$ be ...
8
votes
1answer
136 views

Line Bundle on subvarieties

I've been having problem actually restricting a Line bundle $L$ defined on some projective space $\mathbb C \mathbb P^{N-1}$ to a subvariety $X$. I know how to do this on an abstract level, but ...
8
votes
1answer
452 views

Splitting of quaternion algebras

A rational (definite) quaternion algebra is an algebra of the form $$ \mathcal{K} = \mathbb{Q} + \mathbb{Q}\alpha + \mathbb{Q}\beta + \mathbb{Q}\alpha \beta $$ with $\alpha^2,\beta^2 \in ...
4
votes
0answers
102 views

Approach to elliptic curve $y^2=x^3+1/4+p/a^2$

While taking a brute-force look at this question I discovered that it seems that almost every prime (I'll conjecture every prime larger than 20627) can be written as $p=w^2+wc+d$ for $w,c,d\in ...
15
votes
2answers
447 views

Reference request in number theory for an analyst.

I am a confirmed mathochist. My background is in analysis, and fairly traditional analysis at that; mainly harmonic functions, subharmonic functions and boundary behaviour of functions, but I have for ...
5
votes
2answers
137 views

Computing rank using $3$-Descent

For an elliptic curve $E$ over $\Bbb{Q}$, we know from the proof of the Mordell-Weil theorem that the weak Mordell-Weil group of $E$ is $E(\Bbb{Q})/2E(\Bbb{Q})$. It is well known that $$ 0 \rightarrow ...
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3answers
1k views

History of elliptic curves

In one sense elliptic curves are a rather modern object as some of its properties have been studied only in the last century or so. But in another sense there are a very classical object for studying ...
2
votes
2answers
95 views

sum of torsion of an elliptic curve

It is clear from the isomorphism between elliptic curves over $\mathbb{C}$ and complex tori that the sum of the $m$-torsion points is the identity in the group law of the elliptic curve. How generally ...
2
votes
1answer
135 views

Elliptic Curves over Noncommutative rings

It is known that we can define elliptic curves over commutative rings. However can we define an elliptic curve over a noncommutative ring? This question is considered to some extent in this thesis ...
3
votes
2answers
324 views

Elliptic curves over a finite field $\mathbb{F}_p$ where $p$ is prime.

Let $Y^2=f(X)$ be an Elliptic curve over a finite field $\mathbb{F}_p$ where $f(X)=X^3+aX+b$ In an undergraduate coursebook on an Applied Algebra course it states that "It is plausible to suggest ...
5
votes
1answer
234 views

A question about modular curves and base change

Let $X$ be a smooth projective geometrically connected curve over a number field $K$. Suppose that the curve $X\times_{K,\sigma} \mathbf{C}$ is a modular curve for some $\sigma:K\to \mathbf{C}$. Can ...
2
votes
1answer
133 views

Silverman's Lefschetz Principle

Let K be a field of characteristic 0, E/K an elliptic curve. The "Lefschetz principle" implies that $E[m] \simeq \mathbb{Z}/m \times \mathbb{Z}/m$, but for this to follow from the result for complex ...
1
vote
1answer
133 views

Conductor of $ABC$, Frey-Hellegouarch curves, and twists

In page 109 of de Weger's paper, he says that for coprime $A, B, C$ the conductor $N$ of the Frey-Hellegouarch curve $$ E: y^2 = x(x - A)(x + B) $$ equals $N(A,B,C)$ (product of primes dividing $ABC$ ...
2
votes
1answer
108 views

Database for size of Ш

Are there are any references that record the cardinality of Ш for elliptic curves for which Ш is known? Also their corresponding conductors. EDIT: Following the Qiaochu Yuan's comment's I should ...
2
votes
2answers
147 views

Epsilon conjecture analog

Recently this question caught my eye. Is there a relation to the modularity problem of elliptic curves over $\mathbb{Q}(\zeta_m)$ and this problem? Namely, if all elliptic curves over ...
3
votes
3answers
373 views

Rankin-Selberg zeta function

I was reading this paper by de Weger and in conjecture 7 he mentions "the Riemann hypothesis for the Rankin-Selberg zeta function associated to the weight 3/2 modular form associated to E (an elliptic ...
1
vote
1answer
215 views

Consequences of Szpiro's conjecture

Let $E/\mathbb{Q}$ be an elliptic curve. Recall that Szpiro's conjecture says that for every $\epsilon > 0$, there exists $C_\epsilon$ such that $$ |\Delta_E| \leq C_\epsilon(N_E)^{6 + \epsilon}, ...
2
votes
1answer
50 views

Bounding the product of exponents

I was reading de Weger's paper on bounding the cardinality of the Tate-Shafarevich group and in lemma 1 (pg 111), he claims that for any $n \in \mathbb{N}$, we have that $$ c(n) << N^{((log \; ...
4
votes
2answers
192 views

Exposition on Modular Curves

I was recently reading this paper by Weston, whereby he talks about the modular curves $X_0(11)$ and $X_1(11)$. I was wondering if anyone can recommend a more general exposition of modular curves ...
2
votes
1answer
77 views

The 2-primary Part of Ш

I was reading Silverman's Arithmetic of Elliptic Curves I have a question on computing the Mordell-Weil group of an elliptic curve over $E(\mathbb{Q})$. Adapting the argument given in Silverman we ...
6
votes
1answer
232 views

UPDATE: How to find the order of elliptic curve over finite field extension

I want to find the order of elliptic curve over the finite field extension $\mathbb{F}_{p^2}$, where $E(\mathbb{F}_{p^2}):y^2=x^3+ax+b $ I am using the method illustrated by John J. McGee in his ...
2
votes
3answers
2k views

How to find the order of elliptic curve over finite field extension

I want to find the order of elliptic curve over the finite field $\mathbb{F}_{5^2}$, where $E(\mathbb{F}_{5^2}):y^2=x^3+10x+17$. I am using the method illustrated by John J. McGee in his thesis ...
2
votes
1answer
306 views

Point addition on an elliptic curve over $\mathbb{F}_{5^2}$

I have the elliptic curve equation $E(\mathbb F_{5^2}): y^2=x^3+10x+17$, and I have that the points $(3,7)$ and $(8,3)$ belong to $E$. According to the addition law, the slope ...
4
votes
1answer
232 views

Global minimal model of elliptic curve over $\mathbb{Q}$

I am basically trying to solve the cannonball problem using elliptic curves. In other words I have to show that the only integer points on the "elliptic curve" $6y^2 = 2x^3 + 3x^2 + x$ are $(0,0), ...
3
votes
0answers
319 views

Elliptic curves, 2-torsion and branch points.

I'm currently reading through Ravi Vakil's notes on Algebraic Geometry. I've been having trouble grasping some things conceptually though and I hope that you can help me. For an elliptic curve (E,p) ...
5
votes
3answers
298 views

The elliptic curve $y^2 = 23328x^3-890273x^2+14755570x-7^7$

The elliptic curve, $$y^2 = 23328x^3-890273x^2+14755570x-7^7 \tag{1}$$ has the small solution $x = 58$. I know how to find other rational points, but the number of digits in the denominator gets ...
3
votes
3answers
219 views

Reference: Elliptic curves as complex tori

I'm looking for books which contain a more or less self-contained description of how elliptic curves over $\mathbb{C}$ - that is, nonsingular plane cubic curves - can be realized as a quotient of the ...
3
votes
1answer
677 views

Reference request for “Weierstrass equation” and “Weierstrass normal form”

I would like to know more about the history of the widely used terms "Weierstrass equation" and "Weierstrass normal form", as they appear in the theory of elliptic curves. When were these terms first ...
0
votes
1answer
139 views

Are elliptic curves also Galois covers of degree 3

Let E be an elliptic curve with equation $y^2=x^3+Ax+B$. The projection onto the $x$-coordinate is a Galois morphism of degree $2$. But what about the projection onto the $y$-coordinate? Is it ...
7
votes
1answer
194 views

How can I determine in practice whether two elliptic curves over $\mathbb{Q}$ have isomorphic $p$-torsion?

Let $E_1$ and $E_2$ be elliptic curves over $\mathbb{Q}$ with good, ordinary reduction at an odd prime $p$. I'm wondering how to determine whether $E_1[p]$ and $E_2[p]$ are isomorphic ...
3
votes
1answer
132 views

Can an algebraic group only have trivial elements over $k$

Let $G$ be an algebraic group over $k$ such that $G(k) = \{e\}$ is the trivial group. Does this imply that $G_{\overline{k}}$ is trivial? I think the answer is no. I think you can just take an ...
5
votes
1answer
126 views

Complex elliptic curve for the “conjugate” lattice

Let $\Lambda$ be a lattice in $\mathbb{C}$, and $E=\mathbb{C}/\Lambda$ the corresponding complex elliptic curve. Let $\bar{\Lambda}$ be the "conjugate" lattice, i.e. the one obtained by conjugating ...
2
votes
1answer
313 views

Form of minimal integral Weierstrass equation for elliptic curve over $Q$ with good reduction at $2$ and $3$.

If $E$ is an elliptic curve over $\mathbb{Q}$ which has good reduction at $2$ and $3$, is it always possible to find a minimal integral Weierstrass equation for $E$ of the form $y^2 = x^3 + Ax + B$ ...
0
votes
2answers
323 views

Nontrivial Rational solutions to $y^2=4 x^n + 1$

Are there any nontrivial rational solutions to the following equation: $$y^2=4 x^n + 1,$$ where $n>2$?
2
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1answer
211 views

How to know whether an elliptic curve has a low-degree isogeny?

Given an elliptic curve with a Weierstrass equation, is there any easy way to see whether it has got an isogeny of low degree?
3
votes
2answers
178 views

Does there exist a finite morphism of algebraic curves such that…

Let $K\subset L$ be a finite field extension. Let $X$ and $Y$ be (smooth projective geometrically connected) curves over $L$. Let $f:X\to Y$ be a finite morphism of curves over $L$. Assume that ...
1
vote
1answer
55 views

The group $E(\mathbb{F}_q)/NE(\mathbb{F}_q)$

Let $E$ be an elliptic curve defined over the finite field $\mathbb{F}_q$ and let $N\geq 1$. We also make the following assumptions: $T \in E(\mathbb{F}_q)[N]$ is a point of exact order $N$, ...
8
votes
1answer
287 views

Euler Product of Modular L-series

This question is probably really easy to someone that knows the theory of modular forms well, so I apologize if this is obvious. Suppose $E_1$ and $E_2$ are elliptic curves over $\mathbb{Q}$ and the ...
4
votes
4answers
510 views

Elliptic curves with finitely many rational points

A conjecture by Goldfeld says that half of all elliptic curves have rank zero (i.e. their Mordell-Weil group has finite order.) Are there any known infinite families of elliptic curves (over ...
7
votes
1answer
367 views

Special privilege enjoyed by Elliptic Curves with Complex Multiplication

I think after reading the title one may understand the intention of me, this question is concerned about the Elliptic curves having a Complex Multiplication. I have been reading many theorems, ( ...
5
votes
1answer
70 views

Minimal degree of a field extension to obtain an elliptic curve

Let $K$ be a number field and let $X$ be a smooth projective geometrically connected curve over $K$ of genus $1$. There exists a number field $L/K$ such that $X$ has a $L$-rational point. Let $L$ be ...
3
votes
1answer
125 views

Computing the free-part

I wanted to ask about some existing algorithms for computing points over elliptic curves. Background : We know that the famous theorem of Mordell and Weil says that " Group of rational points on an ...
1
vote
1answer
80 views

Does the following define a point of the modular curve $X_1(n)$

Let $X$ be a compact connected Riemann surface of genus $1$ and suppose that there is a finite morphism $X\to \mathbf{P}^1$ of degree $n$ which ramifies totally over $0$ and $\infty$. Let $f^{-1}(0)$ ...