All Questions
1,978 questions
3
votes
0
answers
65
views
p-torsion in the Tate-Shafarevich group of supersingular elliptic curves
Let $E$ be a supersingular elliptic curve over $\mathbb{F}_p(t)$. Is something known on the $p$-torsion of the Tate–Shafarevich group in this case? In particular, I would like to know if (or if known ...
- 103
0
votes
0
answers
58
views
Given $N=pq$, with what complexity we can find integer $a : q-\sqrt{q} < a <q+\sqrt{q}$?
Related to open problem and this question.
Let $N=p q$ be integer with unknown factorization.
Q1 Given $N=pq$, with what complexity we can find integer $a : q-\sqrt{q} < a <q+\sqrt{q}$?
Assume ...
- 25.4k
3
votes
0
answers
36
views
Avoiding class/unit group computation when computing $p$-Selmer groups
Let $K$ be a number field, $S$ be a finite set of places of $K$, and $K(S,p)$ be the $p$-Selmer group of the $S$-integers of $K$, that is the set of nonzero elements of $K$ modulo $p$-th powers whose ...
1
vote
0
answers
89
views
Generic reducedness of geometric generic fibre
Let $f:X\to Y$ be a surjective morphism between two projective schemes over a field of characteristic $p>0$. Also assume that $X$ is smooth,$Y$ smooth & irreducible and $f_*\mathcal{O}_X=\...
- 5,986
0
votes
0
answers
132
views
How near are a groupoid and its 'preorderification'?
As remarks, a groupoid is a category with only (categorical) isomorphisms as its morphisms and a preorder is a category only having one morphism between each object. If we choose one isomorphism by ...
1
vote
1
answer
121
views
Rational functions on elliptic curves over global fields with given support
Let $E$ be an elliptic curve over a global field $k$. Let $x_1, \dots, x_r$ be a set of generators of $E(k) / E(k)_{tor}$ (or more generally, a $\mathbb Q$-basis of $E(k)_{\mathbb Q}$), and let $x_0$ ...
- 77
2
votes
0
answers
123
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Polynomial discriminant equation
This is a fairly straightforward question, and I am hoping a definitive answer exists.
Does there exist a quadratic form $A \in \mathbb{C}[x_1, x_2, x_3, x_4]$ and a cubic form $B \in \mathbb{C}[x_1, ...
- 27k
2
votes
1
answer
125
views
Questions about elliptic curves with level-$n$ structure
Let $n$ be a positive integer, which is $4$ or a prime number $l$.
Let $E$ be an elliptic curve defined over a number field $K$.
Assume that all the $n$-torsion points of $E$ are defined over $K$, i.e....
- 77
4
votes
1
answer
183
views
About the reduction type of the Kodaira symbol of elliptic curves defined over p-adic local fields
Let $K$ be a finite extension of $\mathbb{Q}_p$, and let $E$ be an elliptic curve defined over $K$. Tate's algorithm can be used to compute the Kodaira symbol of the reduction type of $E$.
However, I ...
- 77
5
votes
2
answers
378
views
Are there integer solutions of $m^4+m^2n^2+n^4=k^2$?
The recent question about Sets of integers with same sum and same sum of reciprocals, with its wealth of solutions, raises naturally the question: Can we require all those numbers to be squares? Of ...
- 13.4k
6
votes
0
answers
135
views
Reconstructing a scheme from its quotient stack
Let $X/S$ be a scheme over a base $S$, with a group action by a nice group $G/S$ (typically $G/S$ affine smooth).
Can we reconstruct $X$ from its quotient stack $[X/G]$?
It seems that we can expect $X$...
- 645
1
vote
0
answers
137
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 $\bar k$...
- 81
0
votes
0
answers
190
views
About Chern classes via Atiyah class
I am trying to understand a construction of the Chern classes of a vector bundle $\mathcal{E}$ via the Atiyah class, like is done in this text and here in section 1.4. I am interested in the case ...
- 348
0
votes
0
answers
141
views
State of the art on attempts to solve the elliptic curve discrete logarithm problem through transfering the problem to a weaker curve
Let an elliptic curve $E$, and 2 points on such curve $P$ and $O$ the methods I’m talking about consist in creating a weaker elliptic curve $F$ and mapping $P$ and $O$ to $F$ while successfully ...
- 87
2
votes
1
answer
308
views
Can the number of elements of order 4 in the Tate–Shafarevich group grow arbitrarily large?
Let $E/K$ be a number field. For quadratic field extensions $L/K$, it is known that $\operatorname{Ш}(E/L)[2]$ can be arbitrarily large (cf. P. L. Clark and S. Sharif, "Period, index and ...
- 1,541
7
votes
0
answers
141
views
Average number of $\mathbb{F}_p$-points over twists of a variety
Let $p \gg 1$ be a sufficiently large prime. I recently stumbled across a fascinating fact about the number of $\mathbb{F}_p$-points on elliptic curves over finite fields. Specifically, we have:
Fact ...
4
votes
0
answers
130
views
mod $p$ local Galois representation attached to elliptic curves
In the paper, lemma 4.4. The author gives the form of the representation of $G_p$ on $E[p]$ of the form
$$\begin{pmatrix} \varepsilon\chi & *\\0 & \chi^{-1} \end{pmatrix}.$$
Do they assumed ...
- 275
5
votes
1
answer
379
views
Factorisation of division polynomial
Let $\Psi_n$ denote the $n$-th division polynomial associated with the elliptic curve $y^2 = x^3 + A$, where $n$ is a natural number. The division polynomials are defined recursively, as described in ...
- 127
2
votes
1
answer
138
views
small monodromy for polarized Abelian families over a torus?
In Lawrence-Venkatesh, they proved in Prop 5.3 a
beautiful finiteness property for a locus, successfully avoiding the using of Tate conjecture. Note that the introduction of $size_v$ and friendly ...
- 131
2
votes
0
answers
126
views
Full level structure Deligne-Rapoport v.s. Katz-Mazur
For modular curves over schemes there are two main references that I use, namely Deligne Rapoport [DR], and Katz-Mazur [KM]. However I recently noticed that there is a difference in conventions in ...
- 2,224
1
vote
0
answers
157
views
Degeneracy of the Cassels-Tate pairing $\operatorname{Ш}(E/K)[n]\times \operatorname{Ш}(E/K)[n]\to \Bbb{Q}/\Bbb{Z}$
$\DeclareMathOperator{\Sha}{Ш}$ Let $E/K$ be an elliptic curve over a number field $K$. Let $\Sha (E/K)$ be the Tate-Shafarevich group, and let $n\ge 2$ be an integer. According to Theorem 15 in the ...
- 1,541
2
votes
0
answers
110
views
How to apply Pohlig Hellman using a very limited set of auxiliary inputs in that case?
So I was reading about Talotti, Paier, and Miculan - ECC’s Achilles’ Heel: Unveiling Weak Keys in Standardized Curves. The underlying idea is to lift the discrete logarithm problem to $\mathrm{prime}−...
- 87
6
votes
1
answer
407
views
Good reduction for the universal elliptic curve
Let $X$ be a modular curve, i.e. a quotient of the upper half plane $\mathbb{H}$ by a congruence subgroup $\Gamma$. When $\Gamma=\Gamma_0(N)$, it is known that $X$ has a smooth model denoted $\mathcal{...
- 2,907
2
votes
1
answer
240
views
Cohomology of torsion points on elliptic curves
$\DeclareMathOperator\Gal{Gal}$Let $E$ be an elliptic curve defined over a number field $K$. Put $G:=\Gal(\bar{K}/K)$, and for each valuation $v$ of $K$, put $G_v:=\Gal(\bar{K_v}/K_v)$. Consider the ...
- 622
2
votes
0
answers
43
views
The vector space dimension of Selmer group of abelian variety
Let $A/K$ be an abelian variety with $\mathbb{Z}[\mu_p] \subset End_K(A).$
Let $\pi$ be the prime of $p$, i.e. $(p)=(\pi^{p-1})$.
I want to obtain the relation of Selmer groups $Sel_\pi(A/K)$ and $...
- 85
2
votes
0
answers
78
views
Detect all isogenies of an elliptic curve over a given number field
Given $K$ a number field and $E/K$ an elliptic curve, is there an algorithm which gives all the elliptic curves $F/K$ isogenous to $E$ (up to isomorphism)?
Or is there a bound on how many $F/K$ are ...
- 637
1
vote
0
answers
82
views
Behavior of translation functors in characteristic $p$
Let $G$ be a semisimple and simply connected algebraic group over an algebraically closed field of characteristic $p>0$, and let $\mathfrak g$ be the Lie algebra of $G$. Let $U_\chi(\mathfrak g)$ ...
- 2,974
7
votes
1
answer
193
views
Constructing non-split $\mathbf{G}_m$-extensions of elliptic curves
I would like to find examples of abelian surfaces $A$ over a DVR $R$ with residue field $k$, so that the special fibre of $A$ is a non-split $\mathbf{G}_{m/k}$-extension of an elliptic curve over $k$.
...
- 265
0
votes
1
answer
136
views
Multiplication-by-m map as an isogeny
I'm reading Luca De Feo's slides; on the slide 12 it's written that the multiplication map $[m] : E \rightarrow E$ is an isogeny. I do not understand why this isogeny is non-cyclic. At the first ...
4
votes
1
answer
243
views
On the degeneration of the elliptic surface $E(n)$
The following matter should be widely known (if true). I am sorry for my ignorance!
For the natural $n$, let $E(n)$ be the corresponding elliptic surface.
In the analytic world, there exists a well-...
- 153
1
vote
1
answer
120
views
Reference request for the isomorphism $H^1(G_{K_v},E)[n]\cong (E(K_v)/nE(K_v))^*$ in the context of Tate-duality
Let $E/K$ be an elliptic curve over a number field $K$. Let $M_K$ be the set of all places of $K$. Let $K_v$ be a completion of $K$ at $v$.
I'm searching for a reference for the statement of the ...
- 1,541
3
votes
1
answer
114
views
The cyclic twist of elliptic curve is a principally polarized abelian variety
Let $L/K$ is a cyclic extension of degree $p$, and let $E/K$ be an elliptic curve.
Let $E^L$ be the kernel of the map $Res^L_{K}(E) \rightarrow E$, where $Res^L_{K}(E)$ is the Weil-restriction.
Is the ...
- 85
10
votes
2
answers
404
views
Impact of the squarefreeness of the level for modular forms
I often notice papers and results that assume that the level is squarefree in the setting of modular forms, but have a hard time figuring how where this impacts or simplifies the argument. Is there in ...
- 249
3
votes
1
answer
414
views
Twists of elliptic curves
I have a few questions regarding twists of elliptic curves.
In the context of the Shafarevich group, I see people refer to the group of twists of an elliptic curve $E/\mathbb{Q}$ by $H^1(\mathbb{Q}, ...
- 2,907
2
votes
1
answer
147
views
Finiteness and bounds for elliptic curves realizing a given galois representation
Let $\rho: \text{Gal}(\overline{\mathbb{Q}}/\mathbb{Q}) \to \text{GL}_2(\mathbb{Z}_p)$ be a continuous, irreducible Galois representation. Consider the set $\mathcal{L}_\rho$ of all elliptic curves $...
3
votes
1
answer
180
views
Galois cohomology for rational torsion of elliptic curves
Let $E/K$ be an elliptic curve over a number field.
Let $M=K(E[p])$.
I want to know $H^1(M/K,E[p])$: for $p=2$, it is $0$, but what about the case $p>2$?
Is it always zero?
In fact, I want to know ...
- 85
1
vote
0
answers
69
views
Is it in theory possible to perform general Miller’s algorithm inversion as used with the optimal ate pairing with large trace in subexponential time?
Let’s I have the following :
2 curves $G_1$ defined on $F_p$ and $G_2$ being the $G_1$ curve’s twist defined on $F_p^2$ both having the same prime order ; a large trace ; and $F_p^{12}$ as their ...
- 87
-5
votes
1
answer
153
views
On Mordell equation $y^2=x^3+k$ [closed]
Have the Mordell equation $y^2=x^3+k$ solved for all integer $k$ or not?
Please Could you tell me about a good review papers about such equation.
- 17
3
votes
0
answers
88
views
cubic twists of Mordell curve and their rank
Let $a$ be a non-zero integer. Consider the elliptic curve $E_a/\mathbb{Q}$ given by the equation
$$
E_a: y^2 = x^3 + a.
$$
For a cube-free integer $D$, define the elliptic curves $E_{aD^2}/\mathbb{Q}$...
- 1,283
1
vote
1
answer
93
views
A correspondence between pairs of isogenies and representation numbers
This question is re-posted from MSE because it didn't seem to get any traction/responses there.
This is a question from this paper about a correspondence between representation numbers of quadratic ...
- 185
2
votes
1
answer
151
views
Flexes and projective equivalence of smooth cubics
I am trying to study Kock and Vainsencher's book "An invitation to Quantum Cohomology", working my way through the exercises. One of them ($0$th chapter) asks two prove that two elliptic ...
25
votes
3
answers
3k
views
Background for the Elkies-Klagsbrun curve of rank 29
Elkies and Klagsbrun have recently announced an elliptic curve over Q of rank (at least) 29, improving on the previous record from 2006!
https://web.math.pmf.unizg.hr/~duje/tors/z1.html
It has trivial ...
- 1,139
5
votes
1
answer
340
views
Equations for dual cubic curves
Suppose I have a cubic curve $C$ (over $\mathbb C$) in Weierstrass form $$y^2=x^3+ax+b.$$
I would like to find the degree $6$ equation for protectively dual curve $C^*$. Do you know any place where ...
- 14.3k
0
votes
0
answers
66
views
Parametrization of elliptic curve with differential equation $(x,y)=(f(x),f'(x))$ involving Lambert $W$ function
For non-zero complex $A$, define the curve over the complex numbers
$C: x^2 y^2-A x-y=0$. $C$ is an elliptic curve.
$C$ has the differential equation parametrization $(x,y)=(f(x),f'(x))$
where
$$ f(x)=...
- 25.4k
5
votes
0
answers
126
views
Using Lang–Trotter to get bounds on averages of Fourier coefficients
Let $E$ be an elliptic curve over $\mathbf{Q}$ and let $(a_n)$ be the sequence of Fourier coefficients for the weight two newform attached to $E$. The coefficients $a_p$ are the Frobenius traces given ...
- 265
10
votes
2
answers
286
views
Finding a model for $X_G$ with $G\subseteq \mathrm{GL}_2(\mathbb{Z}/N\mathbb{Z})$
I'm studying modular curves as part of my doctorate work and would like to understand how one gets from a subgroup $G$ of $\operatorname{GL}_2(\mathbb{Z}/N\mathbb{Z})$ to an equation for $X_G$. By $...
- 195
4
votes
0
answers
100
views
Structure of points of elliptic curves in field with restricted ramification
Let $k$ be a finite field of characteristic $p$ and let $C$ be a curve over $k$. Let $E$ be a non-constant elliptic curve over $k(C)$. Taking the Néron model of $E$ and removing the singular fibers ...
- 177
7
votes
1
answer
233
views
Proven results for the refined Birch Swinnerton-Dyer conjecture over rationals when rank at most $1$
For an elliptic curve, $E$, defined over $\mathbb{Q}$ and with the Mordell-Weil group, $E(\mathbb{Q})$, having rank, $r$, the Birch Swinnerton-Dyer (BSD) conjecture states that
$$
c_{E} = \lim_{s \...
- 73
3
votes
0
answers
139
views
Do the denominators of A006571(n)/A366450(n) have a Dirichlet generating function? Because they partially match A071974(n) and A056622(n)?
Consider the expansion: $$A006571(n) = q \prod _{k=1}^{\infty } \left(1-q^k\right)^2 \left(1-q^{11 k}\right)^2 \label{1}\tag{1}$$
A006571
and the triple sum:
$$A366450(n)=\sum _{k=1}^n \left(\sum _{y=...
- 1,183
2
votes
1
answer
204
views
What does the Serre functor of equivariant category of fractional CY category look like?
I am considering the following set up. Let $\mathcal{A}$ be a fractional Calabi-Yau category and denote by $S$ the Serre functor and $S^m=[n]$. Now I consider a finite group action $G$ on $\mathcal{A}$...
- 1,982