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GL2 action on torsion sections of elliptic curves

I am reading Kato's $p$-adic Hodge theory paper and I am confused about a rather embarrassing and admittedly very minor thing, but it is nevertheless important. In Section 1.6 of Kato, it is claimed ...
Hodge-Tate's user avatar
1 vote
1 answer
61 views

Meaning of this Eisenstein series notation from Gross–Zagier paper [duplicate]

In equation (2.14) of their paper [1], Gross–Zagier define the following Eisenstein series \begin{align} E_N(z, s) = \sum_{\gamma \in \bigg(\begin{matrix} \ast & \ast \\ 0 & \ast \end{matrix}\...
Joseph Harrison's user avatar
1 vote
1 answer
238 views

Isomorphism of lattices/complex tori

This is essentially a reference request (apologies if it is a duplicate): it is known that every lattice $\Lambda$ in $\mathbb{C}$ is isomorphic to one of the form $\mathbb{Z} \oplus \mathbb{Z}[\tau]$ ...
user0134's user avatar
  • 404
0 votes
0 answers
128 views

why is $\Gamma(1)\setminus H$ a 2-sphere with one point missing?

I am reading Silverman's book about elliptic curves. $\Gamma(1):=SL_{2}(\mathbb{Z})/\{\pm 1\}$ is the modular group, and $H$ is the upper half plane. The author says that the geometric description ...
MathEric's user avatar
  • 1,957
2 votes
1 answer
78 views

To prove that the Elliptic modular function is invariant under the modular transformation

I am not being able to understand that the Elliptic modular function $J(\tau)=\frac{g_2(w_1,w_2)^3}{g_2(w_1,w_2)^3-27g_3(w_1,w_2)^2}$ is invariant under the modular transformation $\tau\mapsto \frac{a\...
Partha's user avatar
  • 1,449