# Questions tagged [modular-forms]

Questions about modular forms and related areas

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### Can you identify this irrational number?

There is a certain number, say $v$. I can prove it is irrational. That would be more interesting if it is expressible in terms of known values ... zeta functions, Catalan's number, L-functions, etc. ...
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### Why can Hecke operators be regarded as finite flat cohomological correspondence?

I'm reading the paper "Higher Hida and Coleman theories on the modular curve" by G.Boxer and V.Pilloni. But I'm confused with the different views towards Hecke operators. $N$ is an integer ...
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### Experiments with Voronoï summation

In order to test my understanding of the Voronoï summation formula, I tried to apply it to a simple estimation of partial sums of Fourier coefficients of cusp forms. The result I obtained cannot ...
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### Finding a new level-$7$ pi formula using the relation $j_{7A}(\tau) = \left(\sqrt{j_{7B}(\tau)}+\frac{7}{\sqrt{j_{7B}(\tau)}}\right)^2$

(Note: This third method continues from this post.) There are level-$7$ pi formulas based on the McKay-Thompson series $T_{7A}$ and Cooper's $s_7$ sequence in this paper. This third method, among ...
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### Ramanujan's pi formulas with a twist (nine years later)

(Note: The second method described here continues this post.) About nine years ago, I made an MO post "Ramanujan's pi formulas with a twist". An answer was informative, but not completely ...
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### Context for Wiles defect criterion and patching

This is not a homework or a project question, just me trying to get acquainted to the subject: I am an MSc student who recently came across the Wiles defect numerical criterion (see, for example, ...
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### Fourier series of Eisenstein series — elegant and very good approximation

I played around with the Fourier series of the Eisenstein series resp. divisor sums and did some calculations, see below. Although the deduction is not rigorous / wrong (as the power series for the ...
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### Eta product of squared tau function

The Ramanujan tau function is the coefficient of the 24th power of the Dedekind eta function. $$\eta(x)^{24}= x\prod_{m=1}^\infty (1 - x^m)^{24} =\sum_{n=1}^\infty \tau(n)\,x^n ,$$ I want to know ...
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### Evaluation of mock modular forms at elliptic points

The holomorphic function $$F(\tau)=-\frac{1}{\vartheta_4(\tau)}\sum_{n\in\mathbb Z}\frac{(-1)^nq^{\frac{n^2}{2}-\frac 18}}{1-q^{n-\frac12}}=2q^{\frac38}(1+3q^{\frac12}+7q+14q^{\frac32}+\dots),$$ is a ...
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### Motivation for $p$-stabilization in Hida theory

I'm currently reading Hida's paper "A $p$-adic measure attached to the zeta functions associated with two elliptic modular forms". The setup is the following: let $f$ be a weight $2$ newform ...
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### Can Taniyama-Shimura conjecture be generalized to curves of higher genus (within Langlands framework)?

The Shimura-Taniyama-Weil conjecture asserts that if E is an elliptic curve over Q, then there is an integer N ≥ 1 and a weight-two cusp form f of level N, normalized so that a1(f) = 1, such that ap(E)...
### Compute the principal polarization on $J_0(N)$ in terms of modular symbols
If we consider the modular curve $X = X_0(N)$ as a curve over $\mathbb C$ then one can describe the jacobian $J(X)$ as $H^0(X,\Omega^1_X)^\vee/H_1(X,\mathbb Z)$ as one can do for any curve $X$. ...