• Title/Summary/Keyword: congruence of Fourier coefficients

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DETERMINATION OF THE FRICKE FAMILIES

  • Eum, Ick Sun;Shin, Dong Hwa
    • Journal of the Korean Mathematical Society
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    • v.53 no.6
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    • pp.1445-1457
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    • 2016
  • For a positive integer N divisible by 4, let ${\mathcal{O}}^1_N({\mathbb{Q}})$ be the ring of weakly holomorphic modular functions for the congruence subgroup ${\Gamma}^1(N)$ with rational Fourier coefficients. We present explicit generators of the ring ${\mathcal{O}}^1_N({\mathbb{Q}})$ over ${\mathbb{Q}}$ in terms of both Fricke functions and Siegel functions, from which we are able to classify all Fricke families of such level N.

EIGENVALUES AND CONGRUENCES FOR THE WEIGHT 3 PARAMODULAR NONLIFTS OF LEVELS 61, 73, AND 79

  • Cris Poor;Jerry Shurman;David S. Yuen
    • Journal of the Korean Mathematical Society
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    • v.61 no.5
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    • pp.997-1033
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    • 2024
  • We use Borcherds products to give a new construction of the weight 3 paramodular nonlift eigenform fN for levels N = 61, 73, 79. We classify the congruences of fN to Gritsenko lifts. We provide techniques that compute eigenvalues to support future modularity applications. Our method does not compute Hecke eigenvalues from Fourier coefficients but instead uses elliptic modular forms, specifically the restrictions of Gritsenko lifts and their images under the slash operator to modular curves.