English

Counterexamples to the local-global divisibility over elliptic curves

Number Theory 2017-05-05 v1

Abstract

Let p5p \geq 5 be a prime number. We find all the possible subgroups GG of GL2(Z/pZ){\rm GL}_2 ( \mathbb{Z} / p \mathbb{Z} ) such that there exists a number field kk and an elliptic curve E{\mathcal{E}} defined over kk such that the Gal(k(E[p])/k){\rm Gal} ( k ( {\mathcal{E}}[p] ) / k )-module E[p]{\mathcal{E}}[p] is isomorphic to the GG-module (Z/pZ)2( \mathbb{Z} / p \mathbb{Z} )^2 and there exists nNn \in \mathbb{N} such that the local-global divisibility by pnp^n does not hold over E(k){\mathcal{E}} ( k ).

Keywords

Cite

@article{arxiv.1705.01880,
  title  = {Counterexamples to the local-global divisibility over elliptic curves},
  author = {Gabriele Ranieri},
  journal= {arXiv preprint arXiv:1705.01880},
  year   = {2017}
}

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20 pages