摘要

Let phi : E -> E' be an isogeny of prime degree l between elliptic curves defined over a number field. We describe how to perform phi-descents on the nontrivial elements in the Shafarevich-Tate group of E' which are killed by the dual isogeny 'phi'. This makes computation of l-Selmer groups of elliptic curves admitting an l-isogeny over Q feasible for l = 5,7 in cases where a phi-descent on E is insufficient and a full l-descent would be infeasible. As an application we complete the verification of the full Birch and Swinnerton-Dyer conjectural formula for all elliptic curves over Q of rank zero or one and conductor less than 5000.

  • 出版日期2012-12-15