A Jesús Muñoz Díaz por su cumpleaños Contents 1. Introduction. 1 2. Elliptic sheaves and Hecke correspondences. Euler products 3 2.1. Elliptic sheaves 3 2.2. ∞-Level structures 5 2.3. Hecke correspondences 6 2.4. Euler products 8 3. Isogenies and Hecke correspondences 9 3.1. Isogenies for elliptic sheaves 9 3.2. Trivial correspondences 11 4. Ideal class group anhilators for the cyclotomic funct...