Stickelberger ideals and Fitting ideals of class groups for abelian number fields

In this paper, we determine completely the initial Fitting ideal of the minus part of the ideal class group of an abelian number field over Q up to the 2-component. This answers an open question of Mazur and Wiles (Invent Math 76:179-330, 1984) up to the 2-component, and proves Conjecture 0.1 in Kurihara (J Reine Angew Math 561:39-86, 2003). We also study Brumer's conjecture and prove a stronger version for a CM-field, assuming certain conditions, in particular on the Galois group.