Kida's formula and congruences

  • Robert Pollack

  • Tom Weston


We consider a generalization of a result of Kida in classical Iwasawa theory which relates Iwasawa invariants of pp-extensions of number fields. In this paper, we consider Selmer groups of a general class of Galois representations which includes the case of pp-ordinary Hilbert modular forms and pp-supersingular modular forms.