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 -extensions of number fields. In this paper, we consider Selmer groups of a general class of Galois representations which includes the case of -ordinary Hilbert modular forms and -supersingular modular forms.