∀ {A : Type u_1} {K : Type u_2} [inst : CommRing A] [inst_1 : Field K] [inst_2 : Algebra A K]
  [inst_3 : IsFractionRing A K] [inst_4 : IsDedekindDomain A] (n : ℕ) (a : FractionalIdeal (nonZeroDivisors A) K),
  CommGroupWithZero.zpow (Int.negSucc n) a = (CommGroupWithZero.zpow (↑n.succ) a)⁻¹