∀ {K : Type u_1} [inst : Field K] {θ : NumberField.RingOfIntegers K} {p : ℕ} [inst_1 : Fact (Nat.Prime p)]
  [inst_2 : NumberField K] (hp : ¬p ∣ RingOfIntegers.exponent θ) {Q : Polynomial (ZMod p)}
  (hQ : Q ∈ RingOfIntegers.monicFactorsMod θ p),
  (Ideal.span {↑p}).inertiaDeg ↑((NumberField.Ideal.primesOverSpanEquivMonicFactorsMod hp).symm ⟨Q, hQ⟩) = Q.natDegree