{A : Type u_1} →
  {B : Type u_2} →
    [inst : CommRing A] →
      [inst_1 : CommRing B] →
        [inst_2 : Algebra A B] →
          (G : Type u_3) →
            [inst_3 : Group G] →
              [Finite G] →
                [inst_5 : MulSemiringAction G B] →
                  [SMulCommClass G A B] →
                    (P : Ideal A) →
                      (Q : Ideal B) →
                        [Q.IsPrime] →
                          [inst_8 : Q.LiesOver P] →
                            [Algebra.IsInvariant A B G] →
                              ↥(MulAction.stabilizer G Q) ⧸ (Ideal.inertia G Q).subgroupOf (MulAction.stabilizer G Q) ≃*
                                (B ⧸ Q) ≃ₐ[A ⧸ P] B ⧸ Q