∀ {R : Type u} [inst : CommRing R] {A : Type u_1} {B : Type u_2} [inst_1 : CommRing A] [inst_2 : CommRing B]
  [inst_3 : Algebra R A] [inst_4 : Algebra R B] [inst_5 : Algebra A B] [IsScalarTower R A B],
  IsScalarTower R (A ⧸ RingHom.ker (algebraMap A B) ^ 2) B