∀ {R : Type u_3} {P : Type u_1} {S : Type u_2} [inst : CommRing R] [inst_1 : CommRing P] [inst_2 : CommRing S]
  [inst_3 : Algebra R P] [inst_4 : Algebra P S] [inst_5 : Algebra R S] [inst_6 : IsScalarTower R P S]
  (hf' : RingHom.ker (algebraMap P S) ^ 2 = ⊥) (g : { g // (IsScalarTower.toAlgHom R P S).comp g = AlgHom.id R S }),
  retractionOfSectionOfKerSqZero (↑g) hf' ⋯ ∘ₗ KaehlerDifferential.kerToTensor R P S = LinearMap.id