∀ (R S T : Type u) [inst : CommRing R] [inst_1 : CommRing S] [inst_2 : CommRing T] [inst_3 : Algebra R S]
  [inst_4 : Algebra R T],
  CategoryTheory.CategoryStruct.comp (AlgebraicGeometry.pullbackSpecIso R S T).hom
      (AlgebraicGeometry.Spec.map (CommRingCat.ofHom (algebraMap S (TensorProduct R S T)))) =
    CategoryTheory.Limits.pullback.fst (AlgebraicGeometry.Spec.map (CommRingCat.ofHom (algebraMap R S)))
      (AlgebraicGeometry.Spec.map (CommRingCat.ofHom (algebraMap R T)))