∀ (R S T : Type u_1) [inst : CommRing R] [inst_1 : CommRing S] [inst_2 : CommRing T] [inst_3 : Algebra R S]
  [inst_4 : Algebra R T],
  CategoryTheory.Limits.HasPullback (AlgebraicGeometry.Scheme.Spec.map (CommRingCat.ofHom (algebraMap R S)).op)
    (AlgebraicGeometry.Scheme.Spec.map (CommRingCat.ofHom (algebraMap R T)).op)