∀ (R A B : Type u) [inst : CommRing R] [inst_1 : CommRing A] [inst_2 : CommRing B] [inst_3 : Algebra R A]
  [inst_4 : Algebra R B],
  CategoryTheory.IsPushout (CommRingCat.ofHom (algebraMap R A)) (CommRingCat.ofHom (algebraMap R B))
    (CommRingCat.ofHom Algebra.TensorProduct.includeLeftRingHom)
    (CommRingCat.ofHom Algebra.TensorProduct.includeRight.toRingHom)