∀ {X Y : AlgebraicGeometry.Scheme} (U : (X ⨿ Y).Opens),
  (AlgebraicGeometry.Scheme.Hom.opensFunctor CategoryTheory.Limits.coprod.inl).obj
        ((TopologicalSpace.Opens.map CategoryTheory.Limits.coprod.inl.base).obj U) ⊓
      (AlgebraicGeometry.Scheme.Hom.opensFunctor CategoryTheory.Limits.coprod.inr).obj
        ((TopologicalSpace.Opens.map CategoryTheory.Limits.coprod.inr.base).obj U) =
    ⊥