∀ {X Y : AlgebraicGeometry.Scheme} (f : X ⟶ Y) [AlgebraicGeometry.IsSchemeTheoreticallyDominant f]
  [AlgebraicGeometry.QuasiCompact f] (U : Y.Opens),
  Function.Injective ⇑(CategoryTheory.ConcreteCategory.hom (AlgebraicGeometry.Scheme.Hom.app f U))