∀ {R : Type u_1} [inst : CommRing R] {A : Type u_2} [inst_1 : CommRing A] [inst_2 : Algebra R A],
  IsIntegrallyClosedIn R A =
    (Function.Injective ⇑(algebraMap R A) ∧ ∀ {x : A}, IsIntegral R x → ∃ y, (algebraMap R A) y = x)