∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] [inst_1 : CategoryTheory.Abelian C]
  (S : CategoryTheory.ShortComplex C),
  S.Exact ↔
    { X₁ := CategoryTheory.Abelian.image S.f, X₂ := S.X₂, X₃ := S.X₃, f := CategoryTheory.Abelian.image.ι S.f, g := S.g,
        zero := ⋯ }.Exact