∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Preadditive C]
  {S : CategoryTheory.ShortComplex C} (h : S.Splitting),
  (CategoryTheory.CategoryStruct.comp S.op.f h.s.op).unop = (CategoryTheory.CategoryStruct.id S.op.X₁).unop