∀ {ι : Type u_4} {ι' : Type u_3} {c : ComplexShape ι} {c' : ComplexShape ι'} {C : Type u_2}
  [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Limits.HasZeroMorphisms C]
  (K : HomologicalComplex C c') (e : c.Embedding c') [inst_2 : e.IsTruncGE] [inst_3 : ∀ (i' : ι'), K.HasHomology i']
  (j k : ι) {j' : ι'} (hj' : e.f j = j') (hj : e.BoundaryGE j) (hjk : c.Rel j k),
  CategoryTheory.CategoryStruct.comp
      (CategoryTheory.Iso.refl (CategoryTheory.Limits.KernelFork.ofι (K.homologyι j') ⋯).pt).hom
      (CategoryTheory.Limits.Fork.ι
        ((CategoryTheory.Limits.Cones.postcompose
              (CategoryTheory.Limits.parallelPair.ext (K.truncGE'XIsoOpcycles e hj' hj) (K.truncGE'XIso e ⋯ ⋯) ⋯
                  ⋯).hom).obj
          (CategoryTheory.Limits.KernelFork.ofι
            (CategoryTheory.CategoryStruct.comp (K.homologyι j') (K.truncGE'XIsoOpcycles e hj' hj).inv) ⋯))) =
    CategoryTheory.Limits.Fork.ι (CategoryTheory.Limits.KernelFork.ofι (K.homologyι j') ⋯)