∀ {ι : Type u_3} {V : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} V] {c : ComplexShape ι}
  [inst_1 : CategoryTheory.Limits.HasZeroMorphisms V] (X : HomologicalComplex V c) (x x_1 x_2 : ι),
  CategoryTheory.CategoryStruct.comp (X.d x_1 x).op (X.d x_2 x_1).op = 0