English
The diagram composed with XOpIso and d_op commutes with the opposite differential; i.e., the two ways of forming the opposite commute.
Русский
Диаграмма с XOpIso и d_op коммутирует с противоположной дифференциалом.
LaTeX
$$XOpIso_hom_d_op : (XOpIso K i).hom ≫ (d K j i).op = d K.op i j ≫ (XOpIso K j).hom$$
Lean4
/-- The canonical isomorphism `X K.op i ≅ Opposite.op (X K i)`. -/
noncomputable def XOpIso (i : Option ι) : X K.op i ≅ Opposite.op (X K i) :=
match i with
| some _ => Iso.refl _
| none => IsZero.iso (isZero_X _ rfl) (isZero_X K rfl).op