Module Input.
Definition F: functor := CovariantFunctor_MixVariantFunctor KI.F.
Definition other := unit.
Definition Rel A := @eq (F A).

Lemma Rel_fmap : forall A B (f:A -> B) (s:B -> A) x y,
Rel A x y ->
Rel B (fmap F f s x) (fmap F f s y).