Module KI:=KI'.Module KO:=KO'.Definition knot: Type := KO.K0.knot.Definition ageable_knot : ageable knot := KO.K0.ageable_knot.Definition predicate: Type := KO.predicate.Definition squash : (nat * KI.F predicate) -> knot :=
    fun k => KO.K0.squash
     (fst k, fmap KI.F (bij_f _ _ KO.pkp) (bij_g _ _ KO.pkp) (snd k)).Definition unsquash : knot -> (nat * KI.F predicate) :=
    fun k => let (n, f) := KO.K0.unsquash k in
      (n, fmap KI.F (bij_g _ _ KO.pkp) (bij_f _ _ KO.pkp) f).Definition approx : nat -> predicate -> predicate :=
    fun n => (bij_g _ _ KO.pkp) oo KO.K0.approx n oo (bij_f _ _ KO.pkp).

Lemma knot_age1 : forall k:knot, age1 k = match unsquash k with | (O,_) => None | (S n,x) => Some (squash (n,x)) end.