Module KO:=KO'.
Definition knot: Type := KO.K0.knot.
Definition ageable_knot : ageable knot := KO.K0.ageable_knot.
Existing Instance 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 approx_spec : forall n p ko,
proj1_sig (bij_f _ _ KO.pkp (approx n p)) ko =
if (le_gt_dec n (level (fst ko)))
then KI.T_bot
else proj1_sig (bij_f _ _ KO.pkp p) ko.