Definition squash_unsquash := K.squash_unsquash.Definition unsquash_squash := K.unsquash_squash.Definition knot_age1 := K.knot_age1.Definition knot_level := K.knot_level.Definition knot_rel (k1 k2:knot) :=
    let (n,f) := unsquash k1 in
    let (n',f') := unsquash k2 in
    n = n' /\ KI.Rel assert f f'.

Lemma approx_approx2 : forall m n, approx n = approx (m+n) oo approx n.