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 pred_ext : forall (p1 p2: assert), (forall x, proj1_sig p1 x = proj1_sig p2 x) -> p1 = p2.