Definition squash_unsquash := K.squash_unsquash.Definition unsquash_squash := K.unsquash_squash.Definition knot_age1 := K.knot_age1.Definition knot_level := K.knot_level.

Lemma pred_ext : forall (p1 p2: pred (knot * other)), (forall x, p1 x = p2 x) -> p1 = p2.