Module Type KNOT__COVARIANT_HERED_PROP_OTH.
Declare Module KI : KNOT_INPUT__COVARIANT_HERED_PROP_OTH.
Parameter knot : Type.
Parameter ageable_knot : ageable knot.
Existing Instance ageable_knot.
Definition ag_knot_other := ag_prod knot other ageable_knot.
Existing Instance ag_knot_other.
Parameter squash : (nat * F (pred (knot * other))) -> knot.
Parameter unsquash : knot -> (nat * F (pred (knot * other))).
Parameter approx : nat -> pred (knot * other) -> pred (knot * other).

(* Definitions of the "ageable" operations *)
Axiom knot_level : forall (k:knot),
level k = fst (unsquash k).